1 | /**************************************************************************
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2 | *
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3 | * QueryParser.cpp -- Query parser for a simple query language
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4 | * Copyright (C) 2000 Rodger McNab
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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 | **************************************************************************/
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21 |
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22 | #include "GSDLQueryParser.h"
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23 | #include "GSDLQueryLex.h"
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24 |
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25 |
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26 | static QueryNode *ParseExpression (UCArray::const_iterator &here,
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27 | UCArray::const_iterator end,
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28 | int defaultBoolCOmbine,
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29 | int defaultStemMethod);
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30 |
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31 | static QueryNode *AndAdd (QueryNode *t1, QueryNode *t2) {
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32 | if (t1 == NULL) return t2;
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33 | if (t2 == NULL) return t1;
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34 |
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35 | AndQueryNode *andNode = new AndQueryNode;
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36 | andNode->leftNode = t1;
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37 | andNode->rightNode = t2;
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38 | return andNode;
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39 | }
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40 |
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41 | static QueryNode *OrAdd (QueryNode *t1, QueryNode *t2) {
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42 | if (t1 == NULL) return t2;
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43 | if (t2 == NULL) return t1;
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44 |
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45 | OrQueryNode *orNode = new OrQueryNode;
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46 | orNode->leftNode = t1;
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47 | orNode->rightNode = t2;
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48 | return orNode;
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49 | }
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50 |
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51 | static QueryNode *NotAdd (QueryNode *t1, QueryNode *t2) {
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52 | if (t1 == NULL) return t2;
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53 | if (t2 == NULL) return t1;
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54 |
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55 | NotQueryNode *notNode = new NotQueryNode;
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56 | notNode->queryNode = t1;
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57 | notNode->notNode = t2;
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58 | return notNode;
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59 | }
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60 |
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61 | // expects the opening bracket to have already been parsed
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62 | // and discarded
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63 | static QueryNode *ParseBracketExpression (UCArray::const_iterator &here,
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64 | UCArray::const_iterator end,
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65 | int defaultBoolCombine,
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66 | int defaultStemMethod) {
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67 | // get everything in the expression
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68 | QueryNode *curTree = ParseExpression (here, end, defaultBoolCombine,
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69 | defaultStemMethod);
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70 |
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71 | // gobble up tokens until a closing bracket is found
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72 | // or the end of the string
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73 | LexEl el;
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74 | while (ParseLexEl (here, end, el)) {
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75 | if (el.lexType == CloseBracketE) break;
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76 | }
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77 |
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78 | return curTree;
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79 | }
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80 |
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81 | static int ParseInt (UCArray::const_iterator &here,
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82 | UCArray::const_iterator end) {
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83 | LexEl el;
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84 | UCArray::const_iterator oldHere = here;
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85 | if (ParseLexEl (here, end, el) && el.lexType == IntegerE)
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86 | return el.num;
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87 |
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88 | here = oldHere; // not an integer
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89 | return 0;
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90 | }
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91 |
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92 | // default is within 20 words
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93 | static void SetRangeValues (TermNode &termNode,
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94 | UCArray &nearby) {
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95 | UCArray NEARBY; SetCStr(NEARBY, "NEAR");
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96 | if (nearby == NEARBY) { // no modifier
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97 | termNode.startRange = -21;
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98 | termNode.endRange = 20;
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99 | }
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100 | else { // extract number
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101 | UCArray::const_iterator here = nearby.begin()+4;
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102 | UCArray::const_iterator end = nearby.end();
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103 | int size=0;
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104 | while (here != end) {
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105 | size = size*10 + (*here-'0');
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106 | here++;
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107 | }
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108 | termNode.startRange = -1 * (size+1);
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109 | termNode.endRange = size;
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110 | }
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111 | }
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112 |
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113 | static unsigned long GetStemMethod(LexEl &el, int defaultStemMethod) {
