From d1400eeb1401dee32729d2752b8ca4a072766068 Mon Sep 17 00:00:00 2001
From: Brad Richardson <everythingfunctional@protonmail.com>
Date: Wed, 14 Oct 2020 13:51:18 -0500
Subject: Add test for modules a program uses

---
 bootstrap/src/BuildModel.hs                   | 106 ++++++++++++++++++++++++++
 bootstrap/unit_test/SourceConstructionTest.hs |   7 ++
 2 files changed, 113 insertions(+)

diff --git a/bootstrap/src/BuildModel.hs b/bootstrap/src/BuildModel.hs
index b8bc122..dab8aed 100644
--- a/bootstrap/src/BuildModel.hs
+++ b/bootstrap/src/BuildModel.hs
@@ -1,10 +1,31 @@
 module BuildModel where
 
+import           Control.Applicative            ( (<|>) )
+import           Data.Char                      ( isAsciiLower
+                                                , isDigit
+                                                , toLower
+                                                )
+import           Data.Maybe                     ( fromMaybe
+                                                , mapMaybe
+                                                )
 import           Data.List                      ( intercalate )
 import           System.FilePath                ( (</>)
                                                 , (<.>)
                                                 , splitDirectories
                                                 )
+import           Text.ParserCombinators.ReadP   ( ReadP
+                                                , char
+                                                , eof
+                                                , many
+                                                , many1
+                                                , option
+                                                , readP_to_S
+                                                , satisfy
+                                                , skipSpaces
+                                                , string
+                                                )
+
+data LineContents = ModuleUsed String | Other
 
 data RawSource = RawSource {
     rawSourceFilename :: FilePath
@@ -14,6 +35,7 @@ data RawSource = RawSource {
 data Source = Program {
     programSourceFileName :: FilePath
   , programObjectFileName :: FilePath -> FilePath
+  , programModulesUsed :: [String]
 }
 
 processRawSource :: RawSource -> Source
@@ -27,8 +49,92 @@ processRawSource rawSource =
                                             sourceFileName
                                           )
                                       <.> "o"
+        , programModulesUsed    = getModulesUsed rawSource
         }
 
 pathSeparatorsToUnderscores :: FilePath -> FilePath
 pathSeparatorsToUnderscores fileName =
   intercalate "_" (splitDirectories fileName)
+
+getModulesUsed :: RawSource -> [String]
+getModulesUsed rawSource =
+  let fileLines    = lines $ rawSourceContents rawSource
+      lineContents = map parseFortranLine fileLines
+  in  contentsToModuleNames lineContents
+
+contentsToModuleNames :: [LineContents] -> [String]
+contentsToModuleNames = mapMaybe contentToMaybeModuleName
+ where
+  contentToMaybeModuleName content = case content of
+    ModuleUsed moduleName -> Just moduleName
+    _                     -> Nothing
+
+readFileLinesIO :: FilePath -> IO [String]
+readFileLinesIO file = do
+  contents <- readFile file
+  return $ lines contents
+
+parseFortranLine :: String -> LineContents
+parseFortranLine line =
+  let line'  = map toLower line
+      result = readP_to_S doFortranLineParse line'
+  in  getResult result
+ where
+  getResult (_ : (contents, _) : _) = contents
+  getResult [(contents, _)        ] = contents
+  getResult []                      = Other
+
+doFortranLineParse :: ReadP LineContents
+doFortranLineParse = option Other fortranUsefulContents
+
+fortranUsefulContents :: ReadP LineContents
+fortranUsefulContents = useStatement
+
+useStatement :: ReadP LineContents
+useStatement = do
+  skipSpaces
+  _ <- string "use"
+  skipAtLeastOneWhiteSpace
+  modName <- validIdentifier
+  skipSpaceCommaOrEnd
+  return $ ModuleUsed modName
+
+skipAtLeastOneWhiteSpace :: ReadP ()
+skipAtLeastOneWhiteSpace = do
+  _ <- many1 whiteSpace
+  return ()
+
+skipSpaceOrEnd :: ReadP ()
+skipSpaceOrEnd = eof <|> skipAtLeastOneWhiteSpace
+
+skipSpaceCommaOrEnd :: ReadP ()
+skipSpaceCommaOrEnd = eof <|> skipComma <|> skipAtLeastOneWhiteSpace
+
+skipComma :: ReadP ()
+skipComma = do
+  _ <- char ','
+  return ()
+
+whiteSpace :: ReadP Char
+whiteSpace = satisfy (`elem` " \t")
+
+validIdentifier :: ReadP String
+validIdentifier = do
+  first <- validFirstCharacter
+  rest  <- many validIdentifierCharacter
+  return $ first : rest
+
+validFirstCharacter :: ReadP Char
+validFirstCharacter = alphabet
+
+validIdentifierCharacter :: ReadP Char
+validIdentifierCharacter = alphabet <|> digit <|> underscore
+
+alphabet :: ReadP Char
+alphabet = satisfy isAsciiLower
+
+digit :: ReadP Char
+digit = satisfy isDigit
+
+underscore :: ReadP Char
+underscore = char '_'
diff --git a/bootstrap/unit_test/SourceConstructionTest.hs b/bootstrap/unit_test/SourceConstructionTest.hs
index 24122c5..751d10c 100644
--- a/bootstrap/unit_test/SourceConstructionTest.hs
+++ b/bootstrap/unit_test/SourceConstructionTest.hs
@@ -31,12 +31,15 @@ test = return $ givenInput
       , then'
         "its object file name is the 'flattened' path of the source file with '.o' appended"
         checkProgramObjectFileName
+      , then' "it knows what modules it uses directly" checkProgramModulesUsed
       ]
   ]
 
 exampleProgram :: RawSource
 exampleProgram = RawSource programSourceFileName' $ unlines
   [ "program some_program"
+  , "  use module1"
+  , "  USE MODULE2"
   , "  implicit none"
   , "  print *, \"Hello, World!\""
   , "end program"
@@ -59,3 +62,7 @@ checkProgramObjectFileName p@(Program{}) =
   assertEquals ("." </> "some_file_somewhere.f90.o")
     $ (programObjectFileName p) "."
 checkProgramObjectFileName _ = fail' "wasn't a Program"
+
+checkProgramModulesUsed :: Source -> Result
+checkProgramModulesUsed p@(Program{}) = assertEquals ["module1", "module2"] $ programModulesUsed p
+checkProgramModulesUsed _ = fail' "wasn't a Program"
-- 
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