1 | /**************************************************************************
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2 | *
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3 | * bool_optimiser -- optimise boolean parse tree
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4 | * Copyright (C) 1994,95 Tim Shimmin
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5 | *
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6 | * This program is free software; you can redistribute it and/or modify
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7 | * it under the terms of the GNU General Public License as published by
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8 | * the Free Software Foundation; either version 2 of the License, or
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9 | * (at your option) any later version.
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10 | *
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11 | * This program is distributed in the hope that it will be useful,
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12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 | * GNU General Public License for more details.
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15 | *
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16 | * You should have received a copy of the GNU General Public License
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17 | * along with this program; if not, write to the Free Software
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18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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19 | *
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20 | * $Id: bool_optimiser.c 3745 2003-02-20 21:20:24Z mdewsnip $
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21 | *
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22 | **************************************************************************/
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23 |
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24 | /*
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25 | $Log$
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26 | Revision 1.1 2003/02/20 21:18:23 mdewsnip
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27 | Addition of MG package for search and retrieval
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28 |
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29 | Revision 1.1 1999/08/10 21:17:42 sjboddie
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30 | renamed mg-1.3d directory mg
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31 |
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32 | Revision 1.1 1998/11/17 09:34:20 rjmcnab
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33 | *** empty log message ***
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34 |
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35 | * Revision 1.4 1995/07/27 04:54:55 tes
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36 | * Committing optimiser before I add the code
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37 | * to find diff-nodes in any kind of tree.
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38 | *
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39 | * Revision 1.3 1994/10/20 00:02:55 tes
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40 | * Fixed bug with bool_optimiser:
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41 | * - it couldn't handle "false | false"
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42 | * - it couldn't handle "true & true"
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43 | * These would collapse into an empty list and cause an error.
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44 | *
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45 | * Revision 1.2 1994/10/18 06:11:02 tes
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46 | * The boolean optimiser seems to be modifying the parse tree
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47 | * like it is supposed to.
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48 | * Paragraph ranking now works without any text files if required to.
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49 | *
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50 | * Revision 1.1 1994/10/12 01:15:28 tes
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51 | * Found bugs in the existing boolean query optimiser.
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52 | * So decided to rewrite it.
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53 | * I accidentally deleted query.bool.y, but I have replaced it
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54 | * with bool_parser.y (which I have forgotten to add here ! ;-(
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55 | *
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56 | */
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57 |
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58 | static char *RCSID = "$Id: bool_optimiser.c 3745 2003-02-20 21:20:24Z mdewsnip $";
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59 |
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60 | #include "sysfuncs.h"
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61 |
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62 | #include "memlib.h"
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63 | #include "bool_tree.h"
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64 | #include "term_lists.h"
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65 | #include "messages.h"
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66 |
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67 | typedef int (*CompFunc) (const void *, const void *);
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68 | typedef void (*TreeFunc) (bool_tree_node *);
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69 |
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70 | /* --- routines --- */
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71 | static void PermeateNots (bool_tree_node * tree);
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72 | static void DoubleNeg (bool_tree_node * not_tree);
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73 | static void AndDeMorgan (bool_tree_node * not_tree);
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74 | static void OrDeMorgan (bool_tree_node * not_tree);
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75 | static int AndDistribute (bool_tree_node * tree);
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76 | static void DNF_Distribute (bool_tree_node * tree);
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77 | static void ReplaceWithChildren (bool_tree_node * tree);
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78 | static void CollapseTree (bool_tree_node * tree);
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79 | static void AndTrueFalse (bool_tree_node * and_tree);
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80 | static void OrTrueFalse (bool_tree_node * or_tree);
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81 | static void TF_Idempotent (bool_tree_node * tree);
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82 | static void AndNotToDiff (bool_tree_node * and_tree, TreeFunc recurs_func);
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83 | static void DiffDNF (bool_tree_node * or_node);
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84 | static void DiffTree (bool_tree_node * tree);
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85 | static void AndSort (bool_tree_node * and_tree, TermList * tl, CompFunc comp);
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86 | static void AndOrSort (bool_tree_node * tree, TermList * tl);
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87 | static void AndSortDNF (bool_tree_node * or_node, TermList * tl);
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88 | static void MarkOrTerms (bool_tree_node * tree, TermList * tl);
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89 | static int calc_sum_ft (bool_tree_node * term_tree, TermList * tl);
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90 | static int AndOrSort_comp (const void *A, const void *B);
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91 | static int AndSort_comp (const void *A, const void *B);
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92 |
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93 | /* =========================================================================
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94 | * Function: OptimiseBoolTree
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95 | * Description:
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96 | * For case 2:
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97 | * Do three major steps:
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98 | * (i) put into standard form
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99 | * -> put into DNF (disjunctive normal form - or of ands)
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100 | * Use DeMorgan's, Double-negative, Distributive rules
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101 | * (ii) simplify
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102 | * apply idempotency rules
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103 | * (iii) ameliorate
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104 | * convert &! to diff nodes, order terms by frequency,...
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105 | * Could also do the matching idempotency laws i.e. ...
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106 | * (A | A), (A | !A), (A & !A), (A & A), (A & (A | B)), (A | (A & B))
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107 | * Job for future.... ;-)
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108 | * Input:
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109 | * Output:
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110 | * ========================================================================= */
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111 |
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112 | void
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113 | OptimiseBoolTree (bool_tree_node * parse_tree, TermList * tl, int type)
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114 | {
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115 | switch (type)
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116 | {
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117 | case 1:
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118 | /* --- sorts for and of or-terms --- */
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119 | PermeateNots (parse_tree);
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120 | TF_Idempotent (parse_tree);
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121 | CollapseTree (parse_tree);
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122 | DiffTree (parse_tree);
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123 | MarkOrTerms (parse_tree, tl);
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124 | AndOrSort (parse_tree, tl);
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125 | break;
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126 | case 2:
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127 | /* --- put into DNF --- */
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128 | PermeateNots (parse_tree);
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129 | TF_Idempotent (parse_tree);
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130 | DNF_Distribute (parse_tree);
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131 | CollapseTree (parse_tree);
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132 | AndSortDNF (parse_tree, tl);
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133 | DiffDNF (parse_tree);
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134 | break;
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135 | default:
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136 | /* --- do nothing --- */
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137 | break;
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138 | } /*switch */
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139 | } /*OptimiseBoolTree */
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140 |
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141 | /* =========================================================================
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142 | * Function: DoubleNeg
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143 | * Description:
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144 | * !(!(a) = a
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145 | * Assumes binary tree.
