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%%%-------------------------------------------------------------------
%%% @author Eric Merritt <[email protected]>
%%% @copyright 2011 Erlware, LLC.
%%% @doc
%%% A module that supports providing state manipulation services to the system.
%%% @end
%%%-------------------------------------------------------------------
-module(rcl_provider).
%% API
-export([new/2,
do/2,
format_error/1,
format_error/2,
format/1]).
-export_type([t/0]).
-include_lib("relcool/include/relcool.hrl").
%%%===================================================================
%%% Types
%%%===================================================================
-opaque t() :: {?MODULE, module()}.
-callback init(rcl_state:t()) -> {ok, rcl_state:t()} | relcool:error().
-callback do(rcl_state:t()) -> {ok, rcl_state:t()} | relcool:error().
-callback format_error(Reason::term()) -> iolist().
%%%===================================================================
%%% API
%%%===================================================================
%% @doc create a new provider object from the specified module. The
%% module should implement the provider behaviour.
%%
%% @param ModuleName The module name.
%% @param State0 The current state of the system
-spec new(module(), rcl_state:t()) ->
{t(), {ok, rcl_state:t()}} | relcool:error().
new(ModuleName, State0) when is_atom(ModuleName) ->
State1 = ModuleName:init(State0),
case code:which(ModuleName) of
non_existing ->
?RCL_ERROR({non_existing, ModuleName});
_ ->
{{?MODULE, ModuleName}, State1}
end.
%% @doc Manipulate the state of the system, that new state
%%
%% @param Provider the provider object
%% @param State the current state of the system
-spec do(Provider::t(), rcl_state:t()) ->
{ok, rcl_state:t()} | relcool:error().
do({?MODULE, Mod}, State) ->
Mod:do(State).
%% @doc format an error produced from a provider.
-spec format_error(Reason::term()) -> iolist().
format_error({non_existing, ModuleName}) ->
io_lib:format("~p does not exist in the system", [ModuleName]).
%% @doc format an error produced from a provider.
-spec format_error(t(), Reason::term()) -> iolist().
format_error({?MODULE, Mod}, Error) ->
Mod:format_error(Error).
%% @doc print the provider module name
%%
%% @param T - The provider
%% @return An iolist describing the provider
-spec format(t()) -> iolist().
format({?MODULE, Mod}) ->
erlang:atom_to_list(Mod).
|
