Merge pull request #11 from devanshj/buncha-improvements

Fixes: grammar for super invocation, Features: `walk`, `createVisitor`

Author: urish

.gitignore

@@ -1,2 +1,7 @@
 node_modules
 dist
+src/parser/JavaParser.ts
+src/parser/JavaParserListener.ts
+src/parser/JavaParserVisitor.ts
+src/parser/JavaLexer.ts
+src/parser/JavaContexts.ts

README.md

@@ -1,6 +1,6 @@
 # java-ast
 
-Java Parser for JavaScript/TypeScript, based on [antlr4ts](https://www.npmjs.com/package/antlr4ts)
+Java Parser for JavaScript/TypeScript, based on [antlr4ts](https://www.npmjs.com/package/antlr4ts), grammar taken from [antlr4's java grammar](https://github.com/antlr/grammars-v4/tree/master/java/java) too (so please report bugs and open pull requests related to grammars upstream)
 
 [![npm version](https://img.shields.io/npm/v/java-ast.svg)](https://www.npmjs.com/package/java-ast)
 [![Build Status](https://travis-ci.org/urish/java-ast.png?branch=master)](https://travis-ci.org/urish/java-ast)
@@ -9,8 +9,28 @@ Java Parser for JavaScript/TypeScript, based on [antlr4ts](https://www.npmjs.com
 ## Usage Example
 
 ```typescript
-import { parse } from './index';
+import { parse, createVisitor } from 'java-ast';
 
-const ast = parse(`package test;\n\nclass TestClass {}\n`);
-// do something with ast, e.g. console.log(ast.toStringTree());
+const countMethods = (source: string) => {
+  let ast = parse(source);
+
+  return createVisitor({
+    visitMethodDeclaration: () => 1,
+    defaultResult: () => 0,
+    aggregateResult: (a, b) => a + b,
+  }).visit(ast);
+};
+
+console.log(
+  countMethods(`
+    class A {
+      int a;
+      void b() {}
+      void c() {}
+    }
+    class B {
+      void z() {}
+    }
+  `),
+); // logs 3
 ```

generate-contexts.js

@@ -0,0 +1,35 @@
+// @ts-check
+
+const fs = require('fs').promises;
+const path = require('path');
+const { EOL } = require('os');
+
+const listenerFilePath = path.join(__dirname, '/src/parser/JavaParserListener.ts');
+const contextsFilePath = path.join(__dirname, '/src/parser/JavaContexts.ts');
+
+const main = () =>
+  fs
+    .stat(listenerFilePath)
+    .catch(
+      () => 'src/parser/JavaParserListener.ts not found use generate:parser script to generate it',
+    )
+    .then(() => fs.readFile(listenerFilePath, 'utf-8'))
+    .then((listenerSource) =>
+      listenerSource
+        .split(EOL)
+        .map((l) => {
+          let matches = l.match(/import\s*\{\s*(.*Context)\s*\}.*/);
+          if (matches === null) return null;
+          return matches[1];
+        })
+        .filter((c) => c !== null),
+    )
+    .then((contexts) => contexts.reduce((list, context) => list + `  ${context},${EOL}`, ''))
+    .then((exportList) => `export {${EOL}${exportList}} from './JavaParser';`)
+    .then((contextsSource) => fs.writeFile(contextsFilePath, contextsSource));
+
+main().catch((error) => {
+  if (typeof error !== 'string') throw error;
+  console.log('Failure: ' + error);
+  process.exit(1);
+});