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146 | * Input:
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147 | * Output:
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148 | * ========================================================================= */
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149 | static void
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150 | DoubleNeg (bool_tree_node * not_tree)
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151 | {
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152 | bool_tree_node *child = BOOL_CHILD (not_tree);
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153 | bool_tree_node *a = BOOL_CHILD (child);
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154 | bool_tree_node *sibling = BOOL_SIBLING (not_tree);
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155 |
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156 | /* copy a into not tree */
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157 | bcopy (a, not_tree, sizeof (bool_tree_node));
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158 |
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159 | BOOL_SIBLING (not_tree) = sibling;
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160 |
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161 | Xfree (child);
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162 | Xfree (a);
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163 |
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164 | }
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165 |
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166 | /* =========================================================================
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167 | * Function: AndDeMorgan
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168 | * Description:
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169 | * DeMorgan's rule for 'not' of an 'and' i.e. !(a & b) <=> (!a) | (!b)
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170 | * Assumes Binary Tree
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171 | * Input:
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172 | * not of and tree
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173 | * Output:
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174 | * or of not trees
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175 | * ========================================================================= */
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176 |
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177 | static void
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178 | AndDeMorgan (bool_tree_node * not_tree)
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179 | {
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180 | bool_tree_node *child = BOOL_CHILD (not_tree);
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181 | bool_tree_node *a = BOOL_CHILD (child);
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182 | bool_tree_node *b = BOOL_SIBLING (a);
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183 | bool_tree_node *new_not = NULL;
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184 |
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185 | /* change 'not' to 'or' */
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186 | BOOL_TAG (not_tree) = N_or;
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187 |
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188 | /* change 'and' to 'not' */
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189 | BOOL_TAG (child) = N_not;
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190 |
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191 | /* 'a' no longer has a sibling */
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192 | BOOL_SIBLING (a) = NULL;
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193 |
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194 | /* 'a's old sibling is now a child of a new not */
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195 | new_not = CreateBoolTreeNode (N_not, b, NULL);
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196 | BOOL_SIBLING (child) = new_not;
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197 | }
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198 |
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199 | /* =========================================================================
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200 | * Function: OrDeMorgan
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201 | * Description:
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202 | * DeMorgan's rule for 'not' of an 'or' i.e. !(a | b) <=> (!a) & (!b)
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203 | * Assumes Binary Tree
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204 | * Input:
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205 | * not of and tree
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206 | * Output:
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207 | * or of not trees
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208 | * ========================================================================= */
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209 |
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210 | static void
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211 | OrDeMorgan (bool_tree_node * not_tree)
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212 | {
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213 | bool_tree_node *child = BOOL_CHILD (not_tree);
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214 | bool_tree_node *a = BOOL_CHILD (child);
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215 | bool_tree_node *b = BOOL_SIBLING (a);
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216 | bool_tree_node *new_not = NULL;
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217 |
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218 | /* change 'not' to 'and' */
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219 | BOOL_TAG (not_tree) = N_and;
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220 |
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221 | /* change 'or' to 'not' */
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222 | BOOL_TAG (child) = N_not;
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223 |
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224 | /* 'a' no longer has a sibling */
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225 | BOOL_SIBLING (a) = NULL;
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226 |
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227 | /* 'a's old sibling is now a child of a new not */
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228 | new_not = CreateBoolTreeNode (N_not, b, NULL);
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229 | BOOL_SIBLING (child) = new_not;
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230 | }
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231 |
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232 | /* =========================================================================
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233 | * Function: PermeateNots
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234 | * Description:
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235 | * Use DeMorgan's and Double-negative
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236 | * Assumes tree in binary form (i.e. No ands/ors collapsed)
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237 | * Input:
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238 | * Output:
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239 | * ========================================================================= */
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240 |
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241 | static void
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242 | PermeateNots (bool_tree_node * tree)
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243 | {
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244 | if (!tree)
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245 | return;
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246 |
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247 | if (BOOL_TAG (tree) == N_not)
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248 | {
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249 | switch (BOOL_TAG (BOOL_CHILD (tree)))
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250 | {
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251 | case N_not:
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252 | DoubleNeg (tree);
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253 | /** NOTE: I do not go on to do the children **/
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254 | /* I permeate the nots on the tree here & leave it at that */
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255 | /* In this case I do not know what type 'tree' will end up */
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256 | PermeateNots (tree);
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257 | return;
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258 | case N_and:
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259 | AndDeMorgan (tree);
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260 | break;
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261 | case N_or:
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262 | OrDeMorgan (tree);
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263 | break;
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264 | default:
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265 | /* leave alone */
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266 | break;
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267 | }
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268 | }
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269 |
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270 | /* Permeate Nots for children */
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271 | if (BOOL_HAS_CHILD (tree))
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272 | {
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273 | PermeateNots (BOOL_CHILD (tree));
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274 | PermeateNots (BOOL_SIBLING (BOOL_CHILD (tree)));
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275 | }
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276 |
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277 | }
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278 |
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279 | /* =========================================================================
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280 | * Function: DNF_Distribute
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281 | * Description:
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282 | * Input:
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283 | * Output:
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284 | * ========================================================================= */
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285 |
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286 |
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287 | #define ITER_LIMIT 500 /* if reach limit then probably in trouble */
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288 |
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289 | static void
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290 | DNF_Distribute (bool_tree_node * tree)
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291 | {
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292 | int i = 0;
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293 |
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294 | /* multiple passes until no change */
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295 | /* not very smart :-( */
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296 | while (1)
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297 | {
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298 | if (AndDistribute (tree) == 0)
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299 | return;
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300 | if (i == ITER_LIMIT)
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301 | FatalError (1, "DNF infinite loop");
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302 | i++;
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303 | } /*while */
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304 |
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305 | }
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306 |
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307 | /* =========================================================================
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308 | * Function: AndDistribute
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309 | * Description:
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310 | * (a | b) & A <=> (a & A) | (b & A)
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311 | * Input:
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312 | * binary tree of "AND" , "OR"s.
