less.js/lib/less/tree/attribute.js

module.exports = function (tree) {

var Attribute = function (key, op, value) {
    this.key = key;
    this.op = op;
    this.value = value;
};
Attribute.prototype = {
    type: "Attribute",
    eval: function (env) {
        return new(Attribute)(this.key.eval ? this.key.eval(env) : this.key,
            this.op, (this.value && this.value.eval) ? this.value.eval(env) : this.value);
    },
    genCSS: function (env, output) {
        output.add(this.toCSS(env));
    },
    toCSS: function (env) {
        var value = this.key.toCSS ? this.key.toCSS(env) : this.key;

        if (this.op) {
            value += this.op;
            value += (this.value.toCSS ? this.value.toCSS(env) : this.value);
        }

        return '[' + value + ']';
    }
};
return Attribute;
};