# grater
> An ECMAScript parser
Latest version **0.0.1-alpha.1** (published 2021-06-04) · Apache-2.0 license · 0 weekly downloads
## Install
```sh
npm install grater
pnpm add grater
yarn add grater
bun add grater
```
## Health
**Score 20/100 (F)** — status: abandoned.
Positive: esm support; no vulnerabilities.
Warnings: low downloads; no types; pre 1.0.
Negative: abandoned; low maintenance score.
## Facts
| | |
|---|---|
| Version | 0.0.1-alpha.1 |
| Published | 2021-06-04 |
| First published | 2021-06-02 |
| Weekly downloads | 0 |
| License | Apache-2.0 |
| TypeScript types | none |
| Module format | ESM + CommonJS |
| Node | >=6.0.0 |
| Dependencies | 0 |
| Unpacked size | 783.1 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 2 |
| Author | NanYang |
| Maintainers | nanyang24 |
## Links
- npm: https://www.npmjs.com/package/grater
- Repository: https://github.com/nanyang24/grater
- Issues: https://github.com/nanyang24/grater/issues
- npm.io page: https://npm.io/package/grater
## Recent versions
- 0.0.1-alpha.1 (latest) — 2021-06-04
- 0.0.1-alpha.0 (init) — 2021-06-02
## README
Grater
Grater is an [ECMAScript](https://tc39.es/ecma262/index.html) abstract syntax trees (AST) Parser, according to [The ESTree Spec](https://github.com/estree/estree)
> What is an Abstract syntax tree (AST)?
>
> Abstract syntax trees are [data structures](https://en.wikipedia.org/wiki/Data_structure) widely used in [compilers](https://en.wikipedia.org/wiki/Compiler), due to their property of representing the structure of program code. An AST is usually the result of the [syntax analysis](https://en.wikipedia.org/wiki/Parsing) phase of a compiler.
🚧 **Work in progress**
It's too early to release the source files to the public, but get a taste of it. [Here](https://nanyang24.github.io/Grater)
## 📝 Feature To-Do List
- ES5
- RegularExpressionLiteral
- HoistableDeclaration
- LabelStatement
- ES6/ES2015 & More ES Feature
- Scope
- JSX Expressions
- More test cases covered & running [Test262](https://github.com/tc39/test262)
- Support TC39 proposals via options
## 💡 What the Grater can be used for?
1. Parse Javascript
2. Syntax checker
3. Lint
4. Convert the syntax of different ECMA versions
5. Global API for performing AST operations and tree walkers
## Install
```bash
# yarn
yarn add grater
# npm
npm install grater
```
## Usage
```js
import { parseScript } from 'grater';
parseScript(`
Array.prototype.customReduce = function (fn, initialValue) {
// fn(acc, cur, ?index, ?originArray)
var sourceArray = this;
var acc, currentIndex
if(initialValue) {
acc = initialValue
currentIndex = 0
} else {
acc = sourceArray[0]
currentIndex = 1
}
while(currentIndex < sourceArray.length) {
var currentValue = sourceArray[currentIndex]
acc = fn(acc, currentValue, currentIndex, sourceArray)
currentIndex ++
}
return acc;
};
`);
```
AST in JSON
```js
{
"type": "Program",
"sourceType": "script",
"body": [
{
"type": "ExpressionStatement",
"expression": {
"type": "AssignmentExpression",
"left": {
"type": "MemberExpression",
"object": {
"type": "MemberExpression",
"object": {
"type": "Identifier",
"name": "Array"
},
"computed": false,
"property": {
"type": "Identifier",
"name": "prototype"
}
},
"computed": false,
"property": {
"type": "Identifier",
"name": "customReduce"
}
},
"operator": "=",
"right": {
"type": "FunctionExpression",
"id": null,
"params": [
{
