Equation Solver using Map/Reduce

eq.js

function parse(eq) {
	var nest = 0;
	eq = eq.reduce(function(acc, val) {
		if (val == '(') {
			nest++;
		} else if (val == ')') {
			nest--;
		}

		if (val == '(' && nest == 1) {
			acc.push([])
		} else if (val == ')' && nest == 0) {
			acc[acc.length - 1] = parse(acc[acc.length - 1]);
		} else if (nest > 0) {
			acc[acc.length - 1].push(val);
		} else  {
			if (isNaN(val)) {
				acc.push(val)
			} else {
				acc.push(Number(val));
			}
		}
		return acc;
	}, []);
	return eq;
}

function solve(eq) {
	var op = null;
	eq = eq.reduce(function(acc, val) {
		if (Array.isArray(val)) {
			val = solve(val);
		}
		acc.push(val);
		return acc;
	}, []);

	['^', ['*', 'x', '/', '÷'], ['+', '-']].map(function(op) {
		var calc = null;
		eq = eq.reduce(function(acc, val) {
			if (calc) {
				switch(calc) {
					case '^': acc[acc.length - 1] = Math.pow(acc[acc.length - 1], val); break;
					case 'x': case '*': acc[acc.length - 1] *= val; break;
					case '÷': case '/': acc[acc.length - 1] /= val; break;
					case '+': acc[acc.length - 1] += val; break;
					case '-': acc[acc.length - 1] -= val; break;
				}
				calc = null;
			} else if ((Array.isArray(op) && op.indexOf(val) != -1) || op == val) {
				calc = val;
			} else {
				acc.push(val);
			}
			return acc;
		}, []);
	});

	return eq[0];
}

[
	[1, '+', 2, '*', 3, '+', 4, '*', 5, '+', 6],				// 1 + 2 * 3 + 4 * 5 + 6 = 33
	['(', '(', 2, '+', 3, ')', '^', '2', ')', '*', 1.5],			// ( ( 2 + 3 ) ^ 2 ) * 1.5 = 37.5
	[6, '+', 5, '-', 4, '*', 3, '/', 2, '^', '(', 1, '+', 0, ')'],		// 6 + 5 - 4 * 3 / 2 ^ ( 1 + 0 ) = 5
	['(', '(', 6, '+', 4, ')', '*' ,'(', 3, '-', 1, ')', ')', '/', 5]	// ( ( 6 + 4 ) * ( 3 - 1 ) ) / 5 = 4
].map(function(t) {
	console.log(t.join(' '), '=', solve(parse(t)));
});