scsh-0.6/scsh/filemtch.scm

108 lines
4.6 KiB
Scheme

;;; Code for processing file names with regular expressions.
;;; Copyright (c) 1994 by David Albertz (dalbertz@clark.lcs.mit.edu).
;;; Copyright (c) 1994 by Olin Shivers (shivers@clark.lcs.mit.edu).
;;; This code is freely available for use by anyone for any purpose,
;;; so long as you don't charge money for it, remove this notice, or
;;; hold us liable for any results of its use. --enjoy.
;;; Usage: (file-match root dots? . pattern-list)
;;; root Search starts from here. Usefully "." (cwd)
;;; dots? => if true, dot files will be matched.
;;; if false, dot files will not be matched.
;;; pattern-list := a list of
;;; - strings
;;; These are split at /'s and then
;;; treated as Posix regexp strings.
;;; - regexps (typically made with RX macro)
;;; - predicates
;;; Each member of the list corresponds to one
;;; or more levels in a directory. (A string
;;; with embedded "/" characters corresponds
;;; to multiple levels.)
;;; Example:
;;; (file-match "." #f "foo" "bar" "\\.c$")
;;; means match files that end in ".c"
;;; if they reside in a directory with
;;; a name that contains "bar", which
;;; itself must reside in a directory
;;; with a name that contains "foo".
;;; Here are two more equivalent specs
;;; for the example above:
;;; (file-match "." #f "foo/bar/\\.c$")
;;; (file-match "." #f (rx "foo") (rx "bar")
;;; (rx ".c" eos))
;;; If a member in the list is a predicate,
;;; the predicate must be a procedure of
;;; one argument. This procedure is applied
;;; to the file name being processed. If it
;;; returns true, then the file is considered
;;; a match.
;;; Return: list of matching file names (strings)
;;; The matcher never considers "." or "..".
;;; Subtle point:
;;; If a file-match predicate raises an error condition, it is caught by
;;; FILE-MATCH, and the file under consideration is not matched. This
;;; means that (file-match "." #f file-directory?) doesn't error out
;;; if you happen to run it in a directory containing a dangling symlink
;;; when FILE-DIRECTORY? is applied to the bogus symlink.
(define (file-match root dot-files? . patterns)
(let ((patterns (apply append
(map (lambda (p) (if (string? p)
(map posix-string->regexp (split-pat p))
p))
patterns))))
(let recur ((root root)
(patterns patterns))
(if (pair? patterns)
(let* ((pattern (car patterns))
(patterns (cdr patterns))
(dir (file-name-as-directory root))
(matcher (cond ((regexp? pattern)
(lambda (f) (regexp-search? re f)))
;; This arm makes a file-matcher using
;; predicate PATTERN. If PATTERN signals
;; an error condition while it is being
;; run, our matcher catches it and returns
;; #f.
((procedure? pattern)
(lambda (f)
(call-with-current-continuation
(lambda (abort)
(with-handler (lambda (condition more)
(if (error? condition)
(abort #f)
(more)))
(lambda ()
(pattern (string-append dir f))))))))
(else
(error "Bad file-match pattern" pattern))))
(candidates (maybe-directory-files root dot-files?))
(winners (filter matcher candidates)))
(apply append (map (lambda (fn) (recur (string-append dir fn)
patterns))
winners)))
;; All done
(cons root '())))))
;;; Split the pattern at the /'s. Slashes are assumed to *separate*
;;; subpatterns, not terminate them.
(define (split-pat pat)
(if (procedure? pat) (list pat)
(let lp ((i (string-length pat))
(ans '()))
(cond ((string-index-right pat #\/ i) =>
(lambda (j) (lp j (cons (substring pat (+ j 1) i) ans))))
(else
(cons (substring pat 0 i) ans))))))