make number of comparison in emojify() fewer (#4500)

fix style

"©"削除処理をemojione_lightに移動

app/javascript/mastodon/emoji.js

@@ -3,34 +3,28 @@ import Trie from 'substring-trie';
 
 const trie = new Trie(Object.keys(unicodeMapping));
 
-const excluded = ['™', '©', '®'];
-
-function emojify(str) {
-  // This walks through the string from start to end, ignoring any tags (<p>, <br>, etc.)
-  // and replacing valid unicode strings
-  // that _aren't_ within tags with an <img> version.
-  // The goal is to be the same as an emojione.regUnicode replacement, but faster.
-  let i = -1;
-  let insideTag = false;
-  let match;
-  while (++i < str.length) {
-    const char = str.charAt(i);
-    if (insideTag && char === '>') {
-      insideTag = false;
-    } else if (char === '<') {
-      insideTag = true;
-    } else if (!insideTag && (match = trie.search(str.substring(i)))) {
-      const unicodeStr = match;
-      if (unicodeStr in unicodeMapping && excluded.indexOf(unicodeStr) === -1) {
-        const [filename, shortCode] = unicodeMapping[unicodeStr];
-        const alt      = unicodeStr;
-        const replacement =  `<img draggable="false" class="emojione" alt="${alt}" title=":${shortCode}:" src="/emoji/${filename}.svg" />`;
-        str = str.substring(0, i) + replacement + str.substring(i + unicodeStr.length);
-        i += (replacement.length - unicodeStr.length); // jump ahead the length we've added to the string
+const emojify = str => {
+  let rtn = '';
+  for (;;) {
+    let match, i = 0;
+    while (i < str.length && str[i] !== '<' && !(match = trie.search(str.slice(i)))) {
+      i += str.codePointAt(i) < 65536 ? 1 : 2;
+    }
+    if (i === str.length)
+      break;
+    else if (str[i] === '<') {
+      let tagend = str.indexOf('>', i + 1) + 1;
+      if (!tagend)
+        break;
+      rtn += str.slice(0, tagend);
+      str = str.slice(tagend);
+    } else {
+      const [filename, shortCode] = unicodeMapping[match];
+      rtn += str.slice(0, i) + `<img draggable="false" class="emojione" alt="${match}" title=":${shortCode}:" src="/emoji/${filename}.svg" />`;
+      str = str.slice(i + match.length);
     }
   }
-  }
-  return str;
-}
+  return rtn + str;
+};
 
 export default emojify;

app/javascript/mastodon/emojione_light.js

@@ -4,8 +4,10 @@
 const emojione = require('emojione');
 
 const mappedUnicode = emojione.mapUnicodeToShort();
+const excluded = ['®', '©', '™'];
 
 module.exports.unicodeMapping = Object.keys(emojione.jsEscapeMap)
+  .filter(c => !excluded.includes(c))
   .map(unicodeStr => [unicodeStr, mappedUnicode[emojione.jsEscapeMap[unicodeStr]]])
   .map(([unicodeStr, shortCode]) => ({ [unicodeStr]: [emojione.emojioneList[shortCode].fname, shortCode.slice(1, shortCode.length - 1)] }))
   .reduce((x, y) => Object.assign(x, y), { });