5. GNAT Utility Programs

This chapter describes a number of utility programs:

It also describes how several of these tools can be used in conjunction with project files: Using Project Files with GNAT Tools

Other GNAT utilities are described elsewhere in this manual:

5.1. The File Cleanup Utility gnatclean

gnatclean is a tool that allows the deletion of files produced by the compiler, binder and linker, including ALI files, object files, tree files, expanded source files, library files, interface copy source files, binder generated files and executable files.

5.1.1. Running gnatclean

The gnatclean command has the form:

$ gnatclean switches names

where names is a list of source file names. Suffixes .ads and adb may be omitted. If a project file is specified using switch -P, then names may be completely omitted.

In normal mode, gnatclean delete the files produced by the compiler and, if switch -c is not specified, by the binder and the linker. In informative-only mode, specified by switch -n, the list of files that would have been deleted in normal mode is listed, but no file is actually deleted.

5.1.2. Switches for gnatclean

gnatclean recognizes the following switches:

--version
Display Copyright and version, then exit disregarding all other options.
--help
If --version was not used, display usage, then exit disregarding all other options.
--subdirs=subdir
Actual object directory of each project file is the subdirectory subdir of the object directory specified or defaulted in the project file.
--unchecked-shared-lib-imports
By default, shared library projects are not allowed to import static library projects. When this switch is used on the command line, this restriction is relaxed.
-c
Only attempt to delete the files produced by the compiler, not those produced by the binder or the linker. The files that are not to be deleted are library files, interface copy files, binder generated files and executable files.
-D dir
Indicate that ALI and object files should normally be found in directory dir.
-F
When using project files, if some errors or warnings are detected during parsing and verbose mode is not in effect (no use of switch -v), then error lines start with the full path name of the project file, rather than its simple file name.
-h
Output a message explaining the usage of gnatclean.
-n
Informative-only mode. Do not delete any files. Output the list of the files that would have been deleted if this switch was not specified.
-Pproject
Use project file project. Only one such switch can be used. When cleaning a project file, the files produced by the compilation of the immediate sources or inherited sources of the project files are to be deleted. This is not depending on the presence or not of executable names on the command line.
-q
Quiet output. If there are no errors, do not output anything, except in verbose mode (switch -v) or in informative-only mode (switch -n).
-r
When a project file is specified (using switch -P), clean all imported and extended project files, recursively. If this switch is not specified, only the files related to the main project file are to be deleted. This switch has no effect if no project file is specified.
-v
Verbose mode.
-vPx
Indicates the verbosity of the parsing of GNAT project files. Switches Related to Project Files.
-Xname=value
Indicates that external variable name has the value value. The Project Manager will use this value for occurrences of external(name) when parsing the project file. See Switches Related to Project Files.
-aOdir
When searching for ALI and object files, look in directory dir.
-Idir
Equivalent to -aOdir.
-I-
Do not look for ALI or object files in the directory where gnatclean was invoked.

5.2. The GNAT Library Browser gnatls

gnatls is a tool that outputs information about compiled units. It gives the relationship between objects, unit names and source files. It can also be used to check the source dependencies of a unit as well as various characteristics.

5.2.1. Running gnatls

The gnatls command has the form

$ gnatls switches object_or_ali_file

The main argument is the list of object or ali files (see The Ada Library Information Files) for which information is requested.

In normal mode, without additional option, gnatls produces a four-column listing. Each line represents information for a specific object. The first column gives the full path of the object, the second column gives the name of the principal unit in this object, the third column gives the status of the source and the fourth column gives the full path of the source representing this unit. Here is a simple example of use:

$ gnatls *.o
./demo1.o            demo1            DIF demo1.adb
./demo2.o            demo2             OK demo2.adb
./hello.o            h1                OK hello.adb
./instr-child.o      instr.child      MOK instr-child.adb
./instr.o            instr             OK instr.adb
./tef.o              tef              DIF tef.adb
./text_io_example.o  text_io_example   OK text_io_example.adb
./tgef.o             tgef             DIF tgef.adb

The first line can be interpreted as follows: the main unit which is contained in object file demo1.o is demo1, whose main source is in demo1.adb. Furthermore, the version of the source used for the compilation of demo1 has been modified (DIF). Each source file has a status qualifier which can be:

OK (unchanged)
The version of the source file used for the compilation of the specified unit corresponds exactly to the actual source file.
MOK (slightly modified)
The version of the source file used for the compilation of the specified unit differs from the actual source file but not enough to require recompilation. If you use gnatmake with the option -m (minimal recompilation), a file marked MOK will not be recompiled.
DIF (modified)
No version of the source found on the path corresponds to the source used to build this object.
??? (file not found)
No source file was found for this unit.
HID (hidden, unchanged version not first on PATH)
The version of the source that corresponds exactly to the source used for compilation has been found on the path but it is hidden by another version of the same source that has been modified.

5.2.2. Switches for gnatls

gnatls recognizes the following switches:

--version
Display Copyright and version, then exit disregarding all other options.
--help
If --version was not used, display usage, then exit disregarding all other options.
-a
Consider all units, including those of the predefined Ada library. Especially useful with -d.
-d
List sources from which specified units depend on.
-h
Output the list of options.
-o
Only output information about object files.
-s
Only output information about source files.
-u
Only output information about compilation units.
-files=file
Take as arguments the files listed in text file file. Text file file may contain empty lines that are ignored. Each nonempty line should contain the name of an existing file. Several such switches may be specified simultaneously.
-aOdir, -aIdir, -Idir, -I-, -nostdinc
Source path manipulation. Same meaning as the equivalent gnatmake flags (Switches for gnatmake).
-aPdir
Add dir at the beginning of the project search dir.
--RTS=rts-path
Specifies the default location of the runtime library. Same meaning as the equivalent gnatmake flag (Switches for gnatmake).
-v

Verbose mode. Output the complete source, object and project paths. Do not use the default column layout but instead use long format giving as much as information possible on each requested units, including special characteristics such as:

  • Preelaborable: The unit is preelaborable in the Ada sense.
  • No_Elab_Code: No elaboration code has been produced by the compiler for this unit.
  • Pure: The unit is pure in the Ada sense.
  • Elaborate_Body: The unit contains a pragma Elaborate_Body.
  • Remote_Types: The unit contains a pragma Remote_Types.
  • Shared_Passive: The unit contains a pragma Shared_Passive.
  • Predefined: This unit is part of the predefined environment and cannot be modified by the user.
  • Remote_Call_Interface: The unit contains a pragma Remote_Call_Interface.

5.2.3. Example of gnatls Usage

Example of using the verbose switch. Note how the source and object paths are affected by the -I switch.

$ gnatls -v -I.. demo1.o

GNATLS 5.03w (20041123-34)
Copyright 1997-2004 Free Software Foundation, Inc.

Source Search Path:
   <Current_Directory>
   ../
   /home/comar/local/adainclude/

Object Search Path:
   <Current_Directory>
   ../
   /home/comar/local/lib/gcc-lib/x86-linux/3.4.3/adalib/

Project Search Path:
   <Current_Directory>
   /home/comar/local/lib/gnat/

./demo1.o
   Unit =>
     Name   => demo1
     Kind   => subprogram body
     Flags  => No_Elab_Code
     Source => demo1.adb    modified

The following is an example of use of the dependency list. Note the use of the -s switch which gives a straight list of source files. This can be useful for building specialized scripts.

$ gnatls -d demo2.o
./demo2.o   demo2        OK demo2.adb
                         OK gen_list.ads
                         OK gen_list.adb
                         OK instr.ads
                         OK instr-child.ads

$ gnatls -d -s -a demo1.o
demo1.adb
/home/comar/local/adainclude/ada.ads
/home/comar/local/adainclude/a-finali.ads
/home/comar/local/adainclude/a-filico.ads
/home/comar/local/adainclude/a-stream.ads
/home/comar/local/adainclude/a-tags.ads
gen_list.ads
gen_list.adb
/home/comar/local/adainclude/gnat.ads
/home/comar/local/adainclude/g-io.ads
instr.ads
/home/comar/local/adainclude/system.ads
/home/comar/local/adainclude/s-exctab.ads
/home/comar/local/adainclude/s-finimp.ads
/home/comar/local/adainclude/s-finroo.ads
/home/comar/local/adainclude/s-secsta.ads
/home/comar/local/adainclude/s-stalib.ads
/home/comar/local/adainclude/s-stoele.ads
/home/comar/local/adainclude/s-stratt.ads
/home/comar/local/adainclude/s-tasoli.ads
/home/comar/local/adainclude/s-unstyp.ads
/home/comar/local/adainclude/unchconv.ads

5.3. The Cross-Referencing Tools gnatxref and gnatfind

The compiler generates cross-referencing information (unless you set the -gnatx switch), which are saved in the .ali files. This information indicates where in the source each entity is declared and referenced. Note that entities in package Standard are not included, but entities in all other predefined units are included in the output.

Before using any of these two tools, you need to compile successfully your application, so that GNAT gets a chance to generate the cross-referencing information.

The two tools gnatxref and gnatfind take advantage of this information to provide the user with the capability to easily locate the declaration and references to an entity. These tools are quite similar, the difference being that gnatfind is intended for locating definitions and/or references to a specified entity or entities, whereas gnatxref is oriented to generating a full report of all cross-references.

To use these tools, you must not compile your application using the -gnatx switch on the gnatmake command line (see Building with gnatmake). Otherwise, cross-referencing information will not be generated.

5.3.1. gnatxref Switches

The command invocation for gnatxref is:

$ gnatxref [ switches ] sourcefile1 [ sourcefile2 ... ]

where

sourcefile1 [, sourcefile2 ...]

identify the source files for which a report is to be generated. The withed units will be processed too. You must provide at least one file.

These file names are considered to be regular expressions, so for instance specifying source*.adb is the same as giving every file in the current directory whose name starts with source and whose extension is adb.

You shouldn’t specify any directory name, just base names. gnatxref and gnatfind will be able to locate these files by themselves using the source path. If you specify directories, no result is produced.

The following switches are available for gnatxref:

--version
Display Copyright and version, then exit disregarding all other options.
--help
If --version was not used, display usage, then exit disregarding all other options.
-a
If this switch is present, gnatfind and gnatxref will parse the read-only files found in the library search path. Otherwise, these files will be ignored. This option can be used to protect Gnat sources or your own libraries from being parsed, thus making gnatfind and gnatxref much faster, and their output much smaller. Read-only here refers to access or permissions status in the file system for the current user.
-aIDIR
When looking for source files also look in directory DIR. The order in which source file search is undertaken is the same as for gnatmake.
aODIR
When -searching for library and object files, look in directory DIR. The order in which library files are searched is the same as for gnatmake.
-nostdinc
Do not look for sources in the system default directory.
-nostdlib
Do not look for library files in the system default directory.
--ext=extension
Specify an alternate ali file extension. The default is ali and other extensions (e.g. gli for C/C++ sources) may be specified via this switch. Note that if this switch overrides the default, which means that only the new extension will be considered.
--RTS=rts-path
Specifies the default location of the runtime library. Same meaning as the equivalent gnatmake flag (Switches for gnatmake).
-d
If this switch is set gnatxref will output the parent type reference for each matching derived types.
-f
If this switch is set, the output file names will be preceded by their directory (if the file was found in the search path). If this switch is not set, the directory will not be printed.
-g
If this switch is set, information is output only for library-level entities, ignoring local entities. The use of this switch may accelerate gnatfind and gnatxref.
-IDIR
Equivalent to -aODIR -aIDIR.
-pFILE

Specify a configuration file to use to list the source and object directories.

If a file is specified, then the content of the source directory and object directory lines are added as if they had been specified respectively by -aI and -aO.

See Configuration Files for gnatxref and gnatfind for the syntax of this configuration file.

-u
Output only unused symbols. This may be really useful if you give your main compilation unit on the command line, as gnatxref will then display every unused entity and ‘with’ed package.
-v
Instead of producing the default output, gnatxref will generate a tags file that can be used by vi. For examples how to use this feature, see Examples of gnatxref Usage. The tags file is output to the standard output, thus you will have to redirect it to a file.

All these switches may be in any order on the command line, and may even appear after the file names. They need not be separated by spaces, thus you can say gnatxref -ag instead of gnatxref -a -g.

5.3.2. gnatfind Switches

The command invocation for gnatfind is:

$ gnatfind [ switches ]  pattern[:sourcefile[:line[:column]]]
      [file1 file2 ...]

with the following iterpretation of the command arguments:

pattern

An entity will be output only if it matches the regular expression found in pattern, see Regular Expressions in gnatfind and gnatxref.

Omitting the pattern is equivalent to specifying *, which will match any entity. Note that if you do not provide a pattern, you have to provide both a sourcefile and a line.

Entity names are given in Latin-1, with uppercase/lowercase equivalence for matching purposes. At the current time there is no support for 8-bit codes other than Latin-1, or for wide characters in identifiers.

sourcefile
gnatfind will look for references, bodies or declarations of symbols referenced in sourcefile, at line line and column column. See Examples of gnatfind Usage for syntax examples.
line
A decimal integer identifying the line number containing the reference to the entity (or entities) to be located.
column
A decimal integer identifying the exact location on the line of the first character of the identifier for the entity reference. Columns are numbered from 1.
file1 file2 ...

The search will be restricted to these source files. If none are given, then the search will be conducted for every library file in the search path. These files must appear only after the pattern or sourcefile.

These file names are considered to be regular expressions, so for instance specifying source*.adb is the same as giving every file in the current directory whose name starts with source and whose extension is adb.

