Add a state display provider

The provider is used for debugging to help displaying current rebar's state.

Usage:
  rebar3 state

6 files changed, 62 insertions, 4 deletions

diff --git a/README.md b/README.md
index cddb843..873a990 100644
--- a/README.md
+++ b/README.md
@@ -42,6 +42,7 @@ locations ([hex.pm](http://hex.pm), git, hg, and so on).
 | relup      | Creates relup from 2 releases |
 | report     | Report on environment and versions for bug reports |
 | shell      | Run shell with project apps in path |
+| state      | Display configuration state |
 | tar        | Package release into tarball |
 | tree       | Print dependency tree |
 | unlock     | Unlock dependencies |
diff --git a/src/rebar.app.src b/src/rebar.app.src
index 58fee02..bd0f871 100644
--- a/src/rebar.app.src
+++ b/src/rebar.app.src
@@ -66,6 +66,7 @@
                      rebar_prv_relup,
                      rebar_prv_report,
                      rebar_prv_shell,
+                     rebar_prv_state,
                      rebar_prv_tar,
                      rebar_prv_unlock,
                      rebar_prv_update,
diff --git a/src/rebar3.erl b/src/rebar3.erl
index 9106bb8..01d3d7f 100644
--- a/src/rebar3.erl
+++ b/src/rebar3.erl
@@ -247,10 +247,11 @@ set_global_flag(State, Options, Flag) ->
 %%
 global_option_spec_list() ->
     [
-    %% {Name, ShortOpt, LongOpt, ArgSpec, HelpMsg}
-    {help,     $h, "help",     undefined, "Print this help."},
-    {version,  $v, "version",  undefined, "Show version information."},
-    {task,     undefined, undefined, string, "Task to run."}
+    %% {Name,  ShortOpt,  LongOpt,    ArgSpec,   HelpMsg}
+    {help,     $h,        "help",     undefined, "Print this help."},
+    {version,  $v,        "version",  undefined, "Show version information."},
+    {task,     undefined, undefined,  string,    "Task to run."},
+    {state,    undefined, "state",    undefined, "Display configuration state"}
     ].
 
 handle_error(rebar_abort) ->
diff --git a/src/rebar_hooks.erl b/src/rebar_hooks.erl
index 4e6d486..a5ab048 100644
--- a/src/rebar_hooks.erl
+++ b/src/rebar_hooks.erl
@@ -81,6 +81,7 @@ run_hooks(Dir, post, Command, Opts, State) ->
 run_hooks(Dir, Type, Command, Opts, State) ->
     case rebar_opts:get(Opts, Type, []) of
         [] ->
+            ?DEBUG("run_hooks(~p, ~p, ~p) -> no hooks defined\n", [Dir, Type, Command]),
             ok;
         Hooks ->
             Env = create_env(State, Opts),
diff --git a/src/rebar_prv_state.erl b/src/rebar_prv_state.erl
new file mode 100644
index 0000000..0e2ca21
--- /dev/null
+++ b/src/rebar_prv_state.erl
@@ -0,0 +1,44 @@
+%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
+%% ex: ts=4 sw=4 et
+
+-module(rebar_prv_state).
+
+-behaviour(provider).
+
+-export([init/1,
+         do/1,
+         format_error/1]).
+
+-include("rebar.hrl").
+
+-define(PROVIDER, state).
+-define(DEPS, []).
+
+%% ===================================================================
+%% Public API
+%% ===================================================================
+
+-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
+init(State) ->
+    Provider = providers:create(
+        [{name, ?PROVIDER},
+         {module, ?MODULE},
+         {bare, true},
+         {deps, ?DEPS},
+         {example, "rebar3 state"},
+         {short_desc, "Print current configuration state"},
+         {desc, "Display rebar configuration for debugging purpose"},
+         {opts, []}]),
+    State1 = rebar_state:add_provider(State, Provider),
+    {ok, State1}.
+
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
+do(State) ->
+    L = rebar_state:to_list(State),
+    io:put_chars("State:\n"),
+    [io:format("  ~w: ~p\n", [K, V]) || {K,V} <- L],
+    {ok, State}.
+
+-spec format_error(any()) -> iolist().
+format_error(Reason) ->
+    io_lib:format("~p", [Reason]).
diff --git a/src/rebar_state.erl b/src/rebar_state.erl
index 0c07b2a..a97eca5 100644
--- a/src/rebar_state.erl
+++ b/src/rebar_state.erl
@@ -36,6 +36,7 @@
 
          deps_names/1,
 
+         to_list/1,
 
          resources/1, resources/2, add_resource/2,
          providers/1, providers/2, add_provider/2]).
@@ -406,6 +407,15 @@ create_logic_providers(ProviderModules, State0) ->
             throw({error, "Failed creating providers. Run with DEBUG=1 for stacktrace."})
     end.
 
+to_list(#state_t{opts=O, code_paths=CP, default=D} = State) ->
+    O1     = dict:to_list(O),
+    CP1    = dict:to_list(CP),
+    D1     = dict:to_list(D),
+    State1 = State#state_t{opts=O1, code_paths=CP1, default=D1},
+    Fields = record_info(fields, state_t),
+    Values = tl(tuple_to_list(State1)),
+    lists:zip(Fields, Values).
+
 %% ===================================================================
 %% Internal functions
 %% ===================================================================