racket/collects/htdp/dir.rkt
2010-04-27 16:50:15 -06:00

79 lines
2.3 KiB
Racket

#lang scheme
(require htdp/error
lang/prim
(only-in scheme/base [file-size s:file-size]))
(provide
create-dir ; path -> Directory
; structure
dir?
make-dir
dir-name
dir-dirs
dir-files
; structure
file? make-file file-name file-content file-size
)
;; Structures:
(define-struct dir (name dirs files) #:transparent)
(define-struct file (name size content) #:transparent)
(define-primitive create-dir create-dir/proc)
;; Data:
;; Directory = (make-dir Symbol (listof Dir) (listof File))
;; File = (make-file Symbol Number (union '() X))
(define (create-dir/proc a-path)
(check-arg 'create-dir (string? a-path) "string" "first" a-path)
(let ([a-path! (string->path a-path)])
(if (directory-exists? a-path!)
(car (explore (list a-path!)))
(error 'create-dir "not a directory: ~e" a-path))))
;; explore : (listof String[directory-names]) -> (listof Directory)
(define (explore dirs)
(map (lambda (d)
(let-values ([(fs ds) (pushd d directory-files&directories)])
(make-dir
(string->symbol (path->string (my-split-path d)))
(explore (map (lambda (x) (build-path d x)) ds))
(map make-file
(map (compose string->symbol path->string) fs)
(map (lambda (x) (if (file-exists? x) (s:file-size x) 0))
(map (lambda (x) (build-path d x)) fs))
(map (lambda (x) (if (link-exists? x) 'link null)) fs)))))
dirs))
;; String -> String
(define (my-split-path d)
(let-values ([(base name mbd?) (split-path d)])
(if (string? base) name d)))
;; pushd : String[directory-name] (-> X) -> X
(define (pushd d f)
(parameterize ([current-directory d])
(f)))
;; directory-files&directories :
;; (-> (values (listof String[file-names]) (listof String[directory-names])))
(define (directory-files&directories)
(let ((contents (directory-list)))
(values
(filter (lambda (x) (or (file-exists? x) (link-exists? x))) contents)
(filter (lambda (x) (and (directory-exists? x) (not (link-exists? x))))
contents))))
;; get-file-content : file -> (int -> string)
;; to read a file on demand as a string
;; option to expand the library ...
;; cache it ...
(define (get-file-content f)
(read-string (file-size f)
(open-input-file (symbol->string (file-name f)))))