Split in lib and tests

1 files changed, 107 insertions, 0 deletions

diff --git a/lib/Language/Elna/Parser.hs b/lib/Language/Elna/Parser.hs
new file mode 100644
index 0000000..cd8f927
--- /dev/null
+++ b/lib/Language/Elna/Parser.hs
@@ -0,0 +1,107 @@
+module Language.Elna.Parser
+    ( Parser
+    , programP
+    ) where
+
+import Control.Monad (void)
+import Data.Text (Text)
+import qualified Data.Text as Text
+import Data.Void (Void)
+import Language.Elna.AST
+    ( Declaration(..)
+    , Identifier(..)
+    , Parameter(..)
+    , Program(..)
+    , TypeExpression(..)
+    , VariableDeclaration(..)
+    )
+import Text.Megaparsec (Parsec, (<?>), optional, between, sepBy)
+import Text.Megaparsec.Char (alphaNumChar, letterChar, space1)
+import qualified Text.Megaparsec.Char.Lexer as Lexer
+import Control.Applicative (Alternative(..))
+import Data.Maybe (isJust)
+
+type Parser = Parsec Void Text
+
+space :: Parser ()
+space = Lexer.space space1 (Lexer.skipLineComment "//")
+    $ Lexer.skipBlockComment "/*" "*/"
+
+lexeme :: forall a. Parser a -> Parser a
+lexeme = Lexer.lexeme space
+
+symbol :: Text -> Parser Text
+symbol = Lexer.symbol space
+
+blockP :: forall a. Parser a -> Parser a
+blockP = between (symbol "{") (symbol "}")
+
+procedureP :: Parser ()
+procedureP = void $ symbol "proc"
+
+parensP :: forall a. Parser a -> Parser a
+parensP = between (symbol "(")  (symbol ")")
+
+openBracketP :: Parser ()
+openBracketP = void $ symbol "["
+
+closingBracketP :: Parser ()
+closingBracketP = void $ symbol "]"
+
+colonP :: Parser ()
+colonP = void $ symbol ":"
+
+semicolonP :: Parser ()
+semicolonP = void $ symbol ";"
+
+identifierP :: Parser Identifier
+identifierP =
+    let wordParser = (:) <$> letterChar <*> many alphaNumChar <?> "identifier"
+     in fmap Identifier $ lexeme $ Text.pack <$> wordParser
+
+typeExpressionP :: Parser TypeExpression
+typeExpressionP = arrayTypeExpression
+    <|> NamedType <$> identifierP
+    <?> "type expression"
+  where
+    arrayTypeExpression = flip ArrayType
+        <$> (symbol "array" *> openBracketP *> lexeme Lexer.decimal <* closingBracketP)
+        <*> (symbol "of" *> typeExpressionP)
+
+typeDefinitionP :: Parser Declaration
+typeDefinitionP = TypeDefinition
+    <$> (symbol "type" *> identifierP)
+    <*> (symbol "=" *> typeExpressionP)
+    <?> "type definition"
+
+variableDeclarationP :: Parser VariableDeclaration
+variableDeclarationP = VariableDeclaration
+    <$> (symbol "var" *> identifierP)
+    <*> (colonP *> typeExpressionP)
+    <* semicolonP
+    <?> "variable declaration"
+
+parameterP :: Parser Parameter
+parameterP = paramCons
+    <$> optional (symbol "ref")
+    <*> identifierP
+    <*> (colonP *> typeExpressionP)
+  where
+    paramCons ref name typeName = Parameter name typeName (isJust ref)
+
+parametersP :: Parser [Parameter]
+parametersP = parensP $ sepBy parameterP (symbol ",")
+
+procedureDefinitionP :: Parser Declaration
+procedureDefinitionP = ProcedureDefinition
+    <$> (procedureP *> identifierP)
+    <*> parametersP
+    <*> blockP (many variableDeclarationP)
+    <*> pure mempty -- TODO
+    <?> "procedure definition"
+
+declarationP :: Parser Declaration
+declarationP = typeDefinitionP <|> procedureDefinitionP
+
+programP :: Parser Program
+programP = Program <$> many declarationP