racket/collects/setup/path-relativize.ss
Matthew Flatt 39cedb62ed v3.99.0.2
svn: r7706
2007-11-13 12:40:00 +00:00

76 lines
3.4 KiB
Scheme

(module path-relativize mzscheme
(provide make-relativize)
(define (make-relativize find-main-dir
tag
to-rel-name
from-rel-name)
;; Historical note: this module is based on the old "plthome.ss"
;; The `path->main-collects-relative' and
;; `main-collects-relative->path' functions are used to store paths
;; that are relative to the main "collects" directory, such as in
;; .dep files. This means that if the plt tree is moved, .dep files
;; still work. It is generally fine if
;; `path->main-collects-relative' misses some usages, as long as it
;; works when we prepare a distribution tree. Otherwise, things
;; will continue to work fine and .dep files will just contain
;; absolute path names. These functions work on .dep elements:
;; either a pathname or a pair with a pathname in its cdr; the
;; `path->main-collects-relative' pathname will itself be a pair.
;; We need to compare paths to find when something is in the plt
;; tree -- this does some basic "normalization" that should work
;; fine: getting rid of `.' and `..', collapsing multiple
;; `/'s to one `/', and converting '/'s to '\'s under Windows.
(define (simplify-path* bytes)
(path->bytes (normal-case-path (simplify-path (bytes->path bytes)))))
(define main-collects-dir/
(delay (let ([dir (find-main-dir)])
(and dir (simplify-path* (path->bytes (path->directory-path dir)))))))
(define (maybe-cdr-op fname f)
(lambda (x)
(cond [(and (pair? x) (not (eq? tag (car x))))
(cons (car x) (f (cdr x)))]
[else (f x)])))
;; path->main-collects-relative* : path-or-bytes -> datum-containing-bytes-or-path
(define (path->main-collects-relative* path)
(let* ([path (cond [(bytes? path) path]
[(path? path) (path->bytes path)]
[else (error 'path->main-collects-relative
"expecting a byte-string, got ~e" path)])]
[path* (simplify-path* path)]
[main-collects-dir/ (force main-collects-dir/)]
[mcd-len (bytes-length main-collects-dir/)])
(cond [(and path*
mcd-len
(> (bytes-length path*) mcd-len)
(equal? (subbytes path* 0 mcd-len)
main-collects-dir/))
(cons tag (subbytes path* mcd-len))]
[(equal? path* main-collects-dir/) (cons tag #"")]
[else path])))
;; main-collects-relative->path* : datum-containing-bytes-or-path -> path
(define (main-collects-relative->path* path)
(cond [(and (pair? path)
(eq? tag (car path))
(bytes? (cdr path)))
(let ([dir (or (find-main-dir)
;; No main "collects"/"doc"/whatever? Use original working directory:
(find-system-path 'orig-dir))])
(if (equal? (cdr path) #"")
dir
(build-path dir (bytes->path (cdr path)))))]
[(bytes? path) (bytes->path path)]
[else path]))
(values
(maybe-cdr-op to-rel-name path->main-collects-relative*)
(maybe-cdr-op from-rel-name main-collects-relative->path*))))