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Text File | 1996-09-28 | 13KB | 268 lines

------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- N L I S T S -- -- -- -- S p e c -- -- -- -- $Revision: 1.14 $ -- -- -- -- Copyright (c) 1992,1993,1994,1995 NYU, All Rights Reserved -- -- -- -- The GNAT library is free software; you can redistribute it and/or modify -- -- it under terms of the GNU Library General Public License as published by -- -- the Free Software Foundation; either version 2, or (at your option) any -- -- later version. The GNAT library is distributed in the hope that it will -- -- be useful, but WITHOUT ANY WARRANTY; without even the implied warranty -- -- of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU -- -- Library General Public License for more details. You should have -- -- received a copy of the GNU Library General Public License along with -- -- the GNAT library; see the file COPYING.LIB. If not, write to the Free -- -- Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. -- -- -- ------------------------------------------------------------------------------ -- This package provides facilities for manipulating lists of nodes (see -- package Atree for format and implementation of tree nodes). The Link field -- of the nodes is used as the forward pointer for these lists. See also -- package Elists which provides another form of lists that are not threaded -- through the nodes (and therefore allow nodes to be on multiple lists). with System; with Types; use Types; package Nlists is -- A node list is a list that is threaded through nodes (using the Link -- field). This means that it takes minimum space, but a node can be on -- at most one such node list. For each node list, a list header is -- allocated in the lists table, and a List_Id value references this -- header which may be used to access the nodes in the list using the -- set of routines that define the interface. -- Note: node lists can contain either nodes or entities (extended nodes) -- or a mixture of nodes and extended nodes. function Last_List_Id return List_Id; pragma Inline (Last_List_Id); -- Returns Id of last allocated list header function Lists_Address return System.Address; pragma Inline (Lists_Address); -- Return address of Lists table (used in Back_End for Gigi call) function Num_Lists return Nat; pragma Inline (Num_Lists); -- Number of currently allocated lists function New_List return List_Id; -- Creates a new empty node list. Typically this is used to initialize -- a field in some other node which points to a node list where the list -- is then subsequently filled in using Append calls. function Empty_List return List_Id renames New_List; -- Used in contexts where an empty list (as opposed to an initially empty -- list to be filled in) is required. function New_List (Node : Node_Id) return List_Id; -- Build a new list initially containing the given node function New_List (Node1, Node2 : Node_Id) return List_Id; -- Build a new list initially containing the two given nodes function New_List (Node1, Node2, Node3 : Node_Id) return List_Id; -- Build a new list initially containing the three given nodes function New_List (Node1, Node2, Node3, Node4 : Node_Id) return List_Id; -- Build a new list initially containing the four given nodes function New_List (Node1 : Node_Id; Node2 : Node_Id; Node3 : Node_Id; Node4 : Node_Id; Node5 : Node_Id) return List_Id; -- Build a new list initially containing the five given nodes function New_List (Node1 : Node_Id; Node2 : Node_Id; Node3 : Node_Id; Node4 : Node_Id; Node5 : Node_Id; Node6 : Node_Id) return List_Id; -- Build a new list initially containing the five given nodes function New_List_Copy (List : List_Id) return List_Id; -- Creates a new list containing copies (made with Atree.New_Copy) of every -- node in the original list. If the argument is No_List, then the returned -- result is No_List. If the argument is an empty list, then the returned -- result is a new empty list. function New_List_Copy_Tree (List : List_Id) return List_Id; -- Similar to New_List_Copy, except that the copies are done using the -- Atree.New_Copy_Tree function, which means that a full recursive copy -- of the subtrees in the list is performed, setting proper parents. As -- for New_Copy_Tree, it is illegal to attempt to copy extended nodes -- (entities) either directly or indirectly using this function. function First (List : List_Id) return Node_Id; pragma Inline (First); -- Obtains the first element of the given node list or, if the node list -- has no items, then Empty is returned. It is an error to call First with -- a Node_Id value or No_List. (No_List is not considered to be the same as -- an empty node list). function Last (List : List_Id) return Node_Id; pragma Inline (Last); -- Obtains the last element of the given node list or, if the node list -- has no items, then Empty is returned. It is an error to call Last with -- a Node_Id or No_List. (No_List is not considered to be the same as an -- empty node list). function List_Length (List : List_Id) return Nat; pragma Inline (List_Length); -- Returns number of items in the given list function Next (Node : Node_Id) return Node_Id; pragma Inline (Next); -- This function returns the next node on a node list, or Empty if Node is -- the last element of the node list. The argument must be a member of a -- node list. function Prev (Node : Node_Id) return Node_Id; pragma Inline (Prev); -- This function returns the previous node on a node list list, or Empty if -- Node is the first element of the node