"use strict";

const { NoMatch, NotEnoughInput } = require("../symbols");

module.exports = function* until(instruction, state, context) {
	while (state.currentIndex < state.currentInput.length) {
		let attemptIndex = state.currentIndex;
		let result = yield instruction.rule;

		if (result === NoMatch) {
			state.currentIndex += 1;
			continue;
		} else {
			// Un-consume the terminator we've matched, and continue parsing other rules
			state.currentIndex = attemptIndex;

			if (state.currentIndex > context.startIndex) {
				return state.currentInput.slice(context.startIndex, state.currentIndex);
			} else {
				// Zero-width match; that's a fail
				return NoMatch;
			}
		}
	}

	// Reached the end of the currently available input, and we still haven't encountered our terminator
	return NotEnoughInput;
};