API for Plugins (solves #22)

- includes logging macros and turns them to functions
- exports customized types

src/rebar_api.erl

@@ -0,0 +1,31 @@
+%%% Packages rebar.hrl features and macros into a more generic API
+%%% that can be used by plugin builders.
+-module(rebar_api).
+-include("rebar.hrl").
+-export([abort/0, abort/2,
+         console/2,
+         debug/2, info/2, warn/2, error/2]).
+-export_type([rebar_dict/0, rebar_digraph/0]).
+
+%%%%%%%%%%%%%%%%%%%%%%%
+%%% Error reporting %%%
+%%%%%%%%%%%%%%%%%%%%%%%
+
+%% @doc Interrupts program flow
+abort() -> ?FAIL.
+
+%% @doc like {@link error/2}, except it also raises an
+%% exception to interrupt program flow.
+abort(Str, Args) -> ?ABORT(Str, Args).
+
+%% @doc Prints to the console, including a newline
+console(Str, Args) -> ?CONSOLE(Str, Args).
+
+%% @doc logs with severity `debug'
+debug(Str, Args) -> ?DEBUG(Str, Args).
+%% @doc logs with severity `info'
+info(Str, Args) -> ?INFO(Str, Args).
+%% @doc logs with severity `warn'
+warn(Str, Args) -> ?WARN(Str, Args).
+%% @doc logs with severity `error'
+error(Str, Args) -> ?ERROR(Str, Args).