estree-to-js

Parser / JSON + visitor generator of the markdown estree spec;

Usage

npdejs API

estree-to-js interface:

var estree = require("estree-to-js");
var visitorSource = estree.fetch("es6")
  .then(estree.parse)
  .then(spec => estree.createVisitor(spec, []/*exceptions*/, "MyVisitor"))
  .catch(console.error)

Visitors

Creation of visitor:

var visitor;
visitorSource
  .then(source => eval(source + "\n" + "MyVisitor"))
  .then(MyVisitor => visitor = new MyVisitor());

Print path example

visitors have an accept(node, state, path) method and visitNodeType methods like visitVariableDeclaration(node, state, path). You can customize it to your needs, for example:

var lang = require("lively.lang"), ast = require("lively.ast");
visitor.accept = lang.fun.wrap(visitor.accept, (proceed, node, state, path) => {
  state.push(path.join(".") + " - " + node.type);
  proceed(node, state, path);
});
var state = [];
visitor.accept(ast.parse("var x = 1+3"), state, []);
console.log(state.join("\n")); // =>
                               //   - Program
                               //   body.0 - VariableDeclaration
                               //   body.0.declarations.0 - VariableDeclarator
                               //   ...

Rewriting example

var replacer = (node) => lang.obj.merge(node, {id: {type: "Identifier", name: "foo_" + node.id.name}})
var visitor = new MyVisitor();
visitor.accept = lang.fun.wrap(visitor.accept, (proceed, node, state, path) => {
  if (node.type === "VariableDeclarator") node = replacer(node);
  return proceed(node, state, path);
});
var rewritten = visitor.accept(ast.parse("var x = 1 + 3"), null, []);
ast.stringify(rewritten); // => var foo_x = 1 + 3;

command line

--out			file output file to write
--generate-json-spec	fetch and parse markdown source and generate JSON spec from it (default)
--generate-visitor	generate source code for AST visitor class
--json-spec		file to json spec. If specified it is used instead of fetching + parsing

Examples:

• ./bin/estree-to-js.js es6 prints JSON spec of es6 estree
• ./bin/estree-to-js.js es6 --generate-visitor prints JS source es6 estree visitor class

License

MIT