Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like Query often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Query, and based on these observations, apply Extract Interface, too.
1 | <?php |
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41 | class Query |
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42 | { |
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43 | /** |
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44 | * Functions that set the flag `is_func`. |
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45 | * |
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46 | * @var array |
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47 | */ |
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48 | public static $FUNCTIONS = array( |
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49 | 'SUM', 'AVG', 'STD', 'STDDEV', 'MIN', 'MAX', 'BIT_OR', 'BIT_AND', |
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50 | ); |
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51 | |||
52 | public static $ALLFLAGS = array( |
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53 | /* |
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54 | * select ... DISTINCT ... |
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55 | */ |
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56 | 'distinct' => false, |
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57 | |||
58 | /* |
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59 | * drop ... DATABASE ... |
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60 | */ |
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61 | 'drop_database' => false, |
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62 | |||
63 | /* |
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64 | * ... GROUP BY ... |
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65 | */ |
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66 | 'group' => false, |
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67 | |||
68 | /* |
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69 | * ... HAVING ... |
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70 | */ |
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71 | 'having' => false, |
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72 | |||
73 | /* |
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74 | * INSERT ... |
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75 | * or |
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76 | * REPLACE ... |
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77 | * or |
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78 | * DELETE ... |
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79 | */ |
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80 | 'is_affected' => false, |
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81 | |||
82 | /* |
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83 | * select ... PROCEDURE ANALYSE( ... ) ... |
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84 | */ |
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85 | 'is_analyse' => false, |
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86 | |||
87 | /* |
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88 | * select COUNT( ... ) ... |
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89 | */ |
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90 | 'is_count' => false, |
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91 | |||
92 | /* |
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93 | * DELETE ... |
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94 | */ |
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95 | 'is_delete' => false, // @deprecated; use `querytype` |
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96 | |||
97 | /* |
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98 | * EXPLAIN ... |
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99 | */ |
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100 | 'is_explain' => false, // @deprecated; use `querytype` |
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101 | |||
102 | /* |
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103 | * select ... INTO OUTFILE ... |
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104 | */ |
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105 | 'is_export' => false, |
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106 | |||
107 | /* |
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108 | * select FUNC( ... ) ... |
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109 | */ |
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110 | 'is_func' => false, |
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111 | |||
112 | /* |
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113 | * select ... GROUP BY ... |
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114 | * or |
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115 | * select ... HAVING ... |
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116 | */ |
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117 | 'is_group' => false, |
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118 | |||
119 | /* |
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120 | * INSERT ... |
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121 | * or |
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122 | * REPLACE ... |
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123 | * or |
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124 | * TODO: LOAD DATA ... |
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125 | */ |
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126 | 'is_insert' => false, |
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127 | |||
128 | /* |
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129 | * ANALYZE ... |
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130 | * or |
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131 | * CHECK ... |
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132 | * or |
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133 | * CHECKSUM ... |
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134 | * or |
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135 | * OPTIMIZE ... |
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136 | * or |
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137 | * REPAIR ... |
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138 | */ |
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139 | 'is_maint' => false, |
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140 | |||
141 | /* |
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142 | * CALL ... |
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143 | */ |
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144 | 'is_procedure' => false, |
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145 | |||
146 | /* |
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147 | * REPLACE ... |
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148 | */ |
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149 | 'is_replace' => false, // @deprecated; use `querytype` |
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150 | |||
151 | /* |
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152 | * SELECT ... |
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153 | */ |
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154 | 'is_select' => false, // @deprecated; use `querytype` |
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155 | |||
156 | /* |
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157 | * SHOW ... |
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158 | */ |
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159 | 'is_show' => false, // @deprecated; use `querytype` |
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160 | |||
161 | /* |
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162 | * Contains a subquery. |
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163 | */ |
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164 | 'is_subquery' => false, |
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165 | |||
166 | /* |
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167 | * ... JOIN ... |
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168 | */ |
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169 | 'join' => false, |
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170 | |||
171 | /* |
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172 | * ... LIMIT ... |
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173 | */ |
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174 | 'limit' => false, |
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175 | |||
176 | /* |
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177 | * TODO |
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178 | */ |
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179 | 'offset' => false, |
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180 | |||
181 | /* |
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182 | * ... ORDER ... |
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183 | */ |
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184 | 'order' => false, |
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185 | |||
186 | /* |
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187 | * The type of the query (which is usually the first keyword of |
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188 | * the statement). |
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189 | */ |
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190 | 'querytype' => false, |
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191 | |||
192 | /* |
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193 | * Whether a page reload is required. |
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194 | */ |
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195 | 'reload' => false, |
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196 | |||
197 | /* |
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198 | * SELECT ... FROM ... |
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199 | */ |
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200 | 'select_from' => false, |
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201 | |||
202 | /* |
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203 | * ... UNION ... |
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204 | */ |
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205 | 'union' => false, |
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206 | ); |
