1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
10 -- Copyright (C) 1992-1998 Free Software Foundation, Inc. --
12 -- GNAT is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNAT; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
21 -- MA 02111-1307, USA. --
23 -- As a special exception, if other files instantiate generics from this --
24 -- unit, or you link this unit with other files to produce an executable, --
25 -- this unit does not by itself cause the resulting executable to be --
26 -- covered by the GNU General Public License. This exception does not --
27 -- however invalidate any other reasons why the executable file might be --
28 -- covered by the GNU Public License. --
30 -- GNAT was originally developed by the GNAT team at New York University. --
31 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
33 ------------------------------------------------------------------------------
35 -- This package provides facilities for manipulating lists of nodes (see
36 -- package Atree for format and implementation of tree nodes). Separate list
37 -- elements are allocated to represent elements of these lists, so it is
38 -- possible for a given node to be on more than one element list at a time.
39 -- See also package Nlists, which provides another form that is threaded
40 -- through the nodes themselves (using the Link field), which is more time
41 -- and space efficient, but a node can be only one such list.
43 with Types
; use Types
;
48 -- An element list is represented by a header that is allocated in the
49 -- Elist header table. This header contains pointers to the first and
50 -- last elements in the list, or to No_Elmt if the list is empty.
52 -- The elements in the list each contain a pointer to the next element
53 -- and a pointer to the referenced node. Putting a node into an element
54 -- list causes no change at all to the node itself, so a node may be
55 -- included in multiple element lists, and the nodes thus included may
56 -- or may not be elements of node lists (see package Nlists).
59 -- Initialize allocation of element list tables. Called at the start of
60 -- compiling each new main source file. Note that Initialize must not be
61 -- called if Tree_Read is used.
64 -- Lock tables used for element lists before calling backend
67 -- Initializes internal tables from current tree file using Tree_Read.
68 -- Note that Initialize should not be called if Tree_Read is used.
69 -- Tree_Read includes all necessary initialization.
72 -- Writes out internal tables to current tree file using Tree_Write
74 function Last_Elist_Id
return Elist_Id
;
75 -- Returns Id of last allocated element list header
77 function Elists_Address
return System
.Address
;
78 -- Return address of Elists table (used in Back_End for Gigi call)
80 function Num_Elists
return Nat
;
81 -- Number of currently allocated element lists
83 function Last_Elmt_Id
return Elmt_Id
;
84 -- Returns Id of last allocated list element
86 function Elmts_Address
return System
.Address
;
87 -- Return address of Elmts table (used in Back_End for Gigi call)
89 function Node
(Elmt
: Elmt_Id
) return Node_Id
;
91 -- Returns the value of a given list element. Returns Empty if Elmt
94 function New_Elmt_List
return Elist_Id
;
95 -- Creates a new empty element list. Typically this is used to initialize
96 -- a field in some other node which points to an element list where the
97 -- list is then subsequently filled in using Append calls.
99 function First_Elmt
(List
: Elist_Id
) return Elmt_Id
;
100 pragma Inline
(First_Elmt
);
101 -- Obtains the first element of the given element list or, if the
102 -- list has no items, then No_Elmt is returned.
104 function Last_Elmt
(List
: Elist_Id
) return Elmt_Id
;
105 pragma Inline
(Last_Elmt
);
106 -- Obtains the last element of the given element list or, if the
107 -- list has no items, then No_Elmt is returned.
109 function Next_Elmt
(Elmt
: Elmt_Id
) return Elmt_Id
;
110 pragma Inline
(Next_Elmt
);
111 -- This function returns the next element on an element list. The argument
112 -- must be a list element other than No_Elmt. Returns No_Elmt if the given
113 -- element is the last element of the list.
115 procedure Next_Elmt
(Elmt
: in out Elmt_Id
);
116 pragma Inline
(Next_Elmt
);
117 -- Next_Elmt (Elmt) is equivalent to Elmt := Next_Elmt (Elmt)
119 function Is_Empty_Elmt_List
(List
: Elist_Id
) return Boolean;
120 pragma Inline
(Is_Empty_Elmt_List
);
121 -- This function determines if a given tree id references an element list
122 -- that contains no items.
124 procedure Append_Elmt
(Node
: Node_Id
; To
: Elist_Id
);
125 -- Appends Node at the end of To, allocating a new element.
127 procedure Prepend_Elmt
(Node
: Node_Id
; To
: Elist_Id
);
128 -- Appends Node at the beginning of To, allocating a new element.
130 procedure Insert_Elmt_After
(Node
: Node_Id
; Elmt
: Elmt_Id
);
131 -- Add a new element (Node) right after the pre-existing element Elmt
132 -- It is invalid to call this subprogram with Elmt = No_Elmt.
134 procedure Replace_Elmt
(Elmt
: Elmt_Id
; New_Node
: Node_Id
);
135 pragma Inline
(Replace_Elmt
);
136 -- Causes the given element of the list to refer to New_Node, the node
137 -- which was previously referred to by Elmt is effectively removed from
138 -- the list and replaced by New_Node.
140 procedure Remove_Elmt
(List
: Elist_Id
; Elmt
: Elmt_Id
);
141 -- Removes Elmt from the given list. The node itself is not affected,
142 -- but the space used by the list element may be (but is not required
143 -- to be) freed for reuse in a subsequent Append_Elmt call.
145 procedure Remove_Last_Elmt
(List
: Elist_Id
);
146 -- Removes the last element of the given list. The node itself is not
147 -- affected, but the space used by the list element may be (but is not
148 -- required to be) freed for reuse in a subsequent Append_Elmt call.
150 function No
(List
: Elist_Id
) return Boolean;
152 -- Tests given Id for equality with No_Elist. This allows notations like
153 -- "if No (Statements)" as opposed to "if Statements = No_Elist".
155 function Present
(List
: Elist_Id
) return Boolean;
156 pragma Inline
(Present
);
157 -- Tests given Id for inequality with No_Elist. This allows notations like
158 -- "if Present (Statements)" as opposed to "if Statements /= No_Elist".
160 function No
(Elmt
: Elmt_Id
) return Boolean;
162 -- Tests given Id for equality with No_Elmt. This allows notations like
163 -- "if No (Operation)" as opposed to "if Operation = No_Elmt".
165 function Present
(Elmt
: Elmt_Id
) return Boolean;
166 pragma Inline
(Present
);
167 -- Tests given Id for inequality with No_Elmt. This allows notations like
168 -- "if Present (Operation)" as opposed to "if Operation /= No_Elmt".