Parse conditions ([word/string] [operator] [word/string])
function () {
			var leftNode = this.parseBaseExpression();

			if (this.currentToken.type == 'operator') {
				var operator = this.currentToken.value;
				this.readNextToken();

				// If there are 2 adjacent operators, join them with a space (exemple: IS NOT)
				if (this.currentToken.type == 'operator') {
					operator += ' ' + this.currentToken.value;
					this.readNextToken();
				}

				var rightNode = this.parseBaseExpression();

				leftNode = {'operator': operator, 'left': leftNode, 'right': rightNode};
			}

			return leftNode;
		}