doc/String.html

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  68                         <div id="method-list-section" class="section">
  69                                 <h3 class="section-header">Methods</h3>
  70                                 <ul class="link-list">
  71
  72                                         <li><a href="#method-i-porter2_ends_with_short_syllable%3F">#porter2_ends_with_short_syllable?</a></li>
  73
  74                                         <li><a href="#method-i-porter2_is_short_word%3F">#porter2_is_short_word?</a></li>
  75
  76                                         <li><a href="#method-i-porter2_postprocess">#porter2_postprocess</a></li>
  77
  78                                         <li><a href="#method-i-porter2_preprocess">#porter2_preprocess</a></li>
  79
  80                                         <li><a href="#method-i-porter2_r1">#porter2_r1</a></li>
  81
  82                                         <li><a href="#method-i-porter2_r2">#porter2_r2</a></li>
  83
  84                                         <li><a href="#method-i-porter2_stem">#porter2_stem</a></li>
  85
  86                                         <li><a href="#method-i-porter2_stem_verbose">#porter2_stem_verbose</a></li>
  87
  88                                         <li><a href="#method-i-porter2_step0">#porter2_step0</a></li>
  89
  90                                         <li><a href="#method-i-porter2_step1a">#porter2_step1a</a></li>
  91
  92                                         <li><a href="#method-i-porter2_step1b">#porter2_step1b</a></li>
  93
  94                                         <li><a href="#method-i-porter2_step1c">#porter2_step1c</a></li>
  95
  96                                         <li><a href="#method-i-porter2_step2">#porter2_step2</a></li>
  97
  98                                         <li><a href="#method-i-porter2_step3">#porter2_step3</a></li>
  99
 100                                         <li><a href="#method-i-porter2_step4">#porter2_step4</a></li>
 101
 102                                         <li><a href="#method-i-porter2_step5">#porter2_step5</a></li>
 103
 104                                         <li><a href="#method-i-porter2_tidy">#porter2_tidy</a></li>
 105
 106                                         <li><a href="#method-i-stem">#stem</a></li>
 107
 108                                 </ul>
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 134
 135                                         <li><a href="./Porter2.html">Porter2</a></li>
 136
 137                                         <li><a href="./String.html">String</a></li>
 138
 139                                         <li><a href="./TestPorter2.html">TestPorter2</a></li>
 140
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 143                         </div>
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 147         </div>
 148
 149         <div id="documentation">
 150                 <h1 class="class">String</h1>
 151
 152                 <div id="description">
 153                         <h2>The Porter 2 stemmer</h2>
 154 <p>
 155 This is the Porter 2 stemming algorithm, as described at  <a
 156 href="http://snowball.tartarus.org/algorithms/english/stemmer.html">snowball.tartarus.org/algorithms/english/stemmer.html</a>
 157 The original paper is:
 158 </p>
 159 <p>
 160 Porter, 1980, &#8220;An algorithm for suffix stripping&#8221;,
 161 <em>Program</em>, Vol. 14, no. 3, pp 130-137
 162 </p>
 163 <p>
 164 Constants for the stemmer are in the <a href="Porter2.html">Porter2</a>
 165 module.
 166 </p>
 167 <p>
 168 Procedures that implement the stemmer are added to the <a
 169 href="String.html">String</a> class.
 170 </p>
 171 <p>
 172 The stemmer algorithm is implemented in the <a
 173 href="String.html#method-i-porter2_stem">porter2_stem</a> procedure.
 174 </p>
 175 <h2>Internationalisation</h2>
 176 <p>
 177 There isn&#8217;t much, as this is a stemmer that only works for English.
 178 </p>
 179 <p>
 180 The <tt>gb_english</tt> flag to the various procedures allows the stemmer
 181 to treat the British  English &#8217;-ise&#8217; the same as the American
 182 English &#8217;-ize&#8217;.
 183 </p>
 184 <h2>Longest suffixes</h2>
 185 <p>
 186 Several places in the algorithm require matching the longest suffix of a
 187 word. The  regexp engine in Ruby 1.9 seems to handle alterntives in regexps
 188 by finding the  alternative that matches at the first position in the
 189 string. As we&#8217;re only talking  about suffixes, that first match is
 190 also the longest suffix. If the regexp engine changes, this behaviour may
 191 change and break the stemmer.
 192 </p>
 193
 194                 </div>
 195
 196                 <!-- Constants -->
 197
 198
 199                 <!-- Attributes -->
 200
 201
 202                 <!-- Methods -->
 203
 204                 <div id="public-instance-method-details" class="method-section section">
 205                         <h3 class="section-header">Public Instance Methods</h3>
 206
 207
 208                         <div id="porter-ends-with-short-syllable--method" class="method-detail ">
 209                                 <a name="method-i-porter2_ends_with_short_syllable%3F"></a>
 210
 211                                 <div class="method-heading">
 212
 213                                         <span class="method-name">porter2_ends_with_short_syllable?</span><span
 214                                                 class="method-args">()</span>
 215                                         <span class="method-click-advice">click to toggle source</span>
 216
 217                                 </div>
 218
 219                                 <div class="method-description">
 220
 221                                         <p>
 222 Returns true if the word ends with a short syllable
 223 </p>
 224
 225
 226
 227                                         <div class="method-source-code"
 228                                                 id="porter-ends-with-short-syllable--source">
 229 <pre>
 230     <span class="ruby-comment cmt"># File lib/porter2.rb, line 87</span>
 231 87:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_ends_with_short_syllable?</span>
 232 88:     <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/#{Porter2::SHORT_SYLLABLE}$/</span> <span class="ruby-operator">?</span> <span class="ruby-keyword kw">true</span> <span class="ruby-operator">:</span> <span class="ruby-keyword kw">false</span>
 233 89:   <span class="ruby-keyword kw">end</span></pre>
 234                                         </div>
 235
 236                                 </div>
 237
 238
 239
 240
 241                         </div>
 242
 243
 244                         <div id="porter-is-short-word--method" class="method-detail ">
 245                                 <a name="method-i-porter2_is_short_word%3F"></a>
 246
 247                                 <div class="method-heading">
 248
 249                                         <span class="method-name">porter2_is_short_word?</span><span
 250                                                 class="method-args">()</span>
 251                                         <span class="method-click-advice">click to toggle source</span>
 252
 253                                 </div>
 254
 255                                 <div class="method-description">
 256
 257                                         <p>
 258 A word is short if it ends in a short syllable, and R1 is null
 259 </p>
 260
 261
 262
 263                                         <div class="method-source-code"
 264                                                 id="porter-is-short-word--source">
 265 <pre>
 266     <span class="ruby-comment cmt"># File lib/porter2.rb, line 93</span>
 267 93:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_is_short_word?</span>
 268 94:     <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_ends_with_short_syllable?</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r1</span>.<span class="ruby-identifier">empty?</span>
 269 95:   <span class="ruby-keyword kw">end</span></pre>
 270                                         </div>
 271
 272                                 </div>
 273
 274
 275
 276
 277                         </div>
 278
 279
 280                         <div id="porter-postprocess-method" class="method-detail ">
 281                                 <a name="method-i-porter2_postprocess"></a>
 282
