d3-jsnext/generate/src/ast/Scope.js

d3, but futuristic

export default class Scope {
	constructor ( options ) {
		options = options || {};

		this.parent = options.parent;
		this.depth = this.parent ? this.parent.depth + 1 : 0;
		this.names = options.params || [];
	}

	add ( name ) {
		this.names.push( name );
	}

	contains ( name ) {
		return !!this.findDefiningScope( name );
	}

	findDefiningScope ( name ) {
		if ( ~this.names.indexOf( name ) ) {
			return this;
		}

		if ( this.parent ) {
			return this.parent.findDefiningScope( name );
		}

		return null;
	}
}