Simple static analyser module

code/Pico/StaticAnalyser.hs

@@ -0,0 +1,36 @@
+module Pico.StaticAnalyser (
+    analyseProgram
+    ) where
+
+import System.IO
+import Pico.AbsPico
+
+type Analysis = [String]
+
+analyseProgram :: Program -> Analysis
+analyseProgram (Program st stmt) =
+  let 
+    outputChanges = or (map outputUnchangedAnalysis stmt)
+  in 
+    case outputChanges of
+      True -> []
+      False -> ["Output unchanged"]
+
+-- | Analyse if the program contains any assignment to the output variable
+outputUnchangedAnalysis :: Stmt -> Bool
+outputUnchangedAnalysis (Block stmt) =
+  or (map outputUnchangedAnalysis stmt)
+
+outputUnchangedAnalysis (IfThenElse _ stmtThen stmtElse) =
+  or [outputUnchangedAnalysis stmtThen, outputUnchangedAnalysis stmtElse]
+
+outputUnchangedAnalysis (IfThen _ stmtThen) =
+  outputUnchangedAnalysis stmtThen
+
+outputUnchangedAnalysis (While _ stmt) =
+  outputUnchangedAnalysis stmt
+
+outputUnchangedAnalysis (Assignment (Ident "output") _) = 
+  True
+outputUnchangedAnalysis _ = 
+  False

code/Pico/StaticAnalysisTest.hs

@@ -0,0 +1,101 @@
+module Pico.StaticAnalysisTest where
+
+import Prelude hiding (GTE, LTE)
+import System.IO
+
+import Pico.AbsPico
+import Pico.Interpreter
+import Pico.StaticAnalyser
+import Pico.Parser hiding (assignment, var)
+
+import Test.HUnit
+
+st :: SymbolTable
+st = [ Decl (Ident "x") TInteger
+     , Decl (Ident "output") TInteger
+     ]
+
+testSuite = TestList [ 
+  TestLabel "outputUnchangedTest" outputUnchangedTest,
+  TestLabel "outputChangedTest" outputChangedTest,
+  TestLabel "condOutputChangeTest" condOutputChangeTest,
+  TestLabel "ifThenElseOutputTest" ifThenElseOutputTest,
+  TestLabel "whileOutputTest" whileOutputTest
+  ]
+
+assignment str exp = Assignment (Ident str) exp
+var str = Var (Ident str)
+
+-- | Simple outputUnchanged statement test
+outputUnchangedProgram :: Program
+outputUnchangedProgram = Program st [stubVar]
+
+stubVar :: Stmt
+stubVar = assignment "x" (EXPValue (INTValue 10))
+
+outputUnchangedTest = TestCase (assertEqual "x = 10;" 
+                      (["Output unchanged"]) (analyseProgram outputUnchangedProgram)) 
+
+-- | Simple outputChanged statement test
+outputChangedProgram :: Program
+outputChangedProgram = Program st [outputAssign]
+
+outputAssign :: Stmt
+outputAssign = assignment "output" (EXPValue (INTValue 10))
+
+outputChangedTest = TestCase (assertEqual "output = 10;" 
+                      ([]) (analyseProgram outputChangedProgram)) 
+
+-- | Simple conditional output change statement test
+condOutputChangeProgram :: Program
+condOutputChangeProgram = Program st [ifBlock]
+
+ifBlock :: Stmt
+ifBlock = IfThen trueExp ifBody
+
+ifBody :: Stmt
+ifBody = assignment "output" (EXPValue (INTValue 20))
+
+condOutputChangeTest = TestCase (assertEqual "for if(1){ output = 20 }" 
+                      ([]) (analyseProgram condOutputChangeProgram)) 
+
+-- | Simple conditional output change with ifThenElse statement test
+condIfThenElseProgram :: Program
+condIfThenElseProgram = Program st [ifElseBlock]
+
+ifElseBlock :: Stmt
+ifElseBlock = IfThenElse trueExp statement1 statement2
+
+statement1 :: Stmt
+statement1 = assignment "x" (EXPValue (INTValue 1))
+
+statement2 :: Stmt
+statement2 = assignment "output" (EXPValue (INTValue 2))
+
+ifThenElseOutputTest = TestCase (assertEqual "if(0){x = 1} else {output = 2}" 
+                           ([]) (analyseProgram condIfThenElseProgram)) 
+
+-- | Simple conditional output change with while statement test
+condWhileProgram :: Program
+condWhileProgram = Program st [x1, whileBlock]
+
+x1 :: Stmt
+x1 = assignment "x" (EXPValue (INTValue 1))
+
+whileBlock :: Stmt
+whileBlock = While whileExp whileStmt
+
+whileExp :: Expression
+whileExp = var "x"
+
+whileStmt :: Stmt
+whileStmt = 
+  Block [assignment "output" (Add (var "output") (var "x"))]
+
+-- Test while block with var expression
+whileOutputTest = TestCase (assertEqual "x = 1; while(x){output+1}"
+                      ([]) (analyseProgram condWhileProgram))
+
+-- | True expression
+trueExp :: Expression
+trueExp = (EXPValue (INTValue 1))