(function (tree) {

// // A function call node. // tree.Call = function (name, args, index, currentFileInfo) {

this.name = name;
this.args = args;
this.index = index;
this.currentFileInfo = currentFileInfo;

}; tree.Call.prototype = {

type: "Call",
accept: function (visitor) {
    if (this.args) {
        this.args = visitor.visitArray(this.args);
    }
},
//
// When evaluating a function call,
// we either find the function in `tree.functions` [1],
// in which case we call it, passing the  evaluated arguments,
// if this returns null or we cannot find the function, we 
// simply print it out as it appeared originally [2].
//
// The *functions.js* file contains the built-in functions.
//
// The reason why we evaluate the arguments, is in the case where
// we try to pass a variable to a function, like: `saturate(@color)`.
// The function should receive the value, not the variable.
//
eval: function (env) {
    var args = this.args.map(function (a) { return a.eval(env); }),
        nameLC = this.name.toLowerCase(),
        result, func;

    if (nameLC in tree.functions) { // 1.
        try {
            func = new tree.functionCall(env, this.currentFileInfo);
            result = func[nameLC].apply(func, args);
            if (result != null) {
                return result;
            }
        } catch (e) {
            throw { type: e.type || "Runtime",
                    message: "error evaluating function `" + this.name + "`" +
                             (e.message ? ': ' + e.message : ''),
                    index: this.index, filename: this.currentFileInfo.filename };
        }
    }

    return new tree.Call(this.name, args, this.index, this.currentFileInfo);
},

genCSS: function (env, output) {
    output.add(this.name + "(", this.currentFileInfo, this.index);

    for(var i = 0; i < this.args.length; i++) {
        this.args[i].genCSS(env, output);
        if (i + 1 < this.args.length) {
            output.add(", ");
        }
    }

    output.add(")");
},

toCSS: tree.toCSS

};

})(require('../tree'));