 283                                 <div class="method-heading">
 284
 285                                         <span class="method-name">porter2_postprocess</span><span
 286                                                 class="method-args">()</span>
 287                                         <span class="method-click-advice">click to toggle source</span>
 288
 289                                 </div>
 290
 291                                 <div class="method-description">
 292
 293                                         <p>
 294 Turn all Y letters into y
 295 </p>
 296
 297
 298
 299                                         <div class="method-source-code"
 300                                                 id="porter-postprocess-source">
 301 <pre>
 302      <span class="ruby-comment cmt"># File lib/porter2.rb, line 289</span>
 303 289:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_postprocess</span>
 304 290:     <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">gsub</span>(<span class="ruby-regexp re">/Y/</span>, <span class="ruby-value str">'y'</span>)
 305 291:   <span class="ruby-keyword kw">end</span></pre>
 306                                         </div>
 307
 308                                 </div>
 309
 310
 311
 312
 313                         </div>
 314
 315
 316                         <div id="porter-preprocess-method" class="method-detail ">
 317                                 <a name="method-i-porter2_preprocess"></a>
 318
 319                                 <div class="method-heading">
 320
 321                                         <span class="method-name">porter2_preprocess</span><span
 322                                                 class="method-args">()</span>
 323                                         <span class="method-click-advice">click to toggle source</span>
 324
 325                                 </div>
 326
 327                                 <div class="method-description">
 328
 329                                         <p>
 330 Preprocess the word.  Remove any initial &#8217;, if present. Then, set
 331 initial y, or y after a vowel, to Y
 332 </p>
 333 <p>
 334 (The comment to &#8216;establish the regions R1 and R2&#8217; in the
 335 original description  is an implementation optimisation that identifies
 336 where the regions start. As no modifications are made to the word that
 337 affect those positions, you may want to cache them now. This implementation
 338 doesn&#8217;t do that.)
 339 </p>
 340
 341
 342
 343                                         <div class="method-source-code"
 344                                                 id="porter-preprocess-source">
 345 <pre>
 346     <span class="ruby-comment cmt"># File lib/porter2.rb, line 53</span>
 347 53:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_preprocess</span>
 348 54:     <span class="ruby-identifier">w</span> = <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">dup</span>
 349 55:
 350 56:     <span class="ruby-comment cmt"># remove any initial apostrophe</span>
 351 57:     <span class="ruby-identifier">w</span>.<span class="ruby-identifier">gsub!</span>(<span class="ruby-regexp re">/^'*(.)/</span>, <span class="ruby-value str">'\1'</span>)
 352 58:
 353 59:     <span class="ruby-comment cmt"># set initial y, or y after a vowel, to Y</span>
 354 60:     <span class="ruby-identifier">w</span>.<span class="ruby-identifier">gsub!</span>(<span class="ruby-regexp re">/^y/</span>, <span class="ruby-value str">&quot;Y&quot;</span>)
 355 61:     <span class="ruby-identifier">w</span>.<span class="ruby-identifier">gsub!</span>(<span class="ruby-node">/(#{Porter2::V})y/</span>, <span class="ruby-value str">'\1Y'</span>)
 356 62:
 357 63:     <span class="ruby-identifier">w</span>
 358 64:   <span class="ruby-keyword kw">end</span></pre>
 359                                         </div>
 360
 361                                 </div>
 362
 363
 364
 365
 366                         </div>
 367
 368
 369                         <div id="porter-r--method" class="method-detail ">
 370                                 <a name="method-i-porter2_r1"></a>
 371
 372                                 <div class="method-heading">
 373
 374                                         <span class="method-name">porter2_r1</span><span
 375                                                 class="method-args">()</span>
 376                                         <span class="method-click-advice">click to toggle source</span>
 377
 378                                 </div>
 379
 380                                 <div class="method-description">
 381
 382                                         <p>
 383 R1 is the portion of the word after the first non-vowel after the first
 384 vowel (with words beginning &#8216;gener-&#8217;, &#8216;commun-&#8217;,
 385 and &#8216;arsen-&#8217; treated as special cases
 386 </p>
 387
 388
 389
 390                                         <div class="method-source-code"
 391                                                 id="porter-r--source">
 392 <pre>
 393     <span class="ruby-comment cmt"># File lib/porter2.rb, line 69</span>
 394 69:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_r1</span>
 395 70:     <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/^(gener|commun|arsen)(?&lt;r1&gt;.*)/</span>
 396 71:       <span class="ruby-constant">Regexp</span>.<span class="ruby-identifier">last_match</span>(<span class="ruby-value">:r1</span>)
 397 72:     <span class="ruby-keyword kw">else</span>
 398 73:       <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/#{Porter2::V}#{Porter2::C}(?&lt;r1&gt;.*)$/</span>
 399 74:       <span class="ruby-constant">Regexp</span>.<span class="ruby-identifier">last_match</span>(<span class="ruby-value">:r1</span>) <span class="ruby-operator">||</span> <span class="ruby-value str">&quot;&quot;</span>
 400 75:     <span class="ruby-keyword kw">end</span>
 401 76:   <span class="ruby-keyword kw">end</span></pre>
 402                                         </div>
 403
 404                                 </div>
 405
 406
 407
 408
 409                         </div>
 410
 411
 412                         <div id="porter-r--method" class="method-detail ">
 413                                 <a name="method-i-porter2_r2"></a>
 414
 415                                 <div class="method-heading">
 416
 417                                         <span class="method-name">porter2_r2</span><span
 418                                                 class="method-args">()</span>
 419                                         <span class="method-click-advice">click to toggle source</span>
 420
 421                                 </div>
 422
 423                                 <div class="method-description">
 424
 425                                         <p>
 426 R2 is the portion of R1 (<a
 427 href="String.html#method-i-porter2_r1">porter2_r1</a>) after the first
 428 non-vowel after the first vowel
 429 </p>
 430
 431
 432
 433                                         <div class="method-source-code"
 434                                                 id="porter-r--source">
 435 <pre>
 436     <span class="ruby-comment cmt"># File lib/porter2.rb, line 80</span>
 437 80:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_r2</span>
 438 81:     <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r1</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/#{Porter2::V}#{Porter2::C}(?&lt;r2&gt;.*)$/</span>
 439 82:     <span class="ruby-constant">Regexp</span>.<span class="ruby-identifier">last_match</span>(<span class="ruby-value">:r2</span>) <span class="ruby-operator">||</span> <span class="ruby-value str">&quot;&quot;</span>
 440 83:   <span class="ruby-keyword kw">end</span></pre>
 441                                         </div>
 442
 443                                 </div>
 444
 445
 446
 447
 448                         </div>
 449
 450
 451                         <div id="porter-stem-method" class="method-detail ">
 452                                 <a name="method-i-porter2_stem"></a>
 453
 454                                 <div class="method-heading">
 455
 456                                         <span class="method-name">porter2_stem</span><span
 457                                                 class="method-args">(gb_english = false)</span>
 458                                         <span class="method-click-advice">click to toggle source</span>
