@buxlabs/ast v0.11.0

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.

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

count

Count ast nodes of given type.

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

find

Find all nodes of given type.

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

each

Iterate over all nodes of given type.

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

first

First first node of given type.

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

last

Find last node of given type.

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

remove

Remove all nodes that match the criteria.

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

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

walk

Walks over all nodes

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

traverse

Walks over all nodes

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

replace

Replace all nodes that match the criteria.

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

prepend

Prepend a node to the body.

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

append

Append a node to the body.

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

wrap

Wrap body with given node.

const source = 'const a = 1;'
const ast = new AbstractSyntaxTree(source)
ast.wrap(body => {
    return [
      {
        type: 'ExpressionStatement',
        expression: {
          type: 'CallExpression',
          callee: {
            type: 'FunctionExpression',
            params: [],
            body: {
              type: 'BlockStatement',
              body
            }
          },
          arguments: []
        }
      }
    ]
})

unwrap

Change the code to the first BlockStatement body

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

template

Create ast partials from templates

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

mark

Add cid to all nodes

const ast = new AbstractSyntaxTree('const a = 1;')
ast.mark()
assert(ast.first('Program').cid === 1)
assert(ast.first('VariableDeclaration').cid === 2)

toSource

Convert the ast to string.

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

const source = 'const a = 1;'
const ast = new AbstractSyntaxTree(source)
const { source, map } = ast.toSource({ sourceMap: true })

toSourceMap

Generates a source map.

const source = 'const a = 1;'
const ast = new AbstractSyntaxTree(source)
const map = ast.toSourceMap()