Add initial support for "Whole words" searching in the viewer

As outlined in https://bugzilla.mozilla.org/show_bug.cgi?id=1282759 the internal Firefox name for the feature is `entireWord`, hence that name is used here as well for consistency (with "Whole words" being limited to the UI).

Given existing limitations of the PDF.js search functionality, e.g. the existing problems of searching across "new lines", there's some edge-cases where "Whole words" searching will ignore (valid) results.
However, considering that this is a pre-existing issue related to the way that the find controller joins text-content together, that shouldn't have to block this new feature in my opionion.

*Please note:* In order to enable this feature in the `MOZCENTRAL` version, a small follow-up patch for [PdfjsChromeUtils.jsm](https://hg.mozilla.org/mozilla-central/file/tip/browser/extensions/pdfjs/content/PdfjsChromeUtils.jsm) will be required once this has landed in `mozilla-central`.

l10n/en-US/viewer.properties

@@ -165,6 +165,7 @@ find_next.title=Find the next occurrence of the phrase
 find_next_label=Next
 find_highlight=Highlight all
 find_match_case_label=Match case
+find_entire_word_label=Whole words
 find_reached_top=Reached top of document, continued from bottom
 find_reached_bottom=Reached end of document, continued from top
 find_not_found=Phrase not found

l10n/sv-SE/viewer.properties

@@ -165,6 +165,7 @@ find_next.title=Hitta nästa förekomst av frasen
 find_next_label=Nästa
 find_highlight=Markera alla
 find_match_case_label=Matcha versal/gemen
+find_entire_word_label=Hela ord
 find_reached_top=Nådde början av dokumentet, började från slutet
 find_reached_bottom=Nådde slutet på dokumentet, började från början
 find_not_found=Frasen hittades inte

web/app.js

@@ -1971,6 +1971,7 @@ function webViewerFind(evt) {
     query: evt.query,
     phraseSearch: evt.phraseSearch,
     caseSensitive: evt.caseSensitive,
+    entireWord: evt.entireWord,
     highlightAll: evt.highlightAll,
     findPrevious: evt.findPrevious,
   });
@@ -1981,6 +1982,7 @@ function webViewerFindFromUrlHash(evt) {
     query: evt.query,
     phraseSearch: evt.phraseSearch,
     caseSensitive: false,
+    entireWord: false,
     highlightAll: true,
     findPrevious: false,
   });
@@ -2117,6 +2119,7 @@ function webViewerKeyDown(evt) {
               query: findState.query,
               phraseSearch: findState.phraseSearch,
               caseSensitive: findState.caseSensitive,
+              entireWord: findState.entireWord,
               highlightAll: findState.highlightAll,
               findPrevious: cmd === 5 || cmd === 12,
             });

web/firefoxcom.js

@@ -168,7 +168,8 @@ class MozL10n {
     'find',
     'findagain',
     'findhighlightallchange',
-    'findcasesensitivitychange'
+    'findcasesensitivitychange',
+    'findentirewordchange',
   ];
   let handleEvent = function(evt) {
     if (!PDFViewerApplication.initialized) {
@@ -180,13 +181,14 @@ class MozL10n {
       query: evt.detail.query,
       phraseSearch: true,
       caseSensitive: !!evt.detail.caseSensitive,
+      entireWord: !!evt.detail.entireWord,
       highlightAll: !!evt.detail.highlightAll,
       findPrevious: !!evt.detail.findPrevious,
     });
   };
 
-  for (let i = 0, len = events.length; i < len; i++) {
-    window.addEventListener(events[i], handleEvent);
+  for (let event of events) {
+    window.addEventListener(event, handleEvent);
   }
 })();
 

web/pdf_find_bar.js

@@ -31,6 +31,7 @@ class PDFFindBar {
     this.findField = options.findField || null;
     this.highlightAll = options.highlightAllCheckbox || null;
     this.caseSensitive = options.caseSensitiveCheckbox || null;
+    this.entireWord = options.entireWordCheckbox || null;
     this.findMsg = options.findMsg || null;
     this.findResultsCount = options.findResultsCount || null;
     this.findStatusIcon = options.findStatusIcon || null;
@@ -83,6 +84,10 @@ class PDFFindBar {
       this.dispatchEvent('casesensitivitychange');
     });
 