 459
 460                                 </div>
 461
 462                                 <div class="method-description">
 463
 464                                         <p>
 465 Perform the stemming procedure. If <tt>gb_english</tt> is true, treat
 466 &#8217;-ise&#8217; and similar suffixes as &#8217;-ize&#8217; in American
 467 English.
 468 </p>
 469
 470
 471
 472                                         <div class="method-source-code"
 473                                                 id="porter-stem-source">
 474 <pre>
 475      <span class="ruby-comment cmt"># File lib/porter2.rb, line 297</span>
 476 297:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_stem</span>(<span class="ruby-identifier">gb_english</span> = <span class="ruby-keyword kw">false</span>)
 477 298:     <span class="ruby-identifier">preword</span> = <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_tidy</span>
 478 299:     <span class="ruby-keyword kw">return</span> <span class="ruby-identifier">preword</span> <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">preword</span>.<span class="ruby-identifier">length</span> <span class="ruby-operator">&lt;=</span> <span class="ruby-value">2</span>
 479 300:
 480 301:     <span class="ruby-identifier">word</span> = <span class="ruby-identifier">preword</span>.<span class="ruby-identifier">porter2_preprocess</span>
 481 302:
 482 303:     <span class="ruby-keyword kw">if</span> <span class="ruby-constant">Porter2</span><span class="ruby-operator">::</span><span class="ruby-constant">SPECIAL_CASES</span>.<span class="ruby-identifier">has_key?</span> <span class="ruby-identifier">word</span>
 483 304:       <span class="ruby-constant">Porter2</span><span class="ruby-operator">::</span><span class="ruby-constant">SPECIAL_CASES</span>[<span class="ruby-identifier">word</span>]
 484 305:     <span class="ruby-keyword kw">else</span>
 485 306:       <span class="ruby-identifier">w1a</span> = <span class="ruby-identifier">word</span>.<span class="ruby-identifier">porter2_step0</span>.<span class="ruby-identifier">porter2_step1a</span>
 486 307:       <span class="ruby-keyword kw">if</span> <span class="ruby-constant">Porter2</span><span class="ruby-operator">::</span><span class="ruby-constant">STEP_1A_SPECIAL_CASES</span>.<span class="ruby-identifier">include?</span> <span class="ruby-identifier">w1a</span>
 487 308:         <span class="ruby-identifier">w1a</span>
 488 309:       <span class="ruby-keyword kw">else</span>
 489 310:         <span class="ruby-identifier">w1a</span>.<span class="ruby-identifier">porter2_step1b</span>(<span class="ruby-identifier">gb_english</span>).<span class="ruby-identifier">porter2_step1c</span>.<span class="ruby-identifier">porter2_step2</span>(<span class="ruby-identifier">gb_english</span>).<span class="ruby-identifier">porter2_step3</span>(<span class="ruby-identifier">gb_english</span>).<span class="ruby-identifier">porter2_step4</span>(<span class="ruby-identifier">gb_english</span>).<span class="ruby-identifier">porter2_step5</span>.<span class="ruby-identifier">porter2_postprocess</span>
 490 311:       <span class="ruby-keyword kw">end</span>
 491 312:     <span class="ruby-keyword kw">end</span>
 492 313:   <span class="ruby-keyword kw">end</span></pre>
 493                                         </div>
 494
 495                                 </div>
 496
 497
 498                                 <div class="aliases">
 499                                         Also aliased as: <a href="String.html#method-i-stem">stem</a>
 500                                 </div>
 501
 502
 503
 504                         </div>
 505
 506
 507                         <div id="porter-stem-verbose-method" class="method-detail ">
 508                                 <a name="method-i-porter2_stem_verbose"></a>
 509
 510                                 <div class="method-heading">
 511
 512                                         <span class="method-name">porter2_stem_verbose</span><span
 513                                                 class="method-args">(gb_english = false)</span>
 514                                         <span class="method-click-advice">click to toggle source</span>
 515
 516                                 </div>
 517
 518                                 <div class="method-description">
 519
 520                                         <p>
 521 A verbose version of <a
 522 href="String.html#method-i-porter2_stem">porter2_stem</a> that prints the
 523 output of each stage to STDOUT
 524 </p>
 525
 526
 527
 528                                         <div class="method-source-code"
 529                                                 id="porter-stem-verbose-source">
 530 <pre>
 531      <span class="ruby-comment cmt"># File lib/porter2.rb, line 316</span>
 532 316:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_stem_verbose</span>(<span class="ruby-identifier">gb_english</span> = <span class="ruby-keyword kw">false</span>)
 533 317:     <span class="ruby-identifier">preword</span> = <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_tidy</span>
 534 318:     <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;Preword: #{preword}&quot;</span>
 535 319:     <span class="ruby-keyword kw">return</span> <span class="ruby-identifier">preword</span> <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">preword</span>.<span class="ruby-identifier">length</span> <span class="ruby-operator">&lt;=</span> <span class="ruby-value">2</span>
 536 320:
 537 321:     <span class="ruby-identifier">word</span> = <span class="ruby-identifier">preword</span>.<span class="ruby-identifier">porter2_preprocess</span>
 538 322:     <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;Preprocessed: #{word}&quot;</span>
 539 323:
 540 324:     <span class="ruby-keyword kw">if</span> <span class="ruby-constant">Porter2</span><span class="ruby-operator">::</span><span class="ruby-constant">SPECIAL_CASES</span>.<span class="ruby-identifier">has_key?</span> <span class="ruby-identifier">word</span>
 541 325:       <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;Returning #{word} as special case #{Porter2::SPECIAL_CASES[word]}&quot;</span>
 542 326:       <span class="ruby-constant">Porter2</span><span class="ruby-operator">::</span><span class="ruby-constant">SPECIAL_CASES</span>[<span class="ruby-identifier">word</span>]
 543 327:     <span class="ruby-keyword kw">else</span>
 544 328:       <span class="ruby-identifier">r1</span> = <span class="ruby-identifier">word</span>.<span class="ruby-identifier">porter2_r1</span>
