search resolution option (#436)

* add search resolution setting

* move finding next substring to method

* use regex literal

* fix comments

* fix comments

* add options update function

* update test

8 files changed, 69 insertions, 6 deletions

diff --git a/ext/data/schemas/options-schema.json b/ext/data/schemas/options-schema.json
index f5b24160..65c4102e 100644
--- a/ext/data/schemas/options-schema.json
+++ b/ext/data/schemas/options-schema.json
@@ -728,9 +728,18 @@
                                     "convertHiraganaToKatakana",
                                     "convertKatakanaToHiragana",
                                     "collapseEmphaticSequences",
-                                    "textReplacements"
+                                    "textReplacements",
+                                    "searchResolution"
                                 ],
                                 "properties": {
+                                    "searchResolution": {
+                                        "type": "string",
+                                        "enum": [
+                                            "letter",
+                                            "word"
+                                        ],
+                                        "default": "letter"
+                                    },
                                     "convertHalfWidthCharacters": {
                                         "type": "string",
                                         "enum": ["false", "true", "variant"],
diff --git a/ext/js/background/backend.js b/ext/js/background/backend.js
index ae78a97b..68d4e0c8 100644
--- a/ext/js/background/backend.js
+++ b/ext/js/background/backend.js
@@ -2417,7 +2417,8 @@ export class Backend {
                 convertHiraganaToKatakana,
                 convertKatakanaToHiragana,
                 collapseEmphaticSequences,
-                textReplacements: textReplacementsOptions
+                textReplacements: textReplacementsOptions,
+                searchResolution
             }
         } = options;
         const textReplacements = this._getTranslatorTextReplacements(textReplacementsOptions);
@@ -2444,6 +2445,7 @@ export class Backend {
             convertHiraganaToKatakana,
             convertKatakanaToHiragana,
             collapseEmphaticSequences,
+            searchResolution,
             textReplacements,
             enabledDictionaryMap,
             excludeDictionaryDefinitions
diff --git a/ext/js/data/options-util.js b/ext/js/data/options-util.js
index c219bed3..eb9af9b6 100644
--- a/ext/js/data/options-util.js
+++ b/ext/js/data/options-util.js
@@ -555,7 +555,8 @@ export class OptionsUtil {
             {async: false, update: this._updateVersion18.bind(this)},
             {async: false, update: this._updateVersion19.bind(this)},
             {async: false, update: this._updateVersion20.bind(this)},
-            {async: true,  update: this._updateVersion21.bind(this)}
+            {async: true,  update: this._updateVersion21.bind(this)},
+            {async: false, update: this._updateVersion22.bind(this)}
         ];
         /* eslint-enable no-multi-spaces */
         if (typeof targetVersion === 'number' && targetVersion < result.length) {
@@ -1174,6 +1175,18 @@ export class OptionsUtil {
     }
 
     /**
+     * @type {import('options-util').ModernUpdateFunctionAsync}
+     */
+    _updateVersion22(options) {
+        //  Added translation.searchResolution
+        for (const {options: profileOptions} of options.profiles) {
+            profileOptions.translation.searchResolution = 'letter';
+        }
+
+        return options;
+    }
+
+    /**
      * @param {string} url
      * @returns {Promise<chrome.tabs.Tab>}
      */
diff --git a/ext/js/language/translator.js b/ext/js/language/translator.js
index 733955c2..36ed8b43 100644
--- a/ext/js/language/translator.js
+++ b/ext/js/language/translator.js
@@ -329,8 +329,12 @@ export class Translator {
                 text2 = jp.collapseEmphaticSequences(text2, collapseEmphaticFull, sourceMap);
             }
 
-            for (let i = text2.length; i > 0; --i) {
-                const source = text2.substring(0, i);
+            for (
+                let source = text2, i = text2.length;
+                i > 0;
+                i = this._getNextSubstringLength(options.searchResolution, i, source)
+            ) {
+                source = text2.substring(0, i);
                 if (used.has(source)) { break; }
                 used.add(source);
                 const rawSource = sourceMap.source.substring(0, sourceMap.getSourceLength(i));
@@ -343,6 +347,20 @@ export class Translator {
     }
 
