The structure DIR-STREAMS defines procedures to represent and process
directories as streams of files and sub-directories. Using a lazy data
structure to represent directories allows the library to minimize
access to the file system. Files within streams are represented by the
data type FS-OBJECT which essentially extends scsh's FILE-INFO type by
a field for the file name.

In addition the structure STREAM provides a library for stream
processing but we intend to replace this library with SRFI-40
soon. This is also the reason for the lack of documentation for the
STREAM package.

================================================================================

After installation, use the switch

-lel dir-streams/load.scm

to load this library.

================================================================================

(dir-stream-from-dir-name dir-name [chase?] [parent]) -> dir-stream

Constructor for dir-streams. The CHASE? option indicates whether
symbolic links should be followed or not and defaults to #t. PARENT is
the directory relative to which DIR-NAME should be interpreted. It
defaults to "" and is only mildly useful.


(dir-stream? thing) -> boolean

Type predicate for dir-streams.


(dir-stream-info dir-stream) -> fs-object

Returns the fs-object corresponding to the directory.


(fs-object? thing) -> boolean

Type predicate for file-objects.


(fs-object-parent fs-object) -> string

The parent directory of the fs-object.



(fs-object-name fs-object) -> string

The file name of FS-OBJECT.



(fs-object-info fs-object) -> file-info

The file-info record of FS-OBJECT.



(fs-object-file-name fs-object) -> string

The path of FS-OBJECT.



(dir-stream-files-stream dir-stream) -> fs-object stream

A stream of the fs-objects of the files within the directory
represented by DIR-STREAM.



(dir-stream-subdir-stream dir-stream) -> dir-stream stream 

A stream of dir-streams of the subdirectories within the directory
represented by DIR-STREAM.


(dir-stream-filter dir-stream file-pred dir-pred) -> dir-stream

Applies the predicate DIR-PRED to all the subdirectories and FILE-PRED
to all the files within directory. The returned stream contains only
the files and subdirectories for which the predicates return #t.


(dir-stream-fold-right ds make-dir-stream
		       files-make-stream files-stream-empty 
		       subdirs-make-stream subdirs-empty) -> return type of make-dir-stream

Replaces the constructors of the dir-stream by the supplied procedures.
Example:
(define (disc-usage ds)
  (dir-stream-fold-right ds (lambda (fso sum subdirs) (list (fs-object-filename fso)
							    (apply + sum (map cadr subdirs))
							    subdirs))
			 (lambda (fso accu)
			   (+ accu (file-info:size (fs-object-info fso))))
			 0
			 cons
			 '()))


(dir-stream-map dir-stream file-f dir-f) -> dir-stream

Applies FILE-F to all files in DIR-STREAM and DIR-F to all directories
in DIR-STREAM and returns the resulting dir-stream.


(dir-stream-filter-map dir-stream file-f dir-f) -> dir-stream

Applies FILE-F to all files in DIR-STREAM and DIR-F to all directories
in DIR-STREAM and returns the dir-stream containing all the non-false
results of FILE-F and DIR-F.


(dir-stream-for-each dir-stream file-f dir-f) -> unspecific

Applies FILE-F to all files in DIR-STREAM and DIR-F to all directories
in DIR-STREAM.




The structure DIR-STREAM-PREDICATES defines some predicates the user
might find useful when programming with dir-streams. 

(fs-object-size-less-than? fs-object size) -> {#t, #f}
(fs-object-size-greater-than? fs-object size) -> {#t, #f}

Check whether the lenght of the file represented by FS-OBJECT is
less/more than SIZE bytes.



(days->seconds days) -> integer
(hours->seconds hours) -> integer
(minutes->seconds minutes) -> integer

Auxiliary functions for converting an integer representing a count of
days/hours/minutes to an integer representing that amount of time in
seconds.



(fs-object-last-modified-in? fs-object pair) -> {#t, #f}
(fs-object-last-accessed-in? fs-object pair) -> {#t, #f}
(fs-object-created-in? fs-object pair) -> {#t, #f}

PAIR is a pair representing an interval of time. These functions check
whether the date when then file represented by FS-OBJECT was last
modified/last-accessed/created lies in this interval (includes left
and right boundary of the interval).



(fs-object-name-matches? fs-object regexp) -> {#t, #f}

Returns #t if REGEXP-SEARCH? for regexp matches the filename of the
file represented by FS-OBJECT.



(ds-object-file-name-matches? fs-object regexp) -> {#t, #f}

Returns #t if REGEXP-SEARCH? for regexp matches the filename
(including the absolute path) of the file represented by FS-OBJECT.