 545 329:       <span class="ruby-identifier">r2</span> = <span class="ruby-identifier">word</span>.<span class="ruby-identifier">porter2_r2</span>
 546 330:       <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;R1 = #{r1}, R2 = #{r2}&quot;</span>
 547 331:
 548 332:       <span class="ruby-identifier">w0</span> = <span class="ruby-identifier">word</span>.<span class="ruby-identifier">porter2_step0</span> ; <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;After step 0:  #{w0} (R1 = #{w0.porter2_r1}, R2 = #{w0.porter2_r2})&quot;</span>
 549 333:       <span class="ruby-identifier">w1a</span> = <span class="ruby-identifier">w0</span>.<span class="ruby-identifier">porter2_step1a</span> ; <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;After step 1a: #{w1a} (R1 = #{w1a.porter2_r1}, R2 = #{w1a.porter2_r2})&quot;</span>
 550 334:
 551 335:       <span class="ruby-keyword kw">if</span> <span class="ruby-constant">Porter2</span><span class="ruby-operator">::</span><span class="ruby-constant">STEP_1A_SPECIAL_CASES</span>.<span class="ruby-identifier">include?</span> <span class="ruby-identifier">w1a</span>
 552 336:         <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;Returning #{w1a} as 1a special case&quot;</span>
 553 337:         <span class="ruby-identifier">w1a</span>
 554 338:       <span class="ruby-keyword kw">else</span>
 555 339:         <span class="ruby-identifier">w1b</span> = <span class="ruby-identifier">w1a</span>.<span class="ruby-identifier">porter2_step1b</span>(<span class="ruby-identifier">gb_english</span>) ; <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;After step 1b: #{w1b} (R1 = #{w1b.porter2_r1}, R2 = #{w1b.porter2_r2})&quot;</span>
 556 340:         <span class="ruby-identifier">w1c</span> = <span class="ruby-identifier">w1b</span>.<span class="ruby-identifier">porter2_step1c</span> ; <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;After step 1c: #{w1c} (R1 = #{w1c.porter2_r1}, R2 = #{w1c.porter2_r2})&quot;</span>
 557 341:         <span class="ruby-identifier">w2</span> = <span class="ruby-identifier">w1c</span>.<span class="ruby-identifier">porter2_step2</span>(<span class="ruby-identifier">gb_english</span>) ; <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;After step 2:  #{w2} (R1 = #{w2.porter2_r1}, R2 = #{w2.porter2_r2})&quot;</span>
 558 342:         <span class="ruby-identifier">w3</span> = <span class="ruby-identifier">w2</span>.<span class="ruby-identifier">porter2_step3</span>(<span class="ruby-identifier">gb_english</span>) ; <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;After step 3:  #{w3} (R1 = #{w3.porter2_r1}, R2 = #{w3.porter2_r2})&quot;</span>
 559 343:         <span class="ruby-identifier">w4</span> = <span class="ruby-identifier">w3</span>.<span class="ruby-identifier">porter2_step4</span>(<span class="ruby-identifier">gb_english</span>) ; <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;After step 4:  #{w4} (R1 = #{w4.porter2_r1}, R2 = #{w4.porter2_r2})&quot;</span>
 560 344:         <span class="ruby-identifier">w5</span> = <span class="ruby-identifier">w4</span>.<span class="ruby-identifier">porter2_step5</span> ; <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;After step 5:  #{w5}&quot;</span>
 561 345:         <span class="ruby-identifier">wpost</span> = <span class="ruby-identifier">w5</span>.<span class="ruby-identifier">porter2_postprocess</span> ; <span class="ruby-identifier">puts</span> <span class="ruby-node">&quot;After postprocess: #{wpost}&quot;</span>
 562 346:         <span class="ruby-identifier">wpost</span>
 563 347:       <span class="ruby-keyword kw">end</span>
 564 348:     <span class="ruby-keyword kw">end</span>
 565 349:   <span class="ruby-keyword kw">end</span></pre>
 566                                         </div>
 567
 568                                 </div>
 569
 570
 571
 572
 573                         </div>
 574
 575
 576                         <div id="porter-step--method" class="method-detail ">
 577                                 <a name="method-i-porter2_step0"></a>
 578
 579                                 <div class="method-heading">
 580
 581                                         <span class="method-name">porter2_step0</span><span
 582                                                 class="method-args">()</span>
 583                                         <span class="method-click-advice">click to toggle source</span>
 584
 585                                 </div>
 586
 587                                 <div class="method-description">
 588
 589                                         <p>
 590 Search for the longest among the suffixes,
 591 </p>
 592 <ul>
 593 <li><p>
 594 &#8216;
 595 </p>
 596 </li>
 597 <li><p>
 598 &#8217;s
 599 </p>
 600 </li>
 601 <li><p>
 602 &#8217;s&#8217;
 603 </p>
 604 </li>
 605 </ul>
 606 <p>
 607 and remove if found.
 608 </p>
 609
 610
 611
 612                                         <div class="method-source-code"
 613                                                 id="porter-step--source">
 614 <pre>
 615      <span class="ruby-comment cmt"># File lib/porter2.rb, line 103</span>
 616 103:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_step0</span>
 617 104:     <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub!</span>(<span class="ruby-regexp re">/(.)('s'|'s|')$/</span>, <span class="ruby-value str">'\1'</span>) <span class="ruby-operator">||</span> <span class="ruby-keyword kw">self</span>
 618 105:   <span class="ruby-keyword kw">end</span></pre>
 619                                         </div>
 620
 621                                 </div>
 622
 623
 624
 625
 626                         </div>
 627
 628
 629                         <div id="porter-step-a-method" class="method-detail ">
 630                                 <a name="method-i-porter2_step1a"></a>
 631
 632                                 <div class="method-heading">
 633
 634                                         <span class="method-name">porter2_step1a</span><span
 635                                                 class="method-args">()</span>
 636                                         <span class="method-click-advice">click to toggle source</span>
 637
 638                                 </div>
 639
 640                                 <div class="method-description">
 641
 642                                         <p>
 643 Search for the longest among the following suffixes, and perform the action
 644 indicated.
