17. Projects: manipulating gpr files

The package GNATCOLL.Projects provides an extensive interface to parse, manipulate and edit project files (.gpr files).

Although the interface is best used using the Ada05 notation, it is fully compatible with Ada95.

Here is a quick example on how to use the interface, although the spec file itself contains much more detailed information on all the subprograms related to the manipulation of project files:

pragma Ada_05;
with GNATCOLL.Projects; use GNATCOLL.Projects;
with GNATCOLL.VFS;      use GNATCOLL.VFS;

procedure Test_Project is
   Tree  : Project_Tree;
   Files : File_Array_Access;
begin
   Tree.Load (GNATCOLL.VFS.Create (+"path_to_project.gpr"));

   --  List the source files for project and all imported projects

   Files := Tree.Root_Project.Source_Files (Recursive => True);
   for F in Files'Range loop
      Put_Line ("File is: " & Files (F).Display_Full_Name);
   end loop;

   Tree.Unload;
end Test_Project;

17.1. Defining a project with user-defined packages and reading them.

If you want to use GNATCOLL.Projects with a GPR file that contains specific packages and attributes, you must procede in several steps. The following example will show you how to do it:

pragma Ada_05;
with GNATCOLL.Projects; use GNATCOLL.Projects;
with GNATCOLL.VFS;      use GNATCOLL.VFS;

procedure Test_Project is
   Tree  : Project_Tree;
   Virtual_File : VFS; --  We assume it points to a valid file.
begin
   --  1
   Register_New_Attribute ("String", "Package_Name");
   Register_New_Attribute ("List", "Package_Name", Is_List => True);
   Register_New_Attribute ("Index", "Package_Name", Is_Index => True);

   --  2
   Tree.Load (Root_Project_Path => VFS,
              Packages_To_Check => All_Packs);

    declare --  3
      String_Attribute := constant Attribute_Pkg_String :=
              Build ("string", "package_name")

      Index_Attribute := constant Attribute_Pkg_List :=
              Build ("index", "package_name")

      List_Attribute := constant Attribute_Pkg_List :=
              Build ("list", "package_name")
   begin --  4
      for Val in Tree.Root_Project.Attribute_Value (List_Attribute).all loop
              Put_Line ("Value:" & Val.all);
      end loop;

      declare
         Indexed_Value : constant String := Tree.Root_Project.
            Attribute_Value (Index_Attribute, Index => "Index").all
      begin
         Put_Line ("Indexed_Value:" & Indexed_Value);
      end;
   end;
end Test_Project;

Step 1: We register all the attributes that we want for a given package.

If the package does not already exists it is created.

Step 2: We load the project into the projects hierarchy. We tell Tree.Load to

check all packages otherwise it will not load any packages.

Step 3: We read the Attributes from the project. An attribute can be an

Attribute_Pkg_String (representing a plain string) or an Attribute_Pkg_List (representing a list or an index).

Step 4: We can do something with those values. Here we print the plain string

and the content of the list, aswell as an indexed value from the index.