✨ use espree in eslint deps

Author: mysticatea

.github/workflows/CI.yml

@@ -1,7 +1,7 @@
 name: CI
 on:
   push:
-    branches: [master]
+    branches: [master, try]
   pull_request:
     branches: [master]
   schedule:
@@ -21,7 +21,7 @@ jobs:
         with:
           node-version: 14
       - name: Install Packages
-        run: npm install
+        run: npm install && cd test/fixtures/eslint && npm install
       - name: Lint
         run: npm run -s lint
 

src/script/espree.ts

@@ -0,0 +1,69 @@
+import Module from "module"
+import path from "path"
+import { ESLintExtendedProgram, ESLintProgram } from "../ast"
+
+/**
+ * The interface of a result of ESLint custom parser.
+ */
+export type ESLintCustomParserResult = ESLintProgram | ESLintExtendedProgram
+
+/**
+ * The interface of ESLint custom parsers.
+ */
+export interface ESLintCustomParser {
+    parse(code: string, options: any): ESLintCustomParserResult
+    parseForESLint?(code: string, options: any): ESLintCustomParserResult
+}
+
+const createRequire: (filename: string) => (filename: string) => any =
+    // Added in v12.2.0
+    (Module as any).createRequire ||
+    // Added in v10.12.0, but deprecated in v12.2.0.
+    Module.createRequireFromPath ||
+    // Polyfill - This is not executed on the tests on node@>=10.
+    /* istanbul ignore next */
+    (filename => {
+        const mod = new Module(filename)
+
+        mod.filename = filename
+        mod.paths = (Module as any)._nodeModulePaths(path.dirname(filename))
+        ;(mod as any)._compile("module.exports = require;", filename)
+        return mod.exports
+    })
+
+let espreeCache: ESLintCustomParser | null = null
+
+function isLinterPath(p: string): boolean {
+    return (
+        // ESLint 6 and above
+        p.includes(
+            `eslint${path.sep}lib${path.sep}linter${path.sep}linter.js`,
+        ) ||
+        // ESLint 5
+        p.includes(`eslint${path.sep}lib${path.sep}linter.js`)
+    )
+}
+
+/**
+ * Load `espree` from the loaded ESLint.
+ * If the loaded ESLint was not found, just returns `require("espree")`.
+ */
+export function getEspree(): ESLintCustomParser {
+    if (!espreeCache) {
+        // Lookup the loaded eslint
+        const linterPath = Object.keys(require.cache).find(isLinterPath)
+        if (linterPath) {
+            try {
+                espreeCache = createRequire(linterPath)("espree")
+            } catch {
+                // ignore
+            }
+        }
+        if (!espreeCache) {
+            //eslint-disable-next-line @mysticatea/ts/no-require-imports
+            espreeCache = require("espree")
+        }
+    }
+
+    return espreeCache!
+}

src/script/index.ts

@@ -17,7 +17,6 @@ import {
     ESLintForOfStatement,
     ESLintFunctionExpression,
     ESLintPattern,
-    ESLintProgram,
     ESLintVariableDeclaration,
     ESLintUnaryExpression,
     HasLocation,
@@ -39,6 +38,7 @@ import {
     analyzeExternalReferences,
     analyzeVariablesAndExternalReferences,
 } from "./scope-analyzer"
+import { ESLintCustomParser, getEspree } from "./espree"
 
 // [1] = spacing before the aliases.
 // [2] = aliases.
@@ -51,14 +51,6 @@ const DUMMY_PARENT: any = {}
 const IS_FUNCTION_EXPRESSION = /^\s*([\w$_]+|\([^)]*?\))\s*=>|^function\s*\(/u
 const IS_SIMPLE_PATH = /^[A-Za-z_$][\w$]*(?:\.[A-Za-z_$][\w$]*|\['[^']*?'\]|\["[^"]*?"\]|\[\d+\]|\[[A-Za-z_$][\w$]*\])*$/u
 
-/**
- * The interface of ESLint custom parsers.
- */
-interface ESLintCustomParser {
-    parse(code: string, options: any): ESLintCustomParserResult
-    parseForESLint?(code: string, options: any): ESLintCustomParserResult
-}
-
 /**
  * Do post-process of parsing an expression.
  *
@@ -548,11 +540,6 @@ export interface ExpressionParseResult<T extends Node> {
     variables: Variable[]
 }
 
-/**
- * The interface of a result of ESLint custom parser.
- */
-export type ESLintCustomParserResult = ESLintProgram | ESLintExtendedProgram
-
 /**
  * Parse the given source code.
  *
@@ -568,8 +555,7 @@ export function parseScript(
         typeof parserOptions.parser === "string"
             ? // eslint-disable-next-line @mysticatea/ts/no-require-imports
               require(parserOptions.parser)
-            : // eslint-disable-next-line @mysticatea/ts/no-require-imports
-              require("espree")
+            : getEspree()
     const result: any =
         // eslint-disable-next-line @mysticatea/ts/unbound-method
         typeof parser.parseForESLint === "function"

test/espree.js

@@ -0,0 +1,60 @@
+"use strict"
+
+const path = require("path")
+
+/**
+ * Spawn a child process to run `childMain()`.
+ */
+function parentMain() {
+    const { spawn } = require("child_process")
+
+    describe("Loading espree from ESLint", () => {
+        it("should load espree from the ESLint location.", done => {
+            spawn(process.execPath, [__filename, "--child"], {
+                stdio: "inherit",
+            })
+                .on("error", done)
+                .on("exit", code =>
+                    code
+                        ? done(new Error(`Exited with non-zero: ${code}`))
+                        : done()
+                )
+        })
+    })
+}
+
+/**
+ * Check this parser loads the `espree` from the location of the loaded ESLint.
+ */
+function childMain() {
+    const assert = require("assert")
+    const { Linter } = require("./fixtures/eslint")
+    const linter = new Linter()
+    linter.defineParser("vue-eslint-parser", require("../src"))
+
+    const beforeEsprees = Object.keys(require.cache).filter(isEspreePath)
+
+    linter.verify(
+        "<script>'hello'</script>",
+        { parser: "vue-eslint-parser" },
+        { filename: "a.vue" }
+    )
+
+    const afterEsprees = Object.keys(require.cache).filter(isEspreePath)
+
+    assert.strictEqual(
+        afterEsprees.length,
+        beforeEsprees.length,
+        "espree should be loaded from the expected place"
+    )
+}
+
+function isEspreePath(p) {
+    return p.includes(`${path.sep}node_modules${path.sep}espree${path.sep}`)
+}
+
+if (process.argv.includes("--child")) {
+    childMain()
+} else {
+    parentMain()
+}