Проверка, можно ли составить строку из множеств подстрок (в том числе и вложенных подстрок)

sets.deep.js

"use strict";

function TokenList (rest, part) {
	this.rest = rest.rest.substr(part.length);
	this.stack = rest.stack.concat([part]);
	this.substr = String.prototype.substr.bind(this.rest);
	this.indexOf = String.prototype.indexOf.bind(this.rest);
}

function Input (start) {
	this.rest = start;
	this.stack = [];
	this.substr = String.prototype.substr.bind(this.rest);
	this.indexOf = String.prototype.indexOf.bind(this.rest);
}

function* check (rest, tree) {
	if (tree instanceof Set) {
		for (let value of tree) {
			if (typeof value === 'string') {
				if (rest.indexOf(value) === 0) {
					yield new TokenList(rest, value);
				}
			} else {
				yield* check(rest, value);
			}
		}
	} else {
		if (typeof tree[0] === 'string') {
			if (rest.indexOf(tree[0]) === 0) {
				if (tree.length - 1) {
					yield* check(new TokenList(rest, tree[0]), tree.slice(1));
				} else {
					yield new TokenList(rest, tree[0]);
				}
			}
		} else {
			for (let str of check(rest, tree[0])) {
				if (tree.length - 1) {
					yield* check(str, tree.slice(1));
				} else {
					yield str;
				}
			}
		}
	}
}

function restore(k, v) {
	if (v.hasOwnProperty('v')) {
		return new Set(v.v);
	}
	return v;
}

/**
 * Пример
 */

var code = '{"v":[[{"v":["a",[{"v":["","b"]},"e"],"c"]}," ",{"v":["a","b","c"]}," c"]]}',
	ast = JSON.parse(code, restore);

//console.log(require('util').inspect(ast, false, 10));

if (check('be b c', ast).next().value.rest == '') {
	console.log('yes')
} else {
	console.log('no');
}