 645 </p>
 646 <table>
 647 <tr><td valign="top">sses</td><td><p>
 648 replace by ss
 649 </p>
 650 </td></tr>
 651 <tr><td valign="top">ied, ies</td><td><p>
 652 replace by i if preceded by more than one letter, otherwise by ie
 653 </p>
 654 </td></tr>
 655 <tr><td valign="top">s</td><td><p>
 656 delete if the preceding word part contains a vowel not immediately before
 657 the s
 658 </p>
 659 </td></tr>
 660 <tr><td valign="top">us, ss</td><td><p>
 661 do nothing
 662 </p>
 663 </td></tr>
 664 </table>
 665
 666
 667
 668                                         <div class="method-source-code"
 669                                                 id="porter-step-a-source">
 670 <pre>
 671      <span class="ruby-comment cmt"># File lib/porter2.rb, line 113</span>
 672 113:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_step1a</span>
 673 114:     <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/sses$/</span>
 674 115:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/sses$/</span>, <span class="ruby-value str">'ss'</span>)
 675 116:     <span class="ruby-keyword kw">elsif</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/..(ied|ies)$/</span>
 676 117:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/(ied|ies)$/</span>, <span class="ruby-value str">'i'</span>)
 677 118:     <span class="ruby-keyword kw">elsif</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/(ied|ies)$/</span>
 678 119:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/(ied|ies)$/</span>, <span class="ruby-value str">'ie'</span>)
 679 120:     <span class="ruby-keyword kw">elsif</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/(us|ss)$/</span>
 680 121:       <span class="ruby-keyword kw">self</span>
 681 122:     <span class="ruby-keyword kw">elsif</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/s$/</span>
 682 123:       <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/(#{Porter2::V}.+)s$/</span>
 683 124:         <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/s$/</span>, <span class="ruby-value str">''</span>)
 684 125:       <span class="ruby-keyword kw">else</span>
 685 126:         <span class="ruby-keyword kw">self</span>
 686 127:       <span class="ruby-keyword kw">end</span>
 687 128:     <span class="ruby-keyword kw">else</span>
 688 129:       <span class="ruby-keyword kw">self</span>
 689 130:     <span class="ruby-keyword kw">end</span>
 690 131:   <span class="ruby-keyword kw">end</span></pre>
 691                                         </div>
 692
 693                                 </div>
 694
 695
 696
 697
 698                         </div>
 699
 700
 701                         <div id="porter-step-b-method" class="method-detail ">
 702                                 <a name="method-i-porter2_step1b"></a>
 703
 704                                 <div class="method-heading">
 705
 706                                         <span class="method-name">porter2_step1b</span><span
 707                                                 class="method-args">(gb_english = false)</span>
 708                                         <span class="method-click-advice">click to toggle source</span>
 709
 710                                 </div>
 711
 712                                 <div class="method-description">
 713
 714                                         <p>
 715 Search for the longest among the following suffixes, and perform the action
 716 indicated.
 717 </p>
 718 <table>
 719 <tr><td valign="top">eed, eedly</td><td><p>
 720 replace by ee if the suffix is also in R1
 721 </p>
 722 </td></tr>
 723 <tr><td valign="top">ed, edly, ing, ingly</td><td><p>
 724 delete if the preceding word part contains a vowel and,  after the
 725 deletion:
 726 </p>
 727 <ul>
 728 <li><p>
 729 if the word ends at, bl or iz: add e, or
 730 </p>
 731 </li>
 732 </ul>
 733 <ul>
 734 <li><p>
 735 if the word ends with a double: remove the last letter, or
 736 </p>
 737 </li>
 738 </ul>
 739 <ul>
 740 <li><p>
 741 if the word is short: add e
 742 </p>
 743 </li>
 744 </ul>
 745 </td></tr>
 746 </table>
 747 <p>
 748 (If gb_english is <tt>true</tt>, treat the &#8216;is&#8217; suffix as
 749 &#8216;iz&#8217; above.)
 750 </p>
 751
 752
 753
 754                                         <div class="method-source-code"
 755                                                 id="porter-step-b-source">
 756 <pre>
 757      <span class="ruby-comment cmt"># File lib/porter2.rb, line 143</span>
 758 143:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_step1b</span>(<span class="ruby-identifier">gb_english</span> = <span class="ruby-keyword kw">false</span>)
 759 144:     <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/(eed|eedly)$/</span>
 760 145:       <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r1</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/(eed|eedly)$/</span>
 761 146:         <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/(eed|eedly)$/</span>, <span class="ruby-value str">'ee'</span>)
 762 147:       <span class="ruby-keyword kw">else</span>
 763 148:         <span class="ruby-keyword kw">self</span>
 764 149:       <span class="ruby-keyword kw">end</span>
 765 150:     <span class="ruby-keyword kw">else</span>
 766 151:       <span class="ruby-identifier">w</span> = <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">dup</span>
 767 152:       <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">w</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/#{Porter2::V}.*(ed|edly|ing|ingly)$/</span>
 768 153:         <span class="ruby-identifier">w</span>.<span class="ruby-identifier">sub!</span>(<span class="ruby-regexp re">/(ed|edly|ing|ingly)$/</span>, <span class="ruby-value str">''</span>)
 769 154:         <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">w</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/(at|lb|iz)$/</span>
 770 155:           <span class="ruby-identifier">w</span> <span class="ruby-operator">+=</span> <span class="ruby-value str">'e'</span>
 771 156:         <span class="ruby-keyword kw">elsif</span> <span class="ruby-identifier">w</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/is$/</span> <span class="ruby-keyword kw">and</span> <span class="ruby-identifier">gb_english</span>
 772 157:           <span class="ruby-identifier">w</span> <span class="ruby-operator">+=</span> <span class="ruby-value str">'e'</span>
 773 158:         <span class="ruby-keyword kw">elsif</span> <span class="ruby-identifier">w</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/#{Porter2::Double}$/</span>
 774 159:           <span class="ruby-identifier">w</span>.<span class="ruby-identifier">chop!</span>
 775 160:         <span class="ruby-keyword kw">elsif</span> <span class="ruby-identifier">w</span>.<span class="ruby-identifier">porter2_is_short_word?</span>
 776 161:           <span class="ruby-identifier">w</span> <span class="ruby-operator">+=</span> <span class="ruby-value str">'e'</span>
 777 162:         <span class="ruby-keyword kw">end</span>
 778 163:       <span class="ruby-keyword kw">end</span>
 779 164:       <span class="ruby-identifier">w</span>
 780 165:     <span class="ruby-keyword kw">end</span>
 781 166:   <span class="ruby-keyword kw">end</span></pre>
 782                                         </div>
 783
 784                                 </div>
 785
 786
 787
 788
 789                         </div>
 790
 791
 792                         <div id="porter-step-c-method" class="method-detail ">
 793                                 <a name="method-i-porter2_step1c"></a>
 794
 795                                 <div class="method-heading">
 796
 797                                         <span class="method-name">porter2_step1c</span><span
 798                                                 class="method-args">()</span>
 799                                         <span class="method-click-advice">click to toggle source</span>
 800
 801                                 </div>
 802
 803                                 <div class="method-description">
 804
 805                                         <p>
 806 Replace a suffix of y or Y by i if it is preceded by a non-vowel which is
 807 not the first letter of the word.