The location of the spec of the entity will always be displayed, even if it isn’t in one of file1, file2, ... The occurrences of the entity in the separate units of the ones given on the command line will also be displayed.

Note that if you specify at least one file in this part, gnatfind may sometimes not be able to find the body of the subprograms.

At least one of ‘sourcefile’ or ‘pattern’ has to be present on the command line.

The following switches are available:

--version
Display Copyright and version, then exit disregarding all other options.
--help
If --version was not used, display usage, then exit disregarding all other options.
-a
If this switch is present, gnatfind and gnatxref will parse the read-only files found in the library search path. Otherwise, these files will be ignored. This option can be used to protect Gnat sources or your own libraries from being parsed, thus making gnatfind and gnatxref much faster, and their output much smaller. Read-only here refers to access or permission status in the file system for the current user.
-aIDIR
When looking for source files also look in directory DIR. The order in which source file search is undertaken is the same as for gnatmake.
-aODIR
When searching for library and object files, look in directory DIR. The order in which library files are searched is the same as for gnatmake.
-nostdinc
Do not look for sources in the system default directory.
-nostdlib
Do not look for library files in the system default directory.
--ext=extension
Specify an alternate ali file extension. The default is ali and other extensions (e.g. gli for C/C++ sources when using -fdump-xref) may be specified via this switch. Note that if this switch overrides the default, which means that only the new extension will be considered.
--RTS=rts-path
Specifies the default location of the runtime library. Same meaning as the equivalent gnatmake flag (Switches for gnatmake).
-d
If this switch is set, then gnatfind will output the parent type reference for each matching derived types.
-e
By default, gnatfind accept the simple regular expression set for pattern. If this switch is set, then the pattern will be considered as full Unix-style regular expression.
-f
If this switch is set, the output file names will be preceded by their directory (if the file was found in the search path). If this switch is not set, the directory will not be printed.
-g
If this switch is set, information is output only for library-level entities, ignoring local entities. The use of this switch may accelerate gnatfind and gnatxref.
-IDIR
Equivalent to -aODIR -aIDIR.
-pFILE

Specify a configuration file to use to list the source and object directories.

If a file is specified, then the content of the source directory and object directory lines are added as if they had been specified respectively by -aI and -aO.

See Configuration Files for gnatxref and gnatfind for the syntax of this configuration file.

-r
By default, gnatfind will output only the information about the declaration, body or type completion of the entities. If this switch is set, the gnatfind will locate every reference to the entities in the files specified on the command line (or in every file in the search path if no file is given on the command line).
-s
If this switch is set, then gnatfind will output the content of the Ada source file lines were the entity was found.
-t
If this switch is set, then gnatfind will output the type hierarchy for the specified type. It act like -d option but recursively from parent type to parent type. When this switch is set it is not possible to specify more than one file.

All these switches may be in any order on the command line, and may even appear after the file names. They need not be separated by spaces, thus you can say gnatxref -ag instead of gnatxref -a -g.

As stated previously, gnatfind will search in every directory in the search path. You can force it to look only in the current directory if you specify * at the end of the command line.

5.3.3. Configuration Files for gnatxref and gnatfind

Configuration files are used by gnatxref and gnatfind to specify the list of source and object directories to consider. They can be specified via the -p switch.

The following lines can be included, in any order in the file:

  • src_dir=DIR
    [default: "./"]. Specifies a directory where to look for source files. Multiple src_dir lines can be specified and they will be searched in the order they are specified.
  • obj_dir=DIR
    [default: "./"]. Specifies a directory where to look for object and library files. Multiple obj_dir lines can be specified, and they will be searched in the order they are specified

Any other line will be silently ignored.

5.3.4. Regular Expressions in gnatfind and gnatxref

As specified in the section about gnatfind, the pattern can be a regular expression. Two kinds of regular expressions are recognized:

  • Globbing pattern

    These are the most common regular expression. They are the same as are generally used in a Unix shell command line, or in a DOS session.

    Here is a more formal grammar:

    regexp ::= term
    term   ::= elmt            -- matches elmt
    term   ::= elmt elmt       -- concatenation (elmt then elmt)
    term   ::= *               -- any string of 0 or more characters
    term   ::= ?               -- matches any character
    term   ::= [char {char}]   -- matches any character listed
    term   ::= [char - char]   -- matches any character in range
    
  • Full regular expression

    The second set of regular expressions is much more powerful. This is the type of regular expressions recognized by utilities such as grep.

    The following is the form of a regular expression, expressed in same BNF style as is found in the Ada Reference Manual:

    regexp ::= term {| term}   -- alternation (term or term ...)
    
    term ::= item {item}       -- concatenation (item then item)
    
    item ::= elmt              -- match elmt
    item ::= elmt *            -- zero or more elmt's
    item ::= elmt +            -- one or more elmt's
    item ::= elmt ?            -- matches elmt or nothing
    
    elmt ::= nschar            -- matches given character
    elmt ::= [nschar {nschar}]   -- matches any character listed
    elmt ::= [^ nschar {nschar}] -- matches any character not listed
    elmt ::= [char - char]     -- matches chars in given range
    elmt ::= \\ char            -- matches given character
    elmt ::= .                 -- matches any single character
    elmt ::= ( regexp )        -- parens used for grouping
    
    char ::= any character, including special characters
    nschar ::= any character except ()[].*+?^
    

    Here are a few examples:

    abcde|fghi

    will match any of the two strings abcde and fghi,

    abc*d

    will match any string like abd, abcd, abccd, abcccd, and so on,

    [a-z]+

    will match any string which has only lowercase characters in it (and at least one character.

5.3.5. Examples of gnatxref Usage

5.3.5.1. General Usage

For the following examples, we will consider the following units:

main.ads:
1: with Bar;
2: package Main is
3:     procedure Foo (B : in Integer);
4:     C : Integer;
5: private
6:     D : Integer;
7: end Main;

main.adb:
1: package body Main is
2:     procedure Foo (B : in Integer) is
3:     begin
4:        C := B;
5:        D := B;
6:        Bar.Print (B);
7:        Bar.Print (C);
8:     end Foo;
9: end Main;

bar.ads:
1: package Bar is
2:     procedure Print (B : Integer);
3: end bar;

The first thing to do is to recompile your application (for instance, in that case just by doing a gnatmake main, so that GNAT generates the cross-referencing information. You can then issue any of the following commands:

  • gnatxref main.adb gnatxref generates cross-reference information for main.adb and every unit ‘with’ed by main.adb.

    The output would be:

    B                                                      Type: Integer
      Decl: bar.ads           2:22
    B                                                      Type: Integer
      Decl: main.ads          3:20
      Body: main.adb          2:20
      Ref:  main.adb          4:13     5:13     6:19
    Bar                                                    Type: Unit
      Decl: bar.ads           1:9
      Ref:  main.adb          6:8      7:8
           main.ads           1:6
    C                                                      Type: Integer
      Decl: main.ads          4:5
      Modi: main.adb          4:8
      Ref:  main.adb          7:19
    D                                                      Type: Integer
      Decl: main.ads          6:5
      Modi: main.adb          5:8
    Foo                                                    Type: Unit
      Decl: main.ads          3:15
      Body: main.adb          2:15
    Main                                                    Type: Unit
      Decl: main.ads          2:9
      Body: main.adb          1:14
    Print                                                   Type: Unit
      Decl: bar.ads           2:15
      Ref:  main.adb          6:12     7:12
    

    This shows that the entity Main is declared in main.ads, line 2, column 9, its body is in main.adb, line 1, column 14 and is not referenced any where.

    The entity Print is declared in bar.ads, line 2, column 15 and it is referenced in main.adb, line 6 column 12 and line 7 column 12.

  • gnatxref package1.adb package2.ads gnatxref will generates cross-reference information for package1.adb, package2.ads and any other package withed by any of these.

5.3.5.2. Using gnatxref with vi

gnatxref can generate a tags file output, which can be used directly from vi. Note that the standard version of vi will not work properly with overloaded symbols. Consider using another free implementation of vi, such as vim.

$ gnatxref -v gnatfind.adb > tags

The following command will generate the tags file for gnatfind itself (if the sources are in the search path!):

$ gnatxref -v gnatfind.adb > tags

From vi, you can then use the command :tag entity (replacing entity by whatever you are looking for), and vi will display a new file with the corresponding declaration of entity.

5.3.6. Examples of gnatfind Usage

  • gnatfind -f xyz:main.adb Find declarations for all entities xyz referenced at least once in main.adb. The references are search in every library file in the search path.

    The directories will be printed as well (as the -f switch is set)

    The output will look like:

    directory/main.ads:106:14: xyz <= declaration
    directory/main.adb:24:10: xyz <= body
    directory/foo.ads:45:23: xyz <= declaration
    

    I.e., one of the entities xyz found in main.adb is declared at line 12 of main.ads (and its body is in main.adb), and another one is declared at line 45 of foo.ads

  • gnatfind -fs xyz:main.adb This is the same command as the previous one, but gnatfind will display the content of the Ada source file lines.

    The output will look like:

    directory/main.ads:106:14: xyz <= declaration
       procedure xyz;
    directory/main.adb:24:10: xyz <= body
       procedure xyz is
    directory/foo.ads:45:23: xyz <= declaration
       xyz : Integer;
    

    This can make it easier to find exactly the location your are looking for.

  • gnatfind -r "*x*":main.ads:123 foo.adb Find references to all entities containing an x that are referenced on line 123 of main.ads. The references will be searched only in main.ads and foo.adb.

  • gnatfind main.ads:123 Find declarations and bodies for all entities that are referenced on line 123 of main.ads.

    This is the same as gnatfind "*":main.adb:123`

  • gnatfind mydir/main.adb:123:45 Find the declaration for the entity referenced at column 45 in line 123 of file main.adb in directory mydir. Note that it is usual to omit the identifier name when the column is given, since the column position identifies a unique reference.

    The column has to be the beginning of the identifier, and should not point to any character in the middle of the identifier.

5.4. The Ada to HTML Converter gnathtml

gnathtml is a Perl script that allows Ada source files to be browsed using standard Web browsers. For installation information, see Installing gnathtml.

Ada reserved keywords are highlighted in a bold font and Ada comments in a blue font. Unless your program was compiled with the gcc -gnatx switch to suppress the generation of cross-referencing information, user defined variables and types will appear in a different color; you will be able to click on any identifier and go to its declaration.

5.4.1. Invoking gnathtml

The command line is as follows:

$ perl gnathtml.pl [ switches ] ada-files

You can specify as many Ada files as you want. gnathtml will generate an html file for every ada file, and a global file called index.htm. This file is an index of every identifier defined in the files.

The following switches are available:

83
Only the Ada 83 subset of keywords will be highlighted.
cc color
This option allows you to change the color used for comments. The default value is green. The color argument can be any name accepted by html.
d
If the Ada files depend on some other files (for instance through with clauses, the latter files will also be converted to html. Only the files in the user project will be converted to html, not the files in the run-time library itself.
D
This command is the same as -d above, but gnathtml will also look for files in the run-time library, and generate html files for them.
ext extension
This option allows you to change the extension of the generated HTML files. If you do not specify an extension, it will default to htm.
f
By default, gnathtml will generate html links only for global entities (‘with’ed units, global variables and types,...). If you specify -f on the command line, then links will be generated for local entities too.
l number
If this switch is provided and number is not 0, then gnathtml will number the html files every number line.
I dir
Specify a directory to search for library files (.ALI files) and source files. You can provide several -I switches on the command line, and the directories will be parsed in the order of the command line.
o dir
Specify the output directory for html files. By default, gnathtml will saved the generated html files in a subdirectory named html/.
p file

If you are using Emacs and the most recent Emacs Ada mode, which provides a full Integrated Development Environment for compiling, checking, running and debugging applications, you may use .gpr files to give the directories where Emacs can find sources and object files.

Using this switch, you can tell gnathtml to use these files. This allows you to get an html version of your application, even if it is spread over multiple directories.

sc color
This switch allows you to change the color used for symbol definitions. The default value is red. The color argument can be any name accepted by html.
t file
This switch provides the name of a file. This file contains a list of file names to be converted, and the effect is exactly as though they had appeared explicitly on the command line. This is the recommended way to work around the command line length limit on some systems.

5.4.2. Installing gnathtml

Perl needs to be installed on your machine to run this script. Perl is freely available for almost every architecture and operating system via the Internet.

On Unix systems, you may want to modify the first line of the script gnathtml, to explicitly specify where Perl is located. The syntax of this line is:

#!full_path_name_to_perl

Alternatively, you may run the script using the following command line:

$ perl gnathtml.pl [ switches ] files

5.5. The Ada-to-XML converter gnat2xml

The gnat2xml tool is an ASIS-based utility that converts Ada source code into XML.

gnat2xml is a project-aware tool (see Using Project Files with GNAT Tools for a description of the project-related switches). The project file package that can specify gnat2xml switches is named gnat2xml.

5.5.1. Switches for gnat2xml

gnat2xml takes Ada source code as input, and produces XML that conforms to the schema.

