Support for new babel types

[tmcw]

Re: babel/babel#2769

Babel 6.0.0 introduces a new NumericLiteral type that currently is not present in ast-types and breaks the tree traversal.

[benjamn]

Have time to submit a pull request?

[hzoo]

It's more than just NumericLiteral - https://github.com/babel/babel/blob/master/doc/ast/spec.md, https://github.com/babel/babel/blob/master/CHANGELOG.md#600

Example changes - https://github.com/babel/acorn-to-esprima/pull/3/files#diff-d45f2be38f06b237a94ba1f97798af79R53

[benjamn]

I'm guessing @tmcw doesn't have time for a pull request, which is totally fine. I'll do this as soon as I can.

[hzoo]

Shouldn't be too bad. I can do it later if you don't - From the changelog

Rename RegexLiteral node to RegExpLiteral.
Rename NumberLiteral node to NumericLiteral.

The MethodDefinition node type has been renamed to ClassMethod and it's FunctionExpression value property has been coerced into the main method node.
The Property node type has been renamed to ObjectProperty.
The Property node type with the boolean flag method has been renamed to ObjectMethod and it's FunctionExpression value property has been coerced into the main method node.
The Literal node type has been unoverloaded and split into BooleanLiteral, RegExpLiteral, NumericLiteral, StringLiteral and NullLiteral.
The SpreadProperty (from object-rest-spread) node type has been split into RestProperty (for ObjectPattern) and SpreadProperty (for ObjectExpression)

[benjamn]

Those are all really worthwhile changes, by the way.

[hzoo]

Should probably propose them to ESTree anyway (lgtm)

[jamestalmage]

I think this is going to be difficult w/o #57.

For example: attempting to add RegExpLiteral per the spec, I added the following definition:

def("RegExpLiteral")
    .bases("Literal")
    .build("pattern", "flags")
    .field("pattern", String)
    .field("flags", String);

Trying to build a RegExpLiteral Node, you get the following error:

b.regExpLiteral("my-pattern", "ig");

 Error: no value or default function given for field "value" of RegExpLiteral("pattern": string, "flags": string)

This is because core.js defines a required value field for Literal, where the Babel spec uses Literal strictly as a super-type for the more specific nodes (StringLiteral, NullLiteral, etc).

Until ast-types is refactored to allow custom Node definitions, these increasingly divergent AST specs are going to represent a problem.

[hzoo]

Update: I made #162