/usr/lib/hugs/packages/base/Foreign/C/String.hs is in libhugs-base-bundled 98.200609.21-5.3.
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-----------------------------------------------------------------------------
-- |
-- Module : Foreign.C.String
-- Copyright : (c) The FFI task force 2001
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : ffi@haskell.org
-- Stability : provisional
-- Portability : portable
--
-- Utilities for primitive marshalling of C strings.
--
-- The marshalling converts each Haskell character, representing a Unicode
-- code point, to one or more bytes in a manner that, by default, is
-- determined by the current locale. As a consequence, no guarantees
-- can be made about the relative length of a Haskell string and its
-- corresponding C string, and therefore all the marshalling routines
-- include memory allocation. The translation between Unicode and the
-- encoding of the current locale may be lossy.
--
-----------------------------------------------------------------------------
module Foreign.C.String ( -- representation of strings in C
-- * C strings
CString, -- = Ptr CChar
CStringLen, -- = (Ptr CChar, Int)
-- ** Using a locale-dependent encoding
-- | Currently these functions are identical to their @CAString@ counterparts;
-- eventually they will use an encoding determined by the current locale.
-- conversion of C strings into Haskell strings
--
peekCString, -- :: CString -> IO String
peekCStringLen, -- :: CStringLen -> IO String
-- conversion of Haskell strings into C strings
--
newCString, -- :: String -> IO CString
newCStringLen, -- :: String -> IO CStringLen
-- conversion of Haskell strings into C strings using temporary storage
--
withCString, -- :: String -> (CString -> IO a) -> IO a
withCStringLen, -- :: String -> (CStringLen -> IO a) -> IO a
charIsRepresentable, -- :: Char -> IO Bool
-- ** Using 8-bit characters
-- | These variants of the above functions are for use with C libraries
-- that are ignorant of Unicode. These functions should be used with
-- care, as a loss of information can occur.
castCharToCChar, -- :: Char -> CChar
castCCharToChar, -- :: CChar -> Char
peekCAString, -- :: CString -> IO String
peekCAStringLen, -- :: CStringLen -> IO String
newCAString, -- :: String -> IO CString
newCAStringLen, -- :: String -> IO CStringLen
withCAString, -- :: String -> (CString -> IO a) -> IO a
withCAStringLen, -- :: String -> (CStringLen -> IO a) -> IO a
-- * C wide strings
-- | These variants of the above functions are for use with C libraries
-- that encode Unicode using the C @wchar_t@ type in a system-dependent
-- way. The only encodings supported are
--
-- * UTF-32 (the C compiler defines @__STDC_ISO_10646__@), or
--
-- * UTF-16 (as used on Windows systems).
CWString, -- = Ptr CWchar
CWStringLen, -- = (Ptr CWchar, Int)
peekCWString, -- :: CWString -> IO String
peekCWStringLen, -- :: CWStringLen -> IO String
newCWString, -- :: String -> IO CWString
newCWStringLen, -- :: String -> IO CWStringLen
withCWString, -- :: String -> (CWString -> IO a) -> IO a
withCWStringLen, -- :: String -> (CWStringLen -> IO a) -> IO a
) where
import Foreign.Marshal.Array
import Foreign.C.Types
import Foreign.Ptr
import Foreign.Storable
import Data.Word
import Data.Char ( chr, ord )
-----------------------------------------------------------------------------
-- Strings
-- representation of strings in C
-- ------------------------------
-- | A C string is a reference to an array of C characters terminated by NUL.
type CString = Ptr CChar
-- | A string with explicit length information in bytes instead of a
-- terminating NUL (allowing NUL characters in the middle of the string).
type CStringLen = (Ptr CChar, Int)
-- exported functions
-- ------------------
--
-- * the following routines apply the default conversion when converting the
-- C-land character encoding into the Haskell-land character encoding
-- | Marshal a NUL terminated C string into a Haskell string.
--
peekCString :: CString -> IO String
peekCString = peekCAString
-- | Marshal a C string with explicit length into a Haskell string.
--
peekCStringLen :: CStringLen -> IO String
peekCStringLen = peekCAStringLen
-- | Marshal a Haskell string into a NUL terminated C string.
