171 lines
8.4 KiB
Ada
171 lines
8.4 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- E L I S T S --
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-- --
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-- S p e c --
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-- --
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-- --
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-- Copyright (C) 1992-1998 Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 2, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
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-- MA 02111-1307, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package provides facilities for manipulating lists of nodes (see
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-- package Atree for format and implementation of tree nodes). Separate list
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-- elements are allocated to represent elements of these lists, so it is
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-- possible for a given node to be on more than one element list at a time.
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-- See also package Nlists, which provides another form that is threaded
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-- through the nodes themselves (using the Link field), which is more time
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-- and space efficient, but a node can be only one such list.
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with Types; use Types;
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with System;
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package Elists is
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-- An element list is represented by a header that is allocated in the
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-- Elist header table. This header contains pointers to the first and
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-- last elements in the list, or to No_Elmt if the list is empty.
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-- The elements in the list each contain a pointer to the next element
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-- and a pointer to the referenced node. Putting a node into an element
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-- list causes no change at all to the node itself, so a node may be
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-- included in multiple element lists, and the nodes thus included may
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-- or may not be elements of node lists (see package Nlists).
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procedure Initialize;
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-- Initialize allocation of element list tables. Called at the start of
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-- compiling each new main source file. Note that Initialize must not be
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-- called if Tree_Read is used.
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procedure Lock;
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-- Lock tables used for element lists before calling backend
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procedure Tree_Read;
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-- Initializes internal tables from current tree file using Tree_Read.
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-- Note that Initialize should not be called if Tree_Read is used.
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-- Tree_Read includes all necessary initialization.
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procedure Tree_Write;
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-- Writes out internal tables to current tree file using Tree_Write
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function Last_Elist_Id return Elist_Id;
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-- Returns Id of last allocated element list header
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function Elists_Address return System.Address;
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-- Return address of Elists table (used in Back_End for Gigi call)
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function Num_Elists return Nat;
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-- Number of currently allocated element lists
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function Last_Elmt_Id return Elmt_Id;
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-- Returns Id of last allocated list element
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function Elmts_Address return System.Address;
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-- Return address of Elmts table (used in Back_End for Gigi call)
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function Node (Elmt : Elmt_Id) return Node_Id;
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pragma Inline (Node);
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-- Returns the value of a given list element. Returns Empty if Elmt
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-- is set to No_Elmt.
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function New_Elmt_List return Elist_Id;
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-- Creates a new empty element list. Typically this is used to initialize
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-- a field in some other node which points to an element list where the
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-- list is then subsequently filled in using Append calls.
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function First_Elmt (List : Elist_Id) return Elmt_Id;
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pragma Inline (First_Elmt);
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-- Obtains the first element of the given element list or, if the
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-- list has no items, then No_Elmt is returned.
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function Last_Elmt (List : Elist_Id) return Elmt_Id;
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pragma Inline (Last_Elmt);
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-- Obtains the last element of the given element list or, if the
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-- list has no items, then No_Elmt is returned.
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function Next_Elmt (Elmt : Elmt_Id) return Elmt_Id;
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pragma Inline (Next_Elmt);
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-- This function returns the next element on an element list. The argument
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-- must be a list element other than No_Elmt. Returns No_Elmt if the given
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-- element is the last element of the list.
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procedure Next_Elmt (Elmt : in out Elmt_Id);
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pragma Inline (Next_Elmt);
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-- Next_Elmt (Elmt) is equivalent to Elmt := Next_Elmt (Elmt)
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function Is_Empty_Elmt_List (List : Elist_Id) return Boolean;
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pragma Inline (Is_Empty_Elmt_List);
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-- This function determines if a given tree id references an element list
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-- that contains no items.
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procedure Append_Elmt (Node : Node_Id; To : Elist_Id);
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-- Appends Node at the end of To, allocating a new element.
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procedure Prepend_Elmt (Node : Node_Id; To : Elist_Id);
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-- Appends Node at the beginning of To, allocating a new element.
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procedure Insert_Elmt_After (Node : Node_Id; Elmt : Elmt_Id);
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-- Add a new element (Node) right after the pre-existing element Elmt
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-- It is invalid to call this subprogram with Elmt = No_Elmt.
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procedure Replace_Elmt (Elmt : Elmt_Id; New_Node : Node_Id);
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pragma Inline (Replace_Elmt);
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-- Causes the given element of the list to refer to New_Node, the node
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-- which was previously referred to by Elmt is effectively removed from
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-- the list and replaced by New_Node.
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procedure Remove_Elmt (List : Elist_Id; Elmt : Elmt_Id);
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-- Removes Elmt from the given list. The node itself is not affected,
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-- but the space used by the list element may be (but is not required
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-- to be) freed for reuse in a subsequent Append_Elmt call.
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procedure Remove_Last_Elmt (List : Elist_Id);
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-- Removes the last element of the given list. The node itself is not
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-- affected, but the space used by the list element may be (but is not
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-- required to be) freed for reuse in a subsequent Append_Elmt call.
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function No (List : Elist_Id) return Boolean;
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pragma Inline (No);
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-- Tests given Id for equality with No_Elist. This allows notations like
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-- "if No (Statements)" as opposed to "if Statements = No_Elist".
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function Present (List : Elist_Id) return Boolean;
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pragma Inline (Present);
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-- Tests given Id for inequality with No_Elist. This allows notations like
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-- "if Present (Statements)" as opposed to "if Statements /= No_Elist".
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function No (Elmt : Elmt_Id) return Boolean;
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pragma Inline (No);
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-- Tests given Id for equality with No_Elmt. This allows notations like
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-- "if No (Operation)" as opposed to "if Operation = No_Elmt".
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function Present (Elmt : Elmt_Id) return Boolean;
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pragma Inline (Present);
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-- Tests given Id for inequality with No_Elmt. This allows notations like
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-- "if Present (Operation)" as opposed to "if Operation /= No_Elmt".
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end Elists;
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