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313 | * Output:
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314 | * return 1 if changed the tree
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315 | * return 0 if there was NO change (no distributive rule to apply)
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316 | * ========================================================================= */
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317 |
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318 | static int
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319 | AndDistribute (bool_tree_node * tree)
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320 | {
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321 | if (!tree)
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322 | return 0;
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323 |
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324 | if (BOOL_TAG (tree) != N_and)
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325 | {
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326 | /* try the children if got some */
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327 | if (BOOL_TAG (tree) == N_or)
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328 | {
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329 | bool_tree_node *left_child = BOOL_CHILD (tree);
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330 | int left = AndDistribute (left_child);
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331 | int right = AndDistribute (BOOL_SIBLING (left_child));
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332 | return (left || right);
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333 | }
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334 |
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335 | /* no children, then no change */
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336 | return 0;
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337 | }
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338 |
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339 | /* AND case */
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340 | {
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341 | /* we have to check the children to see if can distribute */
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342 | bool_tree_node *left_child = BOOL_CHILD (tree);
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343 | bool_tree_node *right_child = BOOL_SIBLING (left_child);
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344 | int swap = 0;
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345 |
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346 | /* If "or" on the right side then do a swap */
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347 | /* This is done for code simplicity */
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348 | if (BOOL_TAG (right_child) == N_or)
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349 | {
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350 | /* do a swap */
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351 | bool_tree_node *temp;
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352 | temp = right_child;
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353 | right_child = left_child;
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354 | left_child = temp;
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355 |
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356 | BOOL_SIBLING (left_child) = right_child;
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357 | BOOL_SIBLING (right_child) = NULL;
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358 | BOOL_CHILD (tree) = left_child;
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359 |
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360 | swap = 1;
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361 | }
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362 |
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363 | /* do the actual distribution */
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364 | if (swap || BOOL_TAG (left_child) == N_or)
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365 | {
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366 | bool_tree_node *A = right_child;
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367 | bool_tree_node *A_copy = CopyBoolTree (A);
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368 | bool_tree_node *a = BOOL_CHILD (left_child);
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369 | bool_tree_node *b = BOOL_SIBLING (a);
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370 |
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371 | /* then can distribute away ... */
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372 | BOOL_TAG (tree) = N_or;
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373 | BOOL_TAG (left_child) = N_and;
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374 | BOOL_SIBLING (left_child) = CreateBoolTreeNode (N_and, b, A);
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375 | BOOL_SIBLING (a) = A_copy;
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376 |
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377 | AndDistribute (tree);
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378 | return 1;
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379 | }
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380 |
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381 | /* if "and" of something other than "or" s then try the children */
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382 | {
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383 | int left = AndDistribute (left_child);
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384 | int right = AndDistribute (right_child);
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385 | return (left || right);
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386 | }
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387 | } /* AND case */
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388 |
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389 | } /*AndDistribute */
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390 |
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391 | /* =========================================================================
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392 | * Function: CollapseTree
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393 | * Description:
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394 | * Collapse "and" and "or"s.
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395 | * Input:
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396 | * Output:
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397 | * ========================================================================= */
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398 |
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399 | static void
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400 | CollapseTree (bool_tree_node * tree)
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401 | {
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402 | if (!tree)
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403 | return;