 808 </p>
 809
 810
 811
 812                                         <div class="method-source-code"
 813                                                 id="porter-step-c-source">
 814 <pre>
 815      <span class="ruby-comment cmt"># File lib/porter2.rb, line 171</span>
 816 171:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_step1c</span>
 817 172:     <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/.+#{Porter2::C}(y|Y)$/</span>
 818 173:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/(y|Y)$/</span>, <span class="ruby-value str">'i'</span>)
 819 174:     <span class="ruby-keyword kw">else</span>
 820 175:       <span class="ruby-keyword kw">self</span>
 821 176:     <span class="ruby-keyword kw">end</span>
 822 177:   <span class="ruby-keyword kw">end</span></pre>
 823                                         </div>
 824
 825                                 </div>
 826
 827
 828
 829
 830                         </div>
 831
 832
 833                         <div id="porter-step--method" class="method-detail ">
 834                                 <a name="method-i-porter2_step2"></a>
 835
 836                                 <div class="method-heading">
 837
 838                                         <span class="method-name">porter2_step2</span><span
 839                                                 class="method-args">(gb_english = false)</span>
 840                                         <span class="method-click-advice">click to toggle source</span>
 841
 842                                 </div>
 843
 844                                 <div class="method-description">
 845
 846                                         <p>
 847 Search for the longest among the suffixes listed in the keys of
 848 Porter2::STEP_2_MAPS.  If one is found and that suffix occurs in R1,
 849 replace it with the value  found in STEP_2_MAPS.
 850 </p>
 851 <p>
 852 (Suffixes &#8216;ogi&#8217; and &#8216;li&#8217; are treated as special
 853 cases in the procedure.)
 854 </p>
 855 <p>
 856 (If gb_english is <tt>true</tt>, replace the &#8216;iser&#8217; and
 857 &#8216;isation&#8217; suffixes with &#8216;ise&#8217;, similarly to how
 858 &#8216;izer&#8217; and &#8216;ization&#8217; are treated.)
 859 </p>
 860
 861
 862
 863                                         <div class="method-source-code"
 864                                                 id="porter-step--source">
 865 <pre>
 866      <span class="ruby-comment cmt"># File lib/porter2.rb, line 188</span>
 867 188:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_step2</span>(<span class="ruby-identifier">gb_english</span> = <span class="ruby-keyword kw">false</span>)
 868 189:     <span class="ruby-identifier">r1</span> = <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r1</span>
 869 190:     <span class="ruby-identifier">s2m</span> = <span class="ruby-constant">Porter2</span><span class="ruby-operator">::</span><span class="ruby-constant">STEP_2_MAPS</span>.<span class="ruby-identifier">dup</span>
 870 191:     <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">gb_english</span>
 871 192:       <span class="ruby-identifier">s2m</span>[<span class="ruby-value str">&quot;iser&quot;</span>] = <span class="ruby-value str">&quot;ise&quot;</span>
 872 193:       <span class="ruby-identifier">s2m</span>[<span class="ruby-value str">&quot;isation&quot;</span>] = <span class="ruby-value str">&quot;ise&quot;</span>
 873 194:     <span class="ruby-keyword kw">end</span>
 874 195:     <span class="ruby-identifier">step_2_re</span> = <span class="ruby-constant">Regexp</span>.<span class="ruby-identifier">union</span>(<span class="ruby-identifier">s2m</span>.<span class="ruby-identifier">keys</span>.<span class="ruby-identifier">map</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">r</span><span class="ruby-operator">|</span> <span class="ruby-constant">Regexp</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">r</span> <span class="ruby-operator">+</span> <span class="ruby-value str">&quot;$&quot;</span>)})
 875 196:     <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-identifier">step_2_re</span>
 876 197:       <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">r1</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/#{$&amp;}$/</span>
 877 198:         <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-node">/#{$&amp;}$/</span>, <span class="ruby-identifier">s2m</span>[<span class="ruby-node">$&amp;</span>])
 878 199:       <span class="ruby-keyword kw">else</span>
 879 200:         <span class="ruby-keyword kw">self</span>
 880 201:       <span class="ruby-keyword kw">end</span>
 881 202:     <span class="ruby-keyword kw">elsif</span> <span class="ruby-identifier">r1</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/li$/</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/(#{Porter2::Valid_LI})li$/</span>
 882 203:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/li$/</span>, <span class="ruby-value str">''</span>)
 883 204:     <span class="ruby-keyword kw">elsif</span> <span class="ruby-identifier">r1</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/ogi$/</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/logi$/</span>
 884 205:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/ogi$/</span>, <span class="ruby-value str">'og'</span>)
 885 206:     <span class="ruby-keyword kw">else</span>
 886 207:       <span class="ruby-keyword kw">self</span>
 887 208:     <span class="ruby-keyword kw">end</span>
 888 209:   <span class="ruby-keyword kw">end</span></pre>
 889                                         </div>
 890
 891                                 </div>
 892
 893
 894
 895
 896                         </div>
 897
 898
 899                         <div id="porter-step--method" class="method-detail ">
 900                                 <a name="method-i-porter2_step3"></a>
 901
 902                                 <div class="method-heading">
 903
 904                                         <span class="method-name">porter2_step3</span><span
 905                                                 class="method-args">(gb_english = false)</span>
 906                                         <span class="method-click-advice">click to toggle source</span>
 907
 908                                 </div>
 909
 910                                 <div class="method-description">
 911
 912                                         <p>
 913 Search for the longest among the suffixes listed in the keys of
 914 Porter2::STEP_3_MAPS.  If one is found and that suffix occurs in R1,
 915 replace it with the value  found in STEP_3_MAPS.