     /**
+     * @param {string} searchResolution
+     * @param {number} currentLength
+     * @param {string} source
+     * @returns {number}
+     */
+    _getNextSubstringLength(searchResolution, currentLength, source) {
+        if (searchResolution === 'word') {
+            return source.search(/[^\p{Letter}][\p{Letter}\p{Number}]*$/u);
+        } else {
+            return currentLength - 1;
+        }
+    }
+
+    /**
      * @param {string} text
      * @param {TextSourceMap} sourceMap
      * @param {import('translation').FindTermsTextReplacement[]} replacements
diff --git a/ext/settings.html b/ext/settings.html
index 323be708..1095e3b7 100644
--- a/ext/settings.html
+++ b/ext/settings.html
@@ -1505,6 +1505,18 @@
         </div>
     </div>
     <div class="settings-group advanced-only">
+        <div class="settings-item advanced-only"><div class="settings-item-inner settings-item-inner-wrappable">
+            <div class="settings-item-left">
+                <div class="settings-item-label">Dictionary search resolution</div>
+                <div class="settings-item-description" lang="en"><p>"A dog"&#x3000;&rarr;&#x3000;search for "A dog","A do", "A d", "A"</p> or <p>"A dog"&#x3000;&rarr;&#x3000;"A dog", "A"</p></div>
+            </div>
+            <div class="settings-item-right">
+                <select data-setting="translation.searchResolution">
+                    <option value="letter">Letter</option>
+                    <option value="word">Word</option>
+                </select>
+            </div>
+        </div></div>
         <div class="settings-item settings-item-button" data-modal-action="show,translation-text-replacement-patterns"><div class="settings-item-inner">
             <div class="settings-item-left">
                 <div class="settings-item-label">Configure custom text replacement patterns&hellip;</div>
diff --git a/test/options-util.test.js b/test/options-util.test.js
index 7bb9767a..daffe886 100644
--- a/test/options-util.test.js
+++ b/test/options-util.test.js
@@ -413,6 +413,7 @@ function createProfileOptionsUpdatedTestData1() {
             convertHiraganaToKatakana: 'false',
             convertKatakanaToHiragana: 'variant',
             collapseEmphaticSequences: 'false',
+            searchResolution: 'letter',
             textReplacements: {
                 searchOriginal: true,
                 groups: []
@@ -601,7 +602,7 @@ function createOptionsUpdatedTestData1() {
             }
         ],
         profileCurrent: 0,
-        version: 21,
+        version: 22,
         global: {
             database: {
                 prefixWildcardsSupported: false
diff --git a/types/ext/settings.d.ts b/types/ext/settings.d.ts
index 8ce82b28..25ea46d9 100644
--- a/types/ext/settings.d.ts
+++ b/types/ext/settings.d.ts
@@ -234,8 +234,11 @@ export type TranslationOptions = {
     convertKatakanaToHiragana: TranslationConvertType;
     collapseEmphaticSequences: TranslationCollapseEmphaticSequences;
     textReplacements: TranslationTextReplacementOptions;
+    searchResolution: SearchResolution;
 };
 
+export type SearchResolution = 'letter' | 'word';
+
 export type TranslationTextReplacementOptions = {
     searchOriginal: boolean;
     groups: TranslationTextReplacementGroup[][];
diff --git a/types/ext/translation.d.ts b/types/ext/translation.d.ts
index 595a5a35..c8938e00 100644
--- a/types/ext/translation.d.ts
+++ b/types/ext/translation.d.ts
@@ -17,6 +17,7 @@
  */
 
 import type * as Dictionary from './dictionary';
+import type {SearchResolution} from 'settings';
 
 // Kanji
 
@@ -116,6 +117,10 @@ export type FindTermsOptions = {
      * A set of dictionary names which should have definitions removed.
      */
     excludeDictionaryDefinitions: Set<string> | null;
+    /**
+     * Whether every substring should be searched for, or only whole words.
+     */
+    searchResolution: SearchResolution;
 };
 
 /**