Usage:

$ gnat2xml [options] filenames [-files filename] [-cargs gcc_switches]

Options:

--help
Generate usage information and quit, ignoring all other options
-h
Same as --help
--version
Print version and quit, ignoring all other options
-Pfile
indicates the name of the project file that describes the set of sources to be processed. The exact set of argument sources depends on other options specified, see below.
-U
If a project file is specified and no argument source is explicitly specified, process all the units of the closure of the argument project. Otherwise this option has no effect.
-U main_unit
If a project file is specified and no argument source is explicitly specified (either directly or by means of -files option), process the closure of units rooted at main_unit. Otherwise this option has no effect.
-Xname=value
Indicates that external variable name in the argument project has the value value. Has no effect if no project is specified as tool argument.
--RTS=rts-path
Specifies the default location of the runtime library. Same meaning as the equivalent gnatmake flag (Switches for gnatmake).
--incremental
Incremental processing on a per-file basis. Source files are only processed if they have been modified, or if files they depend on have been modified. This is similar to the way gnatmake/gprbuild only compiles files that need to be recompiled. A project file is required in this mode.
-jn
In --incremental mode, use n gnat2xml processes to perform XML generation in parallel. If n is 0, then the maximum number of parallel tree creations is the number of core processors on the platform.
--output-dir=dir
Generate one .xml file for each Ada source file, in directory dir. (Default is to generate the XML to standard output.)
-Iinclude-dir
Directories to search for dependencies. You can also set the ADA_INCLUDE_PATH environment variable for this.
--compact
Debugging version, with interspersed source, and a more compact representation of “sloc”. This version does not conform to any schema.
--rep-clauses
generate representation clauses (see Generating Representation Clauses).
-files=filename
Take as arguments the files listed in text file file. Text file file may contain empty lines that are ignored. Each nonempty line should contain the name of an existing file. Several such switches may be specified simultaneously.
-q
Quiet
-v
Verbose
-cargs ...
Options to pass to gcc

If a project file is specified and no argument source is explicitly specified, and no -U is specified, then the set of processed sources is all the immediate units of the argument project.

Example:

$ gnat2xml -v -output-dir=xml-files *.ad[sb]

The above will create *.xml files in the xml-files subdirectory. For example, if there is an Ada package Mumble.Dumble, whose spec and body source code lives in mumble-dumble.ads and mumble-dumble.adb, the above will produce xml-files/mumble-dumble.ads.xml and xml-files/mumble-dumble.adb.xml.

5.5.2. Other Programs

The distribution includes two other programs that are related to gnat2xml:

gnat2xsd is the schema generator, which generates the schema to standard output, based on the structure of Ada as encoded by ASIS. You don’t need to run gnat2xsd in order to use gnat2xml. To generate the schema, type:

$ gnat2xsd > ada-schema.xsd

gnat2xml generates XML files that will validate against ada-schema.xsd.

xml2gnat is a back-translator that translates the XML back into Ada source code. The Ada generated by xml2gnat has identical semantics to the original Ada code passed to gnat2xml. It is not textually identical, however — for example, no attempt is made to preserve the original indentation.

5.5.3. Structure of the XML

The primary documentation for the structure of the XML generated by gnat2xml is the schema (see gnat2xsd above). The following documentation gives additional details needed to understand the schema and therefore the XML.

The elements listed under Defining Occurrences, Usage Occurrences, and Other Elements represent the syntactic structure of the Ada program. Element names are given in lower case, with the corresponding element type Capitalized_Like_This. The element and element type names are derived directly from the ASIS enumeration type Flat_Element_Kinds, declared in Asis.Extensions.Flat_Kinds, with the leading An_ or A_ removed. For example, the ASIS enumeration literal An_Assignment_Statement corresponds to the XML element assignment_statement of XML type Assignment_Statement.

To understand the details of the schema and the corresponding XML, it is necessary to understand the ASIS standard, as well as the GNAT-specific extension to ASIS.

A defining occurrence is an identifier (or character literal or operator symbol) declared by a declaration. A usage occurrence is an identifier (or ...) that references such a declared entity. For example, in:

type T is range 1..10;
X, Y : constant T := 1;

The first ‘T’ is the defining occurrence of a type. The ‘X’ is the defining occurrence of a constant, as is the ‘Y’, and the second ‘T’ is a usage occurrence referring to the defining occurrence of T.

Each element has a ‘sloc’ (source location), and subelements for each syntactic subtree, reflecting the Ada grammar as implemented by ASIS. The types of subelements are as defined in the ASIS standard. For example, for the right-hand side of an assignment_statement we have the following comment in asis-statements.ads:

------------------------------------------------------------------------------
--  18.3  function Assignment_Expression
------------------------------------------------------------------------------

   function Assignment_Expression
     (Statement : Asis.Statement)
      return      Asis.Expression;

------------------------------------------------------------------------------
...
--  Returns the expression from the right hand side of the assignment.
...
--  Returns Element_Kinds:
--       An_Expression

The corresponding sub-element of type Assignment_Statement is:

<xsd:element name="assignment_expression_q" type="Expression_Class"/>

where Expression_Class is defined by an xsd:choice of all the various kinds of expression.

The ‘sloc’ of each element indicates the starting and ending line and column numbers. Column numbers are character counts; that is, a tab counts as 1, not as however many spaces it might expand to.

Subelements of type Element have names ending in ‘_q’ (for ASIS “Query”), and those of type Element_List end in ‘_ql’ (“Query returning List”).

Some subelements are ‘Boolean’. For example, Private_Type_Definition has has_abstract_q and has_limited_q, to indicate whether those keywords are present, as in type T is abstract limited private;. False is represented by a Nil_Element. True is represented by an element type specific to that query (for example, Abstract and Limited).

The root of the tree is a Compilation_Unit, with attributes:

  • unit_kind, unit_class, and unit_origin. These are strings that match the enumeration literals of types Unit_Kinds, Unit_Classes, and Unit_Origins in package Asis.
  • unit_full_name is the full expanded name of the unit, starting from a root library unit. So for package P.Q.R is ..., unit_full_name="P.Q.R". Same for separate (P.Q) package R is ....
  • def_name is the same as unit_full_name for library units; for subunits, it is just the simple name.
  • source_file is the name of the Ada source file. For example, for the spec of P.Q.R, source_file="p-q-r.ads". This allows one to interpret the source locations — the ‘sloc’ of all elements within this Compilation_Unit refers to line and column numbers within the named file.

Defining occurrences have these attributes:

  • def_name is the simple name of the declared entity, as written in the Ada source code.

  • def is a unique URI of the form:

    ada://kind/fully/qualified/name
    

    where:

    • kind indicates the kind of Ada entity being declared (see below), and
    • fully/qualified/name, is the fully qualified name of the Ada entity, with each of ‘fully’, ‘qualified’, and ‘name’ being mangled for uniqueness. We do not document the mangling algorithm, which is subject to change; we just guarantee that the names are unique in the face of overloading.
    • type is the type of the declared object, or null for declarations of things other than objects.

Usage occurrences have these attributes:

  • ref_name is the same as the def_name of the corresponding defining occurrence. This attribute is not of much use, because of overloading; use ref for lookups, instead.
  • ref is the same as the def of the corresponding defining occurrence.

In summary, def_name and ref_name are as in the source code of the declaration, possibly overloaded, whereas def and ref are unique-ified.

Literal elements have this attribute:

  • lit_val is the value of the literal as written in the source text, appropriately escaped (e.g. "&quot;). This applies only to numeric and string literals. Enumeration literals in Ada are not really “literals” in the usual sense; they are usage occurrences, and have ref_name and ref as described above. Note also that string literals used as operator symbols are treated as defining or usage occurrences, not as literals.

Elements that can syntactically represent names and expressions (which includes usage occurrences, plus function calls and so forth) have this attribute:

  • type. If the element represents an expression or the name of an object, ‘type’ is the ‘def’ for the defining occurrence of the type of that expression or name. Names of other kinds of entities, such as package names and type names, do not have a type in Ada; these have type=”null” in the XML.

Pragma elements have this attribute:

  • pragma_name is the name of the pragma. For language-defined pragmas, the pragma name is redundant with the element kind (for example, an assert_pragma element necessarily has pragma_name=”Assert”). However, all implementation-defined pragmas are lumped together in ASIS as a single element kind (for example, the GNAT-specific pragma Unreferenced is represented by an implementation_defined_pragma element with pragma_name=”Unreferenced”).

Defining occurrences of formal parameters and generic formal objects have this attribute:

  • mode indicates that the parameter is of mode ‘in’, ‘in out’, or ‘out’.

All elements other than Not_An_Element have this attribute:

  • checks is a comma-separated list of run-time checks that are needed for that element. The possible checks are: do_accessibility_check, do_discriminant_check,do_division_check,do_length_check, do_overflow_check,do_range_check,do_storage_check,do_tag_check.

The “kind” part of the “def” and “ref” attributes is taken from the ASIS enumeration type Flat_Declaration_Kinds, declared in Asis.Extensions.Flat_Kinds, with the leading An_ or A_ removed, and any trailing _Declaration or _Specification removed. Thus, the possible kinds are as follows:

ordinary_type
task_type
protected_type
incomplete_type
tagged_incomplete_type
private_type
private_extension
subtype
variable
constant
deferred_constant
single_task
single_protected
integer_number
real_number
enumeration_literal
discriminant
component
loop_parameter
generalized_iterator
element_iterator
procedure
function
parameter
procedure_body
function_body
return_variable
return_constant
null_procedure
expression_function
package
package_body
object_renaming
exception_renaming
package_renaming
procedure_renaming
function_renaming
generic_package_renaming
generic_procedure_renaming
generic_function_renaming
task_body
protected_body
entry
entry_body
entry_index
procedure_body_stub
function_body_stub
package_body_stub
task_body_stub
protected_body_stub
exception
choice_parameter
generic_procedure
generic_function
generic_package
package_instantiation
procedure_instantiation
function_instantiation
formal_object
formal_type
formal_incomplete_type
formal_procedure
formal_function
formal_package
formal_package_declaration_with_box

5.5.4. Generating Representation Clauses

If the --rep-clauses switch is given, gnat2xml will generate representation clauses for certain types showing the representation chosen by the compiler. The information is produced by the ASIS ‘Data Decomposition’ facility — see the Asis.Data_Decomposition package for details.

Not all types are supported. For example, Type_Model_Kind must be A_Simple_Static_Model. Types declared within generic units have no representation. The clauses that are generated include attribute_definition_clauses for Size and Component_Size, as well as record_representation_clauses.

There is no guarantee that the generated representation clauses could have actually come from legal Ada code; Ada has some restrictions that are not necessarily obeyed by the generated clauses.

The representation clauses are surrounded by comment elements to indicate that they are automatically generated, something like this:

<comment text="--gen+">
...
<attribute_definition_clause>
...
<comment text="--gen-">
...

5.6. The Coding Standard Verifier gnatcheck

The gnatcheck tool is an ASIS-based utility that checks coding standard compliance of Ada source files according to a given set of semantic rules.

gnatcheck is a project-aware tool (see Using Project Files with GNAT Tools for a description of the project-related switches). The project file package that can specify gnatcheck switches is named Check.

For full details, plese refer to GNATcheck Reference Manual.

5.7. The GNAT Metrics Tool gnatmetric

The gnatmetric tool is an ASIS-based utility for computing various program metrics. It takes an Ada source file as input and generates a file containing the metrics data as output. Various switches control which metrics are computed and output.

gnatmetric is a project-aware tool (see Using Project Files with GNAT Tools for a description of the project-related switches). The project file package that can specify gnatmetric switches is named Metrics.

To compute program metrics, gnatmetric invokes the Ada compiler and generates and uses the ASIS tree for the input source; thus the input must be legal Ada code, and the tool should have all the information needed to compile the input source. To provide this information, you may specify as a tool parameter the project file the input source belongs to. Another possibility is to specify the source search path and needed configuration files in -cargs section of gnatmetric call, see the description of the gnatmetric switches below.

If the set of sources to be processed by gnatmetric contains sources with preprocessing directives then the needed options should be provided to run preprocessor as a part of the gnatmetric call, and the computed metrics will correspond to preprocessed sources.

The gnatmetric command has the form

$ gnatmetric [ switches ] { filename } [ -cargs gcc_switches ]

where:

  • switches specify the metrics to compute and define the destination for the output
  • Each filename is the name (including the extension) of a source file to process. ‘Wildcards’ are allowed, and the file name may contain path information. If no filename is supplied, then the switches list must contain at least one -files switch (see Other gnatmetric Switches). Including both a -files switch and one or more filename arguments is permitted.
  • gcc_switches is a list of switches for gcc. They will be passed on to all compiler invocations made by gnatmetric to generate the ASIS trees. Here you can provide -I switches to form the source search path, and use the -gnatec switch to set the configuration file, use the -gnat05 switch if sources should be compiled in Ada 2005 mode etc.

The following subsections describe the various switches accepted by gnatmetric, organized by category.

5.7.1. Output File Control

gnatmetric has two output formats. It can generate a textual (human-readable) form, and also XML. By default only textual output is generated.

When generating the output in textual form, gnatmetric creates for each Ada source file a corresponding text file containing the computed metrics, except for the case when the set of metrics specified by gnatmetric parameters consists only of metrics that are computed for the whole set of analyzed sources, but not for each Ada source. By default, the name of the file containing metric information for a source is obtained by appending the .metrix suffix to the name of the input source file. If not otherwise specified and no project file is specified as gnatmetric option this file is placed in the same directory as where the source file is located. If gnatmetric has a project file as its parameter, it places all the generated files in the object directory of the project (or in the project source directory if the project does not define an objects directory), if --subdirs option is specified, the files are placed in the subrirectory of this directory specified by this option.

All the output information generated in XML format is placed in a single file. By default the name of this file is metrix.xml. If not otherwise specified and if no project file is specified as gnatmetric option this file is placed in the current directory.

Some of the computed metrics are summed over the units passed to gnatmetric; for example, the total number of lines of code. By default this information is sent to stdout, but a file can be specified with the -og switch.

