Mole

Mole is a collection of parsers to parse the frontend stuffs.

Why Golang

A little bit explanation is good for why Golang is preferred in this project. Nowadays, a programming language is not only the grammar things, it's consist of runtime, stdlib, 3rd-party modules and a healthy community, all these are out-of-box by using Golang, more specifically:

• Golang is productive, its simplicity philosophy(something like Grammar and Garbage-collection) saves more time to the functionalities themselves.
• the functionalities like lint and bundle maybe needed to run as web services while Golang has been proved by many impressive projects such k8s that it's good at service things.

Fine, just all because I'm too fool to use a fancy language

Features

• JavaScript Parser

  • ECMAScript up to ES2021
  • JSX
  • ESTree compatible outputs (AST explorer on WASM)

• TypeScript Parser

  • Type information retained
  • babel/typescript compatible outputs

WIP

• CSS parser
• Less parser
• Scss parser

Using the parser

For using the parser in Mole, the first step is using go get to add Mole as your project's dependency

go get github.com/hsiaosiyuan0/mole

# or using go get via a proxy if you have some network issues
https_proxy=127.0.0.1:1080 go get github.com/hsiaosiyuan0/mole

After the installation is succeeded, below code can be used as a demo:

Click to expand the demo

package main

import (
  "bytes"
  "encoding/json"
  "fmt"
  "log"

  "github.com/hsiaosiyuan0/mole/ecma/estree"
  "github.com/hsiaosiyuan0/mole/ecma/parser"
  "github.com/hsiaosiyuan0/mole/span"
)

func main() {
  // imitate the source code you want to parse
  code := `console.log("hello world")`

  // create a Source instance to handle to the source code
  s := span.NewSource("", code)

  // create a parser, here we use the default options
  opts := parser.NewParserOpts()
  p := parser.NewParser(s, opts)

  // inform the parser do its parsing process
  ast, err := p.Prog()
  if err != nil {
    log.Fatal(err)
  }

  // by default the parsed AST is not the ESTree form because the latter has a little redundancy,
  // however Mole supports to convert its AST to ESTree by using the `estree.ConvertProg` function
  b, err := json.Marshal(estree.ConvertProg(ast.(*parser.Prog), estree.NewConvertCtx(p)))
  if err != nil {
    log.Fatal(err)
  }

  // below is nothing new, we just print the ESTree in JSON form
  var out bytes.Buffer
  json.Indent(&out, b, "", "  ")
  fmt.Println(out.String())
}

The produced AST can be consumed by the ast-walker in Mole, more runnable demos see mole-demo

Development

See dev.md to get more information about how to start development.