// Simple Arithmetics Grammar // ========================== // // Accepts expressions like "2 * (3 + 4)" and computes their value. Expression = head:Term tail:(_ ("+" / "-") _ Term)* { return tail.reduce(function(result, element) { if (element[1] === "+") { return result + element[3]; } if (element[1] === "-") { return result - element[3]; } }, head); } Term = head:Factor tail:(_ ("*" / "/") _ Fac