gcc/ada/exp_imgv.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             E X P _ I M G V                              --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 2000-2023, 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 ------------------------------------------------------------------------------
  25
  26 --  Expand routines for Image, Value and Width attributes. These are the
  27 --  attributes that make use of enumeration type image tables.
  28
  29 with Types; use Types;
  30
  31 package Exp_Imgv is
  32
  33    procedure Build_Enumeration_Image_Tables (E : Entity_Id; N : Node_Id);
  34    --  Build the enumeration image tables for E, which is an enumeration
  35    --  base type. The node N is the point in the tree where the resulting
  36    --  declarations are to be inserted.
  37    --
  38    --  The form of the tables generated is as follows:
  39    --
  40    --    xxxS : constant string (1 .. M) := "chars";
  41    --    xxxN : constant array (0 .. N) of Index_Type := (i1, i2, .., iN, j);
  42    --
  43    --  Here xxxS is a string obtained by concatenating all the names of the
  44    --  enumeration literals in sequence, representing any wide characters
  45    --  according to the current wide character encoding method, and with all
  46    --  letters forced to upper case.
  47    --
  48    --  The array xxxN is an array of indexes into xxxS pointing to the start
  49    --  of each name, with one extra entry at the end, which is the index to
  50    --  the character just past the end of the last literal, i.e. it is the
  51    --  length of xxxS + 1. The element type is the shortest of the possible
  52    --  types that will hold all the values.
  53    --
  54    --  For example, for the type
  55    --
  56    --     type x is (hello,'!',goodbye);
  57    --
  58    --  the generated tables would consist of
  59    --
  60    --      xxxS : constant string (1 .. 15) := "hello'!'goodbye";
  61    --      xxxN : constant array (0 .. 3) of Integer_8 := (1, 6, 9, 16);
  62    --
  63    --  Here Integer_8 is used since 16 < 2**(8-1).
  64    --
  65    --  If the entity E needs the tables, the necessary declarations are built
  66    --  and the fields Lit_Strings and Lit_Indexes of E are set to point to the
  67    --  corresponding entities. If no tables are needed (E is not a user defined
  68    --  enumeration root type, or pragma Discard_Names is in effect), then the
  69    --  declarations are not constructed and the fields remain Empty.
  70    --
  71    --  If the number of enumeration literals is large enough, a (perfect) hash
  72    --  function mapping the literals to their position number is also built and
  73    --  requires additional tables. See the System.Perfect_Hash_Generators unit
  74    --  for a complete description of this processing.
  75
  76    procedure Expand_Image_Attribute (N : Node_Id);
  77    --  This procedure is called from Exp_Attr to expand an occurrence of the
  78    --  attribute Image.
  79
  80    procedure Expand_Wide_Image_Attribute (N : Node_Id);
  81    --  This procedure is called from Exp_Attr to expand an occurrence of the
  82    --  attribute Wide_Image.
  83
  84    procedure Expand_Wide_Wide_Image_Attribute (N : Node_Id);
  85    --  This procedure is called from Exp_Attr to expand an occurrence of the
  86    --  attribute Wide_Wide_Image.
  87
  88    procedure Expand_Valid_Value_Attribute (N : Node_Id);
  89    --  This procedure is called from Exp_Attr to expand an occurrence of the
  90    --  attribute Valid_Value.
  91
  92    procedure Expand_Value_Attribute (N : Node_Id);
  93    --  This procedure is called from Exp_Attr to expand an occurrence of the
  94    --  attribute Value.
  95
  96    type Atype is (Normal, Wide, Wide_Wide);
  97    --  Type of attribute in call to Expand_Width_Attribute
  98
  99    procedure Expand_Width_Attribute (N : Node_Id; Attr : Atype := Normal);
 100    --  This procedure is called from Exp_Attr to expand an occurrence of the
 101    --  attributes Width (Attr = Normal), or Wide_Width (Attr Wide), or
 102    --  Wide_Wide_Width (Attr = Wide_Wide).
 103
 104 end Exp_Imgv;