LFFATE /
ccg
| Total Complexity | 47 |
| Total Lines | 364 |
| Duplicated Lines | 0 % |
| Changes | 1 | ||
| Bugs | 0 | Features | 0 |
Complex classes like Diff 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.
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 Diff, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 17 | class Diff{ |
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| 18 | |||
| 19 | // define the constants |
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| 20 | const UNMODIFIED = 0; |
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| 21 | const DELETED = 1; |
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| 22 | const INSERTED = 2; |
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| 23 | |||
| 24 | /* Returns the diff for two strings. The return value is an array, each of |
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| 25 | * whose values is an array containing two values: a line (or character, if |
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| 26 | * $compareCharacters is true), and one of the constants DIFF::UNMODIFIED (the |
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| 27 | * line or character is in both strings), DIFF::DELETED (the line or character |
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| 28 | * is only in the first string), and DIFF::INSERTED (the line or character is |
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| 29 | * only in the second string). The parameters are: |
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| 30 | * |
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| 31 | * $string1 - the first string |
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| 32 | * $string2 - the second string |
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| 33 | * $compareCharacters - true to compare characters, and false to compare |
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| 34 | * lines; this optional parameter defaults to false |
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| 35 | */ |
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| 36 | public static function compare( |
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| 37 | $string1, $string2, $compareCharacters = false){ |
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| 38 | |||
| 39 | // initialise the sequences and comparison start and end positions |
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| 40 | $start = 0; |
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| 41 | if ($compareCharacters){ |
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| 42 | $sequence1 = $string1; |
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| 43 | $sequence2 = $string2; |
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| 44 | $end1 = strlen($string1) - 1; |
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| 45 | $end2 = strlen($string2) - 1; |
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| 46 | }else{ |
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| 47 | $sequence1 = preg_split('/\R/', $string1); |
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| 48 | $sequence2 = preg_split('/\R/', $string2); |
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| 49 | $end1 = count($sequence1) - 1; |
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| 50 | $end2 = count($sequence2) - 1; |
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| 51 | } |
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| 52 | |||
| 53 | // skip any common prefix |
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| 54 | while ($start <= $end1 && $start <= $end2 |
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| 55 | && $sequence1[$start] == $sequence2[$start]){ |
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| 56 | $start ++; |
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| 57 | } |
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| 58 | |||
| 59 | // skip any common suffix |
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| 60 | while ($end1 >= $start && $end2 >= $start |
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| 61 | && $sequence1[$end1] == $sequence2[$end2]){ |
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| 62 | $end1 --; |
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| 63 | $end2 --; |
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| 64 | } |
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| 65 | |||
| 66 | // compute the table of longest common subsequence lengths |
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| 67 | $table = self::computeTable($sequence1, $sequence2, $start, $end1, $end2); |
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| 68 | |||
| 69 | // generate the partial diff |
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| 70 | $partialDiff = |
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| 71 | self::generatePartialDiff($table, $sequence1, $sequence2, $start); |
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| 72 | |||
| 73 | // generate the full diff |
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| 74 | $diff = array(); |
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| 75 | for ($index = 0; $index < $start; $index ++){ |
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| 76 | $diff[] = array($sequence1[$index], self::UNMODIFIED); |
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| 77 | } |
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| 78 | while (count($partialDiff) > 0) $diff[] = array_pop($partialDiff); |
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| 79 | for ($index = $end1 + 1; |
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| 80 | $index < ($compareCharacters ? strlen($sequence1) : count($sequence1)); |
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| 81 | $index ++){ |
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| 82 | $diff[] = array($sequence1[$index], self::UNMODIFIED); |
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| 83 | } |
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| 84 | |||
| 85 | // return the diff |
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| 86 | return $diff; |
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| 87 | |||
| 88 | } |
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| 89 | |||
| 90 | /* Returns the diff for two files. The parameters are: |
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| 91 | * |
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| 92 | * $file1 - the path to the first file |
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| 93 | * $file2 - the path to the second file |
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| 94 | * $compareCharacters - true to compare characters, and false to compare |
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| 95 | * lines; this optional parameter defaults to false |
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| 96 | */ |
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| 97 | public static function compareFiles( |
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| 105 | |||
| 106 | } |
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| 107 | |||
| 108 | /* Returns the table of longest common subsequence lengths for the specified |
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| 109 | * sequences. The parameters are: |
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| 110 | * |
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| 111 | * $sequence1 - the first sequence |
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| 112 | * $sequence2 - the second sequence |
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| 113 | * $start - the starting index |
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| 114 | * $end1 - the ending index for the first sequence |
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| 115 | * $end2 - the ending index for the second sequence |
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| 116 | */ |
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| 117 | private static function computeTable( |