+    this.entireWord.addEventListener('click', () => {
+      this.dispatchEvent('entirewordchange');
+    });
+
     this.eventBus.on('resize', this._adjustWidth.bind(this));
   }
 
@@ -95,8 +100,9 @@ class PDFFindBar {
       source: this,
       type,
       query: this.findField.value,
-      caseSensitive: this.caseSensitive.checked,
       phraseSearch: true,
+      caseSensitive: this.caseSensitive.checked,
+      entireWord: this.entireWord.checked,
       highlightAll: this.highlightAll.checked,
       findPrevious: findPrev,
     });

web/pdf_find_controller.js

@@ -14,6 +14,7 @@
  */
 
 import { createPromiseCapability } from 'pdfjs-lib';
+import { getCharacterType } from './pdf_find_utils';
 import { getGlobalEventBus } from './dom_events';
 import { scrollIntoView } from './ui_utils';
 
@@ -190,7 +191,30 @@ class PDFFindController {
     }
   }
 
-  _calculatePhraseMatch(query, pageIndex, pageContent) {
+  /**
+   * Determine if the search query constitutes a "whole word", by comparing the
+   * first/last character types with the preceding/following character types.
+   */
+  _isEntireWord(content, startIdx, length) {
+    if (startIdx > 0) {
+      const first = content.charCodeAt(startIdx);
+      const limit = content.charCodeAt(startIdx - 1);
+      if (getCharacterType(first) === getCharacterType(limit)) {
+        return false;
+      }
+    }
+    const endIdx = (startIdx + length - 1);
+    if (endIdx < (content.length - 1)) {
+      const last = content.charCodeAt(endIdx);
+      const limit = content.charCodeAt(endIdx + 1);
+      if (getCharacterType(last) === getCharacterType(limit)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  _calculatePhraseMatch(query, pageIndex, pageContent, entireWord) {
     let matches = [];
     let queryLen = query.length;
     let matchIdx = -queryLen;
@@ -199,12 +223,15 @@ class PDFFindController {
       if (matchIdx === -1) {
         break;
       }
+      if (entireWord && !this._isEntireWord(pageContent, matchIdx, queryLen)) {
+        continue;
+      }
       matches.push(matchIdx);
     }
     this.pageMatches[pageIndex] = matches;
   }
 
-  _calculateWordMatch(query, pageIndex, pageContent) {
+  _calculateWordMatch(query, pageIndex, pageContent, entireWord) {
     let matchesWithLength = [];
     // Divide the query into pieces and search for text in each piece.
     let queryArray = query.match(/\S+/g);
@@ -217,6 +244,10 @@ class PDFFindController {
         if (matchIdx === -1) {
           break;
         }
+        if (entireWord &&
+            !this._isEntireWord(pageContent, matchIdx, subqueryLen)) {
+          continue;
+        }
         // Other searches do not, so we store the length.
         matchesWithLength.push({
           match: matchIdx,
@@ -244,6 +275,7 @@ class PDFFindController {
     let query = this._normalize(this.state.query);
     let caseSensitive = this.state.caseSensitive;
     let phraseSearch = this.state.phraseSearch;
+    const entireWord = this.state.entireWord;
     let queryLen = query.length;
 
     if (queryLen === 0) {
@@ -257,9 +289,9 @@ class PDFFindController {
     }
 
     if (phraseSearch) {
-      this._calculatePhraseMatch(query, pageIndex, pageContent);
+      this._calculatePhraseMatch(query, pageIndex, pageContent, entireWord);
     } else {
-      this._calculateWordMatch(query, pageIndex, pageContent);
+      this._calculateWordMatch(query, pageIndex, pageContent, entireWord);
     }
 
     this._updatePage(pageIndex);

