AWK solution for week 99, part 2

1 files changed, 53 insertions, 0 deletions

diff --git a/challenge-099/abigail/awk/ch-2.awk b/challenge-099/abigail/awk/ch-2.awk
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+++ b/challenge-099/abigail/awk/ch-2.awk
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+#!/usr/bin/awk
+
+#
+# See ../README.md
+#
+
+#
+# Run as: awk -f ch-2.awk < input-file
+#
+
+#
+# Read input from standard input, assuming one exercise per line.
+# Each line consists of a string $S, and a pattern $T, separated
+# by whitespace.
+#
+
+#
+# Recursively count matches:
+#   - If either the string or the pattern is empty, there are no matches.
+#   - Else, + count the matches if we don't match at the first character
+#             if the string.
+#           + if the first character of the string equals the first
+#             character of the pattern:
+#             o  add 1 if the pattern is just one character long
+#             o  else, add the number of matches starting from the
+#                then next character in the string, and the next
+#                character in the pattern.
+#
+
+#
+# Note that we do not have lexical variables in AWK, so we're
+# using a global count variable.
+#
+function matches (string, pattern) {
+    if (length (string) == 0 || length (pattern) == 0) {
+        return 0
+    }
+    matches(substr (string, 2), pattern)
+    if (substr (string, 1, 1) == substr (pattern, 1, 1)) {
+        if (length (pattern) == 1) {
+            count ++
+        }
+        else {
+            matches(substr (string, 2), substr (pattern, 2))
+        }
+    }
+}
+
+{
+    count = 0
+    matches($1, $2)
+    print count
+}