base-4.18.1.0: Basic libraries

Copyright | (c) The University of Glasgow 2008-2011
License | see libraries/base/LICENSE
Maintainer | libraries@haskell.org
Stability | internal
Portability | non-portable
Safe Haskell | Trustworthy
Language | Haskell2010

GHC.Foreign

Contents

- C strings with a configurable encoding

Description

Foreign marshalling support for CStrings with configurable encodings

Synopsis

- type CString = Ptr CChar
- type CStringLen = (Ptr CChar, Int)
- peekCString :: TextEncoding -> CString -> IO String
- peekCStringLen :: TextEncoding -> CStringLen -> IO String
- newCString :: TextEncoding -> String -> IO CString
- newCStringLen :: TextEncoding -> String -> IO CStringLen
- withCString :: TextEncoding -> String -> (CString -> IO a) -> IO a
- withCStringLen :: TextEncoding -> String -> (CStringLen -> IO a) -> IO a
- withCStringsLen :: TextEncoding -> [String] -> (Int -> Ptr CString -> IO a) -> IO a
- charIsRepresentable :: TextEncoding -> Char -> IO Bool

# C strings with a configurable encoding

type CString = Ptr CChar Source #

A C string is a reference to an array of C characters terminated by NUL.

type CStringLen = (Ptr CChar, Int) Source #

A string with explicit length information in bytes instead of a terminating NUL (allowing NUL characters in the middle of the string).

peekCString :: TextEncoding -> CString -> IO String Source #

Marshal a NUL terminated C string into a Haskell string.

peekCStringLen :: TextEncoding -> CStringLen -> IO String Source #

Marshal a C string with explicit length into a Haskell string.

newCString :: TextEncoding -> String -> IO CString Source #

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 `free` or `finalizerFree`.

newCStringLen :: TextEncoding -> String -> IO CStringLen Source #

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 `free` or `finalizerFree`.

withCString :: TextEncoding -> String -> (CString -> IO a) -> IO a Source #

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.

withCStringLen :: TextEncoding -> String -> (CStringLen -> IO a) -> IO a Source #

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.

withCStringsLen :: TextEncoding -> [String] -> (Int -> Ptr CString -> IO a) -> IO a Source #

Marshal a list of Haskell strings into an array of NUL terminated C strings using temporary storage.

- the Haskell strings 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.

charIsRepresentable :: TextEncoding -> Char -> IO Bool Source #

Determines whether a character can be accurately encoded in a `CString`.

Pretty much anyone who uses this function is in a state of sin because whether or not a character is encodable will, in general, depend on the context in which it occurs.