The following switches control the gnatmetric output:

-x
Generate the XML output
-xs
Generate the XML output and the XML schema file that describes the structure of the XML metric report, this schema is assigned to the XML file. The schema file has the same name as the XML output file with .xml suffix replaced with .xsd
-nt
Do not generate the output in text form (implies -x)
-d output_dir
Put text files with detailed metrics into output_dir
-o file_suffix
Use file_suffix, instead of .metrix in the name of the output file.
-og file_name
Put global metrics into file_name
-ox file_name
Put the XML output into file_name (also implies -x)
-sfn
Use ‘short’ source file names in the output. (The gnatmetric output includes the name(s) of the Ada source file(s) from which the metrics are computed. By default each name includes the absolute path. The -sfn switch causes gnatmetric to exclude all directory information from the file names that are output.)

5.7.2. Disable Metrics For Local Units

gnatmetric relies on the GNAT compilation model – one compilation unit per one source file. It computes line metrics for the whole source file, and it also computes syntax and complexity metrics for the file’s outermost unit.

By default, gnatmetric will also compute all metrics for certain kinds of locally declared program units:

  • subprogram (and generic subprogram) bodies;
  • package (and generic package) specs and bodies;
  • task object and type specifications and bodies;
  • protected object and type specifications and bodies.

These kinds of entities will be referred to as eligible local program units, or simply eligible local units, in the discussion below.

Note that a subprogram declaration, generic instantiation, or renaming declaration only receives metrics computation when it appear as the outermost entity in a source file.

Suppression of metrics computation for eligible local units can be obtained via the following switch:

-nolocal
Do not compute detailed metrics for eligible local program units

5.7.3. Specifying a set of metrics to compute

By default all the metrics are computed and reported. The switches described in this subsection allow you to control, on an individual basis, whether metrics are computed and reported. If at least one positive metric switch is specified (that is, a switch that defines that a given metric or set of metrics is to be computed), then only explicitly specified metrics are reported.

5.7.3.1. Line Metrics Control

For any (legal) source file, and for each of its eligible local program units, gnatmetric computes the following metrics:

  • the total number of lines;
  • the total number of code lines (i.e., non-blank lines that are not comments)
  • the number of comment lines
  • the number of code lines containing end-of-line comments;
  • the comment percentage: the ratio between the number of lines that contain comments and the number of all non-blank lines, expressed as a percentage;
  • the number of empty lines and lines containing only space characters and/or format effectors (blank lines)
  • the average number of code lines in subprogram bodies, task bodies, entry bodies and statement sequences in package bodies (this metric is only computed across the whole set of the analyzed units)

gnatmetric sums the values of the line metrics for all the files being processed and then generates the cumulative results. The tool also computes for all the files being processed the average number of code lines in bodies.

You can use the following switches to select the specific line metrics to be computed and reported.

--lines-all
Report all the line metrics
--no-lines-all
Do not report any of line metrics
--lines
Report the number of all lines
--no-lines
Do not report the number of all lines
--lines-code
Report the number of code lines
--no-lines-code
Do not report the number of code lines
--lines-comment
Report the number of comment lines
--no-lines-comment
Do not report the number of comment lines
--lines-eol-comment
Report the number of code lines containing end-of-line comments
--no-lines-eol-comment
Do not report the number of code lines containing end-of-line comments
--lines-ratio
Report the comment percentage in the program text
--no-lines-ratio
Do not report the comment percentage in the program text
--lines-blank
Report the number of blank lines
--no-lines-blank
Do not report the number of blank lines
--lines-average
Report the average number of code lines in subprogram bodies, task bodies, entry bodies and statement sequences in package bodies. The metric is computed and reported for the whole set of processed Ada sources only.
--no-lines-average
Do not report the average number of code lines in subprogram bodies, task bodies, entry bodies and statement sequences in package bodies.

5.7.3.2. Syntax Metrics Control

gnatmetric computes various syntactic metrics for the outermost unit and for each eligible local unit:

  • LSLOC (‘Logical Source Lines Of Code’)

    The total number of declarations and the total number of statements. Note that the definition of declarations is the one given in the reference manual:

    “Each of the following is defined to be a declaration: any basic_declaration; an enumeration_literal_specification; a discriminant_specification; a component_declaration; a loop_parameter_specification; a parameter_specification; a subprogram_body; an entry_declaration; an entry_index_specification; a choice_parameter_specification; a generic_formal_parameter_declaration.”

    This means for example that each enumeration literal adds one to the count, as well as each subprogram parameter.

    Thus the results from this metric will be significantly greater than might be expected from a naive view of counting semicolons.

  • Maximal static nesting level of inner program units

    According to Ada Reference Manual, 10.1(1):

    “A program unit is either a package, a task unit, a protected unit, a protected entry, a generic unit, or an explicitly declared subprogram other than an enumeration literal.”

  • Maximal nesting level of composite syntactic constructs

    This corresponds to the notion of the maximum nesting level in the GNAT built-in style checks (see Style Checking)

  • Number of formal parameters

    Number of formal parameters of a subprogram; if a subprogram does have parameters, then numbers of “in”, “out” and “in out” parameters are also reported. This metric is reported for subprogram specifications and for subprogram instantiations. For subprogram bodies, expression functions and null procedures this metric is reported if the construct acts as a subprogram declaration but is not a completion of previous declaration. This metric is not reported for generic and formal subprograms.

For the outermost unit in the file, gnatmetric additionally computes the following metrics:

  • Public subprograms

    This metric is computed for package specs. It is the number of subprograms and generic subprograms declared in the visible part (including the visible part of nested packages, protected objects, and protected types).

  • All subprograms

    This metric is computed for bodies and subunits. The metric is equal to a total number of subprogram bodies in the compilation unit. Neither generic instantiations nor renamings-as-a-body nor body stubs are counted. Any subprogram body is counted, independently of its nesting level and enclosing constructs. Generic bodies and bodies of protected subprograms are counted in the same way as ‘usual’ subprogram bodies.

  • Public types

    This metric is computed for package specs and generic package declarations. It is the total number of types that can be referenced from outside this compilation unit, plus the number of types from all the visible parts of all the visible generic packages. Generic formal types are not counted. Only types, not subtypes, are included.

    Along with the total number of public types, the following types are counted and reported separately:

    • Abstract types
    • Root tagged types^ (abstract, non-abstract, private, non-private). Type extensions are *not counted
    • Private types (including private extensions)
    • Task types
    • Protected types
  • All types

    This metric is computed for any compilation unit. It is equal to the total number of the declarations of different types given in the compilation unit. The private and the corresponding full type declaration are counted as one type declaration. Incomplete type declarations and generic formal types are not counted. No distinction is made among different kinds of types (abstract, private etc.); the total number of types is computed and reported.

By default, all the syntax metrics are computed and reported. You can use the following switches to select specific syntax metrics.

--syntax-all
Report all the syntax metrics
--no-syntax-all
Do not report any of syntax metrics
--declarations
Report the total number of declarations
--no-declarations
Do not report the total number of declarations
--statements
Report the total number of statements
--no-statements
Do not report the total number of statements
--public-subprograms
Report the number of public subprograms in a compilation unit
--no-public-subprograms
Do not report the number of public subprograms in a compilation unit
--all-subprograms
Report the number of all the subprograms in a compilation unit
--no-all-subprograms
Do not report the number of all the subprograms in a compilation unit
--public-types
Report the number of public types in a compilation unit
--no-public-types
Do not report the number of public types in a compilation unit
--all-types
Report the number of all the types in a compilation unit
--no-all-types
Do not report the number of all the types in a compilation unit
--unit-nesting
Report the maximal program unit nesting level
--no-unit-nesting
Do not report the maximal program unit nesting level
--construct-nesting
Report the maximal construct nesting level
--no-construct-nesting
Do not report the maximal construct nesting level
--param-number
Report the number of subprogram parameters
--no-param-number
Do not report the number of subprogram parameters

5.7.3.3. Complexity Metrics Control

For a program unit that is an executable body (a subprogram body (including generic bodies), task body, entry body or a package body containing its own statement sequence) gnatmetric computes the following complexity metrics:

  • McCabe cyclomatic complexity;
  • McCabe essential complexity;
  • maximal loop nesting level;
  • extra exit points (for subprograms);

The McCabe cyclomatic complexity metric is defined in http://www.mccabe.com/pdf/mccabe-nist235r.pdf

According to McCabe, both control statements and short-circuit control forms should be taken into account when computing cyclomatic complexity. For Ada 2012 we have also take into account conditional expressions and quantified expressions. For each body, we compute three metric values:

  • the complexity introduced by control statements only, without taking into account short-circuit forms (referred as statement complexity in gnatmetric output),
  • the complexity introduced by short-circuit control forms only (referred as expression complexity in gnatmetric output), and
  • the total cyclomatic complexity, which is the sum of these two values (referred as cyclomatic complexity in gnatmetric output).

The cyclomatic complexity is also computed for Ada 2012 expression functions. An expression function cannot have statements as its components, so only one metric value is computed as a cyclomatic complexity of an expression function.

The origin of cyclomatic complexity metric is the need to estimate the number of independent paths in the control flow graph that in turn gives the number of tests needed to satisfy paths coverage testing completeness criterion. Considered from the testing point of view, a static Ada loop (that is, the loop statement having static subtype in loop parameter specification) does not add to cyclomatic complexity. By providing --no-static-loop option a user may specify that such loops should not be counted when computing the cyclomatic complexity metric

The Ada essential complexity metric is a McCabe cyclomatic complexity metric counted for the code that is reduced by excluding all the pure structural Ada control statements. An compound statement is considered as a non-structural if it contains a raise or return statement as it subcomponent, or if it contains a goto statement that transfers the control outside the operator. A selective accept statement with a terminate alternative is considered a non-structural statement. When computing this metric, exit statements are treated in the same way as goto statements unless the -ne option is specified.

The Ada essential complexity metric defined here is intended to quantify the extent to which the software is unstructured. It is adapted from the McCabe essential complexity metric defined in http://www.mccabe.com/pdf/mccabe-nist235r.pdf but is modified to be more suitable for typical Ada usage. For example, short circuit forms are not penalized as unstructured in the Ada essential complexity metric.

When computing cyclomatic and essential complexity, gnatmetric skips the code in the exception handlers and in all the nested program units. The code of assertions and predicates (that is, subprogram preconditions and postconditions, subtype predicates and type invariants) is also skipped.

By default, all the complexity metrics are computed and reported. For more fine-grained control you can use the following switches:

--complexity-all
Report all the complexity metrics
--no-complexity-all
Do not report any of complexity metrics
--complexity-cyclomatic
Report the McCabe Cyclomatic Complexity
--no-complexity-cyclomatic
Do not report the McCabe Cyclomatic Complexity
--complexity-essential
Report the Essential Complexity
--no-complexity-essential
Do not report the Essential Complexity
--loop-nesting
Report maximal loop nesting level
-no-loop-nesting
Do not report maximal loop nesting level
--complexity-average
Report the average McCabe Cyclomatic Complexity for all the subprogram bodies, task bodies, entry bodies and statement sequences in package bodies. The metric is computed and reported for whole set of processed Ada sources only.
--no-complexity-average
Do not report the average McCabe Cyclomatic Complexity for all the subprogram bodies, task bodies, entry bodies and statement sequences in package bodies
-ne
Do not consider exit statements as gotos when computing Essential Complexity
--no-static-loop
Do not consider static loops when computing cyclomatic complexity
--extra-exit-points
Report the extra exit points for subprogram bodies. As an exit point, this metric counts return statements and raise statements in case when the raised exception is not handled in the same body. In case of a function this metric subtracts 1 from the number of exit points, because a function body must contain at least one return statement.
--no-extra-exit-points
Do not report the extra exit points for subprogram bodies

5.7.3.4. Coupling Metrics Control

Coupling metrics measure the dependencies between a given entity and other entities in the program. This information is useful since high coupling may signal potential issues with maintainability as the program evolves.

gnatmetric computes the following coupling metrics:

  • object-oriented coupling, for classes in traditional object-oriented sense;
  • unit coupling, for all the program units making up a program;
  • control coupling, reflecting dependencies between a unit and other units that contain subprograms.

Two kinds of coupling metrics are computed:

  • fan-out coupling (‘efferent coupling’): the number of entities the given entity depends upon. This metric reflects how the given entity depends on the changes in the ‘external world’.
  • fan-in coupling (‘afferent’ coupling): the number of entities that depend on a given entity. This metric reflects how the ‘external world’ depends on the changes in a given entity.

Object-oriented coupling metrics measure the dependencies between a given class (or a group of classes) and the other classes in the program. In this subsection the term ‘class’ is used in its traditional object-oriented programming sense (an instantiable module that contains data and/or method members). A category (of classes) is a group of closely related classes that are reused and/or modified together.

A class K‘s fan-out coupling is the number of classes that K depends upon. A category’s fan-out coupling is the number of classes outside the category that the classes inside the category depend upon.

A class K‘s fan-in coupling is the number of classes that depend upon K. A category’s fan-in coupling is the number of classes outside the category that depend on classes belonging to the category.

Ada’s object-oriented paradigm separates the instantiable entity (type) from the module (package), so the definition of the coupling metrics for Ada maps the class and class category notions onto Ada constructs.

For the coupling metrics, several kinds of modules that define a tagged type or an interface type – library packages, library generic packages, and library generic package instantiations – are considered to be classes. A category consists of a library package (or a library generic package) that defines a tagged or an interface type, together with all its descendant (generic) packages that define tagged or interface types. Thus a category is an Ada hierarchy of library-level program units. Class coupling in Ada is referred to as ‘tagged coupling’, and category coupling is referred to as ‘hierarchy coupling’.

