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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT COMPILER COMPONENTS --
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4 -- --
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5 -- E L I S T S --
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6 -- --
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7 -- S p e c --
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8 -- --
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145
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9 -- Copyright (C) 1992-2019, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 -- This package provides facilities for manipulating lists of nodes (see
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33 -- package Atree for format and implementation of tree nodes). Separate list
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34 -- elements are allocated to represent elements of these lists, so it is
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35 -- possible for a given node to be on more than one element list at a time.
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36 -- See also package Nlists, which provides another form that is threaded
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37 -- through the nodes themselves (using the Link field), which is more time
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38 -- and space efficient, but a node can be only one such list.
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39
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145
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40 -- WARNING: There is a C version of this package. Any changes to this
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41 -- source file must be properly reflected in the C header file elists.h
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42
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111
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43 with Types; use Types;
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44 with System;
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45
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46 package Elists is
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47
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48 -- An element list is represented by a header that is allocated in the
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49 -- Elist header table. This header contains pointers to the first and
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50 -- last elements in the list, or to No_Elmt if the list is empty.
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51
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52 -- The elements in the list each contain a pointer to the next element
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53 -- and a pointer to the referenced node. Putting a node into an element
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54 -- list causes no change at all to the node itself, so a node may be
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55 -- included in multiple element lists, and the nodes thus included may
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56 -- or may not be elements of node lists (see package Nlists).
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57
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58 procedure Initialize;
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59 -- Initialize allocation of element list tables. Called at the start of
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60 -- compiling each new main source file. Note that Initialize must not be
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61 -- called if Tree_Read is used.
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62
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63 procedure Lock;
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64 -- Lock tables used for element lists before calling backend
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65
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66 procedure Unlock;
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67 -- Unlock list tables, in cases where the back end needs to modify them
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68
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69 procedure Tree_Read;
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70 -- Initializes internal tables from current tree file using the relevant
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71 -- Table.Tree_Read routines. Note that Initialize should not be called if
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72 -- Tree_Read is used. Tree_Read includes all necessary initialization.
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73
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74 procedure Tree_Write;
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75 -- Writes out internal tables to current tree file using the relevant
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76 -- Table.Tree_Write routines.
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77
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78 function Last_Elist_Id return Elist_Id;
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79 -- Returns Id of last allocated element list header
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80
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81 function Elists_Address return System.Address;
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82 -- Return address of Elists table (used in Back_End for Gigi call)
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83
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84 function Num_Elists return Nat;
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85 -- Number of currently allocated element lists
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86
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87 function Last_Elmt_Id return Elmt_Id;
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88 -- Returns Id of last allocated list element
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89
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90 function Elmts_Address return System.Address;
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91 -- Return address of Elmts table (used in Back_End for Gigi call)
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92
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93 function Node (Elmt : Elmt_Id) return Node_Or_Entity_Id;
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94 pragma Inline (Node);
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95 -- Returns the value of a given list element. Returns Empty if Elmt
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96 -- is set to No_Elmt.
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97
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98 function New_Elmt_List return Elist_Id;
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99 -- Creates a new empty element list. Typically this is used to initialize
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100 -- a field in some other node which points to an element list where the
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101 -- list is then subsequently filled in using Append calls.
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102
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103 function First_Elmt (List : Elist_Id) return Elmt_Id;
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104 pragma Inline (First_Elmt);
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105 -- Obtains the first element of the given element list or, if the list has
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106 -- no items, then No_Elmt is returned.
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107
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108 function Last_Elmt (List : Elist_Id) return Elmt_Id;
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109 pragma Inline (Last_Elmt);
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110 -- Obtains the last element of the given element list or, if the list has
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111 -- no items, then No_Elmt is returned.
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112
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113 function List_Length (List : Elist_Id) return Nat;
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114 -- Returns number of elements in given List (zero if List = No_Elist)
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115
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116 function Next_Elmt (Elmt : Elmt_Id) return Elmt_Id;
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117 pragma Inline (Next_Elmt);
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118 -- This function returns the next element on an element list. The argument
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119 -- must be a list element other than No_Elmt. Returns No_Elmt if the given
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120 -- element is the last element of the list.