package.json

@@ -25,12 +25,14 @@
     "format": "prettier --write src/**.ts **/*.json",
     "prepublish": "yarn build",
     "generate:parser": "antlr4ts -visitor -o src/parser src/parser/JavaLexer.g4 src/parser/JavaParser.g4",
+    "generate:contexts": "node generate-contexts.js",
     "precommit": "lint-staged",
     "postcommit": "git update-index --again",
     "test": "jest"
   },
   "devDependencies": {
     "@types/jest": "^23.1.5",
+    "@types/node": "^14.0.22",
     "antlr4ts-cli": "^0.4.0-alpha.4",
     "husky": "^0.14.3",
     "jest": "^23.3.0",
@@ -39,7 +41,7 @@
     "rimraf": "^2.6.2",
     "ts-jest": "^23.0.0",
     "tslint": "^5.10.0",
-    "typescript": "~2.8.2"
+    "typescript": "^3.9.6"
   },
   "dependencies": {
     "antlr4ts": "^0.4.1-alpha.0"

src/index.spec.ts

@@ -1,11 +1,65 @@
-import { parse } from './index';
+import { createVisitor, parse, walk } from './index';
 
-describe('Java AST parser', () => {
+describe('parser', () => {
   it('should parse the given Java code and return the AST', () => {
     const tree = parse(`
       class TestClass {
       }
     `);
     expect(tree.children[0].getChild(0).getChild(1).text).toEqual('TestClass');
   });
+
+  it('should handle super invocation with arguments', () => {
+    const tree = parse(`
+      class B extends A {
+        public B() {
+          super(1);
+        }
+      }
+    `);
+
+    const expressions = [];
+    walk({ enterExpression: (c) => expressions.push(c.text) }, tree);
+
+    expect(expressions).toContain('super(1)');
+  });
+
+  it('should allow super alone as expression', () => {
+    const tree = parse(`
+      class B extends A {
+        public B() {
+          super;
+        }
+      }
+    `);
+
+    const expressions = [];
+    walk({ enterExpression: (c) => expressions.push(c.text) }, tree);
+
+    expect(expressions).toContain('super');
+  });
+});
+
+describe('usage example', () => {
+  it('works', () => {
+    const countMethods = (source: string) =>
+      createVisitor({
+        visitMethodDeclaration: () => 1,
+        defaultResult: () => 0,
+        aggregateResult: (a, b) => a + b,
+      }).visit(parse(source));
+
+    expect(
+      countMethods(`
+      class A {
+        int a;
+        void b() {}
+        void c() {}
+      }
+      class B {
+        void z() {}
+      }
+    `),
+    ).toEqual(3);
+  });
 });

src/index.ts

@@ -1,16 +1,137 @@
+// parse
 import { ANTLRInputStream, CommonTokenStream } from 'antlr4ts';
 import { JavaLexer } from './parser/JavaLexer';
 import { CompilationUnitContext, JavaParser } from './parser/JavaParser';
-export { CompilationUnitContext };
+
+// walk
+import { ParseTreeWalker } from 'antlr4ts/tree/ParseTreeWalker';
+import { JavaParserListener } from './parser/JavaParserListener';
+import { JavaParserVisitor } from './parser/JavaParserVisitor';
+
+// createVisitor
+import { AbstractParseTreeVisitor } from 'antlr4ts/tree/AbstractParseTreeVisitor';
+import { ParseTreeVisitor } from 'antlr4ts/tree/ParseTreeVisitor';
+import { RuleNode } from 'antlr4ts/tree/RuleNode';
 