--
-- * the Haskell string may /not/ contain any NUL characters
--
-- * new storage is allocated for the C string and must be
-- explicitly freed using 'Foreign.Marshal.Alloc.free' or
-- 'Foreign.Marshal.Alloc.finalizerFree'.
--
newCString :: String -> IO CString
newCString = newCAString
-- | Marshal a Haskell string into a C string (ie, character array) with
-- explicit length information.
--
-- * new storage is allocated for the C string and must be
-- explicitly freed using 'Foreign.Marshal.Alloc.free' or
-- 'Foreign.Marshal.Alloc.finalizerFree'.
--
newCStringLen :: String -> IO CStringLen
newCStringLen = newCAStringLen
-- | Marshal a Haskell string into a NUL terminated C string using temporary
-- storage.
--
-- * the Haskell string may /not/ contain any NUL characters
--
-- * the memory is freed when the subcomputation terminates (either
-- normally or via an exception), so the pointer to the temporary
-- storage must /not/ be used after this.
--
withCString :: String -> (CString -> IO a) -> IO a
withCString = withCAString
-- | Marshal a Haskell string into a C string (ie, character array)
-- in temporary storage, with explicit length information.
--
-- * the memory is freed when the subcomputation terminates (either
-- normally or via an exception), so the pointer to the temporary
-- storage must /not/ be used after this.
--
withCStringLen :: String -> (CStringLen -> IO a) -> IO a
withCStringLen = withCAStringLen
-- | Determines whether a character can be accurately encoded in a 'CString'.
-- Unrepresentable characters are converted to @\'?\'@.
--
-- Currently only Latin-1 characters are representable.
charIsRepresentable :: Char -> IO Bool
charIsRepresentable c = return (ord c < 256)
-- single byte characters
-- ----------------------
--
-- ** NOTE: These routines don't handle conversions! **
-- | Convert a C byte, representing a Latin-1 character, to the corresponding
-- Haskell character.
castCCharToChar :: CChar -> Char
castCCharToChar ch = chr (fromIntegral (fromIntegral ch :: Word8))
-- | Convert a Haskell character to a C character.
-- This function is only safe on the first 256 characters.
castCharToCChar :: Char -> CChar
castCharToCChar ch = fromIntegral (ord ch)
-- | Marshal a NUL terminated C string into a Haskell string.
--
peekCAString :: CString -> IO String
peekCAString cp = do
cs <- peekArray0 nUL cp
return (cCharsToChars cs)
-- | Marshal a C string with explicit length into a Haskell string.
--
peekCAStringLen :: CStringLen -> IO String
peekCAStringLen (cp, len) = do
cs <- peekArray len cp
return (cCharsToChars cs)
-- | Marshal a Haskell string into a NUL terminated C string.
--
-- * the Haskell string may /not/ contain any NUL characters
--
-- * new storage is allocated for the C string and must be
-- explicitly freed using 'Foreign.Marshal.Alloc.free' or
-- 'Foreign.Marshal.Alloc.finalizerFree'.
--
newCAString :: String -> IO CString
newCAString = newArray0 nUL . charsToCChars
-- | Marshal a Haskell string into a C string (ie, character array) with
-- explicit length information.
--
-- * new storage is allocated for the C string and must be
-- explicitly freed using 'Foreign.Marshal.Alloc.free' or
-- 'Foreign.Marshal.Alloc.finalizerFree'.
--
newCAStringLen :: String -> IO CStringLen
newCAStringLen str = do
a <- newArray (charsToCChars str)
return (pairLength str a)
-- | Marshal a Haskell string into a NUL terminated C string using temporary
-- storage.
--
-- * the Haskell string may /not/ contain any NUL characters
--
-- * the memory is freed when the subcomputation terminates (either
-- normally or via an exception), so the pointer to the temporary
-- storage must /not/ be used after this.
--
withCAString :: String -> (CString -> IO a) -> IO a
withCAString = withArray0 nUL . charsToCChars
-- | Marshal a Haskell string into a C string (ie, character array)
-- in temporary storage, with explicit length information.
