From 4fadab442d6642bd321ba59ec12ec5aec5be6e30 Mon Sep 17 00:00:00 2001
From: Neil Brown <neil@twistedsquare.com>
Date: Sat, 1 Sep 2007 14:40:50 +0000
Subject: [PATCH] Rain: added a pass to turn range constructors into the more
 general array constructor form

---
 RainPassTest.hs | 18 ++++++++++++++++++
 RainPasses.hs   | 25 +++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/RainPassTest.hs b/RainPassTest.hs
index 12a37cc..07b82ad 100644
--- a/RainPassTest.hs
+++ b/RainPassTest.hs
@@ -440,6 +440,22 @@ testParamPass8 = testPassShouldFail "testParamPass6" (matchParamPass orig) (star
 
 --TODO test passing in channel ends
 
+-- | Transform an example list
+testRangeRepPass0 :: Test
+testRangeRepPass0 = testPass "testRangeRepPass0" exp (transformRangeRep orig) (return())
+  where
+    orig = A.ExprConstr m $ A.RangeConstr m (intLiteral 0) (intLiteral 1)
+    exp = tag2 A.ExprConstr DontCare $ tag3 A.RepConstr DontCare (tag4 A.For DontCare (Named "repIndex" DontCare) (intLiteral 0) (intLiteral 2)) 
+      (tag2 A.ExprVariable DontCare $ tag2 A.Variable DontCare $ Named "repIndex" DontCare)
+
+-- | Lists with negative counts should be turned into an empty literal list
+testRangeRepPass1 :: Test
+testRangeRepPass1 = testPass "testRangeRepPass1" exp (transformRangeRep orig) (return())
+  where
+    orig = A.ExprConstr m $ A.RangeConstr m (intLiteral 1) (intLiteral 0)
+    exp = A.Literal m (A.Array [A.Dimension 0] A.Int) $ A.ArrayLiteral m []
+
+
 ---Returns the list of tests:
 tests :: Test
 tests = TestList
@@ -472,6 +488,8 @@ tests = TestList
    ,testParamPass6
    ,testParamPass7
    ,testParamPass8
+   ,testRangeRepPass0
+   ,testRangeRepPass1
  ]
 
 
diff --git a/RainPasses.hs b/RainPasses.hs
index 4b03664..11d41ec 100644
--- a/RainPasses.hs
+++ b/RainPasses.hs
@@ -45,6 +45,8 @@ rainPasses =
          --depends on uniquifyAndResolveVars and recordInfNameTypes       
        ,("Convert seqeach/pareach loops into classic replicated SEQ/PAR",transformEach) 
          --depends on uniquifyAndResolveVars and recordInfNameTypes, and should be done after transformEachRange
+       ,("Convert simple Rain range constructors into more general array constructors",transformRangeRep)
+         --must be done after transformEachRange
      ]
 
 -- | A pass that transforms all instances of 'A.Int' into 'A.Int64'
@@ -255,3 +257,26 @@ transformEach = everywhereM (mkM transformEach')
                  s
            return (spec (A.Rep m newRep s'))
     transformEach' s = return s
+
+-- | A pass that changes all the Rain range constructor expressions into the more general array constructor expressions
+transformRangeRep :: Data t => t -> PassM t
+transformRangeRep = everywhereM (mkM transformRangeRep')
+  where
+    transformRangeRep' :: A.Expression -> PassM A.Expression
+    transformRangeRep' (A.ExprConstr _ (A.RangeConstr m (A.Literal _ _ beginLit) (A.Literal _ _ endLit)))
+      = if (isJust $ checkIntegral beginLit) && (isJust $ checkIntegral endLit)
+          then transformRangeRep'' m (fromJust $ checkIntegral beginLit) (fromJust $ checkIntegral endLit)
+          else dieP m "Items in range constructor (x..y) are not integer literals"
+      where
+        transformRangeRep'' :: Meta -> Integer -> Integer -> PassM A.Expression
+        transformRangeRep'' m begin end 
+          = if (end < begin)
+              then return $ A.Literal m (A.Array [A.Dimension 0] A.Int) $ A.ArrayLiteral m []
+              else do A.Specification _ rep _ <- makeNonceVariable "rep_constr" m A.Int A.VariableName A.ValAbbrev
+                      let count = end - begin + 1
+                      return $ A.ExprConstr m $ A.RepConstr m 
+                        (A.For m rep 
+                          (A.Literal m A.Int (A.IntLiteral m $ show begin)) 
+                          (A.Literal m A.Int (A.IntLiteral m $ show count))
+                        ) (A.ExprVariable m $ A.Variable m rep)
+    transformRangeRep' s = return s