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207 | |||
208 | /** |
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209 | * Gets an array with flags select statement has. |
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210 | * |
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211 | * @param Statement|null $statement the statement to be processed |
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212 | * @param array $flagsi flags set so far |
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213 | * |
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214 | * @return array |
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215 | */ |
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216 | 13 | private static function _getFlagsSelect($statement, $flags) |
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282 | |||
283 | /** |
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284 | * Gets an array with flags this statement has. |
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285 | * |
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286 | * @param Statement|null $statement the statement to be processed |
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287 | * @param bool $all if `false`, false values will not be included |
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288 | * |
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289 | * @return array |
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290 | */ |
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291 | 29 | public static function getFlags($statement, $all = false) |
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371 | |||
372 | /** |
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373 | * Parses a query and gets all information about it. |
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374 | * |
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375 | * @param string $query the query to be parsed |
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376 | * |
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377 | * @return array The array returned is the one returned by |
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378 | * `static::getFlags()`, with the following keys added: |
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379 | * - parser - the parser used to analyze the query; |
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380 | * - statement - the first statement resulted from parsing; |
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381 | * - select_tables - the real name of the tables selected; |
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382 | * if there are no table names in the `SELECT` |
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383 | * expressions, the table names are fetched from the |
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384 | * `FROM` expressions |
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385 | * - select_expr - selected expressions |
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386 | */ |
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387 | 1 | public static function getAll($query) |
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462 | |||
463 | /** |
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464 | * Gets a list of all tables used in this statement. |
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465 | * |
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466 | * @param Statement $statement statement to be scanned |
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467 | * |
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468 | * @return array |
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469 | */ |
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470 | 7 | public static function getTables($statement) |
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511 | |||
512 | /** |
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513 | * Gets a specific clause. |
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514 | * |
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515 | * @param Statement $statement the parsed query that has to be modified |
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516 | * @param TokensList $list the list of tokens |
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517 | * @param string $clause the clause to be returned |
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518 | * @param int|string $type The type of the search. |
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519 | * If int, |
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520 | * -1 for everything that was before |
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521 | * 0 only for the clause |
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522 | * 1 for everything after |
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523 | * If string, the name of the first clause that |
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524 | * should not be included. |
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525 | * @param bool $skipFirst whether to skip the first keyword in clause |
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526 | * |
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527 | * @return string |
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528 | */ |
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529 | 4 | public static function getClause($statement, $list, $clause, $type = 0, $skipFirst = true) |
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643 | |||
644 | /** |
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645 | * Builds a query by rebuilding the statement from the tokens list supplied |
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646 | * and replaces a clause. |
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647 | * |
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648 | * It is a very basic version of a query builder. |
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649 | * |
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650 | * @param Statement $statement the parsed query that has to be modified |
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651 | * @param TokensList $list the list of tokens |
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652 | * @param string $old The type of the clause that should be |
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653 | * replaced. This can be an entire clause. |
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654 | * @param string $new The new clause. If this parameter is omitted |
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655 | * it is considered to be equal with `$old`. |
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656 | * @param bool $onlyType whether only the type of the clause should |
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657 | * be replaced or the entire clause |
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658 | * |
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659 | * @return string |
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660 | */ |
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661 | 3 | public static function replaceClause($statement, $list, $old, $new = null, $onlyType = false) |
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678 | |||
679 | /** |
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680 | * Builds a query by rebuilding the statement from the tokens list supplied |
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681 | * and replaces multiple clauses. |
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682 | * |
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683 | * @param Statement $statement the parsed query that has to be modified |
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684 | * @param TokensList $list the list of tokens |
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685 | * @param array $ops Clauses to be replaced. Contains multiple |
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686 | * arrays having two values: array($old, $new). |
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687 | * Clauses must be sorted. |
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688 | * |
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689 | * @return string |
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690 | */ |
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691 | 1 | public static function replaceClauses($statement, $list, array $ops) |
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735 | |||
736 | /** |
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737 | * Gets the first full statement in the query. |
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738 | * |
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739 | * @param string $query the query to be analyzed |
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740 | * @param string $delimiter the delimiter to be used |
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741 | * |
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742 | * @return array array containing the first full query, the |
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743 | * remaining part of the query and the last |
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744 | * delimiter |
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745 | */ |
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746 | 1 | public static function getFirstStatement($query, $delimiter = null) |
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796 | |||
797 | /** |
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798 | * Gets a starting offset of a specific clause. |
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799 | * |
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800 | * @param Statement $statement the parsed query that has to be modified |
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801 | * @param TokensList $list the list of tokens |
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802 | * @param string $clause the clause to be returned |
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803 | * |
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804 | * @return int |
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805 | */ |
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806 | 136 | public static function getClauseStartOffset($statement, $list, $clause) |
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852 | } |
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853 |