 916 </p>
 917 <p>
 918 (Suffix &#8216;ative&#8217; is treated as a special case in the procedure.)
 919 </p>
 920 <p>
 921 (If gb_english is <tt>true</tt>, replace the &#8216;alise&#8217; suffix
 922 with &#8216;al&#8217;, similarly to how &#8216;alize&#8217; is treated.)
 923 </p>
 924
 925
 926
 927                                         <div class="method-source-code"
 928                                                 id="porter-step--source">
 929 <pre>
 930      <span class="ruby-comment cmt"># File lib/porter2.rb, line 220</span>
 931 220:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_step3</span>(<span class="ruby-identifier">gb_english</span> = <span class="ruby-keyword kw">false</span>)
 932 221:     <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/ative$/</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r2</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/ative$/</span>
 933 222:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/ative$/</span>, <span class="ruby-value str">''</span>)
 934 223:     <span class="ruby-keyword kw">else</span>
 935 224:       <span class="ruby-identifier">s3m</span> = <span class="ruby-constant">Porter2</span><span class="ruby-operator">::</span><span class="ruby-constant">STEP_3_MAPS</span>.<span class="ruby-identifier">dup</span>
 936 225:       <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">gb_english</span>
 937 226:         <span class="ruby-identifier">s3m</span>[<span class="ruby-value str">&quot;alise&quot;</span>] = <span class="ruby-value str">&quot;al&quot;</span>
 938 227:       <span class="ruby-keyword kw">end</span>
 939 228:       <span class="ruby-identifier">step_3_re</span> = <span class="ruby-constant">Regexp</span>.<span class="ruby-identifier">union</span>(<span class="ruby-identifier">s3m</span>.<span class="ruby-identifier">keys</span>.<span class="ruby-identifier">map</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">r</span><span class="ruby-operator">|</span> <span class="ruby-constant">Regexp</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">r</span> <span class="ruby-operator">+</span> <span class="ruby-value str">&quot;$&quot;</span>)})
 940 229:       <span class="ruby-identifier">r1</span> = <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r1</span>
 941 230:       <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-identifier">step_3_re</span> <span class="ruby-keyword kw">and</span> <span class="ruby-identifier">r1</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/#{$&amp;}$/</span>
 942 231:         <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-node">/#{$&amp;}$/</span>, <span class="ruby-identifier">s3m</span>[<span class="ruby-node">$&amp;</span>])
 943 232:       <span class="ruby-keyword kw">else</span>
 944 233:         <span class="ruby-keyword kw">self</span>
 945 234:       <span class="ruby-keyword kw">end</span>
 946 235:     <span class="ruby-keyword kw">end</span>
 947 236:   <span class="ruby-keyword kw">end</span></pre>
 948                                         </div>
 949
 950                                 </div>
 951
 952
 953
 954
 955                         </div>
 956
 957
 958                         <div id="porter-step--method" class="method-detail ">
 959                                 <a name="method-i-porter2_step4"></a>
 960
 961                                 <div class="method-heading">
 962
 963                                         <span class="method-name">porter2_step4</span><span
 964                                                 class="method-args">(gb_english = false)</span>
 965                                         <span class="method-click-advice">click to toggle source</span>
 966
 967                                 </div>
 968
 969                                 <div class="method-description">
 970
 971                                         <p>
 972 Search for the longest among the suffixes listed in the keys of
 973 Porter2::STEP_4_MAPS.  If one is found and that suffix occurs in R2,
 974 replace it with the value  found in STEP_4_MAPS.
 975 </p>
 976 <p>
 977 (Suffix &#8216;ion&#8217; is treated as a special case in the procedure.)
 978 </p>
 979 <p>
 980 (If gb_english is <tt>true</tt>, delete the &#8216;ise&#8217; suffix if
 981 found.)
 982 </p>
 983
 984
 985
 986                                         <div class="method-source-code"
 987                                                 id="porter-step--source">
 988 <pre>
 989      <span class="ruby-comment cmt"># File lib/porter2.rb, line 246</span>
 990 246:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_step4</span>(<span class="ruby-identifier">gb_english</span> = <span class="ruby-keyword kw">false</span>)
 991 247:     <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r2</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/ion$/</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/(s|t)ion$/</span>
 992 248:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/ion$/</span>, <span class="ruby-value str">''</span>)
 993 249:     <span class="ruby-keyword kw">else</span>
 994 250:       <span class="ruby-identifier">s4m</span> = <span class="ruby-constant">Porter2</span><span class="ruby-operator">::</span><span class="ruby-constant">STEP_4_MAPS</span>.<span class="ruby-identifier">dup</span>
 995 251:       <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">gb_english</span>
 996 252:         <span class="ruby-identifier">s4m</span>[<span class="ruby-value str">&quot;ise&quot;</span>] = <span class="ruby-value str">&quot;&quot;</span>
 997 253:       <span class="ruby-keyword kw">end</span>
 998 254:       <span class="ruby-identifier">step_4_re</span> = <span class="ruby-constant">Regexp</span>.<span class="ruby-identifier">union</span>(<span class="ruby-identifier">s4m</span>.<span class="ruby-identifier">keys</span>.<span class="ruby-identifier">map</span> {<span class="ruby-operator">|</span><span class="ruby-identifier">r</span><span class="ruby-operator">|</span> <span class="ruby-constant">Regexp</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">r</span> <span class="ruby-operator">+</span> <span class="ruby-value str">&quot;$&quot;</span>)})
 999 255:       <span class="ruby-identifier">r2</span> = <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r2</span>
1000 256:       <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-identifier">step_4_re</span>
1001 257:         <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">r2</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/#{$&amp;}/</span>
1002 258:           <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-node">/#{$&amp;}$/</span>, <span class="ruby-identifier">s4m</span>[<span class="ruby-node">$&amp;</span>])
1003 259:         <span class="ruby-keyword kw">else</span>
1004 260:           <span class="ruby-keyword kw">self</span>
1005 261:         <span class="ruby-keyword kw">end</span>
1006 262:       <span class="ruby-keyword kw">else</span>
1007 263:         <span class="ruby-keyword kw">self</span>
1008 264:       <span class="ruby-keyword kw">end</span>
1009 265:     <span class="ruby-keyword kw">end</span>
1010 266:   <span class="ruby-keyword kw">end</span></pre>
1011                                         </div>
1012
1013                                 </div>
1014
1015
1016
1017
1018                         </div>
1019
1020
1021                         <div id="porter-step--method" class="method-detail ">
1022                                 <a name="method-i-porter2_step5"></a>
1023
1024                                 <div class="method-heading">
1025
1026                                         <span class="method-name">porter2_step5</span><span
1027                                                 class="method-args">()</span>
1028                                         <span class="method-click-advice">click to toggle source</span>
1029
1030                                 </div>
1031
1032                                 <div class="method-description">
1033
1034                                         <p>
1035 Search for the the following suffixes, and, if found, perform the action
1036 indicated.