For any package serving as a class, its body and subunits (if any) are considered together with its spec when computing dependencies, and coupling metrics are reported for spec units only. Dependencies between classes mean Ada semantic dependencies. For object-oriented coupling metrics, only dependencies on units treated as classes are considered.

Similarly, for unit and control coupling an entity is considered to be the conceptual construct consisting of the entity’s specification, body, and any subunits (transitively). gnatmetric computes the dependencies of all these units as a whole, but metrics are only reported for spec units (or for a subprogram body unit in case if there is no separate spec for the given subprogram).

For unit coupling, dependencies are computed between all kinds of program units. For control coupling, the dependencies of a given unit are limited to those units that define subprograms. Thus control fan-out coupling is reported for all units, but control fan-in coupling is only reported for units that define subprograms.

The following simple example illustrates the difference between unit coupling and control coupling metrics:

package Lib_1 is
    function F_1 (I : Integer) return Integer;
end Lib_1;

package Lib_2 is
    type T_2 is new Integer;
end Lib_2;

package body Lib_1 is
    function F_1 (I : Integer) return Integer is
    begin
       return I + 1;
    end F_1;
end Lib_1;

with Lib_2; use Lib_2;
package Pack is
    Var : T_2;
    function Fun (I : Integer) return Integer;
end Pack;

with Lib_1; use Lib_1;
package body Pack is
    function Fun (I : Integer) return Integer is
    begin
       return F_1 (I);
    end Fun;
end Pack;

If we apply gnatmetric with the --coupling-all option to these units, the result will be:

Coupling metrics:
=================
    Unit Lib_1 (C:\\customers\\662\\L406-007\\lib_1.ads)
       control fan-out coupling  : 0
       control fan-in coupling   : 1
       unit fan-out coupling     : 0
       unit fan-in coupling      : 1

    Unit Pack (C:\\customers\\662\\L406-007\\pack.ads)
       control fan-out coupling  : 1
       control fan-in coupling   : 0
       unit fan-out coupling     : 2
       unit fan-in coupling      : 0

    Unit Lib_2 (C:\\customers\\662\\L406-007\\lib_2.ads)
       control fan-out coupling  : 0
       unit fan-out coupling     : 0
       unit fan-in coupling      : 1

The result does not contain values for object-oriented coupling because none of the argument units contains a tagged type and therefore none of these units can be treated as a class.

The Pack package (spec and body) depends on two units – Lib_1 and Lib_2 – and so its unit fan-out coupling is 2. Since nothing depends on it, its unit fan-in coupling is 0, as is its control fan-in coupling. Only one of the units Pack depends upon defines a subprogram, so its control fan-out coupling is 1.

Lib_2 depends on nothing, so its fan-out metrics are 0. It does not define any subprograms, so it has no control fan-in metric. One unit (Pack) depends on it , so its unit fan-in coupling is 1.

Lib_1 is similar to Lib_2, but it does define a subprogram. Its control fan-in coupling is 1 (because there is one unit depending on it).

When computing coupling metrics, gnatmetric counts only dependencies between units that are arguments of the gnatmetric invocation. Coupling metrics are program-wide (or project-wide) metrics, so you should invoke gnatmetric for the complete set of sources comprising your program. This can be done by invoking gnatmetric with the corresponding project file and with the -U option.

By default, all the coupling metrics are disabled. You can use the following switches to specify the coupling metrics to be computed and reported:

--coupling-all
Report all the coupling metrics
--tagged-coupling-out
Report tagged (class) fan-out coupling
--tagged-coupling-in
Report tagged (class) fan-in coupling
--hierarchy-coupling-out
Report hierarchy (category) fan-out coupling
--hierarchy-coupling-in
Report hierarchy (category) fan-in coupling
--unit-coupling-out
Report unit fan-out coupling
--unit-coupling-in
Report unit fan-in coupling
--control-coupling-out
Report control fan-out coupling
--control-coupling-in
Report control fan-in coupling

5.7.4. Other gnatmetric Switches

Additional gnatmetric switches are as follows:

--version
Display Copyright and version, then exit disregarding all other options.
--help
Display usage, then exit disregarding all other options.
-P file
Indicates the name of the project file that describes the set of sources to be processed. The exact set of argument sources depends on other options specified, see below.
-U
If a project file is specified and no argument source is explicitly specified (either directly or by means of -files option), process all the units of the closure of the argument project. Otherwise this option has no effect.
-U main_unit
If a project file is specified and no argument source is explicitly specified (either directly or by means of -files option), process the closure of units rooted at main_unit. Otherwise this option has no effect.
-Xname=value
Indicates that external variable name in the argument project has the value value. Has no effect if no project is specified as tool argument.
--RTS=rts-path
Specifies the default location of the runtime library. Same meaning as the equivalent gnatmake flag (see Switches for gnatmake).
--subdirs=dir
Use the specified subdirectory of the project objects file (or of the project file directory if the project does not specify an object directory) for tool output files. Has no effect if no project is specified as tool argument r if --no_objects_dir is specified.
--no_objects_dir
Place all the result files into the current directory instead of project objects directory. This corresponds to the gnatcheck behavior when it is called with the project file from the GNAT driver. Has no effect if no project is specified.
-files filename
Take as arguments the files listed in text file file. Text file file may contain empty lines that are ignored. Each nonempty line should contain the name of an existing file. Several such switches may be specified simultaneously.
-jn
Use n processes to carry out the tree creations (internal representations of the argument sources). On a multiprocessor machine this speeds up processing of big sets of argument sources. If n is 0, then the maximum number of parallel tree creations is the number of core processors on the platform.
-t
Print out execution time.
-v
Verbose mode; gnatmetric generates version information and then a trace of sources being processed.
-q
Quiet mode.

If a project file is specified and no argument source is explicitly specified (either directly or by means of -files option), and no -U is specified, then the set of processed sources is all the immediate units of the argument project.

5.8. The GNAT Pretty-Printer gnatpp

The gnatpp tool is an ASIS-based utility for source reformatting / pretty-printing. It takes an Ada source file as input and generates a reformatted version as output. You can specify various style directives via switches; e.g., identifier case conventions, rules of indentation, and comment layout.

gnatpp is a project-aware tool (see Using Project Files with GNAT Tools for a description of the project-related switches). The project file package that can specify gnatpp switches is named Pretty_Printer.

To produce a reformatted file, gnatpp invokes the Ada compiler and generates and uses the ASIS tree for the input source; thus the input must be legal Ada code, and the tool should have all the information needed to compile the input source. To provide this information, you may specify as a tool parameter the project file the input source belongs to. Another possibility is to specify the source search path and needed configuration files in -cargs section of gnatpp call, see the description of the gnatpp switches below.

gnatpp cannot process sources that contain preprocessing directives.

The gnatpp command has the form

$ gnatpp [ switches ] filename [ -cargs gcc_switches ]

where

  • switches is an optional sequence of switches defining such properties as the formatting rules, the source search path, and the destination for the output source file
  • filename is the name (including the extension) of the source file to reformat; wildcards or several file names on the same gnatpp command are allowed. The file name may contain path information; it does not have to follow the GNAT file naming rules
  • gcc_switches is a list of switches for gcc. They will be passed on to all compiler invocations made by gnatpp to generate the ASIS trees. Here you can provide -I switches to form the source search path, use the -gnatec switch to set the configuration file, etc.

5.8.1. Switches for gnatpp

The following subsections describe the various switches accepted by gnatpp, organized by category.

You specify a switch by supplying a name and generally also a value. In many cases the values for a switch with a given name are incompatible with each other (for example the switch that controls the casing of a reserved word may have exactly one value: upper case, lower case, or mixed case) and thus exactly one such switch can be in effect for an invocation of gnatpp. If more than one is supplied, the last one is used. However, some values for the same switch are mutually compatible. You may supply several such switches to gnatpp, but then each must be specified in full, with both the name and the value. Abbreviated forms (the name appearing once, followed by each value) are not permitted.

5.8.1.1. Alignment Control

Programs can be easier to read if certain constructs are vertically aligned. By default, alignment of the following constructs is set ON:

  • : in declarations,
  • := in initializations in declarations,
  • := in assignment statements,
  • => in associations, and
  • at keywords in the component clauses in record representation clauses.
-A0
Set alignment to OFF
-A1
Set alignment to ON

5.8.1.2. Casing Control

gnatpp allows you to specify the casing for reserved words, pragma names, attribute designators and identifiers. For identifiers you may define a general rule for name casing but also override this rule via a set of dictionary files.

Three types of casing are supported: lower case, upper case, and mixed case. ‘Mixed case’ means that the first letter, and also each letter immediately following an underscore, are converted to their uppercase forms; all the other letters are converted to their lowercase forms.

-aL
Attribute designators are lower case
-aU
Attribute designators are upper case
-aM
Attribute designators are mixed case (this is the default)
-kL
Keywords (technically, these are known in Ada as reserved words) are lower case (this is the default)
-kU
Keywords are upper case
-nD
Name casing for defining occurrences are as they appear in the source file (this is the default)
-nU
Names are in upper case
-nL
Names are in lower case
-nM
Names are in mixed case
-neD
Enumeration literal casing for defining occurrences are as they appear in the source file. Overrides -n casing setting.
-neU
Enumeration literals are in upper case. Overrides -n casing setting.
-neL
Enumeration literals are in lower case. Overrides -n casing setting.
-neM
Enumeration literals are in mixed case. Overrides -n casing setting.
-ntD
Names introduced by type and subtype declarations are always cased as they appear in the declaration in the source file. Overrides -n casing setting.
-ntU
Names introduced by type and subtype declarations are always in upper case. Overrides -n casing setting.
-ntL
Names introduced by type and subtype declarations are always in lower case. Overrides -n casing setting.
-ntM
Names introduced by type and subtype declarations are always in mixed case. Overrides -n casing setting.
-nnU
Names introduced by number declarations are always in upper case. Overrides -n casing setting.
-nnL
Names introduced by number declarations are always in lower case. Overrides -n casing setting.
-nnM
Names introduced by number declarations are always in mixed case. Overrides -n casing setting.
-pL
Pragma names are lower case
-pU
Pragma names are upper case
-pM
Pragma names are mixed case (this is the default)
-Dfile

Use file as a dictionary file that defines the casing for a set of specified names, thereby overriding the effect on these names by any explicit or implicit -n switch. To supply more than one dictionary file, use several -D switches.

gnatpp implicitly uses a default dictionary file to define the casing for the Ada predefined names and the names declared in the GNAT libraries.

-D-
Do not use the default dictionary file; instead, use the casing defined by a -n switch and any explicit dictionary file(s)

The structure of a dictionary file, and details on the conventions used in the default dictionary file, are defined in Name Casing.

The -D- and -Dfile switches are mutually compatible.

This group of gnatpp switches controls the layout of comments and complex syntactic constructs. See Formatting Comments for details on their effect.

-c0
All comments remain unchanged.
-c1
GNAT-style comment line indentation. This is the default.
-c3
GNAT-style comment beginning.
-c4
Fill comment blocks.
-c5
Keep unchanged special form comments. This is the default.
--comments-only
Format just the comments.
--no-end-id
Do not insert the name of a unit after end; leave whatever comes after end, if anything, alone.
--no-separate-is
Do not place the keyword is on a separate line in a subprogram body in case if the spec occupies more than one line.
--separate-loop-then
Place the keyword loop in FOR and WHILE loop statements and the keyword then in IF statements on a separate line.
--no-separate-loop-then
Do not place the keyword loop in FOR and WHILE loop statements and the keyword then in IF statements on a separate line. This option is incompatible with the --separate-loop-then option.
--use-on-new-line
Start each USE clause in a context clause from a separate line.
--insert-blank-lines
Insert blank lines where appropriate (between bodies and other large constructs).
--preserve-blank-lines
Preserve blank lines in the input. By default, gnatpp will squeeze multiple blank lines down to one.

The -c switches are compatible with one another, except that the -c0 switch disables all other comment formatting switches.

5.8.1.3. General Text Layout Control

These switches allow control over line length and indentation.

-Mnnn
Maximum line length, nnn from 32...256, the default value is 79
-innn
Indentation level, nnn from 1...9, the default value is 3
-clnnn
Indentation level for continuation lines (relative to the line being continued), nnn from 1...9. The default value is one less than the (normal) indentation level, unless the indentation is set to 1 (in which case the default value for continuation line indentation is also 1)

5.8.1.4. Other Formatting Options

These switches control other formatting not listed above.

--decimal-grouping=n
Put underscores in decimal literals (numeric literals without a base) every n characters. If a literal already has one or more underscores, it is not modified. For example, with --decimal-grouping=3, 1000000 will be changed to 1_000_000.
--based-grouping=n
Same as --decimal-grouping, but for based literals. For example, with --based-grouping=4, 16#0001FFFE# will be changed to 16#0001_FFFE#.
--split-line-before-op
If it is necessary to split a line at a binary operator, by default the line is split after the operator. With this option, it is split before the operator.
--RM-style-spacing
Do not insert an extra blank before various occurrences of ‘(‘ and ‘:’. This also turns off alignment.
-ff
Insert a Form Feed character after a pragma Page.
--call_threshold=nnn
If the number of parameter associations is greater than nnn and if at least one association uses named notation, start each association from a new line. If nnn is 0, no check for the number of associations is made; this is the default.
--par_threshold=nnn
If the number of parameter specifications is greater than nnn (or equal to nnn in case of a function), start each specification from a new line. If nnn is 0, and --no-separate-is was not specified, then the is is placed on a separate line. This feature is disabled by default.