web/pdf_find_utils.js

@@ -0,0 +1,107 @@
+/* Copyright 2018 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const CharacterType = {
+  SPACE: 0,
+  ALPHA_LETTER: 1,
+  PUNCT: 2,
+  HAN_LETTER: 3,
+  KATAKANA_LETTER: 4,
+  HIRAGANA_LETTER: 5,
+  HALFWIDTH_KATAKANA_LETTER: 6,
+  THAI_LETTER: 7,
+};
+
+function isAlphabeticalScript(charCode) {
+  return charCode < 0x2E80;
+}
+
+function isAscii(charCode) {
+  return (charCode & 0xFF80) === 0;
+}
+
+function isAsciiAlpha(charCode) {
+  return (charCode >= /* a = */ 0x61 && charCode <= /* z = */ 0x7A) ||
+         (charCode >= /* A = */ 0x41 && charCode <= /* Z = */ 0x5A);
+}
+
+function isAsciiDigit(charCode) {
+  return (charCode >= /* 0 = */ 0x30 && charCode <= /* 9 = */ 0x39);
+}
+
+function isAsciiSpace(charCode) {
+  return (charCode === /* SPACE = */ 0x20 || charCode === /* TAB = */ 0x09 ||
+          charCode === /* CR = */ 0x0D || charCode === /* LF = */ 0x0A);
+}
+
+function isHan(charCode) {
+  return (charCode >= 0x3400 && charCode <= 0x9FFFF) ||
+         (charCode >= 0xF900 && charCode <= 0xFAFF);
+}
+
+function isKatakana(charCode) {
+  return (charCode >= 0x30A0 && charCode <= 0x30FF);
+}
+
+function isHiragana(charCode) {
+  return (charCode >= 0x3040 && charCode <= 0x309F);
+}
+
+function isHalfwidthKatakana(charCode) {
+  return (charCode >= 0xFF60 && charCode <= 0xFF9F);
+}
+
+function isThai(charCode) {
+  return (charCode & 0xFF80) === 0x0E00;
+}
+
+/**
+ * This function is based on the word-break detection implemented in:
+ * https://hg.mozilla.org/mozilla-central/file/tip/intl/lwbrk/WordBreaker.cpp
+ */
+function getCharacterType(charCode) {
+  if (isAlphabeticalScript(charCode)) {
+    if (isAscii(charCode)) {
+      if (isAsciiSpace(charCode)) {
+        return CharacterType.SPACE;
+      } else if (isAsciiAlpha(charCode) || isAsciiDigit(charCode) ||
+                 charCode === /* UNDERSCORE = */ 0x5F) {
+        return CharacterType.ALPHA_LETTER;
+      }
+      return CharacterType.PUNCT;
+    } else if (isThai(charCode)) {
+      return CharacterType.THAI_LETTER;
+    } else if (charCode === /* NBSP = */ 0xA0) {
+      return CharacterType.SPACE;
+    }
+    return CharacterType.ALPHA_LETTER;
+  }
+
+  if (isHan(charCode)) {
+    return CharacterType.HAN_LETTER;
+  } else if (isKatakana(charCode)) {
+    return CharacterType.KATAKANA_LETTER;
+  } else if (isHiragana(charCode)) {
+    return CharacterType.HIRAGANA_LETTER;
+  } else if (isHalfwidthKatakana(charCode)) {
+    return CharacterType.HALFWIDTH_KATAKANA_LETTER;
+  }
+  return CharacterType.ALPHA_LETTER;
+}
+
+export {
+  CharacterType,
+  getCharacterType,
+};

web/viewer.html

@@ -109,6 +109,8 @@
             <label for="findHighlightAll" class="toolbarLabel" data-l10n-id="find_highlight">Highlight all</label>
             <input type="checkbox" id="findMatchCase" class="toolbarField" tabindex="95">
             <label for="findMatchCase" class="toolbarLabel" data-l10n-id="find_match_case_label">Match case</label>
+            <input type="checkbox" id="findEntireWord" class="toolbarField" tabindex="96">
+            <label for="findEntireWord" class="toolbarLabel" data-l10n-id="find_entire_word_label">Whole words</label>
             <span id="findResultsCount" class="toolbarLabel hidden"></span>
           </div>
 

web/viewer.js

@@ -134,6 +134,7 @@ function getViewerConfiguration() {
       findField: document.getElementById('findInput'),
       highlightAllCheckbox: document.getElementById('findHighlightAll'),
       caseSensitiveCheckbox: document.getElementById('findMatchCase'),
+      entireWordCheckbox: document.getElementById('findEntireWord'),
       findMsg: document.getElementById('findMsg'),
       findResultsCount: document.getElementById('findResultsCount'),
       findStatusIcon: document.getElementById('findStatusIcon'),