feat(linter): ESTree-compatible AST for JS plugins

Author: overlookmotel

apps/oxlint/scripts/build.js

@@ -24,11 +24,18 @@ execSync('pnpm tsdown', { stdio: 'inherit', cwd: oxlintDirPath });
 console.log('Copying files from parser...');
 
 const parserFilePaths = [
+  // Lazy implementation
+  /*
   'src-js/raw-transfer/lazy-common.mjs',
   'src-js/raw-transfer/node-array.mjs',
   'generated/lazy/constructors.mjs',
   'generated/lazy/types.mjs',
   'generated/lazy/walk.mjs',
+  */
+  'generated/deserialize/ts.mjs',
+  'generated/visit/types.mjs',
+  'generated/visit/visitor.d.ts',
+  'generated/visit/walk.mjs',
 ];
 
 for (const parserFilePath of parserFilePaths) {

apps/oxlint/src-js/plugins/lint.ts

@@ -9,10 +9,18 @@ import { registeredRules } from './load.js';
 import { assertIs } from './utils.js';
 import { addVisitorToCompiled, compiledVisitor, finalizeCompiledVisitor, initCompiledVisitor } from './visitor.js';
 
+// Lazy implementation
+/*
 // @ts-expect-error we need to generate `.d.ts` file for this module.
 import { TOKEN } from '../../dist/src-js/raw-transfer/lazy-common.mjs';
 // @ts-expect-error we need to generate `.d.ts` file for this module.
 import { walkProgram } from '../../dist/generated/lazy/walk.mjs';
+*/
+
+// @ts-expect-error we need to generate `.d.ts` file for this module
+import { deserializeProgramOnly } from '../../dist/generated/deserialize/ts.mjs';
+// @ts-expect-error we need to generate `.d.ts` file for this module
+import { walkProgram } from '../../dist/generated/visit/walk.mjs';
 
 // Buffer with typed array views of itself stored as properties
 interface BufferWithArrays extends Uint8Array {
@@ -80,6 +88,14 @@ export function lintFile(filePath: string, bufferId: number, buffer: Uint8Array
       sourceByteLen = uint32[(programPos + SOURCE_LEN_OFFSET) >> 2];
 
     const sourceText = textDecoder.decode(buffer.subarray(0, sourceByteLen));
+
+    // `preserveParens` argument is `false`, to match ESLint.
+    // ESLint does not include `ParenthesizedExpression` nodes in its AST.
+    const program = deserializeProgramOnly(buffer, sourceText, sourceByteLen, false);
+    walkProgram(program, compiledVisitor);
+
+    // Lazy implementation
+    /*
     const sourceIsAscii = sourceText.length === sourceByteLen;
     const ast = {
       buffer,
@@ -91,6 +107,7 @@ export function lintFile(filePath: string, bufferId: number, buffer: Uint8Array
     };
 
     walkProgram(programPos, ast, compiledVisitor);
+    */
   }
 
   // Send diagnostics back to Rust

apps/oxlint/src-js/plugins/types.ts

@@ -1,7 +1,12 @@
+// Lazy implementation
+/*
 // Visitor object returned by a `Rule`'s `create` function.
 export interface Visitor {
   [key: string]: VisitFn;
 }
+*/
+
+export type { VisitorObject as Visitor } from '../../dist/generated/visit/visitor.d.ts';
 
 // Visit function for a specific AST node type.
 export type VisitFn = (node: Node) => void;

apps/oxlint/src-js/plugins/visitor.ts

@@ -72,9 +72,15 @@
 // for objects created by user code in visitors. If ephemeral user-created objects all fit in new space,
 // it will avoid full GC runs, which should greatly improve performance.
 
+// Lazy implementation
+/*
 // TODO(camc314): we need to generate `.d.ts` file for this module.
-// @ts-expect-error
 import { LEAF_NODE_TYPES_COUNT, NODE_TYPE_IDS_MAP, NODE_TYPES_COUNT } from '../../dist/generated/lazy/types.mjs';
+*/
+
+// TODO(camc314): we need to generate `.d.ts` file for this module.
+// @ts-expect-error
+import { LEAF_NODE_TYPES_COUNT, NODE_TYPE_IDS_MAP, NODE_TYPES_COUNT } from '../../dist/generated/visit/types.mjs';
 import { assertIs } from './utils.js';
 
 import type { CompiledVisitorEntry, EnterExit, Node, VisitFn, Visitor } from './types.ts';
@@ -214,7 +220,7 @@ export function addVisitorToCompiled(visitor: Visitor): void {
   for (let i = 0; i < keysLen; i++) {
     let name = keys[i];
 
-    const visitFn = visitor[name];
+    const visitFn = (visitor as { [key: string]: VisitFn })[name];
     if (typeof visitFn !== 'function') {
       throw new TypeError(`'${name}' property of visitor object is not a function`);
     }

apps/oxlint/test/__snapshots__/e2e.test.ts.snap

@@ -444,6 +444,26 @@ Found 1 warning and 6 errors.
 Finished in Xms on 1 file using X threads."
 `;
 