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121
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122 procedure Next_Elmt (Elmt : in out Elmt_Id);
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123 pragma Inline (Next_Elmt);
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124 -- Next_Elmt (Elmt) is equivalent to Elmt := Next_Elmt (Elmt)
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125
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126 function Is_Empty_Elmt_List (List : Elist_Id) return Boolean;
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127 pragma Inline (Is_Empty_Elmt_List);
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128 -- This function determines if a given tree id references an element list
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129 -- that contains no items.
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130
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131 procedure Append_Elmt (N : Node_Or_Entity_Id; To : Elist_Id);
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132 -- Appends N at the end of To, allocating a new element. N must be a
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133 -- non-empty node or entity Id, and To must be an Elist (not No_Elist).
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134
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135 procedure Append_New_Elmt (N : Node_Or_Entity_Id; To : in out Elist_Id);
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136 pragma Inline (Append_New_Elmt);
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137 -- Like Append_Elmt if Elist_Id is not No_List, but if Elist_Id is No_List,
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138 -- then first assigns it an empty element list and then does the append.
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139
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140 procedure Append_Unique_Elmt (N : Node_Or_Entity_Id; To : Elist_Id);
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141 -- Like Append_Elmt, except that a check is made to see if To already
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142 -- contains N and if so the call has no effect.
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143
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144 procedure Prepend_Elmt (N : Node_Or_Entity_Id; To : Elist_Id);
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145 -- Appends N at the beginning of To, allocating a new element
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146
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147 procedure Prepend_Unique_Elmt (N : Node_Or_Entity_Id; To : Elist_Id);
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148 -- Like Prepend_Elmt, except that a check is made to see if To already
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149 -- contains N and if so the call has no effect.
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150
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151 procedure Insert_Elmt_After (N : Node_Or_Entity_Id; Elmt : Elmt_Id);
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152 -- Add a new element (N) right after the pre-existing element Elmt
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153 -- It is invalid to call this subprogram with Elmt = No_Elmt.
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154
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155 function New_Copy_Elist (List : Elist_Id) return Elist_Id;
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156 -- Replicate the contents of a list. Internal list nodes are not shared and
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157 -- order of elements is preserved.
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158
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159 procedure Replace_Elmt (Elmt : Elmt_Id; New_Node : Node_Or_Entity_Id);
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160 pragma Inline (Replace_Elmt);
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161 -- Causes the given element of the list to refer to New_Node, the node
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162 -- which was previously referred to by Elmt is effectively removed from
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163 -- the list and replaced by New_Node.
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164
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165 procedure Remove (List : Elist_Id; N : Node_Or_Entity_Id);
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166 -- Remove a node or an entity from a list. If the list does not contain the
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167 -- item in question, the routine has no effect.
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168
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169 procedure Remove_Elmt (List : Elist_Id; Elmt : Elmt_Id);
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170 -- Removes Elmt from the given list. The node itself is not affected,
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171 -- but the space used by the list element may be (but is not required
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172 -- to be) freed for reuse in a subsequent Append_Elmt call.
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173
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174 procedure Remove_Last_Elmt (List : Elist_Id);
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175 -- Removes the last element of the given list. The node itself is not
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176 -- affected, but the space used by the list element may be (but is not
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177 -- required to be) freed for reuse in a subsequent Append_Elmt call.
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178
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179 function Contains (List : Elist_Id; N : Node_Or_Entity_Id) return Boolean;
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180 -- Perform a sequential search to determine whether the given list contains
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181 -- a node or an entity.
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182
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183 function No (List : Elist_Id) return Boolean;
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184 pragma Inline (No);
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185 -- Tests given Id for equality with No_Elist. This allows notations like
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186 -- "if No (Statements)" as opposed to "if Statements = No_Elist".
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187
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188 function Present (List : Elist_Id) return Boolean;
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189 pragma Inline (Present);
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190 -- Tests given Id for inequality with No_Elist. This allows notations like
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191 -- "if Present (Statements)" as opposed to "if Statements /= No_Elist".
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192
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193 function No (Elmt : Elmt_Id) return Boolean;
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194 pragma Inline (No);
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195 -- Tests given Id for equality with No_Elmt. This allows notations like
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196 -- "if No (Operation)" as opposed to "if Operation = No_Elmt".
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197
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198 function Present (Elmt : Elmt_Id) return Boolean;
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199 pragma Inline (Present);
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200 -- Tests given Id for inequality with No_Elmt. This allows notations like
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201 -- "if Present (Operation)" as opposed to "if Operation /= No_Elmt".
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202
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203 end Elists;
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