diff prolog/library/fileutils.pl @ 0:b12b733d1dd0

Initial check-in.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/prolog/library/fileutils.pl	Sun Mar 23 16:05:36 2014 +0000
@@ -0,0 +1,199 @@
+:- module(fileutils, [
+		with_file/2,
+		with_stream/3,
+		read_lines/2,
+		with_output_to_file/2,
+		with_output_to_file/3,
+		with_input_from_file/2,
+		with_input_from_file/3,
+		write_file_with/3,
+		write_file_with/4,
+		with_input_from/2,
+		find_file/3,
+		match_file/2,
+		file_under/4
+	]).
+
+:- meta_predicate 
+		with_output_to_file(?,0), 
+		with_output_to_file(?,0,+), 
+		with_input_from_file(?,0),
+		with_input_from_file(?,0,+),
+		write_file_with(?,?,0),
+		write_file_with(?,?,0,?),
+		with_input_from(+,0), 
+		with_stream(0,?,0), 
+		with_file(?,0). 
+
+
+%% with_stream( :Opener, -Stream, :Goal) is semidet.
+%
+%  Base predicate for doing things with stream. Opener is a goal which must
+%  prepare the stream, Stream is the variable which will hold the valid
+%  stream handle, and Goal is called with the stream open. The stream is
+%  guaranteed to be closed on exit. Stream will remain unbound on exit.
+%  NB: the idea is that Opener and Goal share the Stream variable, eg:
+%  ==
+%  with_stream( open('out.txt',write,S), S, writeln(S,'Hello!')).
+%  with_stream( open('in.txt',read,S), S, read(S,T)).
+%  ==
+with_stream(Opener,Stream,Goal) :- 
+   copy_term(t(Opener,Stream,Goal),t(O,S,G)),
+	setup_call_cleanup(O,G,close(S)).
+
+
+%% with_file( :Opener, :Goal) is semidet.
+%
+%  Call Goal with an open file as specified by Opener, which can be
+%    * open( +Filename, +Mode, @Stream)
+%    * open( +Filename, +Mode, +Options, @Stream)
+%  Opener is used to call open/3 or open/4. 
+%
+%  @deprecated Use with_stream/3 instead.
+with_file(open(File,Mode,Stream),Goal) :-
+	with_stream(open(File,Mode,Stream),Stream,Goal).
+
+with_file(open(File,Mode,Stream,Options),Goal) :-
+	with_stream(open(File,Mode,Stream,Options), Stream, Goal).
+
+%% with_output_to_file( +File, :Goal) is semidet.
+%% with_output_to_file( +File, :Goal, +Opts) is semidet.
+%
+%  Call Goal redirecting output to the file File, which is opened as with
+%  open(File,write,Str) or open(File,write,Opts,Str).
+%  However, if the option mode(Mode) is present, it is removed from the
+%  list (leaving Opts1) and the file is opened as with open(File,Mode,Opts1,Str).
+%  The default mode is write.
+with_output_to_file(File,Goal) :- with_output_to_file(File,Goal,[]).
+with_output_to_file(File,Goal,Opts) :- write_file_with(File,S,with_output_to(S,Goal),Opts).
+
+
+%% with_input_from_file( +File, :Goal) is semidet.
+%% with_input_from_file( +File, :Goal, +Opts) is semidet.
+%
+%  Call Goal redirecting output to the file File, which is opened as with
+%  open(File,write,Str) or open(File,write,Opts,Str).
+with_input_from_file(File,Goal) :- with_input_from_file(File,Goal,[]).
+with_input_from_file(File,Goal,Opts) :- 
+	with_stream( open(File,read,S,Opts), S, with_input_from(S,Goal)).
+
+%% with_input_from( +Source, :Goal) is semidet.
+%
+%  Temporarily switch current input to object specified by Source while calling Goal as in once/1.
+%  Source is a term like that supplied to with_output_to/2 and can be any of:
+%  	* A stream handle or alias.
+%  	* atom(+Atom) 
+%  	* codes(+Codes)
+%  	* chars(+Chars)
+%  	* string(+String)
+
+with_input_from(atom(A),G) :- !,
+	setup_call_cleanup(
+		atom_to_memory_file(A,MF),
+		setup_call_cleanup(
+			open_memory_file( MF, read, S),
+			with_input_from(S,G),
+			close(S)
+		),
+		free_memory_file(MF)
+	).
