| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT COMPILER COMPONENTS -- |
| -- -- |
| -- E L I S T S -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- $Revision: 1.14 $ -- |
| -- -- |
| -- 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. -- |
| -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- 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; |