list. The argument must be a -- member of a node list. Note that the implementation does not maintain -- back pointers, so this function potentially requires traversal of the -- entire list, or more accurately of the part of the list preceding Node. function Is_Empty_List (List : List_Id) return Boolean; pragma Inline (Is_Empty_List); -- This function determines if a given list id references a node list that -- contains no items. No_List is a not a legitimate argument. function Is_Non_Empty_List (List : List_Id) return Boolean; pragma Inline (Is_Non_Empty_List); -- This function determines if a given list id references a node list that -- contains at least one item. No_List as an argument returns False. function Is_List_Member (Node : Node_Id) return Boolean; pragma Inline (Is_List_Member); -- This function determines if a given node is a member of a node list. -- It is an error for Node to be Empty, or to be a node list. function List_Containing (Node : Node_Id) return List_Id; pragma Inline (List_Containing); -- This function provides a pointer to the node list containing Node. -- Node must be a member of a node list. procedure Append (Node : Node_Id; To : List_Id); -- Appends Node at the end of node list To. Node must be a non-empty node -- that is not already a member of a node list, and To must be a -- node list. An attempt to append an error node is ignored without -- complaint and the list is unchanged. procedure Append_To (To : List_Id; Node : Node_Id); pragma Inline (Append_To); -- Like Append, but arguments are the other way round procedure Append_List (List : List_Id; To : List_Id); -- Appends node list List to the end of node list To. On return, -- List is reset to be empty. procedure Append_List_To (To : List_Id; List : List_Id); pragma Inline (Append_List_To); -- Like Append_List, but arguments are the other way round procedure Insert_After (After : Node_Id; Node : Node_Id); -- Insert Node, which must be a non-empty node that is not already a -- member of a node list, immediately past node After, which must be a -- node that is currently a member of a node list. An attempt to insert -- an error node is ignored without complaint (and the list is unchanged). procedure Insert_List_After (After : Node_Id; List : List_Id); -- Inserts the entire contents of node list List immediately after node -- After, which must be a member of a node list. On return, the node list -- List is reset to be the empty node list. procedure Insert_Before (Before : Node_Id; Node : Node_Id); -- Insert Node, which must be a non-empty node that is not already a -- member of a node list, immediately before Before, which must be a node -- that is currently a member of a node list. An attempt to insert an -- error node is ignored without complaint (and the list is unchanged). procedure Insert_List_Before (Before : Node_Id; List : List_Id); -- Inserts the entire contents of node list List immediately before node -- Before, which must be a member of a node list. On return, the node list -- List is reset to be the empty node list. procedure Prepend (Node : Node_Id; To : List_Id); pragma Inline (Prepend); -- Prepends Node at the start of node list To. Node must be a non-empty -- node that is not already a member of a node list, and To must be a -- node list. An attempt to prepend an error node is ignored without -- complaint and the list is unchanged. procedure Prepend_To (To : List_Id; Node : Node_Id); pragma Inline (Prepend_To); -- Like Prepend, but arguments are the other way round procedure Remove (Node : Node_Id); -- Removes Node, which must be a node that is a member of a node list, -- from this node list. The contents of Node are not otherwise affected. -- Remove is relatively slow, since no back pointers are maintained, -- which means that the list has to be traversed from the head to find -- the removal point. function Remove_Head (List : List_Id) return Node_Id; -- Removes the head element of a node list, and returns the node (whose -- contents are not otherwise affected) as the result. If the node list -- is empty, then Empty is returned. function Remove_Next (Node : Node_Id) return Node_Id; pragma Inline (Remove_Next); -- Removes the item immediately following the given node, and returns it -- as the result. If Node is the last element of the list, then Empty is -- returned. Node must be a member of a list. Unlike Remove, Remove_Next -- is fast and does not involve any list traversal. procedure Initialize; -- Called at the start of compilation of each new main source file to -- initialize the allocation of the list table. Note that Initialize -- must not be called if Tree_Read is used. 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 Parent (List : List_Id) return Node_Id; pragma Inline (Parent); -- Node lists may have a parent in the same way as a node. The function -- accesses the Parent value, which is either Empty when a list header -- is first created, or the value that has been set by Set_Parent. procedure Set_Parent (List : List_Id; Node : Node_Id); pragma Inline (Set_Parent); -- Sets the parent field of the given list to reference the given node function No (List : List_Id) return Boolean; pragma Inline (No); -- Tests given Id for equality with No_List. This allows notations like -- "if No (Statements)" as opposed to "if Statements = No_List". function Present (List : List_Id) return Boolean; pragma Inline (Present); -- Tests given Id for inequality with No_List. This allows notations like -- "if Present (Statements)" as opposed to "if Statements /= No_List". end Nlists;