Add (guix glob).

* guix/glob.scm, tests/glob.scm: New files.
* Makefile.am (MODULES): Add guix/glob.scm.
(SCM_TESTS): Add tests/glob.scm.

1 files changed, 97 insertions, 0 deletions

diff --git a/guix/glob.scm b/guix/glob.scm
new file mode 100644
index 0000000000..4fc5173ac0
--- /dev/null
+++ b/guix/glob.scm
@@ -0,0 +1,97 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2018 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix glob)
+  #:use-module (ice-9 match)
+  #:export (compile-glob-pattern
+            glob-match?))
+
+;;; Commentary:
+;;;
+;;; This is a minimal implementation of "glob patterns" (info "(libc)
+;;; Globbbing").  It is currently limited to simple patterns and does not
+;;; support braces and square brackets, for instance.
+;;;
+;;; Code:
+
+(define (wildcard-indices str)
+  "Return the list of indices in STR where wildcards can be found."
+  (let loop ((index 0)
+             (result '()))
+    (if (= index (string-length str))
+        (reverse result)
+        (loop (+ 1 index)
+              (case (string-ref str index)
+                ((#\? #\*) (cons index result))
+                (else      result))))))
+
+(define (compile-glob-pattern str)
+  "Return an sexp that represents the compiled form of STR, a glob pattern
+such as \"foo*\" or \"foo??bar\"."
+  (define flatten
+    (match-lambda
+      (((? string? str)) str)
+      (x x)))
+
+  (let loop ((index   0)
+             (indices (wildcard-indices str))
+             (result '()))
+    (match indices
+      (()
+       (flatten (cond ((zero? index)
+                       (list str))
+                      ((= index (string-length str))
+                       (reverse result))
+                      (else
+                       (reverse (cons (string-drop str index)
+                                      result))))))
+      ((wildcard-index . rest)
+       (let ((wildcard (match (string-ref str wildcard-index)
+                         (#\? '?)
+                         (#\* '*))))
+         (match (substring str index wildcard-index)
+           (""  (loop (+ 1 wildcard-index)
+                      rest
+                      (cons wildcard result)))
+           (str (loop (+ 1 wildcard-index)
+                      rest
+                      (cons* wildcard str result)))))))))
+
+(define (glob-match? pattern str)
+  "Return true if STR matches PATTERN, a compiled glob pattern as returned by
+'compile-glob-pattern'."
+  (let loop ((pattern pattern)
+             (str str))
+   (match pattern
+     ((? string? literal) (string=? literal str))
+     (((? string? one))   (string=? one str))
+     (('*)  #t)
+     (('?) (= 1 (string-length str)))
+     (()    #t)
+     (('* suffix . rest)
+      (match (string-contains str suffix)
+        (#f    #f)
+        (index (loop rest
+                     (string-drop str
+                                  (+ index (string-length suffix)))))))
+     (('? . rest)
+      (and (>= (string-length str) 1)
+           (loop rest (string-drop str 1))))
+     ((prefix . rest)
+      (and (string-prefix? prefix str)
+           (loop rest (string-drop str (string-length prefix))))))))