fastladder/fastladder

/*
 usage
  new Template("$id") -> $("id")
  new Template("aiueo") -> string
*/
function Template(str){
    if(str.isTemplate){
        str = str.tmpl;
    }
    this.tmpl = str;
    if(str.charAt(0) == "$"){
        var el = _$(str.slice(1));
        this.tmpl = (el.tagName == "textarea") ? el.value : el.innerHTML;
    }
    this.stash = {
        pre : {},
        params : {}
    };
    this.filters = [];
    this.filter_for_param = {};
    this.use_filter = false;
}
Template.prototype = {
    isTemplate: true,
    fill: function(){
        var args = Array.from(arguments);
        var builder = this.compile();
        return builder.apply(this,args);
    },
    pre_fill : function(){

    },
    add_filter: function(expr,filter){
        this.use_filter = true;
        if(expr.isString){
            var f = this.filter_for_param;
            f[expr] ? f[expr].push(filter) : (f[expr] = [filter]);
            return;
        }
        if(expr.isFunction){
            var f = function(value){return filter(value)};
            f.gate = expr;
            this.filters.push(f)
        }
    },
    add_filters : function(o){
        var self = this;
        each(o,function(value,key){
            self.add_filter(key,value)
        });
    },

    get_param : function(key){
        var params = this.stash.params;
        var pre = this.stash.pre;
        if(params.hasOwnProperty(key))
            return params[key]
        else if(pre.hasOwnProperty(key))
            return pre[key]
        return null;
    },

    filtered: function(key){
        var self  = this;
        var value = this.get_param(key);
        var res = value;
        // filters
        if(this.filters.length){
            this.filters.forEach(function(filter){
                if(filter.gate.call(self,value,key,self))
                    res = filter.call(self,res,key,self)
            })
        }else if(this.filter_for_param[key]){
                this.filter_for_param[key].forEach(function(filter){
                    res = filter.call(self,res,key,self)
                })
        }
        return res;
    },
    make_builder: function(buffer_ref){
        var self = this;
        var buf  = buffer_ref;
        return function(){
            var args = Array.from(arguments);
            self.stash.params = {};
            args.forEach(function(p){
                extend(self.stash.params,p)
            });
            return buf.join("")
        };
    },
    compile: function(pre_vars){
        var self = this;
        var buf = [];
        var builder = this.make_builder(buf);
        var sep = /\[\[(.*?)\]\]/g;
        var offset = 0;
        var tmpl = this.tmpl;
        tmpl.replace(sep, function(){
            var a = arguments;
            var stash = self.stash;
            var match_text = a[0];
            var match_idx = a[2];
            var key = a[1].strip();
            buf.push(tmpl.slice(offset,match_idx));
            offset = match_idx + match_text.length;
            var n = {};
            // function
            if(key.charAt(0) == "#"){
                var context = [];
                var expr = key.match(/{(.*)}/)[1];
                context.push("with(this.params){return(");
                context.push(expr);
                context.push(")}");
                n.toString = new Function(context.join("")).bind(stash);
            } else {
                n.toString = function(){
                    var expr = stash.params[key];
                    var res = (expr != null) ?
                        (expr.isFunction)
                            ? "" + expr()
                            : "" + self.filtered(key)
                            : "";
                    return res
                }
            };
            buf.push(n);
        });
        buf.push(tmpl.slice(offset));
        return builder;
    }
};


Template.get = function(id){
    var el = _$(id);
    //TODO refactor later
    if(!el) return new Template('test');
    var is_textarea = (el.tagName.toLowerCase() == "textarea");
    var v = is_textarea ? el.value : el.innerHTML;
    return new Template(v)
}