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|
-----------------------------------------------------------------------------
-- |
-- Module : GHC.Lexeme
-- Copyright : (c) The GHC Team
--
-- Maintainer : ghc-devs@haskell.org
-- Portability : portable
--
-- Functions to evaluate whether or not a string is a valid identifier.
--
module GHC.Lexeme (
-- * Lexical characteristics of Haskell names
startsVarSym, startsVarId, startsConSym, startsConId,
startsVarSymASCII, isVarSymChar, okSymChar
) where
import Prelude -- See note [Why do we import Prelude here?]
import Data.Char
-- | Is this character acceptable in a symbol (after the first char)?
-- See alexGetByte in Lexer.x
okSymChar :: Char -> Bool
okSymChar c
| c `elem` "(),;[]`{}_\"'"
= False
| otherwise
= case generalCategory c of
ConnectorPunctuation -> True
DashPunctuation -> True
OtherPunctuation -> True
MathSymbol -> True
CurrencySymbol -> True
ModifierSymbol -> True
OtherSymbol -> True
_ -> False
startsVarSym, startsVarId, startsConSym, startsConId :: Char -> Bool
startsVarSym c = okSymChar c && c /= ':' -- Infix Ids
startsConSym c = c == ':' -- Infix data constructors
startsVarId c = c == '_' || case generalCategory c of -- Ordinary Ids
LowercaseLetter -> True
OtherLetter -> True -- See #1103
_ -> False
startsConId c = isUpper c || c == '(' -- Ordinary type constructors and data constructors
startsVarSymASCII :: Char -> Bool
startsVarSymASCII c = c `elem` "!#$%&*+./<=>?@\\^|~-"
isVarSymChar :: Char -> Bool
isVarSymChar c = c == ':' || startsVarSym c
|