5.8.1.5. Setting the Source Search Path

To define the search path for the input source file, gnatpp uses the same switches as the GNAT compiler, with the same effects:

-Idir

-I-

-gnatec=path

5.8.1.6. Output File Control

By default the output is sent to a file whose name is obtained by appending the .pp suffix to the name of the input file. If the file with this name already exists, it is overwritten. Thus if the input file is my_ada_proc.adb then gnatpp will produce my_ada_proc.adb.pp as output file. The output may be redirected by the following switches:

--output-dir=dir
Generate output file in directory dir with the same name as the input file. If dir is the same as the directory containing the input file, the input file is not processed; use -rnb if you want to update the input file in place.
-pipe
Send the output to Standard_Output
-o output_file
Write the output into output_file. If output_file already exists, gnatpp terminates without reading or processing the input file.
-of output_file
Write the output into output_file, overwriting the existing file (if one is present).
-r
Replace the input source file with the reformatted output, and copy the original input source into the file whose name is obtained by appending the .npp suffix to the name of the input file. If a file with this name already exists, gnatpp terminates without reading or processing the input file.
-rf
Like -r except that if the file with the specified name already exists, it is overwritten.
-rnb
Replace the input source file with the reformatted output without creating any backup copy of the input source.
--eol=xxx

Specifies the line-ending style of the reformatted output file. The xxx string specified with the switch may be:

  • dos - MS DOS style, lines end with CR LF characters*
  • crlf - the same as dos
  • unix - UNIX style, lines end with LF character*
  • lf - the same as unix
-We

Specify the wide character encoding method for the input and output files. e is one of the following:

  • h - Hex encoding
  • u - Upper half encoding
  • s - Shift/JIS encoding
  • e - EUC encoding
  • 8 - UTF-8 encoding
  • b - Brackets encoding (default value)

Options -o and -of are allowed only if the call to gnatpp contains only one file to reformat.

Option --eol and -W cannot be used together with the -pipe option.

5.8.1.7. Other gnatpp Switches

The additional gnatpp switches are defined in this subsection.

--version
Display copyright and version, then exit disregarding all other options.
--help
Display usage, then exit disregarding all other options.
-P file
Indicates the name of the project file that describes the set of sources to be processed. The exact set of argument sources depends on other options specified; see below.
-U
If a project file is specified and no argument source is explicitly specified (either directly or by means of -files option), process all the units of the closure of the argument project. Otherwise this option has no effect.
-U main_unit
If a project file is specified and no argument source is explicitly specified (either directly or by means of -files option), process the closure of units rooted at main_unit. Otherwise this option has no effect.
-Xname=value
Indicates that external variable name in the argument project has the value value. Has no effect if no project is specified as tool argument.
--RTS=rts-path
Specifies the default location of the runtime library. Same meaning as the equivalent gnatmake flag (Switches for gnatmake).
--incremental
Incremental processing on a per-file basis. Source files are only processed if they have been modified, or if files they depend on have been modified. This is similar to the way gnatmake/gprbuild only compiles files that need to be recompiled. A project file is required in this mode, and the gnat driver (as in gnat pretty) is not supported.
--pp-off=xxx
Use --xxx as the command to turn off pretty printing, instead of the default --!pp off.
--pp-on=xxx
Use --xxx as the command to turn pretty printing back on, instead of the default --!pp on.
-files filename
Take as arguments the files listed in text file file. Text file file may contain empty lines that are ignored. Each nonempty line should contain the name of an existing file. Several such switches may be specified simultaneously.
-jn

Without --incremental, use n processes to carry out the tree creations (internal representations of the argument sources). On a multiprocessor machine this speeds up processing of big sets of argument sources. If n is 0, then the maximum number of parallel tree creations is the number of core processors on the platform. This option cannot be used together with the -r, -rf or -rnb options.

With --incremental, use n gnatpp processes to perform pretty-printing in parallel. n = 0 means the same as above. In this case, the -r, -rf and -rnb options are allowed.

-t
Print out execution time.
-v
Verbose mode
-q
Quiet mode

If a project file is specified and no argument source is explicitly specified (either directly or by means of -files option), and no -U is specified, then the set of processed sources is all the immediate units of the argument project.

5.8.2. Formatting Rules

The following subsections show how gnatpp treats white space, comments, program layout, and name casing. They provide detailed descriptions of the switches shown above.

5.8.2.1. Disabling Pretty Printing

Pretty printing is highly heuristic in nature, and sometimes doesn’t do exactly what you want. If you wish to format a certain region of code by hand, you can turn off pretty printing in that region by surrounding it with special comments that start with --!pp off and --!pp on. The text in that region will then be reproduced verbatim in the output with no formatting.

To disable pretty printing for the whole file, put --!pp off at the top, with no following --!pp on.

The comments must appear on a line by themselves, with nothing preceding except spaces. The initial text of the comment must be exactly --!pp off or --!pp on (case sensitive), but may be followed by arbitrary additional text. For example:

package Interrupts is
   --!pp off -- turn off pretty printing so "Interrupt_Kind" lines up
   type            Interrupt_Kind is
     (Asynchronous_Interrupt_Kind,
       Synchronous_Interrupt_Kind,
             Green_Interrupt_Kind);
   --!pp on -- reenable pretty printing
   ...

You can specify different comment strings using the --pp-off and --pp-on switches. For example, if you say:

$ gnatpp --pp-off=' pp-' *.ad?

then gnatpp will recognize comments of the form -- pp- instead of --!pp off for disabling pretty printing. Note that the leading -- of the comment is not included in the argument to these switches.

5.8.2.2. White Space and Empty Lines

gnatpp does not have an option to control space characters. It will add or remove spaces according to the style illustrated by the examples in the Ada Reference Manual. The output file will contain no lines with trailing white space.

By default, a sequence of one or more blank lines in the input is converted to a single blank line in the output; multiple blank lines are squeezed down to one. The --preserve-blank-lines option turns off the squeezing; each blank line in the input is copied to the output. The --insert-blank-lines option causes additional blank lines to be inserted if not already present in the input (e.g. between bodies).

5.8.2.3. Formatting Comments

Comments in Ada code are of two kinds:

  • a whole-line comment, which appears by itself (possibly preceded by white space) on a line
  • an end-of-line comment, which follows some other Ada code on the same line.

A whole-line comment is indented according to the surrounding code, with some exceptions. Comments that start in column 1 are kept there. If possible, comments are not moved so far to the right that the maximum line length is exceeded. The -c0 option turns off comment formatting. Special-form comments such as SPARK-style --#... are left alone.

For an end-of-line comment, gnatpp tries to leave the same number of spaces between the end of the preceding Ada code and the beginning of the comment as appear in the original source.

The -c3 switch (GNAT style comment beginning) has the following effect:

  • For each whole-line comment that does not end with two hyphens, gnatpp inserts spaces if necessary after the starting two hyphens to ensure that there are at least two spaces between these hyphens and the first non-blank character of the comment.

The -c4 switch specifies that whole-line comments that form a paragraph will be filled in typical word processor style (that is, moving words between lines to make the lines other than the last similar in length ).

The --comments-only switch specifies that only the comments are formatted; the rest of the program text is left alone. The comments are formatted according to the -c3 and -c4 switches; other formatting switches are ignored. For example, --comments-only -c4 means to fill comment paragraphs, and do nothing else. Likewise, --comments-only -c3 ensures comments start with at least two spaces after --, and --comments-only -c3 -c4 does both. If --comments-only is given without -c3 or -c4, then gnatpp doesn’t format anything.

5.8.2.4. Name Casing

gnatpp always converts the usage occurrence of a (simple) name to the same casing as the corresponding defining identifier.

You control the casing for defining occurrences via the -n switch. With -nD (‘as declared’, which is the default), defining occurrences appear exactly as in the source file where they are declared. The other values for this switch – -nU, -nL, -nM – result in upper, lower, or mixed case, respectively. If gnatpp changes the casing of a defining occurrence, it analogously changes the casing of all the usage occurrences of this name.

If the defining occurrence of a name is not in the source compilation unit currently being processed by gnatpp, the casing of each reference to this name is changed according to the value of the -n switch (subject to the dictionary file mechanism described below). Thus gnatpp acts as though the -n switch had affected the casing for the defining occurrence of the name.

The options -ax, -kx, -nex, -ntx, -nnx, and -px allow finer-grained control over casing for attributes, keywords, enumeration literals, types, named numbers and pragmas, respectively. -ntx covers subtypes and task and protected bodies as well.

Some names may need to be spelled with casing conventions that are not covered by the upper-, lower-, and mixed-case transformations. You can arrange correct casing by placing such names in a dictionary file, and then supplying a -D switch. The casing of names from dictionary files overrides any -n switch.

To handle the casing of Ada predefined names and the names from GNAT libraries, gnatpp assumes a default dictionary file. The name of each predefined entity is spelled with the same casing as is used for the entity in the Ada Reference Manual (usually mixed case). The name of each entity in the GNAT libraries is spelled with the same casing as is used in the declaration of that entity.

The -D- switch suppresses the use of the default dictionary file. Instead, the casing for predefined and GNAT-defined names will be established by the -n switch or explicit dictionary files. For example, by default the names Ada.Text_IO and GNAT.OS_Lib will appear as just shown, even in the presence of a -nU switch. To ensure that even such names are rendered in uppercase, additionally supply the -D- switch (or else place these names in upper case in a dictionary file).

A dictionary file is a plain text file; each line in this file can be either a blank line (containing only space characters), an Ada comment line, or the specification of exactly one casing schema.

A casing schema is a string that has the following syntax:

casing_schema ::= identifier | simple_identifier

simple_identifier ::= letter{letter_or_digit}

(See Ada Reference Manual, Section 2.3) for the definition of the identifier lexical element and the letter_or_digit category.)

The casing schema string can be followed by white space and/or an Ada-style comment; any amount of white space is allowed before the string.

If a dictionary file is passed as the value of a -Dfile switch then for every simple name and every identifier, gnatpp checks if the dictionary defines the casing for the name or for some of its parts (the term ‘subword’ is used below to denote the part of a name which is delimited by ‘_’ or by the beginning or end of the word and which does not contain any ‘_’ inside):

  • if the whole name is in the dictionary, gnatpp uses for this name the casing defined by the dictionary; no subwords are checked for this word
  • for every subword gnatpp checks if the dictionary contains the corresponding string of the form simple_identifier, and if it does, the casing of this simple_identifier is used for this subword
  • if the whole name does not contain any ‘_’ inside, and if for this name the dictionary contains two entries – one of the form identifier, and another of the form simple_identifier – then the first one is applied to define the casing of this name
  • if more than one dictionary file is passed as gnatpp switches, each dictionary adds new casing exceptions and overrides all the existing casing exceptions set by the previous dictionaries
  • when gnatpp checks if the word or subword is in the dictionary, this check is not case sensitive

For example, suppose we have the following source to reformat:

procedure test is
   name1 : integer := 1;
   name4_name3_name2 : integer := 2;
   name2_name3_name4 : Boolean;
   name1_var : Float;
begin
   name2_name3_name4 := name4_name3_name2 > name1;
end;

And suppose we have two dictionaries:

*dict1:*
   NAME1
   *NaMe3*
   *Name1*

*dict2:*
  *NAME3*

If gnatpp is called with the following switches:

$ gnatpp -nM -D dict1 -D dict2 test.adb

then we will get the following name casing in the gnatpp output:

procedure Test is
   NAME1             : Integer := 1;
   Name4_NAME3_Name2 : Integer := 2;
   Name2_NAME3_Name4 : Boolean;
   Name1_Var         : Float;
begin
   Name2_NAME3_Name4 := Name4_NAME3_Name2 > NAME1;
end Test;

5.9. The Body Stub Generator gnatstub

gnatstub creates empty but compilable bodies for library unit declarations, and empty but compilable subunit for body stubs.

gnatstub is a project-aware tool. (See Using Project Files with GNAT Tools for a description of the project-related switches but note that gnatstub does not support the -U, -U main_unit, --subdirs=dir, or --no_objects_dir switches.) The project file package that can specify gnatstub switches is named gnatstub.

To create a body or a subunit, gnatstub invokes the Ada compiler and generates and uses the ASIS tree for the input source; thus the input must be legal Ada code, and the tool should have all the information needed to compile the input source. To provide this information, you may specify as a tool parameter the project file the input source belongs to. Another possibility is to specify the source search path and needed configuration files in -cargs section of gnatstub call, see the description of the gnatstub switches below.

If the gnatstub argument source contains preprocessing directives then the needed options should be provided to run preprocessor as a part of the gnatstub call, and the generated body stub will correspond to the preprocessed source.

By default, all the program unit bodies generated by gnatstub raise the predefined Program_Error exception, which will catch accidental calls of generated stubs. This behavior can be changed with option --no-exception (see below).