1037 </p>
1038 <table>
1039 <tr><td valign="top">e</td><td><p>
1040 delete if in R2, or in R1 and not preceded by a short syllable
1041 </p>
1042 </td></tr>
1043 <tr><td valign="top">l</td><td><p>
1044 delete if in R2 and preceded by l
1045 </p>
1046 </td></tr>
1047 </table>
1048
1049
1050
1051                                         <div class="method-source-code"
1052                                                 id="porter-step--source">
1053 <pre>
1054      <span class="ruby-comment cmt"># File lib/porter2.rb, line 272</span>
1055 272:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_step5</span>
1056 273:     <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/ll$/</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r2</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/l$/</span>
1057 274:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/ll$/</span>, <span class="ruby-value str">'l'</span>)
1058 275:     <span class="ruby-keyword kw">elsif</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/e$/</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r2</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/e$/</span>
1059 276:       <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/e$/</span>, <span class="ruby-value str">''</span>)
1060 277:     <span class="ruby-keyword kw">else</span>
1061 278:       <span class="ruby-identifier">r1</span> = <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">porter2_r1</span>
1062 279:       <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/e$/</span> <span class="ruby-keyword kw">and</span> <span class="ruby-identifier">r1</span> <span class="ruby-operator">=~</span> <span class="ruby-regexp re">/e$/</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">not</span> <span class="ruby-keyword kw">self</span> <span class="ruby-operator">=~</span> <span class="ruby-node">/#{Porter2::SHORT_SYLLABLE}e$/</span>
1063 280:         <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">sub</span>(<span class="ruby-regexp re">/e$/</span>, <span class="ruby-value str">''</span>)
1064 281:       <span class="ruby-keyword kw">else</span>
1065 282:         <span class="ruby-keyword kw">self</span>
1066 283:       <span class="ruby-keyword kw">end</span>
1067 284:     <span class="ruby-keyword kw">end</span>
1068 285:   <span class="ruby-keyword kw">end</span></pre>
1069                                         </div>
1070
1071                                 </div>
1072
1073
1074
1075
1076                         </div>
1077
1078
1079                         <div id="porter-tidy-method" class="method-detail ">
1080                                 <a name="method-i-porter2_tidy"></a>
1081
1082                                 <div class="method-heading">
1083
1084                                         <span class="method-name">porter2_tidy</span><span
1085                                                 class="method-args">()</span>
1086                                         <span class="method-click-advice">click to toggle source</span>
1087
1088                                 </div>
1089
1090                                 <div class="method-description">
1091
1092                                         <p>
1093 Tidy up the word before we get down to the algorithm
1094 </p>
1095
1096
1097
1098                                         <div class="method-source-code"
1099                                                 id="porter-tidy-source">
1100 <pre>
1101     <span class="ruby-comment cmt"># File lib/porter2.rb, line 35</span>
1102 35:   <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">porter2_tidy</span>
1103 36:     <span class="ruby-identifier">preword</span> = <span class="ruby-keyword kw">self</span>.<span class="ruby-identifier">to_s</span>.<span class="ruby-identifier">strip</span>.<span class="ruby-identifier">downcase</span>
1104 37:
1105 38:     <span class="ruby-comment cmt"># map apostrophe-like characters to apostrophes</span>
1106 39:     <span class="ruby-identifier">preword</span>.<span class="ruby-identifier">gsub!</span>(<span class="ruby-regexp re">/‘/</span>, <span class="ruby-value str">&quot;'&quot;</span>)
1107 40:     <span class="ruby-identifier">preword</span>.<span class="ruby-identifier">gsub!</span>(<span class="ruby-regexp re">/’/</span>, <span class="ruby-value str">&quot;'&quot;</span>)
1108 41:
1109 42:     <span class="ruby-identifier">preword</span>
1110 43:   <span class="ruby-keyword kw">end</span></pre>
1111                                         </div>
1112
1113                                 </div>
1114
1115
1116
1117
1118                         </div>
1119
1120
1121                         <div id="stem-method" class="method-detail method-alias">
1122                                 <a name="method-i-stem"></a>
1123
1124                                 <div class="method-heading">
1125
1126                                         <span class="method-name">stem</span><span
1127                                                 class="method-args">(gb_english = false)</span>
1128                                         <span class="method-click-advice">click to toggle source</span>
1129
1130                                 </div>
1131
1132                                 <div class="method-description">
1133
1134
1135
1136
1137
1138                                 </div>
1139
1140
1141
1142
1143                                 <div class="aliases">
1144           Alias for: <a href="String.html#method-i-porter2_stem">porter2_stem</a>
1145                                 </div>
1146
1147                         </div>
1148
1149
1150                 </div>
1151
1152
1153         </div>
1154
1155
1156         <div id="rdoc-debugging-section-dump" class="debugging-section">
1157
1158                 <p>Disabled; run with --debug to generate this.</p>
1159
1160         </div>
1161
1162         <div id="validator-badges">
1163                 <p><small><a href="http://validator.w3.org/check/referer">[Validate]</a></small></p>
1164                 <p><small>Generated with the <a href="http://deveiate.org/projects/Darkfish-Rdoc/">Darkfish
1165                         Rdoc Generator</a> 1.1.6</small>.</p>
1166         </div>
1167
1168 </body>
1169 </html>
1170