+exports[`oxlint CLI > should receive ESTree-compatible AST 1`] = `
+"
+  x estree-check(check): Visited nodes: 'Program', 'VariableDeclaration: let', 'Identifier: a', 'ObjectExpression', 'Identifier: x', 'Identifier: y', 'VariableDeclaration:exit: let',
+  | 'VariableDeclaration: const', 'Identifier: b', 'BinaryExpression: *', 'Identifier: x', 'BinaryExpression: +', 'Literal: str', 'Literal: 123', 'VariableDeclaration:exit: const',
+  | 'TSTypeAliasDeclaration', 'Identifier: T', 'TSStringKeyword', 'Program:exit'
+   ,-[index.ts:2:1]
+ 1 |     // All \`Identifier\`s
+ 2 | ,-> let a = { x: y };
+ 3 | |   
+ 4 | |   // No \`ParenthesizedExpression\`s in AST
+ 5 | |   const b = (x * ((('str' + ((123))))));
+ 6 | |   
+ 7 | |   // TS syntax
+ 8 | \`-> type T = string;
+   \`----
+
+Found 0 warnings and 1 error.
+Finished in Xms on 1 file using X threads."
+`;
+
 exports[`oxlint CLI > should receive data via \`context\` 1`] = `
 "
   x context-plugin(log-context): id: context-plugin/log-context
@@ -612,7 +632,7 @@ exports[`oxlint CLI > should work with multiple rules 1`] = `
    \`----
   help: Remove the debugger statement
 
-  x basic-custom-plugin(no-ident-references-named-foo): Unexpected Identifier Reference named foo
+  x basic-custom-plugin(no-identifiers-named-foo): Unexpected Identifier named foo
    ,-[index.js:3:1]
  2 | 
  3 | foo;

apps/oxlint/test/compile-visitor.test.ts

@@ -1,7 +1,13 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+// Lazy implementation
+/*
 // TODO(camc314): we need to generate `.d.ts` file for this module.
 // @ts-expect-error
 import { NODE_TYPE_IDS_MAP } from '../dist/generated/lazy/types.mjs';
+*/
+// TODO(camc314): we need to generate `.d.ts` file for this module
+// @ts-expect-error
+import { NODE_TYPE_IDS_MAP } from '../dist/generated/visit/types.mjs';
 import {
   addVisitorToCompiled,
   compiledVisitor,
@@ -30,6 +36,7 @@ describe('compile visitor', () => {
   });
 
   it('throws if unknown visitor key', () => {
+    // @ts-expect-error
     expect(() => addVisitorToCompiled({ Foo() {} }))
       .toThrow(new Error("Unknown node type 'Foo' in visitor object"));
   });

apps/oxlint/test/e2e.test.ts

@@ -136,6 +136,12 @@ describe('oxlint CLI', () => {
     expect(normalizeOutput(stdout)).toMatchSnapshot();
   });
 
+  it('should receive ESTree-compatible AST', async () => {
+    const { stdout, exitCode } = await runOxlint('test/fixtures/estree');
+    expect(exitCode).toBe(1);
+    expect(normalizeOutput(stdout)).toMatchSnapshot();
+  });
+
   it('should receive data via `context`', async () => {
     const { stdout, exitCode } = await runOxlint('test/fixtures/context_properties');
     expect(exitCode).toBe(1);

apps/oxlint/test/fixtures/basic_custom_plugin_multiple_rules/.oxlintrc.json

@@ -3,7 +3,7 @@
     "rules": {
         "basic-custom-plugin/no-debugger": "error",
         "basic-custom-plugin/no-debugger-2": "error",
-        "basic-custom-plugin/no-ident-references-named-foo": "error"
+        "basic-custom-plugin/no-identifiers-named-foo": "error"
     },
     "ignorePatterns": ["test_plugin/**"]
 }

apps/oxlint/test/fixtures/basic_custom_plugin_multiple_rules/test_plugin/index.js

@@ -27,15 +27,12 @@ export default {
         };
       },
     },
-    "no-ident-references-named-foo": {
+    "no-identifiers-named-foo": {
       create(context) {
         return {
-          IdentifierReference(identifierReference) {
-            if (identifierReference.name == "foo") {
-              context.report({
-                message: "Unexpected Identifier Reference named foo",
-                node: identifierReference,
-              });
+          Identifier(ident) {
+            if (ident.name == "foo") {
+              context.report({ message: "Unexpected Identifier named foo", node: ident});
             }
           },
         };

apps/oxlint/test/fixtures/estree/.oxlintrc.json

@@ -0,0 +1,10 @@
+{
+    "plugins": ["./test_plugin"],
+    "categories": {
+      "correctness": "off"
+    },
+    "rules": {
+        "estree-check/check": "error"
+    },
+    "ignorePatterns": ["test_plugin/**"]
+}