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| 150 | |||
| 151 | } |
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| 152 | |||
| 153 | /* Returns the partial diff for the specificed sequences, in reverse order. |
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| 154 | * The parameters are: |
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| 155 | * |
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| 156 | * $table - the table returned by the computeTable function |
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| 157 | * $sequence1 - the first sequence |
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| 158 | * $sequence2 - the second sequence |
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| 159 | * $start - the starting index |
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| 160 | */ |
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| 161 | private static function generatePartialDiff( |
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| 162 | $table, $sequence1, $sequence2, $start){ |
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| 163 | |||
| 164 | // initialise the diff |
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| 165 | $diff = array(); |
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| 166 | |||
| 167 | // initialise the indices |
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| 168 | $index1 = count($table) - 1; |
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| 169 | $index2 = count($table[0]) - 1; |
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| 170 | |||
| 171 | // loop until there are no items remaining in either sequence |
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| 172 | while ($index1 > 0 || $index2 > 0){ |
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| 173 | |||
| 174 | // check what has happened to the items at these indices |
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| 175 | if ($index1 > 0 && $index2 > 0 |
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| 176 | && $sequence1[$index1 + $start - 1] |
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| 177 | == $sequence2[$index2 + $start - 1]){ |
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| 178 | |||
| 179 | // update the diff and the indices |
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| 180 | $diff[] = array($sequence1[$index1 + $start - 1], self::UNMODIFIED); |
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| 181 | $index1 --; |
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| 182 | $index2 --; |
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| 183 | |||
| 184 | }elseif ($index2 > 0 |
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| 185 | && $table[$index1][$index2] == $table[$index1][$index2 - 1]){ |
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| 186 | |||
| 187 | // update the diff and the indices |
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| 188 | $diff[] = array($sequence2[$index2 + $start - 1], self::INSERTED); |
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| 189 | $index2 --; |
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| 190 | |||
| 191 | }else{ |
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| 192 | |||
| 193 | // update the diff and the indices |
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| 194 | $diff[] = array($sequence1[$index1 + $start - 1], self::DELETED); |
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| 195 | $index1 --; |
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| 196 | |||
| 197 | } |
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| 198 | |||
| 199 | } |
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| 200 | |||
| 201 | // return the diff |
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| 202 | return $diff; |
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| 203 | |||
| 204 | } |
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| 205 | |||
| 206 | /* Returns a diff as a string, where unmodified lines are prefixed by ' ', |
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| 207 | * deletions are prefixed by '- ', and insertions are prefixed by '+ '. The |
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| 208 | * parameters are: |
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| 209 | * |
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| 210 | * $diff - the diff array |
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| 211 | * $separator - the separator between lines; this optional parameter defaults |
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| 212 | * to "\n" |
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| 213 | */ |
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| 214 | public static function toString($diff, $separator = "\n"){ |
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| 215 | |||
| 216 | // initialise the string |
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| 217 | $string = ''; |
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| 218 | |||
| 219 | // loop over the lines in the diff |
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| 220 | foreach ($diff as $line){ |
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| 221 | |||
| 222 | // extend the string with the line |
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| 223 | switch ($line[1]){ |
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| 224 | case self::UNMODIFIED : $string .= ' ' . $line[0];break; |
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| 225 | case self::DELETED : $string .= '- ' . $line[0];break; |
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| 226 | case self::INSERTED : $string .= '+ ' . $line[0];break; |
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| 227 | } |
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| 228 | |||
| 229 | // extend the string with the separator |
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| 230 | $string .= $separator; |
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| 231 | |||
| 232 | } |
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| 233 | |||
| 234 | // return the string |
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| 235 | return $string; |
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| 236 | |||
| 237 | } |
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| 238 | |||
| 239 | /* Returns a diff as an HTML string, where unmodified lines are contained |
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| 240 | * within 'span' elements, deletions are contained within 'del' elements, and |
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| 241 | * insertions are contained within 'ins' elements. The parameters are: |
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| 242 | * |
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| 243 | * $diff - the diff array |
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| 244 | * $separator - the separator between lines; this optional parameter defaults |
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| 245 | * to '<br>' |
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| 246 | */ |
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| 247 | public static function toHTML($diff, $separator = '<br>'){ |
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| 248 | |||
| 249 | // initialise the HTML |
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| 250 | $html = ''; |
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| 251 | |||
| 252 | // loop over the lines in the diff |
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| 253 | foreach ($diff as $line){ |
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| 254 | |||
| 255 | // extend the HTML with the line |
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| 256 | switch ($line[1]){ |
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| 257 | case self::UNMODIFIED : $element = 'span'; break; |
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| 258 | case self::DELETED : $element = 'del'; break; |
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| 259 | case self::INSERTED : $element = 'ins'; break; |