--
-- * the memory is freed when the subcomputation terminates (either
-- normally or via an exception), so the pointer to the temporary
-- storage must /not/ be used after this.
--
withCAStringLen :: String -> (CStringLen -> IO a) -> IO a
withCAStringLen str act = withArray (charsToCChars str) $ act . pairLength str
-- auxiliary definitions
-- ----------------------
-- C's end of string character
--
nUL :: CChar
nUL = 0
-- pair a C string with the length of the given Haskell string
--
pairLength :: String -> a -> (a, Int)
pairLength = flip (,) . length
-- cast [CChar] to [Char]
--
cCharsToChars :: [CChar] -> [Char]
cCharsToChars xs = map castCCharToChar xs
-- cast [Char] to [CChar]
--
charsToCChars :: [Char] -> [CChar]
charsToCChars xs = map castCharToCChar xs
-----------------------------------------------------------------------------
-- Wide strings
-- representation of wide strings in C
-- -----------------------------------
-- | A C wide string is a reference to an array of C wide characters
-- terminated by NUL.
type CWString = Ptr CWchar
-- | A wide character string with explicit length information in bytes
-- instead of a terminating NUL (allowing NUL characters in the middle
-- of the string).
type CWStringLen = (Ptr CWchar, Int)
-- | Marshal a NUL terminated C wide string into a Haskell string.
--
peekCWString :: CWString -> IO String
peekCWString cp = do
cs <- peekArray0 wNUL cp
return (cWcharsToChars cs)
-- | Marshal a C wide string with explicit length into a Haskell string.
--
peekCWStringLen :: CWStringLen -> IO String
peekCWStringLen (cp, len) = do
cs <- peekArray len cp
return (cWcharsToChars cs)
-- | Marshal a Haskell string into a NUL terminated C wide string.
--
-- * the Haskell string may /not/ contain any NUL characters
--
-- * new storage is allocated for the C wide string and must
-- be explicitly freed using 'Foreign.Marshal.Alloc.free' or
-- 'Foreign.Marshal.Alloc.finalizerFree'.
--
newCWString :: String -> IO CWString
newCWString = newArray0 wNUL . charsToCWchars
-- | Marshal a Haskell string into a C wide string (ie, wide character array)
-- with explicit length information.
--
-- * new storage is allocated for the C wide string and must
-- be explicitly freed using 'Foreign.Marshal.Alloc.free' or
-- 'Foreign.Marshal.Alloc.finalizerFree'.
--
newCWStringLen :: String -> IO CWStringLen
newCWStringLen str = do
a <- newArray (charsToCWchars str)
return (pairLength str a)
-- | Marshal a Haskell string into a NUL terminated C wide string using
-- temporary storage.
--
-- * the Haskell string may /not/ contain any NUL characters
--
-- * the memory is freed when the subcomputation terminates (either
-- normally or via an exception), so the pointer to the temporary
-- storage must /not/ be used after this.
--
withCWString :: String -> (CWString -> IO a) -> IO a
withCWString = withArray0 wNUL . charsToCWchars
-- | Marshal a Haskell string into a NUL terminated C wide string using
-- temporary storage.
--
-- * the Haskell string may /not/ contain any NUL characters
--
-- * the memory is freed when the subcomputation terminates (either
-- normally or via an exception), so the pointer to the temporary
-- storage must /not/ be used after this.
--
withCWStringLen :: String -> (CWStringLen -> IO a) -> IO a
withCWStringLen str act = withArray (charsToCWchars str) $ act . pairLength str
-- auxiliary definitions
-- ----------------------
wNUL :: CWchar
wNUL = 0
cWcharsToChars :: [CWchar] -> [Char]
charsToCWchars :: [Char] -> [CWchar]
cWcharsToChars xs = map castCWcharToChar xs
charsToCWchars xs = map castCharToCWchar xs
-- These conversions only make sense if __STDC_ISO_10646__ is defined
-- (meaning that wchar_t is ISO 10646, aka Unicode)
castCWcharToChar :: CWchar -> Char
castCWcharToChar ch = chr (fromIntegral ch )
castCharToCWchar :: Char -> CWchar
castCharToCWchar ch = fromIntegral (ord ch)
|