226 lines
8.2 KiB
Scheme
226 lines
8.2 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2013 Andreas Enge <andreas@enge.fr>
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;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
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;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (guix shell-utils)
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#:use-module (ice-9 match)
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#:use-module (ice-9 rdelim)
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#:use-module (ice-9 regex)
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#:use-module (srfi srfi-1)
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#:use-module (rnrs bytevectors)
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#:use-module (rnrs io ports)
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#:export (dump-port
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mkdir-p
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with-directory-excursion
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substitute
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substitute*))
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;;;
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;;; Directories.
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;;;
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(define (mkdir-p dir)
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"Create directory DIR and all its ancestors."
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(define absolute?
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(string-prefix? "/" dir))
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(define not-slash
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(char-set-complement (char-set #\/)))
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(let loop ((components (string-tokenize dir not-slash))
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(root (if absolute?
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""
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".")))
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(match components
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((head tail ...)
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(let ((path (string-append root "/" head)))
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(catch 'system-error
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(lambda ()
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(mkdir path)
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(loop tail path))
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(lambda args
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(if (= EEXIST (system-error-errno args))
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(loop tail path)
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(apply throw args))))))
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(() #t))))
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(define-syntax-rule (with-directory-excursion dir body ...)
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"Run BODY with DIR as the process's current directory."
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(let ((init (getcwd)))
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(dynamic-wind
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(lambda ()
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(chdir dir))
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(lambda ()
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body ...)
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(lambda ()
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(chdir init)))))
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(define* (dump-port in out
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#:key (buffer-size 16384)
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(progress (lambda (t k) (k))))
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"Read as much data as possible from IN and write it to OUT, using chunks of
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BUFFER-SIZE bytes. Call PROGRESS at the beginning and after each successful
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transfer of BUFFER-SIZE bytes or less, passing it the total number of bytes
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transferred and the continuation of the transfer as a thunk."
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(define buffer
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(make-bytevector buffer-size))
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(define (loop total bytes)
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(or (eof-object? bytes)
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(let ((total (+ total bytes)))
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(put-bytevector out buffer 0 bytes)
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(progress total
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(lambda ()
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(loop total
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(get-bytevector-n! in buffer 0 buffer-size)))))))
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;; Make sure PROGRESS is called when we start so that it can measure
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;; throughput.
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(progress 0
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(lambda ()
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(loop 0 (get-bytevector-n! in buffer 0 buffer-size)))))
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;;;
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;;; Text substitution (aka. sed).
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;;;
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(define (with-atomic-file-replacement file proc)
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"Call PROC with two arguments: an input port for FILE, and an output
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port for the file that is going to replace FILE. Upon success, FILE is
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atomically replaced by what has been written to the output port, and
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PROC's result is returned."
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(let* ((template (string-append file ".XXXXXX"))
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(out (mkstemp! template))
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(mode (stat:mode (stat file))))
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(with-throw-handler #t
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(lambda ()
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(call-with-input-file file
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(lambda (in)
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(let ((result (proc in out)))
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(close out)
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(chmod template mode)
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(rename-file template file)
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result))))
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(lambda (key . args)
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(false-if-exception (delete-file template))))))
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(define (substitute file pattern+procs)
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"PATTERN+PROCS is a list of regexp/two-argument-procedure pairs. For each
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line of FILE, and for each PATTERN that it matches, call the corresponding
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PROC as (PROC LINE MATCHES); PROC must return the line that will be written as
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a substitution of the original line. Be careful about using '$' to match the
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end of a line; by itself it won't match the terminating newline of a line."
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(let ((rx+proc (map (match-lambda
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(((? regexp? pattern) . proc)
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(cons pattern proc))
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((pattern . proc)
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(cons (make-regexp pattern regexp/extended)
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proc)))
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pattern+procs)))
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(with-atomic-file-replacement file
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(lambda (in out)
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(let loop ((line (read-line in 'concat)))
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(if (eof-object? line)
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#t
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(let ((line (fold (lambda (r+p line)
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(match r+p
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((regexp . proc)
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(match (list-matches regexp line)
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((and m+ (_ _ ...))
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(proc line m+))
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(_ line)))))
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line
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rx+proc)))
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(display line out)
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(loop (read-line in 'concat)))))))))
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(define-syntax let-matches
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;; Helper macro for `substitute*'.
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(syntax-rules (_)
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((let-matches index match (_ vars ...) body ...)
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(let-matches (+ 1 index) match (vars ...)
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body ...))
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((let-matches index match (var vars ...) body ...)
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(let ((var (match:substring match index)))
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(let-matches (+ 1 index) match (vars ...)
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body ...)))
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((let-matches index match () body ...)
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(begin body ...))))
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(define-syntax substitute*
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(syntax-rules ()
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"Substitute REGEXP in FILE by the string returned by BODY. BODY is
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evaluated with each MATCH-VAR bound to the corresponding positional regexp
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sub-expression. For example:
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(substitute* file
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((\"hello\")
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\"good morning\\n\")
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((\"foo([a-z]+)bar(.*)$\" all letters end)
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(string-append \"baz\" letter end)))
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Here, anytime a line of FILE contains \"hello\", it is replaced by \"good
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morning\". Anytime a line of FILE matches the second regexp, ALL is bound to
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the complete match, LETTERS is bound to the first sub-expression, and END is
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bound to the last one.
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When one of the MATCH-VAR is `_', no variable is bound to the corresponding
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match substring.
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Alternatively, FILE may be a list of file names, in which case they are
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all subject to the substitutions.
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Be careful about using '$' to match the end of a line; by itself it won't
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match the terminating newline of a line."
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((substitute* file ((regexp match-var ...) body ...) ...)
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(let ()
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(define (substitute-one-file file-name)
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(substitute
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file-name
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(list (cons regexp
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(lambda (l m+)
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;; Iterate over matches M+ and return the
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;; modified line based on L.
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(let loop ((m* m+) ; matches
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(o 0) ; offset in L
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(r '())) ; result
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(match m*
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(()
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(let ((r (cons (substring l o) r)))
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(string-concatenate-reverse r)))
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((m . rest)
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(let-matches 0 m (match-var ...)
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(loop rest
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(match:end m)
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(cons*
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(begin body ...)
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(substring l o (match:start m))
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r))))))))
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...)))
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(match file
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((files (... ...))
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(for-each substitute-one-file files))
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((? string? f)
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(substitute-one-file f)))))))
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