AbstractSyntaxTree

You might find the class useful if you want to abstract away some ast manipulations such as adding, removing, replacing the nodes and others. The test folder is a good starting point for examples of usage. PRs are highly welcome.

Installation

npm install @buxlabs/ast

Methods

has

Check if ast contains a node of given type.

var source = 'var a = "x";'
var ast = new AbstractSyntaxTree(source)
ast.has('VariableDeclaration')

count

Count ast nodes of given type.

var source = 'var a = "x"; var b = "y";'
var ast = new AbstractSyntaxTree(source)
ast.count('VariableDeclaration')

find

Find all nodes of given type.

var source = 'var a = "x";'
var ast = new AbstractSyntaxTree(source)
ast.find('VariableDeclaration')

each

Iterate over all nodes of given type.

var source = 'var a = "x";'
var ast = new AbstractSyntaxTree(source)
ast.each('VariableDeclaration', node => {
  console.log(node)
})

first

First first node of given type.

var source = 'var a = "x";'
var ast = new AbstractSyntaxTree(source)
ast.first('VariableDeclaration')

last

Find last node of given type.

var source = 'var a = "x";'
var ast = new AbstractSyntaxTree(source)
ast.last('VariableDeclaration')

remove

Remove all nodes that match the criteria.

var source = '"use strict"; var b = 4;'
var ast = new AbstractSyntaxTree(source)
ast.remove({ type: 'Literal', value: 'use strict' })

var source = 'function hello () { var foo = "bar"; return "world"; }'
var ast = new AbstractSyntaxTree(source)
ast.remove('BlockStatement > VariableDeclaration')

walk

Walks over all nodes

var source = 'var a = 1'
var ast = new AbstractSyntaxTree(source)
ast.walk((node, parent) => {
  console.log(node, parent) 
})

traverse

Walks over all nodes

var source = 'var a = 1'
var ast = new AbstractSyntaxTree(source)
ast.walk({
  enter (node) {
    console.log(node)
  },
  leave (node) {
    console.log(node)
  }
})

replace

Replace all nodes that match the criteria.

var source = 'var a = 1'
var ast = new AbstractSyntaxTree(source)
ast.replace({
  enter (node) {
    if (node.type === 'VariableDeclaration') {
      node.kind = 'let'
    }
    return node
  }
})

prepend

Prepend a node to the body.

var source = 'var a = 1;'
var ast = new AbstractSyntaxTree(source)
ast.prepend({
  type: 'ExpressionStatement',
  expression: {
    type: 'Literal',
    value: 'use strict'
  }
})

append

Append a node to the body.

var source = 'var a = 1;'
var ast = new AbstractSyntaxTree(source)
ast.append({
  type: 'ExpressionStatement',
  expression: {
    type: 'Literal',
    value: 'test'
  }
})

wrap

Wrap body with given node.

var source = 'var a = 1;'
var ast = new AbstractSyntaxTree(source)
ast.wrap(body => {
    return [
      {
        "type": "ExpressionStatement",
        "expression": {
          "type": "CallExpression",
          "callee": {
            "type": "FunctionExpression",
            "id": null,
            "params": [],
            "defaults": [],
            "body": {
              "type": "BlockStatement",
              "body": body
            },
            "rest": null,
            "generator": false,
            "expression": false
          },
          "arguments": []
        }
      }
    ]
})

unwrap

Change the code to the first BlockStatement body

var source = '(function () { console.log(1); }())'
var ast = new AbstractSyntaxTree(source)
ast.unwrap()
ast.toSource()

template

Create ast partials from templates

var source = 'console.log(1);'
var ast = new AbstractSyntaxTree(source)
ast.template('var foo = <%= bar %>;' { bar: { type: 'Literal', value: 1 } })

toSource / toString

Convert the ast to string.

var source = 'var a = 1;'
var ast = new AbstractSyntaxTree(source)
ast.toSource()

rafabernad / ast