Solution to task 1

1 files changed, 118 insertions, 0 deletions

diff --git a/challenge-099/jo-37/perl/ch-1.pl b/challenge-099/jo-37/perl/ch-1.pl
new file mode 100755
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+++ b/challenge-099/jo-37/perl/ch-1.pl
@@ -0,0 +1,118 @@
+#!/usr/bin/perl -s
+
+use v5.20;
+use Test2::V0;
+use experimental 'signatures';
+
+our ($tests, $examples, $verbose);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV == 2;
+usage: $0 [-examples] [-tests] [-verbose] [string pattern]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+-verbose
+    print generated regex
+
+string
+    string to be matched against pattern
+
+pattern
+    shell-like pattern
+
+Use '?' inside pattern to match one arbitrary character, '*' to match
+any number of characters and '\\' to interpret the following single
+character literally.
+
+EOS
+
+
+### Input and Output
+
+say patmatch($ARGV[0], $ARGV[1]) + 0;
+
+
+### Implementation
+
+# Convert pattern part to regex:
+# *  -> .*
+# ?  -> .
+# \x -> x
+# other: quote if necessary
+#
+# Processes $_.
+sub convmeta {
+    return '.*?' if /^\*$/;
+    return '.' if /^\?$/;
+    return quotemeta $1 if /^\\(.)$/;
+    # else:
+    quotemeta;
+}
+
+# Match string against pattern.  Pattern meta characters are:
+# ? : match one character
+# * : match any number of characters
+# \ : use next character literally
+# The special treatment of quoted characters is beyond the specification
+# of this task but it seems to be useful and needful.
+sub patmatch ($str, $pat) {
+
+    # Convert pattern to regex.
+    my $re =  sub {qr/^ @_ $/x}->(
+        map convmeta,
+        $pat =~ m{
+            \G              # start at previous end-of-match position and
+            (               # capture
+                [^*?\\]+    # a group of non-meta chars
+              |             # or    
+                [*?]        # a meta-char
+              |             # or
+                \\.         # a quoted char
+            )
+        }gx);
+    # Reject incomplete patterns.
+    die "invalid pattern: '$'' in '$pat'" if $';
+    
+    say "pattern: '$pat'\nregex:   $re" if $verbose;
+    
+    $str =~ $re;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+        ok patmatch('abcde', 'a*e'), 'example 1';
+        ok !patmatch('abcde', 'a*d'), 'example 2';
+        ok !patmatch('abcde', '?b*d'), 'example 3';
+        ok patmatch('abcde', 'a*c?e'), 'example 4';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+        ok patmatch('ch-1.pl', '*.pl'), 'literal dot matches';
+        ok !patmatch('ch-1-pl', '*.pl'), 'literal dot only matches dot';
+        ok patmatch('abc.*', '*.\*'), 'literal asterisk matches';
+        ok !patmatch('abc.pl', '*.\*'), 'literal asterisk required';
+        ok patmatch('ch-[12].pl', '*-[12].pl'), 'literal charclass matches';
+        ok !patmatch('ch-1.pl', '*-[12].pl'), 'literal charclass required';
+        ok patmatch('ch-1.pl', '*.\p\l'), 'escaped characters';
+        ok patmatch('ab\\cd', '??\\\\??'), 'escaped backslash';
+        ok patmatch('abbccdde', 'a?*?*?e'), 'matching consecutive meta chars';
+        ok !patmatch('abde', 'a?*?*?e'), 'non-matching consecuteive meta chars';
+        ok patmatch('äöü', 'ä?ü'), 'handle multi-byte characters';
+        like dies {patmatch('ab', 'ab\\')}, qr/invalid pattern/,
+            'incomplete quoting sequence';
+	}
+
+    done_testing;
+    exit;
+}