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404 |
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405 | if ((BOOL_TAG (tree) == N_and) || (BOOL_TAG (tree) == N_or))
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406 | {
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407 | bool_tree_node *child = BOOL_CHILD (tree);
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408 | while (child)
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409 | {
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410 | while (BOOL_TAG (child) == BOOL_TAG (tree))
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411 | {
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412 | ReplaceWithChildren (child);
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413 | }
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414 | CollapseTree (child);
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415 | child = BOOL_SIBLING (child);
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416 | }
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417 | }
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418 |
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419 | /* assume "not"s permeated */
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420 | return;
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421 | }
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422 |
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423 | /* =========================================================================
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424 | * Function: ReplaceWithChildren
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425 | * Description:
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426 | * Input:
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427 | * Output:
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428 | * ========================================================================= */
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429 |
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430 | static void
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431 | ReplaceWithChildren (bool_tree_node * tree)
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432 | {
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433 | bool_tree_node *next = BOOL_SIBLING (tree);
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434 | bool_tree_node *child = BOOL_CHILD (tree);
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435 | bool_tree_node *last = LastBoolSibling (child);
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436 |
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437 | bcopy ((char *) child, (char *) tree, sizeof (bool_tree_node));
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438 | Xfree (child);
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439 | BOOL_SIBLING (last) = next;
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440 |
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441 | }
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442 |
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443 | /* =========================================================================
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444 | * Function: TF_Idempotent
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445 | * Description:
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446 | * Applies Idempotency laws which refer to True or False (hence "TF")
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447 | * uses the true or false idempotent rules
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448 | * Input:
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449 | * operates on n-ary trees (not restricted to binary)
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450 | * Output:
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451 | * ========================================================================= */
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452 |
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453 | static void
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454 | TF_Idempotent (bool_tree_node * tree)
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455 | {
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456 | bool_tree_node *child = NULL;
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457 |
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458 | while (tree)
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459 | {
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460 | if (BOOL_HAS_CHILD (tree))
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461 | {
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462 | child = BOOL_CHILD (tree);
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463 | TF_Idempotent (child);
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464 | }
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465 |
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466 | /* --- process node --- */
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467 | switch (BOOL_TAG (tree))
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468 | {
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469 | case N_not:
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470 | child = BOOL_CHILD (tree);
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471 |
|
---|
472 | /* if true then falsify */
|
---|
473 | if (BOOL_TAG (child) == N_all)
|
---|
474 | {
|
---|
475 | BOOL_TAG (tree) = N_none;
|
---|
476 | BOOL_CHILD (tree) = NULL;
|
---|
477 | Xfree (child);
|
---|
478 | break;
|
---|
479 | }
|
---|
480 |
|
---|
481 | /* if false then trueify */
|
---|
482 | if (BOOL_TAG (child) == N_none)
|
---|
483 | {
|
---|
484 | BOOL_TAG (tree) = N_all;
|
---|
485 | BOOL_CHILD (tree) = NULL;
|
---|
486 | Xfree (child);
|
---|
487 | break;
|
---|
488 | }
|
---|
489 |
|
---|
490 | break;
|
---|
491 | case N_and:
|
---|
492 | AndTrueFalse (tree);
|
---|
493 | break;
|
---|
494 | case N_or:
|
---|
495 | OrTrueFalse (tree);
|
---|
496 | break;
|
---|
497 |
|
---|
498 | default:
|
---|
499 | /* do nothing */
|
---|
500 | break;
|
---|
501 | } /*switch */
|
---|
502 |
|
---|
503 | tree = BOOL_SIBLING (tree);
|
---|
504 | } /*while */
|
---|
505 | } /*TF_Idempotent */
|
---|
506 |
|
---|
507 | /* =========================================================================
|
---|
508 | * Function: AndTrueFalse
|
---|
509 | * Description:
|
---|
510 | * If any "false" then falsify whole tree
|
---|
511 | * If any "true" then delete them
|
---|
512 | * Input:
|
---|
513 | * Output:
|
---|
514 | * ========================================================================= */
|
---|
515 |
|
---|
516 | static void
|
---|
517 | AndTrueFalse (bool_tree_node * and_tree)
|
---|
518 | {
|
---|
519 | bool_tree_node *child = BOOL_CHILD (and_tree);
|
---|
520 |
|
---|
521 | bool_tree_node *prev = NULL;
|
---|
522 |
|
---|
523 | while (child)
|
---|
524 | {
|
---|
525 | if (BOOL_TAG (child) == N_none)
|
---|
526 | {
|
---|
527 | FreeBoolTree (&(BOOL_CHILD (and_tree)));
|
---|
528 | BOOL_TAG (and_tree) = N_none;
|
---|
529 | return;
|
---|
530 | }
|
---|
531 |
|
---|
532 | if (BOOL_TAG (child) == N_all)
|
---|
533 | {
|
---|
534 | bool_tree_node *sibling = BOOL_SIBLING (child);
|
---|
535 |
|
---|
536 | /* --- link over child --- */
|
---|
537 | if (!prev)
|
---|
538 | {
|
---|
