gcc/ada/elists.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                               E L I S T S                                --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2009, 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.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This package provides facilities for manipulating lists of nodes (see
  33 --  package Atree for format and implementation of tree nodes). Separate list
  34 --  elements are allocated to represent elements of these lists, so it is
  35 --  possible for a given node to be on more than one element list at a time.
  36 --  See also package Nlists, which provides another form that is threaded
  37 --  through the nodes themselves (using the Link field), which is more time
  38 --  and space efficient, but a node can be only one such list.
  39
  40 with Types;  use Types;
  41 with System;
  42
  43 package Elists is
  44
  45    --  An element list is represented by a header that is allocated in the
  46    --  Elist header table. This header contains pointers to the first and
  47    --  last elements in the list, or to No_Elmt if the list is empty.
  48
  49    --  The elements in the list each contain a pointer to the next element
  50    --  and a pointer to the referenced node. Putting a node into an element
  51    --  list causes no change at all to the node itself, so a node may be
  52    --  included in multiple element lists, and the nodes thus included may
  53    --  or may not be elements of node lists (see package Nlists).
  54
  55    procedure Initialize;
  56    --  Initialize allocation of element list tables. Called at the start of
  57    --  compiling each new main source file. Note that Initialize must not be
  58    --  called if Tree_Read is used.
  59
  60    procedure Lock;
  61    --  Lock tables used for element lists before calling backend
  62
  63    procedure Unlock;
  64    --  Unlock list tables, in cases where the back end needs to modify them
  65
  66    procedure Tree_Read;
  67    --  Initializes internal tables from current tree file using the relevant
  68    --  Table.Tree_Read routines. Note that Initialize should not be called if
  69    --  Tree_Read is used. Tree_Read includes all necessary initialization.
  70
  71    procedure Tree_Write;
  72    --  Writes out internal tables to current tree file using the relevant
  73    --  Table.Tree_Write routines.
  74
  75    function Last_Elist_Id return Elist_Id;
  76    --  Returns Id of last allocated element list header
  77
  78    function Elists_Address return System.Address;
  79    --  Return address of Elists table (used in Back_End for Gigi call)
  80
  81    function Num_Elists return Nat;
  82    --  Number of currently allocated element lists
  83
  84    function Last_Elmt_Id return Elmt_Id;
  85    --  Returns Id of last allocated list element
  86
  87    function Elmts_Address return System.Address;
  88    --  Return address of Elmts table (used in Back_End for Gigi call)
  89
  90    function Node (Elmt : Elmt_Id) return Node_Or_Entity_Id;
  91    pragma Inline (Node);
  92    --  Returns the value of a given list element. Returns Empty if Elmt
  93    --  is set to No_Elmt.
  94
  95    function New_Elmt_List return Elist_Id;
  96    --  Creates a new empty element list. Typically this is used to initialize
  97    --  a field in some other node which points to an element list where the
  98    --  list is then subsequently filled in using Append calls.
  99
 100    function First_Elmt (List : Elist_Id) return Elmt_Id;
 101    pragma Inline (First_Elmt);
 102    --  Obtains the first element of the given element list or, if the list has
 103    --  no items, then No_Elmt is returned.
 104
 105    function Last_Elmt (List : Elist_Id) return Elmt_Id;
 106    pragma Inline (Last_Elmt);
 107    --  Obtains the last element of the given element list or, if the list has
 108    --  no items, then No_Elmt is returned.
 109
 110    function Next_Elmt (Elmt : Elmt_Id) return Elmt_Id;
 111    pragma Inline (Next_Elmt);
 112    --  This function returns the next element on an element list. The argument
 113    --  must be a list element other than No_Elmt. Returns No_Elmt if the given
 114    --  element is the last element of the list.
 115
 116    procedure Next_Elmt (Elmt : in out Elmt_Id);
 117    pragma Inline (Next_Elmt);
 118    --  Next_Elmt (Elmt) is equivalent to Elmt := Next_Elmt (Elmt)
 119
 120    function Is_Empty_Elmt_List (List : Elist_Id) return Boolean;
 121    pragma Inline (Is_Empty_Elmt_List);
 122    --  This function determines if a given tree id references an element list
 123    --  that contains no items.
 124
 125    procedure Append_Elmt (N : Node_Or_Entity_Id; To : Elist_Id);
 126    --  Appends N at the end of To, allocating a new element. N must be a
 127    --  non-empty node or entity Id, and To must be an Elist (not No_Elist).
 128
 129    procedure Append_Unique_Elmt (N : Node_Or_Entity_Id; To : Elist_Id);
 130    --  Like Append_Elmt, except that a check is made to see if To already
 131    --  contains N and if so the call has no effect.
 132
 133    procedure Prepend_Elmt (N : Node_Or_Entity_Id; To : Elist_Id);
 134    --  Appends N at the beginning of To, allocating a new element
 135
 136    procedure Insert_Elmt_After (N : Node_Or_Entity_Id; Elmt : Elmt_Id);
 137    --  Add a new element (N) right after the pre-existing element Elmt
 138    --  It is invalid to call this subprogram with Elmt = No_Elmt.
 139
 140    procedure Replace_Elmt (Elmt : Elmt_Id; New_Node : Node_Or_Entity_Id);
 141    pragma Inline (Replace_Elmt);
 142    --  Causes the given element of the list to refer to New_Node, the node
 143    --  which was previously referred to by Elmt is effectively removed from
 144    --  the list and replaced by New_Node.
 145
 146    procedure Remove_Elmt (List : Elist_Id; Elmt : Elmt_Id);
 147    --  Removes Elmt from the given list. The node itself is not affected,
 148    --  but the space used by the list element may be (but is not required
 149    --  to be) freed for reuse in a subsequent Append_Elmt call.
 150
 151    procedure Remove_Last_Elmt (List : Elist_Id);
 152    --  Removes the last element of the given list. The node itself is not
 153    --  affected, but the space used by the list element may be (but is not
 154    --  required to be) freed for reuse in a subsequent Append_Elmt call.
 155
 156    function No (List : Elist_Id) return Boolean;
 157    pragma Inline (No);
 158    --  Tests given Id for equality with No_Elist. This allows notations like
 159    --  "if No (Statements)" as opposed to "if Statements = No_Elist".
 160
 161    function Present (List : Elist_Id) return Boolean;
 162    pragma Inline (Present);
 163    --  Tests given Id for inequality with No_Elist. This allows notations like
 164    --  "if Present (Statements)" as opposed to "if Statements /= No_Elist".
 165
 166    function No (Elmt : Elmt_Id) return Boolean;
 167    pragma Inline (No);
 168    --  Tests given Id for equality with No_Elmt. This allows notations like
 169    --  "if No (Operation)" as opposed to "if Operation = No_Elmt".
 170
 171    function Present (Elmt : Elmt_Id) return Boolean;
 172    pragma Inline (Present);
 173    --  Tests given Id for inequality with No_Elmt. This allows notations like
 174    --  "if Present (Operation)" as opposed to "if Operation /= No_Elmt".
 175
 176 end Elists;