5.9.1. Running gnatstub

gnatstub invocation has the following form:

$ gnatstub [ switches ] filename [ -cargs gcc_switches ]

where

  • filename
    is the name of the source file that contains a library unit declaration for which a body must be created or a library unit body for which subunits must be created for the body stubs declared in this body. The file name may contain the path information. If the name does not follow GNAT file naming conventions and a set of seitches does not contain a project file that defines naming conventions, the name of the body file must be provided explicitly as the value of the -obody-name option. If the file name follows the GNAT file naming conventions and the name of the body file is not provided, gnatstub takes the naming conventions for the generated source from the project file provided as a parameter of -P switch if any, or creates the name file to generate using the standard GNAT naming conventions.
  • gcc_switches is a list of switches for gcc.
    They will be passed on to all compiler invocations made by gnatstub to generate the ASIS trees. Here you can provide -I switches to form the source search path, use the -gnatec switch to set the configuration file, use the -gnat05 switch if sources should be compiled in Ada 2005 mode etc.
  • switches
    is an optional sequence of switches as described in the next section

5.9.2. Switches for gnatstub

--version
Display Copyright and version, then exit disregarding all other options.
--help
Display usage, then exit disregarding all other options.
-P file
Indicates the name of the project file that describes the set of sources to be processed.
-Xname=value
Indicates that external variable name in the argument project has the value value. Has no effect if no project is specified as tool argument.
--RTS=rts-path
Specifies the default location of the runtime library. Same meaning as the equivalent gnatmake flag (Switches for gnatmake).
--subunits
Generate subunits for body stubs. If this switch is specified, gnatstub expects a library unit body as an agrument file, otherwise a library unit declaration is expected. If a body stub already has a corresponding subunit, gnatstub does not generate anything for it.
-f
If the destination directory already contains a file with the name of the body file for the argument spec file, replace it with the generated body stub. This switch cannot be used together with --subunits.
-hs
Put the comment header (i.e., all the comments preceding the compilation unit) from the source of the library unit declaration into the body stub.
-hg
Put a sample comment header into the body stub.
--header-file=filename
Use the content of the file as the comment header for a generated body stub.
-IDIR, -I-
These switches have the same meaning as in calls to gcc. They define the source search path in the call to gcc issued by gnatstub to compile an argument source file.
-gnatecPATH
This switch has the same meaning as in calls to gcc. It defines the additional configuration file to be passed to the call to gcc issued by gnatstub to compile an argument source file.
-gnatyMn
(n is a non-negative integer). Set the maximum line length that is allowed in a source file. The default is 79. The maximum value that can be specified is 32767. Note that in the special case of configuration pragma files, the maximum is always 32767 regardless of whether or not this switch appears.
-gnatyn
(n is a non-negative integer from 1 to 9). Set the indentation level in the generated body sample to n. The default indentation is 3.
-gnatyo
Order local bodies alphabetically. (By default local bodies are ordered in the same way as the corresponding local specs in the argument spec file.)
-in
Same as -gnatyn`
-k
Do not remove the tree file (i.e., the snapshot of the compiler internal structures used by gnatstub) after creating the body stub.
-ln
Same as -gnatyM`n`
--no-exception
Avoid raising PROGRAM_ERROR in the generated bodies of program unit stubs. This is not always possible for function stubs.
--no-local-header
Do not place local comment header with unit name before body stub for a unit.
-o body-name
Body file name. This should be set if the argument file name does not follow the GNAT file naming conventions. If this switch is omitted the default name for the body will be obtained from the argument file name according to the GNAT file naming conventions.
--dir=dir-name
The path to the directory to place the generated files into. If this switch is not set, the generated library unit body is placed in the current directory, and generated sununits - in the directory where the argument body is located.
-We

Specify the wide character encoding method for the output body file. e is one of the following:

h Hex encoding
u Upper half encoding
s Shift/JIS encoding
e EUC encoding
8 UTF-8 encoding
b Brackets encoding (default value)
-q
Quiet mode: do not generate a confirmation when a body is successfully created, and do not generate a message when a body is not required for an argument unit.
-r
Reuse the tree file (if it exists) instead of creating it. Instead of creating the tree file for the library unit declaration, gnatstub tries to find it in the current directory and use it for creating a body. If the tree file is not found, no body is created. This option also implies -k, whether or not the latter is set explicitly.
-t
Overwrite the existing tree file. If the current directory already contains the file which, according to the GNAT file naming rules should be considered as a tree file for the argument source file, gnatstub will refuse to create the tree file needed to create a sample body unless this option is set.
-v
Verbose mode: generate version information.

5.10. The Unit Test Generator gnattest

gnattest is an ASIS-based utility that creates unit-test skeletons as well as a test driver infrastructure (harness). gnattest creates a skeleton for each visible subprogram in the packages under consideration when they do not exist already.

gnattest is a project-aware tool. (See Using Project Files with GNAT Tools for a description of the project-related switches but note that gnattest does not support the -U, -eL, --subdirs=dir, or --no_objects_dir switches.) The project file package that can specify gnattest switches is named gnattest.

The user can choose to generate a single test driver that will run all individual tests, or separate test drivers for each test. The second option allows much greater flexibility in test execution environment, allows to benefit from parallel tests execution to increase performance, and provides stubbing support.

gnattest also has a mode of operation where it acts as the test aggregator when multiple test executables must be run, in particular when the separate test drivers were generated. In this mode it handles individual tests execution and upon completion reports the summary results of the test run.

In order to process source files from a project, gnattest has to semantically analyze the sources. Therefore, test skeletons can only be generated for legal Ada units. If a unit is dependent on other units, those units should be among the source files of the project or of other projects imported by this one.

Generated skeletons and harnesses are based on the AUnit testing framework. AUnit is an Ada adaptation of the xxxUnit testing frameworks, similar to JUnit for Java or CppUnit for C++. While it is advised that gnattest users read the AUnit manual, deep knowledge of AUnit is not necessary for using gnattest. For correct operation of gnattest, AUnit should be installed and aunit.gpr must be on the project path. Except for some special circumstances (e.g. a custom run-time is used), this should normally be the case out of the box.

5.10.1. Running gnattest

There are two ways of running gnattest.

5.10.1.1. Framework Generation Mode

In this mode gnattest has the following command-line interface:

$ gnattest -Pprojname [ switches ] [ filename ] [ -cargs gcc_switches ]

where

  • -Pprojname
    specifies the project defining the location of source files. When no file names are provided on the command line, all sources in the project are used as input. This switch is required.
  • filename
    is the name of the source file containing the library unit package declaration (the package “spec”) for which a test package will be created. The file name may be given with a path.
  • switches
    is an optional sequence of switches as described below.
  • gcc_switches
    is a list of additional switches for gcc that will be passed to all compiler invocations made by gnattest to generate a set of ASIS trees.

gnattest results can be found in two different places.

  • automatic harness:

    This is the harness code, which is located by default in “gnattest/harness” directory created in the object directory of the main project file. All of this code is generated completely automatically and can be destroyed and regenerated at will, with the exception of the file gnattest_common.gpr, which is created if absent, but never overwritten. It is not recommended to modify other files manually, since these modifications will be lost if gnattest is re-run. The entry point in the harness code is the project file named test_driver.gpr. Tests can be compiled and run using a command such as:

    $ gprbuild -P<harness-dir>/test_driver
    

    Note that if you need to adjust any options used to compile the harness, you can do so by editing the file gnattest_common.gpr.

  • actual unit test skeletons:

    A test skeleton for each visible subprogram is created in a separate file, if it doesn’t exist already. By default, those separate test files are located in a “gnattest/tests” directory that is created in the object directory of corresponding project file. For example, if a source file my_unit.ads in directory src contains a visible subprogram Proc, then the corresponding unit test will be found in file src/tests/my_unit-test_data-tests.adb and will be called Test_Proc_<code>. <code> is a signature encoding used to differentiate test names in case of overloading.

    Note that if the project already has both my_unit.ads and my_unit-test_data.ads, this will cause a name conflict with the generated test package.

5.10.1.2. Test Execution Mode

In this mode gnattest has a the following command-line interface:

$ gnattest test_drivers.list [ switches ]

where

  • test_drivers.list
    is the name of the text file containing the list of executables to treat as test drivers. This file is automatically generated by gnattest, but can be hand-edited to add or remove tests. This switch is required.
  • switches
    is an optional sequence of switches as described below.

5.10.2. Switches for gnattest in framework generation mode

--strict
Return error exit code if there are any compilation errors.
-q
Quiet mode: suppresses noncritical output messages.
-v
Verbose mode: produces additional output about the execution of the tool. When specified alone on the command line, prints tool version and exits.
-r
Recursively considers all sources from all projects.
-files=filename
Take as arguments the files listed in text file file. Text file file may contain empty lines that are ignored. Each nonempty line should contain the name of an existing file. Several such switches may be specified simultaneously.
--RTS=rts-path
Specifies the default location of the runtime library. Same meaning as the equivalent gnatmake flag (Switches for gnatmake). For restricted profiles, gnattest takes into account the run-time limitations when generating the harness.
--additional-tests=projname
Sources described in projname are considered potential additional manual tests to be added to the test suite.
--harness-only
When this option is given, gnattest creates a harness for all sources, treating them as test packages. This option is not compatible with closure computation done by -U main.
--separate-drivers[=val]
Generates a separate test driver for each test or unit under test, rather than a single executable incorporating all tests. val can be “unit” or “test”, or may be omitted, which defaults to “unit”.
--stub
Generates the testing framework that uses subsystem stubbing to isolate the code under test.
--harness-dir=dirname
Specifies the directory that will hold the harness packages and project file for the test driver. If the dirname is a relative path, it is considered relative to the object directory of the project file.
--tests-dir=dirname
All test packages are placed in the dirname directory. If the dirname is a relative path, it is considered relative to the object directory of the project file. When all sources from all projects are taken recursively from all projects, dirname directories are created for each project in their object directories and test packages are placed accordingly.
--subdir=dirname
Test packages are placed in a subdirectory of the corresponding source directory, with the name dirname. Thus, each set of unit tests is located in a subdirectory of the code under test. If the sources are in separate directories, each source directory has a test subdirectory named dirname.
--tests-root=dirname
The hierarchy of source directories, if any, is recreated in the dirname directory, with test packages placed in directories corresponding to those of the sources. If the dirname is a relative path, it is considered relative to the object directory of the project file. When projects are considered recursively, directory hierarchies of tested sources are recreated for each project in their object directories and test packages are placed accordingly.
--stubs-dir=dirname
The hierarchy of directories containing stubbed units is recreated in the dirname directory, with stubs placed in directories corresponding to projects they are derived from. If the dirname is a relative path, it is considered relative to the object directory of the project file. When projects are considered recursively, directory hierarchies of stubs are recreated for each project in their object directories and test packages are placed accordingly.
--exclude-from-stubbing=filename
Disables stubbing of units listed in filename. The file should contain corresponding spec files, one per line.
--exclude-from-stubbing:unit=filename
Same as above, but corresponding units will not be stubbed only when testing specified unit.
--validate-type-extensions
Enables substitution check: run all tests from all parents in order to check substitutability in accordance with the Liskov substitution principle (LSP).
--inheritance-check
Enables inheritance check: run inherited tests against descendants.
--no-inheritance-check
Disables inheritance check.
--test-case-only
Generates test skeletons only for subprograms that have at least one associated pragma or aspect Test_Case.
--skeleton-default=val
Specifies the default behavior of generated skeletons. val can be either “fail” or “pass”, “fail” being the default.
--passed-tests=val
Specifies whether or not passed tests should be shown. val can be either “show” or “hide”, “show” being the default.
--exit-status=val
Specifies whether or not generated test driver should return failure exit status if at least one test fails or crashes. val can be either “on” or “off”, “off” being the default.
--omit-sloc
Suppresses comment line containing file name and line number of corresponding subprograms in test skeletons.
--no-command-line
Don’t add command line support to test driver. Note that regardless of this switch, gnattest will automatically refrain from adding command line support if it detects that the selected run-time doesn’t provide this capability.
--separates
Bodies of all test routines are generated as separates. Note that this mode is kept for compatibility reasons only and it is not advised to use it due to possible problems with hash in names of test skeletons when using an inconsistent casing. Separate test skeletons can be incorporated to monolith test package with improved hash being used by using --transition switch.
--transition
This allows transition from separate test routines to monolith test packages. All matching test routines are overwritten with contents of corresponding separates. Note that if separate test routines had any manually added with clauses they will be moved to the test package body as is and have to be moved by hand.
--test-duration
Adds time measurements for each test in generated test driver.

--tests_root, --subdir and --tests-dir switches are mutually exclusive.

5.10.3. Switches for gnattest in test execution mode

--passed-tests=val
Specifies whether or not passed tests should be shown. val can be either “show” or “hide”, “show” being the default.
--queues=n, -jn
Runs n tests in parallel (default is 1).

5.10.4. Project Attributes for gnattest

Most of the command-line options can also be passed to the tool by adding special attributes to the project file. Those attributes should be put in package Gnattest. Here is the list of attributes:

  • Tests_Root
    is used to select the same output mode as with the --tests-root option. This attribute cannot be used together with Subdir or Tests_Dir.
  • Subdir
    is used to select the same output mode as with the --subdir option. This attribute cannot be used together with Tests_Root or Tests_Dir.
  • Tests_Dir
    is used to select the same output mode as with the --tests-dir option. This attribute cannot be used together with Subdir or Tests_Root.
  • Harness_Dir
    is used to specify the directory in which to place harness packages and project file for the test driver, otherwise specified by --harness-dir.
  • Additional_Tests
    is used to specify the project file, otherwise given by --additional-tests switch.
  • Skeletons_Default
    is used to specify the default behaviour of test skeletons, otherwise specified by --skeleton-default option. The value of this attribute should be either pass or fail.
  • Default_Stub_Exclusion_List
    is used to specify the file with list of units whose bodies should not be stubbed, otherwise specified by --exclude-from-stubbing=filename.
  • Stub_Exclusion_List ("unit")
    is used to specify the file with list of units whose bodies should not be stubbed when testing “unit”, otherwise specified by --exclude-from-stubbing:unit=filename.

