less.js/lib/less/tree/condition.js

var Node = require("./node");

var Condition = function (op, l, r, i, negate) {
    this.op = op.trim();
    this.lvalue = l;
    this.rvalue = r;
    this.index = i;
    this.negate = negate;
};
Condition.prototype = new Node();
Condition.prototype.type = "Condition";
Condition.prototype.accept = function (visitor) {
    this.lvalue = visitor.visit(this.lvalue);
    this.rvalue = visitor.visit(this.rvalue);
};
Condition.prototype.eval = function (context) {
    var result = (function (op, a, b) {
        switch (op) {
            case 'and': return a && b;
            case 'or':  return a || b;
            default:
                switch (Node.compare(a, b)) {
                    case -1:
                        return op === '<' || op === '=<' || op === '<=';
                    case 0:
                        return op === '=' || op === '>=' || op === '=<' || op === '<=';
                    case 1:
                        return op === '>' || op === '>=';
                    default:
                        return false;
                }
        }
    })(this.op, this.lvalue.eval(context), this.rvalue.eval(context));

    return this.negate ? !result : result;
};
module.exports = Condition;