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