Each of those attributes can be overridden from the command line if needed. Other gnattest switches can also be passed via the project file as an attribute list called Gnattest_Switches.

5.10.5. Simple Example

Let’s take a very simple example using the first gnattest example located in:

<install_prefix>/share/examples/gnattest/simple

This project contains a simple package containing one subprogram. By running gnattest:

$ gnattest --harness-dir=driver -Psimple.gpr

a test driver is created in directory driver. It can be compiled and run:

$ cd obj/driver
$ gprbuild -Ptest_driver
$ test_runner

One failed test with the diagnosis “test not implemented” is reported. Since no special output option was specified, the test package Simple.Tests is located in:

<install_prefix>/share/examples/gnattest/simple/obj/gnattest/tests

For each package containing visible subprograms, a child test package is generated. It contains one test routine per tested subprogram. Each declaration of a test subprogram has a comment specifying which tested subprogram it corresponds to. Bodies of test routines are placed in test package bodies and are surrounded by special comment sections. Those comment sections should not be removed or modified in order for gnattest to be able to regenerate test packages and keep already written tests in place. The test routine Test_Inc_5eaee3 located at simple-test_data-tests.adb contains a single statement: a call to procedure Assert. It has two arguments: the Boolean expression we want to check and the diagnosis message to display if the condition is false.

That is where actual testing code should be written after a proper setup. An actual check can be performed by replacing the Assert call with:

Assert (Inc (1) = 2, "wrong incrementation");

After recompiling and running the test driver, one successfully passed test is reported.

5.10.6. Setting Up and Tearing Down the Testing Environment

Besides test routines themselves, each test package has a parent package Test_Data that has two procedures: Set_Up and Tear_Down. This package is never overwritten by the tool. Set_Up is called before each test routine of the package, and Tear_Down is called after each test routine. Those two procedures can be used to perform necessary initialization and finalization, memory allocation, etc. Test type declared in Test_Data package is parent type for the test type of test package and can have user-defined components whose values can be set by Set_Up routine and used in test routines afterwards.

5.10.7. Regenerating Tests

Bodies of test routines and Test_Data packages are never overridden after they have been created once. As long as the name of the subprogram, full expanded Ada names and order of its parameters are the same, and comment sections are intact, the old test routine will fit in its place and no test skeleton will be generated for the subprogram.

This can be demonstrated with the previous example. By uncommenting declaration and body of function Dec in simple.ads and simple.adb, running gnattest on the project, and then running the test driver:

$ gnattest --harness-dir=driver -Psimple.gpr
$ cd obj/driver
$ gprbuild -Ptest_driver
$ test_runner

The old test is not replaced with a stub, nor is it lost, but a new test skeleton is created for function Dec.

The only way of regenerating tests skeletons is to remove the previously created tests together with corresponding comment sections.

5.10.8. Default Test Behavior

The generated test driver can treat unimplemented tests in two ways: either count them all as failed (this is useful to see which tests are still left to implement) or as passed (to sort out unimplemented ones from those actually failing).

The test driver accepts a switch to specify this behavior: --skeleton-default=val, where val is either pass or fail (exactly as for gnattest).

The default behavior of the test driver is set with the same switch as passed to gnattest when generating the test driver.

Passing it to the driver generated on the first example:

$ test_runner --skeleton-default=pass

makes both tests pass, even the unimplemented one.

5.10.9. Testing Primitive Operations of Tagged Types

Creation of test skeletons for primitive operations of tagged types entails a number of features. Test routines for all primitives of a given tagged type are placed in a separate child package named according to the tagged type. For example, if you have tagged type T in package P, all tests for primitives of T will be in P.T_Test_Data.T_Tests.

Consider running gnattest on the second example (note: actual tests for this example already exist, so there’s no need to worry if the tool reports that no new stubs were generated):

$ cd <install_prefix>/share/examples/gnattest/tagged_rec
$ gnattest --harness-dir=driver -Ptagged_rec.gpr

Taking a closer look at the test type declared in the test package Speed1.Controller_Test_Data is necessary. It is declared in:

<install_prefix>/share/examples/gnattest/tagged_rec/obj/gnattest/tests

Test types are direct or indirect descendants of AUnit.Test_Fixtures.Test_Fixture type. In the case of non-primitive tested subprograms, the user doesn’t need to be concerned with them. However, when generating test packages for primitive operations, there are some things the user needs to know.

Type Test_Controller has components that allow assignment of various derivations of type Controller. And if you look at the specification of package Speed2.Auto_Controller, you will see that Test_Auto_Controller actually derives from Test_Controller rather than AUnit type Test_Fixture. Thus, test types mirror the hierarchy of tested types.

The Set_Up procedure of Test_Data package corresponding to a test package of primitive operations of type T assigns to Fixture a reference to an object of that exact type T. Note, however, that if the tagged type has discriminants, the Set_Up only has a commented template for setting up the fixture, since filling the discriminant with actual value is up to the user.

The knowledge of the structure of test types allows additional testing without additional effort. Those possibilities are described below.

5.10.10. Testing Inheritance

Since the test type hierarchy mimics the hierarchy of tested types, the inheritance of tests takes place. An example of such inheritance can be seen by running the test driver generated for the second example. As previously mentioned, actual tests are already written for this example.

$ cd obj/driver
$ gprbuild -Ptest_driver
$ test_runner

There are 6 passed tests while there are only 5 testable subprograms. The test routine for function Speed has been inherited and run against objects of the derived type.

5.10.11. Tagged Type Substitutability Testing

Tagged Type Substitutability Testing is a way of verifying the global type consistency by testing. Global type consistency is a principle stating that if S is a subtype of T (in Ada, S is a derived type of tagged type T), then objects of type T may be replaced with objects of type S (that is, objects of type S may be substituted for objects of type T), without altering any of the desirable properties of the program. When the properties of the program are expressed in the form of subprogram preconditions and postconditions (let’s call them pre and post), the principle is formulated as relations between the pre and post of primitive operations and the pre and post of their derived operations. The pre of a derived operation should not be stronger than the original pre, and the post of the derived operation should not be weaker than the original post. Those relations ensure that verifying if a dispatching call is safe can be done just by using the pre and post of the root operation.

Verifying global type consistency by testing consists of running all the unit tests associated with the primitives of a given tagged type with objects of its derived types.

In the example used in the previous section, there was clearly a violation of type consistency. The overriding primitive Adjust_Speed in package Speed2 removes the functionality of the overridden primitive and thus doesn’t respect the consistency principle. gnattest has a special option to run overridden parent tests against objects of the type which have overriding primitives:

$ gnattest --harness-dir=driver --validate-type-extensions -Ptagged_rec.gpr
$ cd obj/driver
$ gprbuild -Ptest_driver
$ test_runner

While all the tests pass by themselves, the parent test for Adjust_Speed fails against objects of the derived type.

Non-overridden tests are already inherited for derived test types, so the --validate-type-extensions enables the application of overridden tests to objects of derived types.

5.10.12. Testing with Contracts

gnattest supports pragmas Pre, Post, and Test_Case, as well as the corresponding Ada 2012 aspects. Test routines are generated, one per each Test_Case associated with a tested subprogram. Those test routines have special wrappers for tested functions that have composition of pre- and postcondition of the subprogram with “requires” and “ensures” of the Test_Case (depending on the mode, pre and post either count for Nominal mode or do not count for Robustness mode).

The third example demonstrates how this works:

$ cd <install_prefix>/share/examples/gnattest/contracts
$ gnattest --harness-dir=driver -Pcontracts.gpr

Putting actual checks within the range of the contract does not cause any error reports. For example, for the test routine which corresponds to test case 1:

Assert (Sqrt (9.0) = 3.0, "wrong sqrt");

and for the test routine corresponding to test case 2:

Assert (Sqrt (-5.0) = -1.0, "wrong error indication");

are acceptable:

$ cd obj/driver
$ gprbuild -Ptest_driver
$ test_runner

However, by changing 9.0 to 25.0 and 3.0 to 5.0, for example, you can get a precondition violation for test case one. Also, by using any otherwise correct but positive pair of numbers in the second test routine, you can also get a precondition violation. Postconditions are checked and reported the same way.

5.10.13. Additional Tests

gnattest can add user-written tests to the main suite of the test driver. gnattest traverses the given packages and searches for test routines. All procedures with a single in out parameter of a type which is derived from AUnit.Test_Fixtures.Test_Fixture and that are declared in package specifications are added to the suites and are then executed by the test driver. (Set_Up and Tear_Down are filtered out.)

An example illustrates two ways of creating test harnesses for user-written tests. Directory additional_tests contains an AUnit-based test driver written by hand.

<install_prefix>/share/examples/gnattest/additional_tests/

To create a test driver for already-written tests, use the --harness-only option:

gnattest -Padditional/harness/harness.gpr --harness-dir=harness_only \\
  --harness-only
gprbuild -Pharness_only/test_driver.gpr
harness_only/test_runner

Additional tests can also be executed together with generated tests:

gnattest -Psimple.gpr --additional-tests=additional/harness/harness.gpr \\
  --harness-dir=mixing
gprbuild -Pmixing/test_driver.gpr
mixing/test_runner

5.10.14. Individual Test Drivers

By default, gnattest generates a monolithic test driver that aggregates the individual tests into a single executable. It is also possible to generate separate executables for each test or each unit under test, by passing the switch --separate-drivers with corresponding parameter. This approach scales better for large testing campaigns, especially involving target architectures with limited resources typical for embedded development. It can also provide a major performance benefit on multi-core systems by allowing simultaneous execution of multiple tests.

gnattest can take charge of executing the individual tests; for this, instead of passing a project file, a text file containing the list of executables can be passed. Such a file is automatically generated by gnattest under the name test_drivers.list, but it can be hand-edited to add or remove tests, or replaced. The individual tests can also be executed standalone, or from any user-defined scripted framework.

5.10.15. Stubbing

Depending on the testing campaign, it is sometimes necessary to isolate the part of the algorithm under test from its dependencies. This is accomplished via stubbing, i.e. replacing the subprograms that are called from the subprogram under test by stand-in subprograms that match the profiles of the original ones, but simply return predetermined values required by the test scenario.

This mode of test harness generation is activated by the switch --stub.

The implementation approach chosen by gnattest is as follows. For each package under consideration all the packages it is directly depending on are stubbed, excluding the generic packages and package instantiations. The stubs are shared for each package under test. The specs of packages to stub remain intact, while their bodies are replaced, and hide the original bodies by means of extending projects. Also, for each stubbed package, a child package with setter routines for each subprogram declaration is created. These setters are meant to be used to set the behavior of stubbed subprograms from within test cases.

Note that subprograms belonging to the same package as the subprogram under test are not stubbed. This guarantees that the sources being tested are exactly the sources used for production, which is an important property for establishing the traceability between the testing campaign and production code.

Due to the nature of stubbing process, this mode implies the switch --separate-drivers, i.e. an individual test driver (with the corresponding hierarchy of extending projects) is generated for each unit under test.

Note

Developing a stubs-based testing campaign requires good understanding of the infrastructure created by gnattest for this purpose. We recommend following the two stubbing tutorials simple_stubbing and advanced_stubbing provided under <install_prefix>/share/examples/gnattest before attempting to use this powerful feature.

5.10.16. Integration with GNATcoverage

In addition to the harness, gnattest generates a Makefile. This Makefile provides targets for building the test drivers and also the targets for computing the coverage information using GNATcoverage framework when this coverage analysis tool is available. The target coverage fully automates the process: it will first build all test drivers, then run them under GNATcoverage, analyze individual trace files, and finally aggregate them:

make coverage

GNATcoverage options, such as coverage criteria and generated report format, can be adjusted using Makefile variables provided for this purpose.

Note that coverage targets are not generated in the Makefile when –separate-drivers=test is passed to gnattest.

5.10.17. Putting Tests under Version Control

As has been stated earlier, gnattest generates two different types of code, test skeletons and harness. The harness is generated completely automatically each time, does not require manual changes and therefore should not be put under version control. It makes sense to put under version control files containing test data packages, both specs and bodies, and files containing bodies of test packages. Note that test package specs are also generated automatically each time and should not be put under version control. Option --omit-sloc may be useful when putting test packages under version control.

5.10.18. Current Limitations

The tool currently has the following limitations:

  • generic tests for nested generic packages and their instantiations are not supported;
  • tests for protected subprograms and entries are not supported;
  • pragma No_Run_Time is not supported;
  • pragma No_Secondary_Stack is not supported;
  • if pragmas for interfacing with foreign languages are used, manual adjustments might be necessary to make the test harness compilable;
  • use of some constructs, such as elaboration-control pragmas, Type_Invariant aspects, and complex variable initializations that use Subprogram’Access, may result in elaboration circularities in the generated harness.

5.11. Using Project Files with GNAT Tools

This section describes how project files can be used in conjunction with a number of GNAT tools. For a comprehensive description of project files and the overall GNAT Project Manager facility, please refer to the GNAT Project Manager chapter in the GPRbuild and GPR Companion Tools User’s Guide.

If a tool can take a project file as an option and extract the needed information, such a tool is called a project-aware tool.

5.11.2. Tool-specific packages in project files

Each project-aware tool may have a corresponding package in a project file; the package names are given elsewhere in this manual, in the sections that describe the respective tools.

A tool-specific package in a project file may define the Default_Switches attribute indexed by “ada” (as language name). The value of this attribute is a list of switches that will be supplied at tool invocation. Project-specific switches cannot be specified through this attribute.