539 | BOOL_CHILD (and_tree) = sibling;
|
---|
540 | }
|
---|
541 | else
|
---|
542 | {
|
---|
543 | BOOL_SIBLING (prev) = sibling;
|
---|
544 | }
|
---|
545 |
|
---|
546 | Xfree (child);
|
---|
547 | child = sibling;
|
---|
548 | }
|
---|
549 | else
|
---|
550 | {
|
---|
551 | prev = child;
|
---|
552 | child = BOOL_SIBLING (child);
|
---|
553 | }
|
---|
554 | } /*while */
|
---|
555 |
|
---|
556 | child = BOOL_CHILD (and_tree);
|
---|
557 |
|
---|
558 | /* if no children ... */
|
---|
559 | /* => all have been true */
|
---|
560 | if (!child)
|
---|
561 | {
|
---|
562 | BOOL_TAG (and_tree) = N_all;
|
---|
563 | return;
|
---|
564 | }
|
---|
565 |
|
---|
566 | /* If only one child ... */
|
---|
567 | if (!BOOL_SIBLING (child))
|
---|
568 | {
|
---|
569 | /* replace the parent with child - move it up */
|
---|
570 | bool_tree_node *save_sibling = BOOL_SIBLING (and_tree);
|
---|
571 | bcopy ((char *) child, (char *) and_tree, sizeof (bool_tree_node));
|
---|
572 | BOOL_SIBLING (and_tree) = save_sibling;
|
---|
573 | Xfree (child);
|
---|
574 | }
|
---|
575 |
|
---|
576 | } /*AndTrueFalse */
|
---|
577 |
|
---|
578 | /* =========================================================================
|
---|
579 | * Function: OrTrueFalse
|
---|
580 | * Description:
|
---|
581 | * If any "true" then trueify whole tree
|
---|
582 | * If any "false" then delete them
|
---|
583 | * ***** NOTE: This is a reflection of AndTrueFalse *****
|
---|
584 | * Input:
|
---|
585 | * Output:
|
---|
586 | * ========================================================================= */
|
---|
587 |
|
---|
588 | static void
|
---|
589 | OrTrueFalse (bool_tree_node * or_tree)
|
---|
590 | {
|
---|
591 | bool_tree_node *child = BOOL_CHILD (or_tree);
|
---|
592 |
|
---|
593 | bool_tree_node *prev = NULL;
|
---|
594 |
|
---|
595 | while (child)
|
---|
596 | {
|
---|
597 | if (BOOL_TAG (child) == N_all)
|
---|
598 | {
|
---|
599 | FreeBoolTree (&(BOOL_CHILD (or_tree)));
|
---|
600 | BOOL_TAG (or_tree) = N_all;
|
---|
601 | return;
|
---|
602 | }
|
---|
603 |
|
---|
604 | if (BOOL_TAG (child) == N_none)
|
---|
605 | {
|
---|
606 | bool_tree_node *sibling = BOOL_SIBLING (child);
|
---|
607 | if (!prev)
|
---|
608 | {
|
---|
609 | BOOL_CHILD (or_tree) = sibling;
|
---|
610 | }
|
---|
611 | else
|
---|
612 | {
|
---|
613 | BOOL_SIBLING (prev) = sibling;
|
---|
614 | }
|
---|
615 | Xfree (child);
|
---|
616 | child = sibling;
|
---|
617 |
|
---|
618 | }
|
---|
619 | else
|
---|
620 | {
|
---|
621 | prev = child;
|
---|
622 | child = BOOL_SIBLING (child);
|
---|
623 | }
|
---|
624 | } /*while */
|
---|
625 |
|
---|
626 | child = BOOL_CHILD (or_tree);
|
---|
627 |
|
---|
628 | /* if no children ... */
|
---|
629 | /* => all have been false */
|
---|
630 | if (!child)
|
---|
631 | {
|
---|
632 | BOOL_TAG (or_tree) = N_none;
|
---|
633 | return;
|
---|
634 | }
|
---|
635 |
|
---|
636 | /* If only one child ... */
|
---|
637 | if (!BOOL_SIBLING (child))
|
---|
638 | {
|
---|
639 | /* replace the parent with child - move it up */
|
---|
640 | bool_tree_node *save_sibling = BOOL_SIBLING (or_tree);
|
---|
641 | bcopy ((char *) child, (char *) or_tree, sizeof (bool_tree_node));
|
---|
642 | BOOL_SIBLING (or_tree) = save_sibling;
|
---|
643 | Xfree (child);
|
---|
644 | }
|
---|
645 |
|
---|
646 | } /*AndTrueFalse */
|
---|
647 |
|
---|
648 | /* =========================================================================
|
---|
649 | * Function: AndNotToDiff
|
---|
650 | * Description:
|
---|
651 | * Convert an "And" tree with possibly some negated terms into
|
---|
652 | * a "And - neg-terms".
|
---|
653 | * Input:
|
---|
654 | * Expects "And" of only literals - as tree should be in DNF form.
|
---|
655 | * This means that no recursion is necessary.
|
---|
656 | * Output:
|
---|
657 | * ========================================================================= */
|
---|
658 |
|
---|
659 | static void
|
---|
660 | AndNotToDiff (bool_tree_node * and_tree, TreeFunc recurs_func)
|
---|
661 | {
|
---|
662 |
|
---|
663 | /* -------------------------------------------------- */
|
---|
664 | /* --- Divide the children up into positive and negative literals --- */
|
---|
665 | /* Preserves ordering of children */
|
---|
666 | bool_tree_node *pos = NULL;
|
---|
667 | bool_tree_node *neg = NULL;
|
---|
668 | bool_tree_node *last_pos = NULL;
|
---|
669 | bool_tree_node *last_neg = NULL;
|
---|
670 |
|
---|
671 | bool_tree_node *child = BOOL_CHILD (and_tree);
|
---|
672 | while (child)
|
---|
673 | {
|
---|
674 | bool_tree_node *next = BOOL_SIBLING (child);
|
---|
675 | if (BOOL_TAG (child) == N_not)
|
---|
676 | {
|
---|
677 | /* add to end of neg list */
|
---|
678 | if (!neg)
|
---|
679 | neg = child;
|
---|
680 | else
|
---|
681 | BOOL_SIBLING (last_neg) = child;
|
---|
682 | last_neg = child;
|
---|
683 | }
|
---|
684 | else
|
---|
685 | {
|
---|
686 | /* add to end of pos list */
|
---|
687 | if (!pos)
|
---|
688 | pos = child;
|
---|
689 | else
|
---|
690 | BOOL_SIBLING (last_pos) = child;
|
---|
691 | last_pos = child;
|
---|
692 | }
|
---|
693 | child = next;
|
---|
694 | } /*while */
|
---|
695 | if (last_pos)
|
---|
696 | BOOL_SIBLING (last_pos) = NULL;
|
---|
697 | if (last_neg)
|
---|
698 | BOOL_SIBLING (last_neg) = NULL;
|
---|
699 | /* -------------------------------------------------- */
|
---|
700 |
|
---|
701 | if (!neg) /* no negtives => no subtraction */
|
---|
702 | {
|
---|
703 | /* fix up parent's child link */
|
---|
704 | BOOL_CHILD (and_tree) = pos;
|
---|
705 | return;
|
---|
706 | }
|
---|
707 |
|
---|
708 | if (!pos) /* no positives = all negatives */
|
---|
709 | {
|
---|
710 | /* Choose one of the negs for the left-hand-side of the subtraction */
|
---|
711 | /* In particular, choose the first */
|
---|
712 | pos = neg;
|
---|
713 | neg = BOOL_SIBLING (neg);
|
---|
714 | BOOL_SIBLING (pos) = NULL;
|
---|
715 | }
|
---|
716 |
|
---|
717 | /* Get rid of all '!' from not nodes */
|
---|
718 | /* Make a list out of the children */
|
---|
719 | {
|
---|
720 | bool_tree_node *n = neg;
|
---|
721 | bool_tree_node *next = NULL;
|
---|
722 |
|
---|
723 | neg = BOOL_CHILD (neg);
|
---|
724 | while (n)
|
---|
725 | {
|
---|
726 | bool_tree_node *c = BOOL_CHILD (n);
|
---|
727 | next = BOOL_SIBLING (n);
|
---|
728 | Xfree (n);
|
---|
729 | if (next)
|
---|
730 | BOOL_SIBLING (c) = BOOL_CHILD (next);
|
---|
731 | n = next;
|
---|
732 | }
|
---|
733 | }
|
---|
734 |
|
---|
735 | /* --- restructure the tree with "and" and "diff" --- */
|
---|
736 | BOOL_TAG (and_tree) = N_diff;
|
---|
737 | if (!BOOL_SIBLING (pos)) /* i.e. only one pos */
|
---|
738 | {
|
---|
739 | /* (A & !B & !C & !D & ...) ==> A - (B,C,D,...) */
|
---|
740 |
|
---|
741 | BOOL_CHILD (and_tree) = pos;
|
---|
742 | BOOL_SIBLING (pos) = neg;
|
---|
743 | }
|
---|
744 | else
|
---|
745 | {
|
---|
746 | /* (A & !C & B & !D & ...) ==> (A & B & ....) - (C, D, ...) */
|
---|
747 |
|
---|
748 | bool_tree_node *n = CreateBoolNode (N_and);
|
---|
749 | BOOL_CHILD (and_tree) = n;
|
---|
750 | BOOL_CHILD (n) = pos;
|
---|
751 | BOOL_SIBLING (n) = neg;
|
---|
752 | } /*if */
|
---|
753 |
|
---|
754 | if (recurs_func)
|
---|
755 | {
|
---|
756 | recurs_func (BOOL_CHILD (and_tree));
|
---|
757 | }
|
---|
758 |
|
---|
759 | } /*AndNotToDiff */
|
---|
760 |
|
---|
761 | /* =========================================================================
|
---|
762 | * Function: DiffTree
|
---|
763 | * Description:
|
---|
764 | * Applies "AndNotToNeg" to each conjunct.