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| 260 | } |
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| 261 | $html .= |
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| 262 | '<' . $element . '>' |
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| 263 | . htmlspecialchars($line[0]) |
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| 264 | . '</' . $element . '>'; |
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| 265 | |||
| 266 | // extend the HTML with the separator |
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| 267 | $html .= $separator; |
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| 268 | |||
| 269 | } |
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| 270 | |||
| 271 | // return the HTML |
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| 272 | return $html; |
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| 273 | |||
| 274 | } |
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| 275 | |||
| 276 | /* Returns a diff as an HTML table. The parameters are: |
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| 277 | * |
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| 278 | * $diff - the diff array |
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| 279 | * $indentation - indentation to add to every line of the generated HTML; this |
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| 280 | * optional parameter defaults to '' |
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| 281 | * $separator - the separator between lines; this optional parameter |
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| 282 | * defaults to '<br>' |
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| 283 | */ |
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| 284 | public static function toTable($diff, $indentation = '', $separator = '<br>'){ |
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| 285 | |||
| 286 | // initialise the HTML |
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| 287 | $html = $indentation . "<table class=\"diff\">\n"; |
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| 288 | |||
| 289 | // loop over the lines in the diff |
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| 290 | $index = 0; |
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| 291 | while ($index < count($diff)){ |
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| 292 | |||
| 293 | // determine the line type |
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| 294 | switch ($diff[$index][1]){ |
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| 295 | |||
| 296 | // display the content on the left and right |
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| 297 | case self::UNMODIFIED: |
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| 298 | $leftCell = |
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| 299 | self::getCellContent( |
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| 300 | $diff, $indentation, $separator, $index, self::UNMODIFIED); |
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| 301 | $rightCell = $leftCell; |
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| 302 | break; |
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| 303 | |||
| 304 | // display the deleted on the left and inserted content on the right |
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| 305 | case self::DELETED: |
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| 306 | $leftCell = |
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| 307 | self::getCellContent( |
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| 308 | $diff, $indentation, $separator, $index, self::DELETED); |
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| 309 | $rightCell = |
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| 310 | self::getCellContent( |
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| 311 | $diff, $indentation, $separator, $index, self::INSERTED); |
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| 312 | break; |
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| 313 | |||
| 314 | // display the inserted content on the right |
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| 315 | case self::INSERTED: |
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| 316 | $leftCell = ''; |
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| 317 | $rightCell = |
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| 318 | self::getCellContent( |
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| 319 | $diff, $indentation, $separator, $index, self::INSERTED); |
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| 320 | break; |
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| 321 | |||
| 322 | } |
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| 323 | |||
| 324 | // extend the HTML with the new row |
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| 325 | $html .= |
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| 326 | $indentation |
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| 327 | . " <tr>\n" |
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| 328 | . $indentation |
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| 329 | . ' <td class="diff' |
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| 330 | . ($leftCell == $rightCell |
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| 331 | ? 'Unmodified' |
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| 332 | : ($leftCell == '' ? 'Blank' : 'Deleted')) |
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| 333 | . '">' |
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| 334 | . $leftCell |
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| 335 | . "</td>\n" |
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| 336 | . $indentation |
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| 337 | . ' <td class="diff' |
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| 338 | . ($leftCell == $rightCell |
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| 339 | ? 'Unmodified' |
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| 340 | : ($rightCell == '' ? 'Blank' : 'Inserted')) |
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| 341 | . '">' |
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| 342 | . $rightCell |
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| 343 | . "</td>\n" |
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| 344 | . $indentation |
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| 345 | . " </tr>\n"; |
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| 346 | |||
| 347 | } |
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| 348 | |||
| 349 | // return the HTML |
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| 350 | return $html . $indentation . "</table>\n"; |
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| 351 | |||
| 352 | } |
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| 353 | |||
| 354 | /* Returns the content of the cell, for use in the toTable function. The |
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| 355 | * parameters are: |
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| 356 | * |
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| 357 | * $diff - the diff array |
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| 358 | * $indentation - indentation to add to every line of the generated HTML |
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| 359 | * $separator - the separator between lines |
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| 360 | * $index - the current index, passes by reference |
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| 361 | * $type - the type of line |
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| 362 | */ |
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| 363 | private static function getCellContent( |
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| 381 | |||
| 382 | } |
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| 383 | |||
| 384 | } |
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| 385 |
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