------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- E L I S T S -- -- -- -- S p e c -- -- -- -- Copyright (C) 1992-2019, 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 3, 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. -- -- -- -- As a special exception under Section 7 of GPL version 3, you are granted -- -- additional permissions described in the GCC Runtime Library Exception, -- -- version 3.1, as published by the Free Software Foundation. -- -- -- -- You should have received a copy of the GNU General Public License and -- -- a copy of the GCC Runtime Library Exception along with this program; -- -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- -- . -- -- -- -- 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. -- WARNING: There is a C version of this package. Any changes to this -- source file must be properly reflected in the C header file elists.h 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 Unlock; -- Unlock list tables, in cases where the back end needs to modify them procedure Tree_Read; -- Initializes internal tables from current tree file using the relevant -- Table.Tree_Read routines. 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 the relevant -- Table.Tree_Write routines. 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_Or_Entity_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 List_Length (List : Elist_Id) return Nat; -- Returns number of elements in given List (zero if List = No_Elist) 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 (N : Node_Or_Entity_Id; To : Elist_Id); -- Appends N at the end of To, allocating a new element. N must be a -- non-empty node or entity Id, and To must be an Elist (not No_Elist). procedure Append_New_Elmt (N : Node_Or_Entity_Id; To : in out Elist_Id); pragma Inline (Append_New_Elmt); -- Like Append_Elmt if Elist_Id is not No_List, but if Elist_Id is No_List, -- then first assigns it an empty element list and then does the append. procedure Append_Unique_Elmt (N : Node_Or_Entity_Id; To : Elist_Id); -- Like Append_Elmt, except that a check is made to see if To already -- contains N and if so the call has no effect. procedure Prepend_Elmt (N : Node_Or_Entity_Id; To : Elist_Id); -- Appends N at the beginning of To, allocating a new element procedure Prepend_Unique_Elmt (N : Node_Or_Entity_Id; To : Elist_Id); -- Like Prepend_Elmt, except that a check is made to see if To already -- contains N and if so the call has no effect. procedure Insert_Elmt_After (N : Node_Or_Entity_Id; Elmt : Elmt_Id); -- Add a new element (N) right after the pre-existing element Elmt -- It is invalid to call this subprogram with Elmt = No_Elmt. function New_Copy_Elist (List : Elist_Id) return Elist_Id; -- Replicate the contents of a list. Internal list nodes are not shared and -- order of elements is preserved. procedure Replace_Elmt (Elmt : Elmt_Id; New_Node : Node_Or_Entity_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 (List : Elist_Id; N : Node_Or_Entity_Id); -- Remove a node or an entity from a list. If the list does not contain the -- item in question, the routine has no effect. 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 Contains (List : Elist_Id; N : Node_Or_Entity_Id) return Boolean; -- Perform a sequential search to determine whether the given list contains -- a node or an entity. 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;