|
---|
765 | * Unlike DiffDNF, this routine will search throughout the tree for
|
---|
766 | * "and"-nodes. It will call AndNotToNeg with this as its recursive
|
---|
767 | * routine.
|
---|
768 | * Date: 27/July/95
|
---|
769 | * Input:
|
---|
770 | * Output:
|
---|
771 | * ========================================================================= */
|
---|
772 |
|
---|
773 | static void
|
---|
774 | DiffTree (bool_tree_node * tree)
|
---|
775 | {
|
---|
776 | bool_tree_node *t = tree;
|
---|
777 |
|
---|
778 | while (t)
|
---|
779 | {
|
---|
780 | if (BOOL_TAG (t) == N_and)
|
---|
781 | {
|
---|
782 | AndNotToDiff (t, DiffTree);
|
---|
783 | }
|
---|
784 | t = BOOL_SIBLING (t);
|
---|
785 | } /*while */
|
---|
786 |
|
---|
787 | } /*DiffTree */
|
---|
788 |
|
---|
789 | /* =========================================================================
|
---|
790 | * Function: DiffDNF
|
---|
791 | * Description:
|
---|
792 | * Applies "AndNotToNeg" to each conjunct.
|
---|
793 | * Input:
|
---|
794 | * A DNF tree
|
---|
795 | * Output:
|
---|
796 | * A tree possibly with some diffs in it.
|
---|
797 | * ========================================================================= */
|
---|
798 |
|
---|
799 | static void
|
---|
800 | DiffDNF (bool_tree_node * DNF_tree)
|
---|
801 | {
|
---|
802 |
|
---|
803 | if (BOOL_TAG (DNF_tree) == N_or)
|
---|
804 | {
|
---|
805 | bool_tree_node *child = BOOL_CHILD (DNF_tree);
|
---|
806 |
|
---|
807 | while (child)
|
---|
808 | {
|
---|
809 | if (BOOL_TAG (child) == N_and)
|
---|
810 | {
|
---|
811 | AndNotToDiff (child, NULL);
|
---|
812 | }
|
---|
813 | child = BOOL_SIBLING (child);
|
---|
814 | }
|
---|
815 | }
|
---|
816 | else if (BOOL_TAG (DNF_tree) == N_and)
|
---|
817 | {
|
---|
818 | AndNotToDiff (DNF_tree, NULL);
|
---|
819 | }
|
---|
820 | }
|
---|
821 |
|
---|
822 | /* =========================================================================
|
---|
823 | * Function: AndSort_comp
|
---|
824 | * Description:
|
---|
825 | * Input:
|
---|
826 | * Output:
|
---|
827 | * ========================================================================= */
|
---|
828 |
|
---|
829 | /* Module variable, "term_list", used as parameter for comparison function */
|
---|
830 | /* The comparison function only allows certain fixed parameters */
|
---|
831 | static TermList *term_list;
|
---|
832 |
|
---|
833 | static int
|
---|
834 | AndSort_comp (const void *A, const void *B)
|
---|
835 | {
|
---|
836 | const bool_tree_node *const *a = A;
|
---|
837 | const bool_tree_node *const *b = B;
|
---|
838 |
|
---|
839 | if (BOOL_TAG (*a) == N_term && BOOL_TAG (*b) == N_term)
|
---|
840 | {
|
---|
841 | /* look up in term list */
|
---|
842 | int a_doc_count = GetNthWE (term_list, BOOL_TERM (*a))->doc_count;
|
---|
843 | int b_doc_count = GetNthWE (term_list, BOOL_TERM (*b))->doc_count;
|
---|
844 |
|
---|
845 | return a_doc_count - b_doc_count;
|
---|
846 | }
|
---|
847 |
|
---|
848 | if (BOOL_TAG (*a) == N_term && BOOL_TAG (*b) != N_term)
|
---|
849 | return -1;
|
---|
850 |
|
---|
851 | if (BOOL_TAG (*a) != N_term && BOOL_TAG (*b) == N_term)
|
---|
852 | return 1;
|
---|
853 |
|
---|
854 | return 0;
|
---|
855 | } /*AndSort_comp */
|
---|
856 |
|
---|
857 | /* =========================================================================
|
---|
858 | * Function: AndSort
|
---|
859 | * Description:
|
---|
860 | * Sort the list of nodes by increasing doc_count
|
---|
861 | * Using some Neil Sharman code - pretty straight forward.