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114 | // here expect el to contain some of c,s,i,u
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115 | // stem method 0 = c,u 00
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116 | // stem method 1 = i,u 01 - default for DL
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117 | // stem method 2 = c, s 10
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118 | // stem method 3 = i,s 11
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119 |
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120 | unsigned long stem = (unsigned long)defaultStemMethod;
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121 |
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122 | UCArray::const_iterator here = el.text.begin();
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123 | UCArray::const_iterator end = el.text.end();
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124 |
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125 | unsigned char c1 = *here;
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126 | if (!(c1 == 'c'| c1 == 'i' | c1 == 'u' | c1 == 's'))
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127 | return 4; // incorrect format
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128 |
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129 | here++;
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130 | unsigned char c2 = 'a';
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131 | if (here !=end) {
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132 | c2 = *here;
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133 | if (!(c2 == 'c'| c2 == 'i' | c2 == 'u' | c2 == 's'))
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134 | return 4; // incorrect format
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135 | }
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136 |
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137 | if (c1 == 'i'|| c2=='i') stem |= 1; // set bit 0 to 1
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138 | if (c1 == 'c' || c2 == 'c') stem &=0xe; //set bit 0 to 0
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139 | if (c1 == 's'|| c2 == 's') stem |= 2; // set bit 1 to 1
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140 | if (c1 == 'u' || c2 =='u') stem &=0xd; // set bit 1 to 0
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141 | return stem;
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142 | }
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143 |
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144 |
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145 | static void ParseTermModifiers (UCArray::const_iterator &here,
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146 | UCArray::const_iterator end,
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147 | TermNode &termNode,
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148 | int defaultStemMethod) {
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149 |
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150 | termNode.stemMethod = defaultStemMethod;
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151 |
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152 | LexEl el;
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153 | UCArray::const_iterator oldHere = here;
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154 | while (ParseLexEl (here, end, el)) {
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155 | if (el.lexType == TermWeightE) {
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156 | termNode.termWeight = ParseInt (here, end);
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157 |
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158 | } else if (el.lexType == StemMethodE) {
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159 | oldHere = here;
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160 | LexEl stem;
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161 | if (ParseLexEl (here, end, stem) && stem.lexType == TermE) {
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162 | termNode.stemMethod = GetStemMethod(stem, defaultStemMethod);
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163 | if (termNode.stemMethod == 4) { // error so backtrack
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164 | here = oldHere;
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165 | termNode.stemMethod = (unsigned long)defaultStemMethod;
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166 | }
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167 | }else here = oldHere; //ignore - wrong syntax
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168 |
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169 | } else if (el.lexType == RangeE) {
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170 | termNode.startRange = ParseInt (here, end);
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171 | termNode.endRange = ParseInt (here, end);
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172 |
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173 | } else if (el.lexType == AtE) {
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174 | termNode.startRange = termNode.endRange = ParseInt (here, end);
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175 |
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176 | } else {
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177 | // no term modifiers
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178 | here = oldHere;
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179 | break;
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180 | }
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181 |
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182 | oldHere = here;
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183 | }
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184 | }
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185 |
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186 | static void ParseProxModifiers (UCArray::const_iterator &here,
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187 | UCArray::const_iterator end,
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188 | ProxMatchQueryNode *proxNode) {
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189 | // so far only have one - the tag stuff
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190 | LexEl el;
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191 | UCArray::const_iterator oldHere = here;
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192 | while (ParseLexEl (here, end, el)) {
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193 | if (el.lexType == TagE) {
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194 | oldHere = here; // don't backtrack past here
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195 | if (ParseLexEl (here, end, el) && el.lexType == TermE) {
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196 | proxNode->tagNodePtr = new TagNode;
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197 | proxNode->tagNodePtr->tagName = el.text;
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198 |
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199 | }
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200 | else { // error in tag
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201 | here = oldHere;
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202 | }
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203 | } // TagE
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204 | // add in other cases here
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205 | else {
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206 | // no modifiers
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207 | here = oldHere;
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208 | break;
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209 | }
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210 | oldHere = here;
