feat(read-string): optimize read-string performance

baidu · Apr 16, 2021 · 4b80828 · 4b80828
1 parent 3fc320f
commit 4b80828
Showing 1 changed file with 44 additions and 4 deletions.
diff --git a/src/parser/read-string.js b/src/parser/read-string.js
@@ -18,25 +18,65 @@ var ExprType = require('./expr-type');
  */
 function readString(walker) {
     var startCode = walker.currentCode();
-    var startIndex = walker.index;
+    var value = "";
     var charCode;
 
     walkLoop: while ((charCode = walker.nextCode())) {
         switch (charCode) {
             case 92: // \
-                walker.go(1);
+                charCode = walker.nextCode();
+
+                switch (charCode) {
+                    case 117: // \u
+                        value += String.fromCharCode(parseInt(
+                            walker.cut(walker.index + 1, walker.index + 5)
+                        ), 16);
+                        walker.go(4);
+                        break;
+
+                    case 120: // \x
+                        value += String.fromCharCode(parseInt(
+                            walker.cut(walker.index + 1, walker.index + 3)
+                        ), 16);
+                        walker.go(2);
+                        break;
+
+                    case 98:
+                        value += '\b';
+                        break;
+                    case 102:
+                        value += '\f';
+                        break;
+                    case 110:
+                        value += '\n';
+                        break;
+                    case 114:
+                        value += '\r';
+                        break;
+                    case 116:
+                        value += '\t';
+                        break;
+                    case 118:
+                        value += '\v';
+                        break;
+
+                    default:
+                        value += String.fromCharCode(charCode);
+                }
+
                 break;
             case startCode:
                 walker.go(1);
                 break walkLoop;
+            default:
+                value += String.fromCharCode(charCode);
         }
     }
 
-    var literal = walker.cut(startIndex, walker.index);
     return {
         type: ExprType.STRING,
         // 处理字符转义
-        value: (new Function('return ' + literal))()
+        value: value
     };
 }