Determine an expression type

This commit is contained in:
Eugen Wissner 2024-08-07 22:47:35 +02:00
parent 385322235d
commit 573990551c
Signed by: belka
GPG Key ID: A27FDC1E8EE902C0
3 changed files with 77 additions and 4 deletions

3
TODO
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@ -1 +1,4 @@
# Type analysis
- Iterate the tree and apply the expression function on procedure expressions.
- Check statement types.

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@ -22,6 +22,7 @@ common warnings
ghc-options: -Wall
default-extensions:
ExplicitForAll,
LambdaCase,
OverloadedStrings
default-language: GHC2021

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@ -3,12 +3,24 @@ module Language.Elna.TypeAnalysis
, typeAnalysis
) where
import Control.Monad.Trans.Except (Except, runExcept)
import Control.Monad.Trans.Reader (ReaderT, runReaderT)
import Control.Applicative (Alternative(..))
import Control.Monad.Trans.Except (Except, runExcept, throwE)
import Control.Monad.Trans.Reader (ReaderT, asks, runReaderT)
import qualified Language.Elna.AST as AST
import Language.Elna.SymbolTable (SymbolTable)
import Language.Elna.Location (Identifier(..))
import Language.Elna.SymbolTable (Info(..), SymbolTable)
import qualified Language.Elna.SymbolTable as SymbolTable
import Language.Elna.Types (Type(..), booleanType, intType)
import Control.Monad.Trans.Class (MonadTrans(..))
import Control.Monad (unless)
data Error = Error
data Error
= ArithmeticExpressionError Type
| ComparisonExpressionError Type Type
| UnexpectedVariableInfoError Info
| UndefinedSymbolError Identifier
| ArrayIndexError Type
| ArrayAccessError Type
deriving (Eq, Show)
newtype TypeAnalysis a = TypeAnalysis
@ -37,3 +49,60 @@ typeAnalysis globalTable = either Just (const Nothing)
program :: AST.Program -> TypeAnalysis ()
program (AST.Program _declarations) = pure ()
expression :: SymbolTable -> AST.Expression -> TypeAnalysis Type
expression globalTable = \case
AST.VariableExpression identifier -> do
localLookup <- TypeAnalysis $ asks $ SymbolTable.lookup identifier
case localLookup <|> SymbolTable.lookup identifier globalTable of
Just (VariableInfo variableType _) -> pure variableType
Just anotherInfo -> TypeAnalysis $ lift $ throwE
$ UnexpectedVariableInfoError anotherInfo
Nothing -> TypeAnalysis $ lift $ throwE
$ UndefinedSymbolError identifier
AST.LiteralExpression literal' -> literal literal'
AST.NegationExpression negation -> do
operandType <- expression globalTable negation
if operandType == intType
then pure intType
else TypeAnalysis $ lift $ throwE $ ArithmeticExpressionError operandType
AST.SumExpression lhs rhs -> arithmeticExpression lhs rhs
AST.SubtractionExpression lhs rhs -> arithmeticExpression lhs rhs
AST.ProductExpression lhs rhs -> arithmeticExpression lhs rhs
AST.DivisionExpression lhs rhs -> arithmeticExpression lhs rhs
AST.EqualExpression lhs rhs -> comparisonExpression lhs rhs
AST.NonEqualExpression lhs rhs -> comparisonExpression lhs rhs
AST.LessExpression lhs rhs -> comparisonExpression lhs rhs
AST.GreaterExpression lhs rhs -> comparisonExpression lhs rhs
AST.LessOrEqualExpression lhs rhs -> comparisonExpression lhs rhs
AST.GreaterOrEqualExpression lhs rhs -> comparisonExpression lhs rhs
AST.ArrayExpression arrayExpression indexExpression -> do
arrayType <- expression globalTable arrayExpression
indexType <- expression globalTable indexExpression
unless (indexType == intType)
$ TypeAnalysis $ lift $ throwE $ ArrayIndexError indexType
case arrayType of
ArrayType _ baseType -> pure baseType
nonArrayType -> TypeAnalysis $ lift $ throwE
$ ArrayAccessError nonArrayType
where
arithmeticExpression lhs rhs = do
lhsType <- expression globalTable lhs
unless (lhsType == intType)
$ TypeAnalysis $ lift $ throwE $ ArithmeticExpressionError lhsType
rhsType <- expression globalTable rhs
unless (rhsType == intType)
$ TypeAnalysis $ lift $ throwE $ ArithmeticExpressionError rhsType
pure intType
comparisonExpression lhs rhs = do
lhsType <- expression globalTable lhs
rhsType <- expression globalTable rhs
if lhsType == intType && rhsType ==intType
then pure booleanType
else TypeAnalysis $ lift $ throwE $ ComparisonExpressionError lhsType rhsType
literal :: AST.Literal -> TypeAnalysis Type
literal (AST.IntegerLiteral _) = pure intType
literal (AST.HexadecimalLiteral _) = pure intType
literal (AST.CharacterLiteral _) = pure intType
literal (AST.BooleanLiteral _) = pure booleanType