From d5bdc79002348178a6376387316505c708b77b06 Mon Sep 17 00:00:00 2001
From: Jan Sucan <jan@jansucan.com>
Date: Sat, 22 Apr 2023 16:25:42 +0200
Subject: ch08: Copy a needed file from the examples

---
 ch08/GlobRegex.hs | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 ch08/GlobRegex.hs

diff --git a/ch08/GlobRegex.hs b/ch08/GlobRegex.hs
new file mode 100644
index 0000000..1b847f4
--- /dev/null
+++ b/ch08/GlobRegex.hs
@@ -0,0 +1,55 @@
+{-- snippet type --}
+module GlobRegex
+    (
+      globToRegex
+    , matchesGlob
+    ) where
+
+import Text.Regex.Posix ((=~))
+
+globToRegex :: String -> String
+{-- /snippet type --}
+
+{-- snippet rooted --}
+globToRegex cs = '^' : globToRegex' cs ++ "$"
+{-- /snippet rooted --}
+
+{-- snippet asterisk --}
+globToRegex' :: String -> String
+globToRegex' "" = ""
+
+globToRegex' ('*':cs) = ".*" ++ globToRegex' cs
+
+globToRegex' ('?':cs) = '.' : globToRegex' cs
+
+globToRegex' ('[':'!':c:cs) = "[^" ++ c : charClass cs
+globToRegex' ('[':c:cs)     = '['  :  c : charClass cs
+globToRegex' ('[':_)        = error "unterminated character class"
+
+globToRegex' (c:cs) = escape c ++ globToRegex' cs
+{-- /snippet asterisk --}
+
+{-
+{-- snippet last --}
+globToRegex' (c:cs) = escape c ++ globToRegex' cs
+{-- /snippet last --}
+-}
+
+{-- snippet escape --}
+escape :: Char -> String
+escape c | c `elem` regexChars = '\\' : [c]
+         | otherwise = [c]
+    where regexChars = "\\+()^$.{}]|"
+{-- /snippet escape --}
+
+{-- snippet charClass --}
+charClass :: String -> String
+charClass (']':cs) = ']' : globToRegex' cs
+charClass (c:cs)   = c : charClass cs
+charClass []       = error "unterminated character class"
+{-- /snippet charClass --}
+
+{-- snippet matchesGlob --}
+matchesGlob :: FilePath -> String -> Bool
+name `matchesGlob` pat = name =~ globToRegex pat
+{-- /snippet matchesGlob --}
-- 
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