Simplify JS parser handling Hashbang (#10407)

src/language-js/parse-postprocess.js

@@ -3,21 +3,12 @@
 const {
   getLast,
   getNextNonSpaceNonCommentCharacter,
-  getShebang,
 } = require("../common/util");
 const createError = require("../common/parser-create-error");
 const { locStart, locEnd } = require("./loc");
 const { isTypeCastComment } = require("./comments");
 
 function postprocess(ast, options) {
-  if (
-    options.parser === "typescript" ||
-    options.parser === "flow" ||
-    options.parser === "espree"
-  ) {
-    includeShebang(ast, options);
-  }
-
   // Invalid decorators are removed since `@typescript-eslint/typescript-estree` v4
   // https://github.com/typescript-eslint/typescript-eslint/pull/2375
   if (options.parser === "typescript" && options.originalText.includes("@")) {
@@ -256,16 +247,4 @@ function rebalanceLogicalTree(node) {
   });
 }
 
-function includeShebang(ast, options) {
-  const shebang = getShebang(options.originalText);
-
-  if (shebang) {
-    ast.comments.unshift({
-      type: "Line",
-      value: shebang.slice(2),
-      range: [0, shebang.length],
-    });
-  }
-}
-
 module.exports = postprocess;

src/language-js/parser-espree.js

@@ -1,9 +1,9 @@
 "use strict";
-const { getShebang } = require("../common/util");
 const createError = require("../common/parser-create-error");
 const tryCombinations = require("../utils/try-combinations");
 const postprocess = require("./parse-postprocess");
 const createParser = require("./parser/create-parser");
+const replaceHashbang = require("./parser/replace-hashbang");
 
 const parseOptions = {
   range: true,
@@ -33,15 +33,10 @@ function parse(originalText, parsers, options) {
   const { parse, latestEcmaVersion } = require("espree");
   parseOptions.ecmaVersion = latestEcmaVersion;
 
-  // Replace shebang with space
-  const shebang = getShebang(originalText);
-  const text = shebang
-    ? " ".repeat(shebang.length) + originalText.slice(shebang.length)
-    : originalText;
-
+  const textToParse = replaceHashbang(originalText);
   const { result: ast, error: moduleParseError } = tryCombinations(
-    () => parse(text, { ...parseOptions, sourceType: "module" }),
-    () => parse(text, { ...parseOptions, sourceType: "script" })
+    () => parse(textToParse, { ...parseOptions, sourceType: "module" }),
+    () => parse(textToParse, { ...parseOptions, sourceType: "script" })
   );
 
   if (!ast) {

src/language-js/parser-flow.js

@@ -3,6 +3,7 @@
 const createError = require("../common/parser-create-error");
 const postprocess = require("./parse-postprocess");
 const createParser = require("./parser/create-parser");
+const replaceHashbang = require("./parser/replace-hashbang");
 
 // https://github.com/facebook/flow/tree/master/packages/flow-parser#options
 const parseOptions = {
@@ -47,7 +48,7 @@ function createParseError(error) {
 function parse(text, parsers, opts) {
   // Inline the require to avoid loading all the JS if we don't use it
   const { parse } = require("flow-parser");
-  const ast = parse(text, parseOptions);
+  const ast = parse(replaceHashbang(text), parseOptions);
   const [error] = ast.errors;
   if (error) {
     throw createParseError(error);

src/language-js/parser-typescript.js

@@ -4,6 +4,7 @@ const createError = require("../common/parser-create-error");
 const tryCombinations = require("../utils/try-combinations");
 const postprocess = require("./parse-postprocess");
 const createParser = require("./parser/create-parser");
+const replaceHashbang = require("./parser/replace-hashbang");
 
 /** @type {import("@typescript-eslint/typescript-estree").TSESTreeOptions} */
 const parseOptions = {
@@ -33,14 +34,15 @@ function createParseError(error) {
 }
 
 function parse(text, parsers, opts) {
+  const textToParse = replaceHashbang(text);
   const jsx = isProbablyJsx(text);
 
   const { parseWithNodeMaps } = require("@typescript-eslint/typescript-estree");
   const { result, error: firstError } = tryCombinations(
     // Try passing with our best guess first.
-    () => parseWithNodeMaps(text, { ...parseOptions, jsx }),
+    () => parseWithNodeMaps(textToParse, { ...parseOptions, jsx }),
     // But if we get it wrong, try the opposite.
-    () => parseWithNodeMaps(text, { ...parseOptions, jsx: !jsx })
+    () => parseWithNodeMaps(textToParse, { ...parseOptions, jsx: !jsx })
   );
 
   if (!result) {

src/language-js/parser/replace-hashbang.js

@@ -0,0 +1,13 @@
+"use strict";
+
+// Replace `#!` with `//` so `typescript`, `flow`, and `espree` can parse it as line comment
+// Inspired by ESLint parse function https://github.com/eslint/eslint/blob/9d6063add931f0803cae1676d5df307baf114360/lib/linter/linter.js#L635
+function replaceHashbang(text) {
+  if (text.charAt(0) === "#" && text.charAt(1) === "!") {
+    return "//" + text.slice(2);
+  }
+
+  return text;
+}
+
+module.exports = replaceHashbang;