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211 | }//while
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212 |
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213 |
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214 | }
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215 |
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216 | // expects starting brackets to have been parsed
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217 | static void ParseSquareBrackets(UCArray::const_iterator &here,
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218 | UCArray::const_iterator end,
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219 | ProxMatchQueryNode *proxNode,
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220 | int defaultStemMethod) {
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221 |
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222 | LexEl el;
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223 | bool phrase=false;
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224 | bool first=true;
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225 | while (ParseLexEl (here, end, el)) {
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226 | if (el.lexType == TermE || el.lexType == IntegerE) {
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227 | TermNode termNode;
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228 | termNode.term = el.text;
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229 | ParseTermModifiers (here, end, termNode, defaultStemMethod);
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230 | if (phrase) {
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231 | if (first) first=false;
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232 | else {
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233 | termNode.startRange = -2;
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234 | termNode.endRange = -1;
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235 | }
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236 | }
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237 | proxNode->terms.push_back(termNode);
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238 | }
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239 | else if (el.lexType == CloseSquareBracketE) {
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240 | break;
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241 | }
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242 | else if (el.lexType == AndOpE) {
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243 | // ignore, the words are AND'ed anyway
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244 | cerr << "and inside []\n";
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245 | }
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246 | else if (el.lexType == OrOpE) {
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247 | cerr << "or inside []\n";
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248 | }
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249 | else if (el.lexType == QuoteE) {
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250 | // phrase inside square brackets
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251 | if (phrase) phrase=false;
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252 | else phrase=true;
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253 | }
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254 | else {
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255 | //error
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256 | // just ignore for now
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257 | cerr <<"bad syntax inside []\n";
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258 | }
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259 | } // while
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260 |
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261 | }
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262 | // expects the starting quote to have been parsed
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263 | // and discarded
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264 | // now phrases use the case and stem preference options
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265 | // ie can search for a phrase ignoring case
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266 | static void ParsePhrase (UCArray::const_iterator &here,
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267 | UCArray::const_iterator end,
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268 | ProxMatchQueryNode &proxNode,
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269 | int defaultStemMethod) {
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270 | LexEl el;
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271 | bool first = true;
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272 | while (ParseLexEl (here, end, el)) {
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273 | if (el.lexType == TermE || el.lexType == IntegerE) {
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274 | TermNode termNode;
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275 | termNode.term = el.text;
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276 | //termNode.stemMethod = defaultStemMethod;
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277 | ParseTermModifiers (here, end, termNode, defaultStemMethod);
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278 | if (first) {
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279 | first = false;
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280 | }
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281 | else {
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282 | termNode.startRange = -2;
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283 | termNode.endRange = -1;
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284 | }
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285 | proxNode.terms.push_back (termNode);
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286 |
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287 | } else if (el.lexType == QuoteE) {
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288 | break;
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289 |
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290 | } else {
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291 | // error
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292 | break;
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293 | }
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294 | }
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295 | }
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296 |
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297 | static QueryNode *ParseTerm (UCArray::const_iterator &here,
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298 | UCArray::const_iterator end,
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299 | int defaultBoolCombine,
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300 | int defaultStemMethod) {
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301 | LexEl el;
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302 |
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303 | UCArray::const_iterator oldHere = here;
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304 | if (!ParseLexEl (here, end, el)) return NULL;
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305 |
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306 | if (el.lexType == OpenBracketE)
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307 | return ParseBracketExpression (here, end, defaultBoolCombine,
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308 | defaultStemMethod);
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309 |
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310 | ProxMatchQueryNode *proxNode = new ProxMatchQueryNode;
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311 |
