refactor: add nextTokenStart method

babel · Aug 29, 2019 · 4f6dcc4 · 4f6dcc4
1 parent 8244a7a
commit 4f6dcc4
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Showing 2 changed files with 11 additions and 20 deletions.
diff --git a/packages/babel-parser/src/parser/statement.js b/packages/babel-parser/src/parser/statement.js
@@ -8,7 +8,7 @@ import {
   isIdentifierStart,
   keywordRelationalOperator,
 } from "../util/identifier";
-import { lineBreak, skipWhiteSpace } from "../util/whitespace";
+import { lineBreak } from "../util/whitespace";
 import * as charCodes from "charcodes";
 import {
   BIND_CLASS,
@@ -105,10 +105,7 @@ export default class StatementParser extends ExpressionParser {
     if (!this.isContextual("let")) {
       return false;
     }
-    skipWhiteSpace.lastIndex = this.state.pos;
-    const skip = skipWhiteSpace.exec(this.input);
-    // $FlowIgnore
-    const next = this.state.pos + skip[0].length;
+    const next = this.nextTokenStart();
     const nextCh = this.input.charCodeAt(next);
     // For ambiguous cases, determine if a LexicalDeclaration (or only a
     // Statement) is allowed here. If context is not empty then only a Statement
@@ -1760,18 +1757,9 @@ export default class StatementParser extends ExpressionParser {
 
   isAsyncFunction(): boolean {
     if (!this.isContextual("async")) return false;
-
-    const { pos } = this.state;
-
-    skipWhiteSpace.lastIndex = pos;
-    const skip = skipWhiteSpace.exec(this.input);
-
-    if (!skip || !skip.length) return false;
-
-    const next = pos + skip[0].length;
-
+    const next = this.nextTokenStart();
     return (
-      !lineBreak.test(this.input.slice(pos, next)) &&
+      !lineBreak.test(this.input.slice(this.state.pos, next)) &&
       this.input.slice(next, next + 8) === "function" &&
       (next + 8 === this.length ||
         !isIdentifierChar(this.input.charCodeAt(next + 8)))

diff --git a/packages/babel-parser/src/tokenizer/index.js b/packages/babel-parser/src/tokenizer/index.js
@@ -13,11 +13,11 @@ import {
   lineBreakG,
   isNewLine,
   isWhitespace,
+  skipWhiteSpace,
 } from "../util/whitespace";
 import State from "./state";
 
 const VALID_REGEX_FLAGS = new Set(["g", "m", "s", "i", "y", "u"]);
-const skipWhiteSpace = /(?:\s|\/\/.*|\/\*[^]*?\*\/)*/g;
 
 // The following character codes are forbidden from being
 // an immediate sibling of NumericLiteralSeparator _
@@ -169,13 +169,16 @@ export default class Tokenizer extends LocationParser {
     return curr;
   }
 
-  lookaheadCharCode(): number {
+  nextTokenStart(): number {
     const thisTokEnd = this.state.pos;
     skipWhiteSpace.lastIndex = thisTokEnd;
     const skip = skipWhiteSpace.exec(this.input);
     // $FlowIgnore: The skipWhiteSpace ensures to match any string
-    const next = thisTokEnd + skip[0].length;
-    return this.input.charCodeAt(next);
+    return thisTokEnd + skip[0].length;
+  }
+
+  lookaheadCharCode(): number {
+    return this.input.charCodeAt(this.nextTokenStart());
   }
 
   // Toggle strict mode. Re-reads the next number or string to please