2013-07-09 Tim Shen <timshen91@gmail.com>
[official-gcc.git] / gcc / ada / prj-ext.ads
blob01719cf45fb1529746c344fc0d88d0b84c425507
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- P R J . E X T --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 2000-2011, Free Software Foundation, Inc. --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
26 -- Subprograms to set, get and cache external references, to be used as
27 -- External functions in project files.
29 with GNAT.Dynamic_HTables;
31 package Prj.Ext is
33 -------------------------
34 -- External References --
35 -------------------------
37 -- External references influence the way a project tree is processed (in
38 -- particular they provide the values for the typed string variables that
39 -- are then used in case constructions).
41 -- External references are project-tree specific, so that when multiple
42 -- trees are loaded in parallel we can have different scenarios (or even
43 -- load the same tree twice and see different views of it).
45 type External_References is private;
46 No_External_Refs : constant External_References;
48 procedure Initialize
49 (Self : out External_References;
50 Copy_From : External_References := No_External_Refs);
51 -- Initialize Self, and copy all values from Copy_From if needed.
52 -- This has no effect if Self was already initialized.
54 procedure Free (Self : in out External_References);
55 -- Free memory used by Self
57 type External_Source is
58 (From_Command_Line,
59 From_Environment,
60 From_External_Attribute);
61 -- Indicates where was the value of an external reference defined. They are
62 -- prioritized in that order, so that a user can always use the command
63 -- line to override a value coming from his environment, or an environment
64 -- variable to override a value defined in an aggregate project through the
65 -- "for External()..." attribute.
67 procedure Add
68 (Self : External_References;
69 External_Name : String;
70 Value : String;
71 Source : External_Source := External_Source'First);
72 -- Add an external reference (or modify an existing one). No overriding is
73 -- done if the Source's priority is less than the one used to previously
74 -- set the value of the variable. The default for Source is such that
75 -- overriding always occurs.
77 function Value_Of
78 (Self : External_References;
79 External_Name : Name_Id;
80 With_Default : Name_Id := No_Name)
81 return Name_Id;
82 -- Get the value of an external reference, and cache it for future uses
84 function Check
85 (Self : External_References;
86 Declaration : String) return Boolean;
87 -- Check that an external declaration <external>=<value> is correct.
88 -- If it is correct, the external reference is Added.
90 procedure Reset (Self : External_References);
91 -- Clear the internal data structure that stores the external references
92 -- and free any allocated memory.
94 private
95 -- Use a Static_HTable, rather than a Simple_HTable
97 -- The issue is that we need to be able to copy the contents of the table
98 -- (in Initialize), but this isn't doable for Simple_HTable for which
99 -- iterators do not return the key.
101 type Name_To_Name;
102 type Name_To_Name_Ptr is access all Name_To_Name;
103 type Name_To_Name is record
104 Key : Name_Id;
105 Value : Name_Id;
106 Source : External_Source;
107 Next : Name_To_Name_Ptr;
108 end record;
110 procedure Set_Next (E : Name_To_Name_Ptr; Next : Name_To_Name_Ptr);
111 function Next (E : Name_To_Name_Ptr) return Name_To_Name_Ptr;
112 function Get_Key (E : Name_To_Name_Ptr) return Name_Id;
114 package Name_To_Name_HTable is new GNAT.Dynamic_HTables.Static_HTable
115 (Header_Num => Header_Num,
116 Element => Name_To_Name,
117 Elmt_Ptr => Name_To_Name_Ptr,
118 Null_Ptr => null,
119 Set_Next => Set_Next,
120 Next => Next,
121 Key => Name_Id,
122 Get_Key => Get_Key,
123 Hash => Hash,
124 Equal => "=");
125 -- General type for htables associating name_id to name_id. This is in
126 -- particular used to store the values of external references.
128 type Instance_Access is access all Name_To_Name_HTable.Instance;
130 type External_References is record
131 Refs : Instance_Access;
132 -- External references are stored in this hash table (and manipulated
133 -- through subprogrames in prj-ext.ads). External references are
134 -- project-tree specific so that one can load the same tree twice but
135 -- have two views of it, for instance.
136 end record;
138 No_External_Refs : constant External_References := (Refs => null);
140 end Prj.Ext;