8 files changed, 111 insertions, 0 deletions
diff --git a/tests/bkpregex/Setup.hs b/tests/bkpregex/Setup.hs
new file mode 100644
index 0000000..9a994af
--- /dev/null
+++ b/tests/bkpregex/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/tests/bkpregex/bkpregex.cabal b/tests/bkpregex/bkpregex.cabal
new file mode 100644
index 0000000..678ddbb
--- /dev/null
+++ b/tests/bkpregex/bkpregex.cabal
@@ -0,0 +1,29 @@
+name:                bkpregex
+version:             0.1.0.0
+build-type:          Simple
+cabal-version:       >=2.0
+
+library str-impls
+  build-depends:       base, bytestring
+  exposed-modules:     Str.String, Str.ByteString
+  hs-source-dirs:      str-impls
+
+library regex-types
+  build-depends:       base
+  exposed-modules:     Regex.Types
+  hs-source-dirs:      regex-types
+
+library regex-indef
+  build-depends:       base, regex-types
+  signatures:          Str
+  exposed-modules:     Regex
+  hs-source-dirs:      regex-indef
+
+executable regex-example
+  main-is:             Main.hs
+  build-depends:       base, regex-indef, regex-types, str-impls
+  mixins:              regex-indef (Regex as Regex.String)
+                          requires (Str as Str.String),
+                       regex-indef (Regex as Regex.ByteString)
+                          requires (Str as Str.ByteString)
+  hs-source-dirs:      regex-example
diff --git a/tests/bkpregex/regex-example/Main.hs b/tests/bkpregex/regex-example/Main.hs
new file mode 100644
index 0000000..76d2974
--- /dev/null
+++ b/tests/bkpregex/regex-example/Main.hs
@@ -0,0 +1,12 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Main where
+
+import Regex.Types
+import qualified Regex.String
+import qualified Regex.ByteString
+
+nocs = Rep (Alt (Sym 'a') (Sym 'b'))
+onec = Seq nocs (Sym 'c')
+evencs = Seq (Rep (Seq onec onec)) nocs
+main = print (Regex.String.accept evencs "acc") >>
+       print (Regex.ByteString.accept evencs "acc")
diff --git a/tests/bkpregex/regex-indef/Regex.hs b/tests/bkpregex/regex-indef/Regex.hs
new file mode 100644
index 0000000..506566b
--- /dev/null
+++ b/tests/bkpregex/regex-indef/Regex.hs
@@ -0,0 +1,14 @@
+module Regex where
+
+import Prelude hiding (null)
+import Str
+import Regex.Types
+
+accept :: Reg -> Str -> Bool
+accept Eps       u = null u
+accept (Sym c)   u = u == singleton c
+accept (Alt p q) u = accept p u || accept q u
+accept (Seq p q) u =
+    or [accept p u1 && accept q u2 | (u1, u2) <- splits u]
+accept (Rep r) u =
+    or [and [accept r ui | ui <- ps] | ps <- parts u]
diff --git a/tests/bkpregex/regex-indef/Str.hsig b/tests/bkpregex/regex-indef/Str.hsig
new file mode 100644
index 0000000..23bfb8c
--- /dev/null
+++ b/tests/bkpregex/regex-indef/Str.hsig
@@ -0,0 +1,9 @@
+signature Str where
+
+data Str
+instance Eq Str
+
+null :: Str -> Bool
+singleton :: Char -> Str
+splits :: Str -> [(Str, Str)]
+parts :: Str -> [[Str]]
diff --git a/tests/bkpregex/regex-types/Regex/Types.hs b/tests/bkpregex/regex-types/Regex/Types.hs
new file mode 100644
index 0000000..2900749
--- /dev/null
+++ b/tests/bkpregex/regex-types/Regex/Types.hs
@@ -0,0 +1,7 @@
+module Regex.Types where
+
+data Reg = Eps
+         | Sym Char
+         | Alt Reg Reg
+         | Seq Reg Reg
+         | Rep Reg
diff --git a/tests/bkpregex/str-impls/Str/ByteString.hs b/tests/bkpregex/str-impls/Str/ByteString.hs
new file mode 100644
index 0000000..cd49fed
--- /dev/null
+++ b/tests/bkpregex/str-impls/Str/ByteString.hs
@@ -0,0 +1,17 @@
+module Str.ByteString(module Data.ByteString.Char8, module Str.ByteString) where
+
+import Prelude hiding (length, null, splitAt)
+import Data.ByteString.Char8
+import Data.ByteString
+
+type Str = ByteString
+
+splits :: Str -> [(Str, Str)]
+splits s = fmap (\n -> splitAt n s) [0..length s]
+
+parts :: Str -> [[Str]]
+parts s | null s    = [[]]
+        | otherwise = do
+            n <- [1..length s]
+            let (l, r) = splitAt n s
+            fmap (l:) (parts r)
diff --git a/tests/bkpregex/str-impls/Str/String.hs b/tests/bkpregex/str-impls/Str/String.hs
new file mode 100644
index 0000000..bba89de
--- /dev/null
+++ b/tests/bkpregex/str-impls/Str/String.hs
@@ -0,0 +1,21 @@
+module Str.String where
+
+import Prelude hiding (null)
+import qualified Prelude as P
+
+type Str = String
+
+null :: Str -> Bool
+null = P.null
+
+singleton :: Char -> Str
+singleton c = [c]
+
+splits :: Str -> [(Str, Str)]
+splits [] = [([], [])]
+splits (c:cs) = ([], c:cs):[(c:s1,s2) | (s1,s2) <- splits cs]
+
+parts :: Str -> [[Str]]
+parts [] = [[]]
+parts [c] = [[[c]]]
+parts (c:cs) = concat [[(c:p):ps, [c]:p:ps] | p:ps <- parts cs]