"type": "Identifier",
"name": "fn"
},
{
"type": "Identifier",
"name": "initialValue"
}
],
"body": {
"type": "BlockStatement",
"body": [
{
"type": "VariableDeclaration",
"kind": "var",
"declarations": [
{
"type": "VariableDeclarator",
"id": {
"type": "Identifier",
"name": "sourceArray"
},
"init": {
"type": "ThisExpression"
}
}
]
},
{
"type": "VariableDeclaration",
"kind": "var",
"declarations": [
{
"type": "VariableDeclarator",
"id": {
"type": "Identifier",
"name": "acc"
},
"init": null
},
{
"type": "VariableDeclarator",
"id": {
"type": "Identifier",
"name": "currentIndex"
},
"init": null
}
]
},
{
"type": "IfStatement",
"test": {
"type": "Identifier",
"name": "initialValue"
},
"consequent": {
"type": "BlockStatement",
"body": [
{
"type": "ExpressionStatement",
"expression": {
"type": "AssignmentExpression",
"left": {
"type": "Identifier",
"name": "acc"
},
"operator": "=",
"right": {
"type": "Identifier",
"name": "initialValue"
}
}
},
{
"type": "ExpressionStatement",
"expression": {
"type": "AssignmentExpression",
"left": {
"type": "Identifier",
"name": "currentIndex"
},
"operator": "=",
"right": {
"type": "Literal",
"value": 0
}
}
}
]
},
"alternate": {
"type": "BlockStatement",
"body": [
{
"type": "ExpressionStatement",
"expression": {
"type": "AssignmentExpression",
"left": {
"type": "Identifier",
"name": "acc"
},
"operator": "=",
"right": {
"type": "MemberExpression",
"object": {
"type": "Identifier",
"name": "sourceArray"
},
"computed": true,
"property": {
"type": "Literal",
"value": 0
}
}
}
},
{
"type": "ExpressionStatement",
"expression": {
"type": "AssignmentExpression",
"left": {
"type": "Identifier",
"name": "currentIndex"
},
"operator": "=",
"right": {
"type": "Literal",
"value": 1
}
}
}
]
}
},
{
"type": "WhileStatement",
"test": {
"type": "BinaryExpression",
"left": {
"type": "Identifier",
"name": "currentIndex"
},
"right": {
"type": "MemberExpression",
"object": {
"type": "Identifier",
"name": "sourceArray"
},
"computed": false,
"property": {
"type": "Identifier",
"name": "length"
}
},
"operator": "<"
},
"body": {
"type": "BlockStatement",
"body": [
{
"type": "VariableDeclaration",
"kind": "var",
"declarations": [
{
"type": "VariableDeclarator",
"id": {
"type": "Identifier",
"name": "currentValue"
},
"init": {
"type": "MemberExpression",
"object": {
"type": "Identifier",
"name": "sourceArray"
},
"computed": true,
"property": {
"type": "Identifier",
"name": "currentIndex"
}
}
}
]
},
{
"type": "ExpressionStatement",
"expression": {
"type": "AssignmentExpression",
"left": {
"type": "Identifier",
"name": "acc"
},
"operator": "=",
"right": {
"type": "CallExpression",
"callee": {
"type": "Identifier",
"name": "fn"
},
"arguments": [
{
"type": "Identifier",
"name": "acc"
},
{
"type": "Identifier",
"name": "currentValue"
},
{
"type": "Identifier",
"name": "currentIndex"
},
{
"type": "Identifier",
"name": "sourceArray"
}
]
}
}
},
{
"type": "ExpressionStatement",
"expression": {
"type": "UpdateExpression",
"argument": {
"type": "Identifier",
"name": "currentIndex"
},
"operator": "++",
"prefix": false
}
}
]
}
},
{
"type": "ReturnStatement",
"argument": {
"type": "Identifier",
"name": "acc"
}
}
]
},
"async": false,
"generator": false
}
}
}
]
}
```
## License
[Apache License 2.0](https://github.com/nanyang24/Grater/blob/master/LICENSE)
---
_Source: https://npm.io/package/grater · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._