vladimir-vg / elk.erl

Erlang implementation of Mustache, logic-less template engine

Build status:

Background

Initially this project was started as walrus improvement, but then I (Gordeev Vladimir) decided to use neotoma. This turned me to start project from scratch.

Features and compatability

elk.erl almost fully responds to mustache specs. It doesn't support custom delimeters ({{=<% %>=}}) and lambdas (as described in specs). Everything other supported as well (including partials, dotted keys {{person.name}} and dot-tag {{.}}).

Using elk.erl you can pass function to evaluate, instead of actual value. But this is not actually "lambdas" as described in specs.

Source =
    "Hello {{name}}\n"
    "You have just won {{value}} dollars!\n"
    "{{#in_ca}}\n"
    "Well, {{taxed_value}} dollars, after taxes.\n"
    "{{/in_ca}}",

{ok, Template} = elk:compile(Source),
Taxed = fun (State) -> elk:get(value, [<<"value">>], State)*0.6 end,
Context = {proplist, [
    {<<"name">>, "Chris"},
    {<<"value">>, 10000},
    {<<"in_ca">>, true},
    {<<"taxed_value">>, Taxed}]},
elk:render(Template, Context).

will output:

Hello Chris
You have just won 10000 dollars!
Well, 6000.0 dollars, after taxes.

Context format

By default you can pass your mappings as proplists ({proplist, YourPropList}). Also you can use other data structures. To do so you should write module that implements specific interface and put module name into config.

For example, if you want use erlang dict datastructure:

-module(elk_dict_context).

-export([get/2]).

get(Key, Dict) ->
    case dict:is_key(Key, Dict) of
        false -> undefined;
        true -> dict:fetch(Key, Dict)
    end.

and put in config:

{elk, [{contexts, [{proplist, elk_proplist_context}, {dict, elk_dict_context}]}]}

Now you can pass dicts as follows: elk:render(Template, {dict, YourDict}).

By default only one datastructure is defined:

{elk, [{contexts, [{proplist, elk_proplist_context}]}]}

Context module get/2 function should return undefined if no value found for given key and value otherwise.

Contribution

I'm (Gordeev Vladimir) not a native english speaker, so very possible I done a lot of grammar and lexical mistakes. Feel free to send a pull-request.

Also, if you think that some context datastructures should be available by default, you also can send a pull-request.

License

See LICENSE.MIT file.

File src/elk_mochinum.erl was taken from mochiweb repository. (Licensed on MIT, same license as for whole project).