(function (tree) {

tree.Rule = function (name, value, important, merge, index, currentFileInfo, inline) {

this.name = name;
this.value = (value instanceof tree.Value || value instanceof tree.Ruleset) ? value : new(tree.Value)([value]);
this.important = important ? ' ' + important.trim() : '';
this.merge = merge;
this.index = index;
this.currentFileInfo = currentFileInfo;
this.inline = inline || false;
this.variable = name.charAt && (name.charAt(0) === '@');

};

tree.Rule.prototype = {

type: "Rule",
accept: function (visitor) {
    this.value = visitor.visit(this.value);
},
genCSS: function (env, output) {
    output.add(this.name + (env.compress ? ':' : ': '), this.currentFileInfo, this.index);
    try {
        this.value.genCSS(env, output);
    }
    catch(e) {
        e.index = this.index;
        e.filename = this.currentFileInfo.filename;
        throw e;
    }
    output.add(this.important + ((this.inline || (env.lastRule && env.compress)) ? "" : ";"), this.currentFileInfo, this.index);
},
toCSS: tree.toCSS,
eval: function (env) {
    var strictMathBypass = false, name = this.name, evaldValue;
    if (typeof name !== "string") {
        // expand 'primitive' name directly to get
        // things faster (~10% for benchmark.less):
        name = (name.length === 1) 
            && (name[0] instanceof tree.Keyword)
                ? name[0].value : evalName(env, name);
    }
    if (name === "font" && !env.strictMath) {
        strictMathBypass = true;
        env.strictMath = true;
    }
    try {
        evaldValue = this.value.eval(env);

        if (!this.variable && evaldValue.type === "DetachedRuleset") {
            throw { message: "Rulesets cannot be evaluated on a property.",
                    index: this.index, filename: this.currentFileInfo.filename };
        }

        return new(tree.Rule)(name,
                          evaldValue,
                          this.important,
                          this.merge,
                          this.index, this.currentFileInfo, this.inline);
    }
    catch(e) {
        if (typeof e.index !== 'number') {
            e.index = this.index;
            e.filename = this.currentFileInfo.filename;
        }
        throw e;
    }
    finally {
        if (strictMathBypass) {
            env.strictMath = false;
        }
    }
},
makeImportant: function () {
    return new(tree.Rule)(this.name,
                          this.value,
                          "!important",
                          this.merge,
                          this.index, this.currentFileInfo, this.inline);
}

};

function evalName(env, name) {

var value = "", i, n = name.length,
    output = {add: function (s) {value += s;}};
for (i = 0; i < n; i++) {
    name[i].eval(env).genCSS(env, output);
}
return value;

}

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