 /**
  * Parses the given source code and returns the AST
  * @param source Java source code to parse
  */
-export function parse(source: string): CompilationUnitContext {
+export function parse(source: string): ParseTree {
   const chars = new ANTLRInputStream(source);
   const lexer = new JavaLexer(chars);
   const tokens = new CommonTokenStream(lexer);
   const parser = new JavaParser(tokens);
   return parser.compilationUnit();
 }
+
+// Just to create a more user-friendly name as all arguments that are name 'tree' take this
+// (type alias doesn't create a new name)
+// tslint:disable-next-line:no-empty-interface
+export interface ParseTree extends CompilationUnitContext {}
+
+/**
+ * Walks a parse tree
+ * @see https://github.com/antlr/antlr4/blob/master/doc/listeners.md
+ */
+export function walk(listener: JavaParserListener, tree: ParseTree) {
+  ParseTreeWalker.DEFAULT.walk(listener, tree);
+}
+export { JavaParserListener } from './parser/JavaParserListener';
+
+/**
+ * Create a parse tree visitor
+ */
+export function createVisitor<T>(visitor: Visitor<T>): ConcreteVisitor<T>;
+export function createVisitor(visitor: VoidVisitor): ConcreteVisitor<void>;
+export function createVisitor<T>(visitor: Visitor<T>): ConcreteVisitor<T> {
+  // we don't want users to write classes because it's not JavaScript-y
+  // so we'll set implementation of abstract methods and other visit* methods in constructor
+  // @ts-ignore
+  return new class extends AbstractParseTreeVisitor<T> {
+    constructor() {
+      super();
+      Object.assign(this, {
+        defaultResult: () => undefined,
+        aggregateResult: () => undefined,
+        ...visitor,
+      });
+    }
+  }();
+}
+
+export interface Visitor<T>
+  extends AbstractVisitor<T>,
+    OmitStrict<JavaParserVisitor<T>, NonOverridableMethods> {}
+
+export interface VoidVisitor
+  extends OmitStrict<Visitor<void>, 'defaultResult' | 'aggregateResult'> {}
+
+type NonOverridableMethods = keyof ParseTreeVisitor<any>;
+type OmitStrict<T, K extends keyof T> = Omit<T, K>;
+
+// Just to create a better name
+export interface ConcreteVisitor<T> extends AbstractParseTreeVisitor<T> {}
+
+// from AbstractParseTreeVisitor
+interface AbstractVisitor<T> {
+  /**
+   * Gets the default value returned by visitor methods. This value is
+   * returned by the default implementations of
+   * {@link #visitTerminal visitTerminal}, {@link #visitErrorNode visitErrorNode}.
+   * The default implementation of {@link #visitChildren visitChildren}
+   * initializes its aggregate result to this value.
+   *
+   * @return The default value returned by visitor methods.
+   */
+  defaultResult: () => T;
+
+  /**
+   * Aggregates the results of visiting multiple children of a node. After
+   * either all children are visited or {@link #shouldVisitNextChild} returns
+   * {@code false}, the aggregate value is returned as the result of
+   * {@link #visitChildren}.
+   *
+   * <p>The default implementation returns {@code nextResult}, meaning
+   * {@link #visitChildren} will return the result of the last child visited
+   * (or return the initial value if the node has no children).</p>
+   *
+   * @param aggregate The previous aggregate value. In the default
+   * implementation, the aggregate value is initialized to
+   * {@link #defaultResult}, which is passed as the {@code aggregate} argument
+   * to this method after the first child node is visited.
+   * @param nextResult The result of the immediately preceeding call to visit
+   * a child node.
+   *
+   * @return The updated aggregate result.
+   */
+  aggregateResult: (aggregate: T, nextResult: T) => T;
+
+  /**
+   * This method is called after visiting each child in
+   * {@link #visitChildren}. This method is first called before the first
+   * child is visited; at that point {@code currentResult} will be the initial
+   * value (in the default implementation, the initial value is returned by a
+   * call to {@link #defaultResult}. This method is not called after the last
+   * child is visited.
+   *
+   * <p>The default implementation always returns {@code true}, indicating that
+   * {@code visitChildren} should only return after all children are visited.
+   * One reason to override this method is to provide a "short circuit"
+   * evaluation option for situations where the result of visiting a single
+   * child has the potential to determine the result of the visit operation as
+   * a whole.</p>
+   *
+   * @param node The {@link RuleNode} whose children are currently being
+   * visited.
+   * @param currentResult The current aggregate result of the children visited
+   * to the current point.
+   *
+   * @return {@code true} to continue visiting children. Otherwise return
+   * {@code false} to stop visiting children and immediately return the
+   * current aggregate result from {@link #visitChildren}.
+   */
+  shouldVisitNextChild?: (node: RuleNode, currentResult: T) => boolean;
+}
+
+export * from './parser/JavaContexts';