Grater is an ECMAScript abstract syntax trees (AST) Parser, according to The ESTree Spec
What is an Abstract syntax tree (AST)?
Abstract syntax trees are data structures widely used in compilers, due to their property of representing the structure of program code. An AST is usually the result of the syntax analysis 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
- ES5
- RegularExpressionLiteral
- HoistableDeclaration
- LabelStatement
- ES6/ES2015 & More ES Feature
- Scope
- JSX Expressions
- More test cases covered & running Test262
- Support TC39 proposals via options
- Parse Javascript
- Syntax checker
- Lint
- Convert the syntax of different ECMA versions
- Global API for performing AST operations and tree walkers
# yarn
yarn add grater
# npm
npm install graterimport { 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
{
"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
}
}
}
]
}