|
---|
862 | * Note: not-terms are sent to the end of the list
|
---|
863 | * Input:
|
---|
864 | * Output:
|
---|
865 | * ========================================================================= */
|
---|
866 |
|
---|
867 | static void
|
---|
868 | AndSort (bool_tree_node * and_tree, TermList * tl, CompFunc comp)
|
---|
869 | {
|
---|
870 | bool_tree_node **list = NULL;
|
---|
871 | bool_tree_node *child = NULL;
|
---|
872 | int count = 0;
|
---|
873 | int i = 0;
|
---|
874 |
|
---|
875 | if (BOOL_TAG (and_tree) != N_and)
|
---|
876 | return;
|
---|
877 |
|
---|
878 | /* --- Convert linked list into an array for sorting --- */
|
---|
879 | child = BOOL_CHILD (and_tree);
|
---|
880 | count = 0;
|
---|
881 | while (child)
|
---|
882 | {
|
---|
883 | count++;
|
---|
884 | child = BOOL_SIBLING (child);
|
---|
885 | }
|
---|
886 |
|
---|
887 | if (!(list = Xmalloc (sizeof (bool_tree_node *) * count)))
|
---|
888 | return;
|
---|
889 |
|
---|
890 | child = BOOL_CHILD (and_tree);
|
---|
891 | for (i = 0; i < count; i++)
|
---|
892 | {
|
---|
893 | list[i] = child;
|
---|
894 | child = BOOL_SIBLING (child);
|
---|
895 | }
|
---|
896 | /* ----------------------------------------------------- */
|
---|
897 |
|
---|
898 | term_list = tl;
|
---|
899 | qsort (list, count, sizeof (bool_tree_node *), comp);
|
---|
900 |
|
---|
901 | /* --- Convert array back into linked list --- */
|
---|
902 | for (i = 0; i < count - 1; i++)
|
---|
903 | BOOL_SIBLING (list[i]) = list[i + 1];
|
---|
904 | BOOL_SIBLING (list[count - 1]) = NULL;
|
---|
905 | BOOL_CHILD (and_tree) = list[0];
|
---|
906 | Xfree (list);
|
---|
907 | /* ----------------------------------------------------- */
|
---|
908 |
|
---|
909 | } /*AndSort */
|
---|
910 |
|
---|
911 | /* =========================================================================
|
---|
912 | * Function: AndSortDNF
|
---|
913 | * Description:
|
---|
914 | * Input:
|
---|
915 | * Output:
|
---|
916 | * ========================================================================= */
|
---|
917 |
|
---|
918 |
|
---|
919 | static void
|
---|
920 | AndSortDNF (bool_tree_node * DNF_tree, TermList * tl)
|
---|
921 | {
|
---|
922 |
|
---|
923 | if (BOOL_TAG (DNF_tree) == N_or)
|
---|
924 | {
|
---|
925 | bool_tree_node *child = BOOL_CHILD (DNF_tree);
|
---|
926 |
|
---|
927 | while (child)
|
---|
928 | {
|
---|
929 | if (BOOL_TAG (child) == N_and)
|
---|
930 | {
|
---|
931 | AndSort (child, tl, AndSort_comp);
|
---|
932 | }
|
---|
933 | child = BOOL_SIBLING (child);
|
---|
934 | }
|
---|
935 | }
|
---|
936 | else if (BOOL_TAG (DNF_tree) == N_and)
|
---|
937 | {
|
---|
938 | AndSort (DNF_tree, tl, AndSort_comp);
|
---|
939 | }
|
---|
940 | }
|
---|
941 |
|
---|
942 | /* =========================================================================
|
---|
943 | * Function: MarkOrTerms
|
---|
944 | * Description:
|
---|
945 | * Mark or-nodes whose children are all terms.
|
---|
946 | * Also store the sum of the ft's of these nodes.
|
---|
947 | * Input:
|
---|
948 | * Output:
|
---|
949 | * ========================================================================= */
|
---|
950 |
|
---|
951 | static void
|
---|
952 | MarkOrTerms (bool_tree_node * tree, TermList * tl)
|
---|
953 | {
|
---|
954 | if (BOOL_TAG (tree) == N_or)
|
---|
955 | {
|
---|
956 | int found_non_term = 0;
|
---|
957 | bool_tree_node *child = BOOL_CHILD (tree);
|
---|
958 |
|
---|
959 | /* --- check to see if got all terms --- */
|
---|
960 | while (child)
|
---|
961 | {
|
---|
962 | if (BOOL_TAG (child) != N_term)
|
---|
963 | {
|
---|
964 | found_non_term = 1;
|
---|
965 | }
|
---|
966 | if (BOOL_HAS_CHILD (tree))
|
---|
967 | {
|
---|
968 | MarkOrTerms (child, tl);
|
---|
969 | }
|
---|
970 | child = BOOL_SIBLING (child);
|
---|
971 | } /*while */
|
---|
972 |
|
---|
973 | if (!found_non_term)
|
---|
974 | {
|
---|
975 | /* Must have all terms for the OR node */
|
---|
976 | /* So change its tag and calculate its sum */
|
---|
977 | BOOL_TAG (tree) = N_or_terms;
|
---|
978 | BOOL_SUM_FT (tree) = calc_sum_ft (tree, tl);
|
---|
979 | } /*if */
|
---|
980 | /* ------------------------------------- */
|
---|
981 |
|
---|
982 | } /*if OR node */
|
---|
983 |
|
---|
984 | else if (BOOL_HAS_CHILD (tree))
|
---|
985 | {
|
---|
986 | bool_tree_node *child = BOOL_CHILD (tree);
|
---|
987 | while (child)
|
---|
988 | {
|
---|
989 | MarkOrTerms (child, tl);
|
---|
990 | child = BOOL_SIBLING (child);
|
---|
991 | }
|
---|
992 | }
|
---|
993 |
|
---|
994 | } /*MarkOrTerms */
|
---|
995 |
|
---|
996 | /* =========================================================================
|
---|
997 | * Function: calc_sum_ft
|
---|
998 | * Description:
|
---|
999 | * Sums up the ft's of all the terms
|
---|
1000 | * Input:
|
---|
1001 | * Assumes that the tree only contains terms in it
|
---|
1002 | * Output:
|
---|
1003 | * the ft sum
|
---|
1004 | * ========================================================================= */
|
---|
1005 | static int
|
---|
1006 | calc_sum_ft (bool_tree_node * term_tree, TermList * tl)
|
---|
1007 | {
|
---|
1008 | int sum_ft = 0;
|
---|
1009 | bool_tree_node *child = BOOL_CHILD (term_tree);
|
---|
1010 | while (child)
|
---|
1011 | {
|
---|
1012 | sum_ft += GetNthWE (tl, BOOL_TERM (child))->doc_count;
|
---|
1013 | child = BOOL_SIBLING (child);
|
---|
1014 | }
|
---|
1015 | return sum_ft;
|
---|
1016 | }
|
---|
1017 |
|
---|
1018 | /* =========================================================================
|
---|
1019 | * Function: AndOrSort
|
---|
1020 | * Description:
|
---|
1021 | * This is like an AndSort of just terms.