+
+with_input_from(codes(Codes),G) :- !, atom_codes(Atom,Codes), with_input_from(atom(Atom),G).
+with_input_from(chars(Chars),G) :- !, atom_chars(Atom,Chars), with_input_from(atom(Atom),G).
+with_input_from(string(Str),G)  :- !, string_to_atom(Str,Atom), with_input_from(atom(Atom),G).
+
+with_input_from(S,G) :- is_stream(S), !,
+	current_input(S0),
+	setup_call_cleanup(set_input(S),once(G),set_input(S0)).
+
+
+%% write_file_with( +File, @Stream, :Goal, +Options:list) is semidet.
+%% write_file_with( +File, @Stream, :Goal) is semidet.
+%
+%  Call Goal after opening the named file and unifying Stream with a
+%  valid stream. The file is guaranteed to be closed and Stream unbound
+%  on exit. Any options are pased to open/4, except for mode(Mode),
+%  which defaults to write and determines whether the file is opened
+%  in write or append mode.
+
+write_file_with(File,Stream,Goal) :- write_file_with(File,Stream,Goal,[]).
+write_file_with(File,Stream,Goal,Options) :-
+	select_option(mode(Mode),Options,Options1,write),
+	must_be(oneof([write,append]),Mode),
+	with_stream(
+		open(File,Mode,Stream,Options1),
+		Stream,
+		Goal
+	).
+
+
+%% read_lines( +Stream, -Lines:list(list(integer))) is semidet.
+%
+%  Read all lines from Stream and return a list of lists of character codes.
+read_lines(Stream,Lines) :-
+	read_line_to_codes(Stream,Line),
+	(	Line=end_of_file
+	-> Lines=[]
+	;	Lines=[Line|Lines1],
+		read_lines(Stream,Lines1)).
+
+
+%% match_file(+Spec,-File) is nondet.
+%
+%  Unify File with a filename that matches given spec. Yields
+%  alternative matches on backtracking. Can give relative as
+%  well as absolute paths.
+match_file(Spec,File) :-
+	expand_file_search_path(Spec,Path), 
+	expand_file_name(Path,Files), 
+	member(File,Files).
+
+
+%% file_under( +Root, +Pattern, -File, -Path) is nondet.
+%
+%  Enumerate all files under directory root whose names match Pattern.
+%  Root can be a unary term as understood by expand_file_search_path/2.
+%  On exit, File is the fully qualified path to the file and path is
+%  a list of directory names represented as atoms.
+%  Returns absolute file paths only.
+
+file_under(RootSpec,Pattern,File,Path) :- 
+	expand_file_search_path(RootSpec,Root),
+	file_under(Root,Pattern,File,Path,[]).
+
+file_under(Root,Pattern,File) --> {file_in(Root,Pattern,File)}.
+file_under(Root,Pattern,File) --> 
+	{ directory_in(Root,Full,Rel) }, [Rel],
+	file_under(Full,Pattern,File).
+
+file_in(Root,Pattern,File) :-
+	atomic_list_concat([Root,Pattern],'/',Spec),
+	absolute_file_name(Spec,[expand(true),solutions(all)],File).
+
+directory_in(Root,Dir,DirName) :-
+	atom_concat(Root,'/*',Spec),
+	absolute_file_name(Spec,[file_type(directory),expand(true),solutions(all)],Dir),
+	file_base_name(Dir,DirName).
+
+
+%% find_file( +FileSpec, +Extensions:list(atom), -File:atom) is nondet.
+%
+%  Looks for files matching FileSpec ending with one of the given extensions.
+%  FileSpec is initially passed to expand_file_search_path/2 and so can be a unary term.
+%  The resulting atom can include wildcards ('*', '?', '{..}'), environment 
+%  variables ('$var') and an optional leading '~' which is equivalent to '$HOME'. 
+%  (See expand_file_name/2). This predicate succeeds once for
+%  each readable file matching FileSpec and ending with one of the extensions
+%  in Extensions. NB. no dot is prepended to extensions: if you need '*.blah' then
+%  put '.blah' in Extensions.
+%  Returns ABSOLUTE file paths.
+
+find_file(Spec,Exts,File) :-
+	match_file(Spec,Path),
+	match_extension(Path,Exts),
+	absolute_file_name(Path,[access(read)],File).
+
+match_extension(Path,Exts) :-
+	downcase_atom(Path,PathLower), member(Ext,Exts), 
+	atom_concat(_,Ext,PathLower).
+