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312 | if (el.lexType == TermE || el.lexType == IntegerE) {
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313 | TermNode termNode;
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314 | termNode.term = el.text;
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315 | ParseTermModifiers (here, end, termNode, defaultStemMethod);
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316 | oldHere = here; // dont backtrack past here
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317 | if (ParseLexEl(here, end, el) && el.lexType == NearOpE) {
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318 | delete proxNode;
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319 | proxNode = (ProxMatchQueryNode *)ParseTerm(here, end, defaultBoolCombine,
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320 | defaultStemMethod);
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321 | SetRangeValues(termNode, el.text);
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322 | proxNode->terms.push_back (termNode);
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323 | return proxNode;
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324 | }
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325 | else {
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326 | here = oldHere; // backtrack
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327 | proxNode->terms.push_back (termNode);
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328 | ParseProxModifiers(here, end, proxNode);
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329 | return proxNode;
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330 | }
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331 | } else if (el.lexType == QuoteE) {
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332 | ParsePhrase (here, end, *proxNode, defaultStemMethod);
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333 | return proxNode;
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334 | }
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335 | else if (el.lexType == OpenSquareBracketE) {
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336 | ParseSquareBrackets (here, end, proxNode, defaultStemMethod);
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337 | ParseProxModifiers (here, end, proxNode);
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338 | return proxNode;
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339 | }
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340 |
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341 | // not a term
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342 | here = oldHere;
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343 | delete proxNode;
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344 | return NULL;
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345 | }
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346 |
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347 |
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348 | static QueryNode *ParseExpression (UCArray::const_iterator &here,
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349 | UCArray::const_iterator end,
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350 | int defaultBoolCombine,
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351 | int defaultStemMethod) {
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352 | LexEl el;
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353 | QueryNode *curTree = NULL;
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354 |
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355 | UCArray::const_iterator oldHere = here;
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356 | while (ParseLexEl (here, end, el)) {
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357 | if (el.lexType == OpenSquareBracketE ||
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358 | el.lexType == OpenBracketE ||
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359 | el.lexType == TermE ||
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360 | el.lexType == QuoteE ||
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361 | el.lexType == IntegerE ) {
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362 | // el.lexType == TagE) { //tag at end of term now
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363 | // some type of term, back track and parse it
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364 | here = oldHere;
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365 | // if default==1, AND, else if==0, OR
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366 | if (defaultBoolCombine) {
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367 | curTree = AndAdd (curTree, ParseTerm (here, end, defaultBoolCombine,
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368 | defaultStemMethod));
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369 | }
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370 | else {
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371 | curTree = OrAdd (curTree, ParseTerm (here, end, defaultBoolCombine,
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372 | defaultStemMethod));
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373 | }
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374 |
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375 | } else if (el.lexType == AndOpE) {
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376 | curTree = AndAdd (curTree, ParseTerm (here, end, defaultBoolCombine,
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377 | defaultStemMethod));
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378 |
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379 | } else if (el.lexType == OrOpE) {
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380 | curTree = OrAdd (curTree, ParseTerm (here, end, defaultBoolCombine,
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381 | defaultStemMethod));
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382 |
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383 | } else if (el.lexType == NotOpE) {
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384 | curTree = NotAdd (curTree, ParseTerm (here, end, defaultBoolCombine,
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385 | defaultStemMethod));
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386 |
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387 | } else if (el.lexType == CloseBracketE) {
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388 | // parsebracketexpression is waiting for the last bracket, so put it back
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389 | here = oldHere;
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390 | break;
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391 |
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392 | } else break;
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393 |
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394 | oldHere = here;
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395 | }
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396 |
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397 | return curTree;
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398 | }
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399 |
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400 | QueryNode *ParseQuery (const UCArray &queryStr, int defaultBoolCombine,
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401 | int defaultStemMethod) {
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402 | UCArray::const_iterator here = queryStr.begin();
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403 | UCArray::const_iterator end = queryStr.end();
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404 | return ParseExpression (here, end, defaultBoolCombine, defaultStemMethod);
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405 | }
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