|
---|
1022 | * The difference is that we are now also
|
---|
1023 | * considering sorting with <or of terms> by using the sum of f_t's.
|
---|
1024 | * Input:
|
---|
1025 | * Output:
|
---|
1026 | * ========================================================================= */
|
---|
1027 | static void
|
---|
1028 | AndOrSort (bool_tree_node * tree, TermList * tl)
|
---|
1029 | {
|
---|
1030 | if (BOOL_HAS_CHILD (tree))
|
---|
1031 | {
|
---|
1032 |
|
---|
1033 | if (BOOL_TAG (tree) == N_and)
|
---|
1034 | {
|
---|
1035 | AndSort (tree, tl, AndOrSort_comp);
|
---|
1036 | }
|
---|
1037 |
|
---|
1038 | /* Check out any children down the tree */
|
---|
1039 | /* Probably a waste of time */
|
---|
1040 | {
|
---|
1041 | bool_tree_node *child = BOOL_CHILD (tree);
|
---|
1042 | while (child)
|
---|
1043 | {
|
---|
1044 | AndOrSort (child, tl);
|
---|
1045 | child = BOOL_SIBLING (child);
|
---|
1046 | }
|
---|
1047 | } /*do the tree */
|
---|
1048 |
|
---|
1049 | } /*if has children */
|
---|
1050 | } /*AndOrSort */
|
---|
1051 |
|
---|
1052 | /* =========================================================================
|
---|
1053 | * Function: AndOrSort_comp
|
---|
1054 | * Description:
|
---|
1055 | * Comparison function used to order "term"s and "or_terms"s.
|
---|
1056 | * It's purpose is to be used by a sort routine.
|
---|
1057 | * Input:
|
---|
1058 | * Output:
|
---|
1059 | * ========================================================================= */
|
---|
1060 | static int
|
---|
1061 | AndOrSort_comp (const void *A, const void *B)
|
---|
1062 | {
|
---|
1063 | const bool_tree_node *const *a = A;
|
---|
1064 | const bool_tree_node *const *b = B;
|
---|
1065 |
|
---|
1066 | if (BOOL_TAG (*a) == N_term && BOOL_TAG (*b) == N_term)
|
---|
1067 | {
|
---|
1068 | /* look up in term list */
|
---|
1069 | int a_doc_count = GetNthWE (term_list, BOOL_TERM (*a))->doc_count;
|
---|
1070 | int b_doc_count = GetNthWE (term_list, BOOL_TERM (*b))->doc_count;
|
---|
1071 |
|
---|
1072 | return a_doc_count - b_doc_count;
|
---|
1073 | }
|
---|
1074 |
|
---|
1075 | if (BOOL_TAG (*a) == N_term && BOOL_TAG (*b) == N_or_terms)
|
---|
1076 | {
|
---|
1077 | /* look up in term list */
|
---|
1078 | int a_doc_count = GetNthWE (term_list, BOOL_TERM (*a))->doc_count;
|
---|
1079 | int b_doc_count = BOOL_SUM_FT (*b);
|
---|
1080 |
|
---|
1081 | return a_doc_count - b_doc_count;
|
---|
1082 | }
|
---|
1083 |
|
---|
1084 | if (BOOL_TAG (*a) == N_or_terms && BOOL_TAG (*b) == N_term)
|
---|
1085 | {
|
---|
1086 | /* look up in term list */
|
---|
1087 | int a_doc_count = BOOL_SUM_FT (*a);
|
---|
1088 | int b_doc_count = GetNthWE (term_list, BOOL_TERM (*b))->doc_count;
|
---|
1089 |
|
---|
1090 | return a_doc_count - b_doc_count;
|
---|
1091 | }
|
---|
1092 |
|
---|
1093 | if (BOOL_TAG (*a) == N_or_terms && BOOL_TAG (*b) == N_or_terms)
|
---|
1094 | {
|
---|
1095 | /* look up in term list */
|
---|
1096 | int a_doc_count = BOOL_SUM_FT (*a);
|
---|
1097 | int b_doc_count = BOOL_SUM_FT (*b);
|
---|
1098 |
|
---|
1099 | return a_doc_count - b_doc_count;
|
---|
1100 | }
|
---|
1101 |
|
---|
1102 | if ((BOOL_TAG (*a) == N_term || BOOL_TAG (*a) == N_or_terms) &&
|
---|
1103 | (BOOL_TAG (*b) != N_term && BOOL_TAG (*b) != N_or_terms))
|
---|
1104 | return -1;
|
---|
1105 |
|
---|
1106 | if ((BOOL_TAG (*a) != N_term && BOOL_TAG (*a) != N_or_terms) &&
|
---|
1107 | (BOOL_TAG (*b) == N_term || BOOL_TAG (*b) == N_or_terms))
|
---|
1108 | return 1;
|
---|
1109 |
|
---|
1110 | return 0;
|
---|
1111 | } /*AndOrSort_comp */
|
---|