Merge pull request #800 from talentdeficit/extract_path_utils

extract `retarget_path/2', `relative_path/2' and `reduce_path/1' and add tests

2 files changed, 56 insertions, 2 deletions

diff --git a/src/rebar_dir.erl b/src/rebar_dir.erl
index 7220d89..364e197 100644
--- a/src/rebar_dir.erl
+++ b/src/rebar_dir.erl
@@ -23,7 +23,8 @@
          make_relative_path/2,
          src_dirs/1, src_dirs/2,
          extra_src_dirs/1, extra_src_dirs/2,
-         all_src_dirs/1, all_src_dirs/3]).
+         all_src_dirs/1, all_src_dirs/3,
+         retarget_path/2]).
 
 -include("rebar.hrl").
 
@@ -160,3 +161,29 @@ all_src_dirs(Opts) -> all_src_dirs(Opts, [], []).
     list(file:filename_all()).
 all_src_dirs(Opts, SrcDefault, ExtraDefault) ->
     src_dirs(Opts, SrcDefault) ++ extra_src_dirs(Opts, ExtraDefault).
+
+%% given a path if that path is an ancestor of an app dir return the path relative to that
+%% apps outdir. if the path is not an ancestor to any app dirs but is an ancestor of the
+%% project root return the path relative to the project base_dir. if it is not an ancestor
+%% of either return it unmodified
+-spec retarget_path(rebar_state:t(), string()) -> string().
+
+retarget_path(State, Path) ->
+    ProjectApps = rebar_state:project_apps(State),
+    retarget_path(State, Path, ProjectApps).
+
+%% not relative to any apps in project, check to see it's relative to
+%% project root
+retarget_path(State, Path, []) ->
+    case rebar_file_utils:path_from_ancestor(rebar_file_utils:canonical_path(Path), rebar_state:dir(State)) of
+        {ok, NewPath}      -> filename:join([base_dir(State), NewPath]);
+        %% not relative to project root, don't modify
+        {error, badparent} -> Path
+    end;
+%% relative to current app, retarget to the same dir relative to
+%% the app's out_dir
+retarget_path(State, Path, [App|Rest]) ->
+    case rebar_file_utils:path_from_ancestor(rebar_file_utils:canonical_path(Path), rebar_app_info:dir(App)) of
+        {ok, NewPath}      -> filename:join([rebar_app_info:out_dir(App), NewPath]);
+        {error, badparent} -> retarget_path(State, Path, Rest)
+    end.
diff --git a/src/rebar_file_utils.erl b/src/rebar_file_utils.erl
index 732d83f..ea1a6a2 100644
--- a/src/rebar_file_utils.erl
+++ b/src/rebar_file_utils.erl
@@ -37,7 +37,9 @@
          system_tmpdir/0,
          system_tmpdir/1,
          reset_dir/1,
-         touch/1]).
+         touch/1,
+         path_from_ancestor/2,
+         canonical_path/1]).
 
 -include("rebar.hrl").
 
@@ -244,6 +246,31 @@ touch(Path) ->
     ok = file:write_file_info(Path, A#file_info{mtime = calendar:local_time(),
                                                 atime = calendar:local_time()}).
 
+%% for a given path return the path relative to a base directory
+-spec path_from_ancestor(string(), string()) -> {ok, string()} | {error, badparent}.
+
+path_from_ancestor(Target, To) ->
+    path_from_ancestor_(filename:split(canonical_path(Target)),
+                        filename:split(canonical_path(To))).
+
+path_from_ancestor_([Part|Target], [Part|To]) -> path_from_ancestor_(Target, To);
+path_from_ancestor_([], [])                   -> {ok, ""};
+path_from_ancestor_(Target, [])               -> {ok, filename:join(Target)};
+path_from_ancestor_(_, _)                     -> {error, badparent}.
+
+
+%% reduce a filepath by removing all incidences of `.' and `..'
+-spec canonical_path(string()) -> string().
+
+canonical_path(Dir) -> canonical_path([], filename:split(filename:absname(Dir))).
+
+canonical_path([], [])                -> filename:nativename("/");
+canonical_path(Acc, [])               -> filename:join(lists:reverse(Acc));
+canonical_path(Acc, ["."|Rest])       -> canonical_path(Acc, Rest);
+canonical_path([_|Acc], [".."|Rest])  -> canonical_path(Acc, Rest);
+canonical_path([], [".."|Rest])       -> canonical_path([], Rest);
+canonical_path(Acc, [Component|Rest]) -> canonical_path([Component|Acc], Rest).
+
 %% ===================================================================
 %% Internal functions
 %% ===================================================================