antlr4ts
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ANTLR 4 runtime for JavaScript written in Typescript
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* **Releases:** See the [GitHub Releases](https://github.com/tunnelvisionlabs/antlr4ts/releases) page for release notes and
links to the distribution
* **Feedback:** Use [GitHub Issues](https://github.com/tunnelvisionlabs/antlr4ts/issues) for issues (bugs, enhancements,
features, and questions)
This project has separate requirements for developers and end users.
> :bulb: The requirements listed on this page only cover user scenarios - that is, scenarios where developers wish to
> use ANTLR 4 for parsing tasks inside of a TypeScript application. If you are interested in contributing to ANTLR 4
> itself, see [CONTRIBUTING.md](CONTRIBUTING.md) for contributor documentation.
Parsers generated by the ANTLR 4 TypeScript target have a runtime dependency on the
[](https://www.npmjs.com/package/antlr4ts) package. The package is tested and known to work with Node.js 6.7.
The tool used to generate TypeScript code from an ANTLR 4 grammar is written in Java. To fully utilize the ANTLR 4
TypeScript target (including the ability to regenerate code from a grammar file after changes are made), a Java Runtime
Environment (JRE) needs to be installed on the developer machine. The generated code itself uses several features new to
TypeScript 2.0.
* Java Runtime Environment 1.6+ (1.8+ recommended)
* TypeScript 2.0+
## Getting started
1. Install `antlr4ts` as a runtime dependency using your preferred package manager.
```bash
npm install antlr4ts --save
```
```bash
yarn add antlr4ts
```
2. Install `antlr4ts-cli` as a development dependency using your preferred package manager.
```bash
npm install antlr4ts-cli --save-dev
```
```bash
yarn add -D antlr4ts-cli
```
3. Add a grammar to your project, e.g. **path/to/MyGrammar.g4**
4. Add a script to **package.json** for compiling your grammar to TypeScript
```
"scripts": {
// ...
"antlr4ts": "antlr4ts -visitor path/to/MyGrammar.g4"
}
```
5. Use your grammar in TypeScript
```typescript
import { ANTLRInputStream, CommonTokenStream } from 'antlr4ts';
// Create the lexer and parser
let inputStream = new ANTLRInputStream("text");
let lexer = new MyGrammarLexer(inputStream);
let tokenStream = new CommonTokenStream(lexer);
let parser = new MyGrammarParser(tokenStream);
// Parse the input, where `compilationUnit` is whatever entry point you defined
let tree = parser.compilationUnit();
```
The two main ways to inspect the tree are by using a listener or a visitor, you can read about the differences between the two [here](https://github.com/antlr/antlr4/blob/master/doc/listeners.md).
```typescript
// ...
import { MyGrammarParserListener } from './MyGrammarParserListener'
import { FunctionDeclarationContext } from './MyGrammarParser'
import { ParseTreeWalker } from 'antlr4ts/tree/ParseTreeWalker'
class EnterFunctionListener implements MyGrammarParserListener {
// Assuming a parser rule with name: `functionDeclaration`
enterFunctionDeclaration(context: FunctionDeclarationContext) {
console.log(`Function start line number ${context._start.line}`)
// ...
}
// other enterX functions...
}
// Create the listener
const listener: MyGrammarParserListener = new EnterFunctionListener();
// Use the entry point for listeners
ParseTreeWalker.DEFAULT.walk(listener, tree)
```
Note you must pass the `-visitor` flag to antlr4ts to get the generated visitor file.
```typescript
// ...
import { MyGrammarParserVisitor } from './MyGrammarParserVisitor'
import { AbstractParseTreeVisitor } from 'antlr4ts/tree/AbstractParseTreeVisitor'
// Extend the AbstractParseTreeVisitor to get default visitor behaviour
class CountFunctionsVisitor extends AbstractParseTreeVisitor<number> implements MyGrammarParserVisitor<number> {
defaultResult() {
return 0
}
aggregateResult(aggregate: number, nextResult: number) {
return aggregate + nextResult
}
visitFunctionDeclaration(context: FunctionDeclarationContext): number {
return 1 + super.visitChildren(context)
}
}
// Create the visitor
const countFunctionsVisitor = new CountFunctionsVisitor()
// Use the visitor entry point
countFunctionsVisitor.visit(tree)
```