1:- module(file_extras, [
    2    apply_directory_tree/2,     % :Goal, +RootDirectory:atom
    3    fold_directory_tree/4,      % :Goal, +RootDirectory:atom, +State0, -StateFinal
    4    path_to_posix/2             % +Path:atom, -Posix:atom
    5]).

    9:- meta_predicate 
   10    apply_directory_tree(1, +),
   11    fold_directory_tree(3, +, +, -).   12
   13:- multifile
   14    mime:mime_extension/2.   15
   16%%% PUBLIC PREDICATES %%%%%%%%%%%%%%%%%%%%%%%%%%

 apply_directory_tree(:Goal, +RootDirectory:atom) is det

Calls call(Goal, Arg) for each file or sub-directory in the RootDirectory tree, recursively. The scan is the depth-first.

The argument Arg is one of

• directory(Directory, Path) where Directory is name of the directory without the path and Path is path (from RootDirectory) to the directory itself, including the Directory name. If the Goal fails then the complete content of the directory is skipped.
• file(File, Path) where File is name of the file without the path and Path is path (from RootDirectory) to the file itself, including the File name. The success or failure of the Goal is ignored.

   31apply_directory_tree(Goal, Root) :-    
   32    directory_file_path(Parent, Dir, Root),
   33    apply_directory_tree(
   34        [Arg, State, State] >> call(Goal, Arg),
   35        Parent,
   36        [Dir], _, _).

 fold_directory_tree(:Goal, +RootDirectory:atom, +State0, -StateFinal) is det

Calls call(Goal, Arg, StatePrev, StateNext) for each file or sub-directory in the RootDirectory tree, recursively. The scan is the depth-first.

The argument Arg is one of

• directory(Directory, Path) where Directory is name of the directory without the path and Path is path (from RootDirectory) to the directory itself, including the Directory name. If the Goal fails then the complete content of the directory is skipped.
• file(File, Path) where File is name of the file without the path and Path is path (from RootDirectory) to the file itself, including the File name. The success or failure of the Goal is ignored.

  The State0 is initial state and StateFinal is accumulated stated after scanning all directories and files for which the Goal succeeded. Files in directories where Goal failed for the directory level are skipped.

   54fold_directory_tree(Goal, Root, State0, StateFinal) :-    
   55    directory_file_path(Parent, Dir, Root),
   56    apply_directory_tree(Goal, Parent, [Dir], State0, StateFinal).

 path_to_posix(+Path:atom, -Posix:atom) is det

Succeeds if Posix unifies with Path, given that backslashes in Path are replaced by forward slashes in Posix. Utility for windows paths, seems like multiple built-in predicates are sensitive to it.

   62path_to_posix(Path, Posix) :-
   63    atomic_list_concat(Segments, '\\', Path),
   64    atomic_list_concat(Segments, '/', Posix).
   65
   66
   67%%% PRIVATE PREDICATES %%%%%%%%%%%%%%%%%%%%%%%%%
   68
   69apply_directory_tree(_, _, [], State, State) :- !.
   70 apply_directory_tree(Goal, Parent, [Dir| SameLevel], State0, StateFinal) :-    
   71    directory_file_path(Parent, Dir, Path),
   72    exists_directory(Path),
   73    (   call(Goal, directory(Dir, Path), State0, State1)
   74    ->  directory_files(Path, Entries),
   75        exclude([D] >> memberchk(D, ['.','..']), Entries, Entries1),  
   76        !,
   77        apply_directory_tree(Goal, Path, Entries1, State1, State2)
   78    ;   true
   79    ),
   80    !,
   81    apply_directory_tree(Goal, Parent, SameLevel, State2, StateFinal),
   82    !.
   83 apply_directory_tree(Goal, Parent, [File| SameLevel], State0, StateFinal) :-    
   84    directory_file_path(Parent, File, Path),
   85    exists_file(Path),
   86    ignore(call(Goal, file(File, Path), State0, State1)),
   87    apply_directory_tree(Goal, Parent, SameLevel, State1, StateFinal),
   88    !.
   89
   90mime:mime_extension(rtf, 'application/rtf')