never executed always true always false

    1 -- Copyright (C) 2018-2024 Jun Zhang <zhangjunphy[at]gmail[dot]com>
    2 --
    3 -- This file is a part of decafc.
    4 --
    5 -- decafc is free software: you can redistribute it and/or modify it under the
    6 -- terms of the MIT (X11) License as described in the LICENSE file.
    7 --
    8 -- decafc is distributed in the hope that it will be useful, but WITHOUT ANY
    9 -- WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
   10 -- FOR A PARTICULAR PURPOSE.  See the X11 license for more details.
   11 
   12 -- Parser -- Re-export Happy parser functionalities
   13 module Parser
   14   ( parse,
   15     Program (..),
   16     ImportDecl (..),
   17     FieldDecl (..),
   18     MethodDecl (..),
   19     FieldElem (..),
   20     Type (..),
   21     Argument (..),
   22     Block (..),
   23     Statement (..),
   24     Location (..),
   25     AssignExpr (..),
   26     MethodCall (..),
   27     ImportArg (..),
   28     CounterUpdate (..),
   29     Expr (..),
   30   )
   31 where
   32 
   33 import Data.ByteString.Lazy (ByteString)
   34 import Lexer (Alex (..), Token, runAlex, getAlexState, AlexUserState(..), AlexState(..))
   35 import Parser.Grammar
   36 import Parser.Tree
   37 import Util.SourceLoc as SL
   38 import Data.Text qualified as Text
   39 import Types
   40 
   41 parse :: ByteString -> Either [CompileError] Program
   42 parse input = case runAlex input parseAndHandleError of
   43         Left m -> Left [CompileError Nothing $ Text.pack m]
   44         Right (errs, _) | not $ null errs -> Left errs
   45         Right (_, program) -> Right program
   46   where
   47     parseAndHandleError = parseInternal >>= \program -> do
   48       state <- getAlexState
   49       let AlexUserState{errors = errors} = alex_ust state 
   50       return (errors, program)