View.hs

{-|
Module      : Botan.Bindings.View
Description : View functions
Copyright   : (c) 2023-2024, Apotheca Labs
              (c) 2024-2025, Haskell Foundation
License     : BSD-3-Clause
Maintainer  : joris@well-typed.com, leo@apotheca.io
Stability   : experimental
Portability : POSIX

This module is based on the [View
Functions](https://botan.randombit.net/handbook/api_ref/ffi.html#view-functions)
section of the C Botan FFI documentation.
-}

{-# LANGUAGE CApiFFI #-}

module Botan.Bindings.View (
    BotanViewContext
    -- * View binary
  , BotanViewBinFn
  , BotanViewBinCallback
  , mallocBotanViewBinCallback
  , freeBotanViewBinCallback
    -- * View string
  , BotanViewStrFn
  , BotanViewStrCallback
  , mallocBotanViewStrCallback
  , freeBotanViewStrCallback
  ) where

import           Botan.Bindings.ConstPtr
import           Data.Word
import           Foreign.C.Types
import           Foreign.Ptr


type BotanViewContext a = Ptr a

{-------------------------------------------------------------------------------
  View binary
-------------------------------------------------------------------------------}

type BotanViewBinFn ctx
    =   BotanViewContext ctx    -- ^ __view_ctx__: some application context
    ->  ConstPtr Word8          -- ^ __data__: the binary data
    ->  CSize                   -- ^ __len__: the length of data in bytes
    ->  CInt

type BotanViewBinCallback ctx = FunPtr (BotanViewBinFn ctx)

-- NOTE: Wrapper stubs can't be used with CApiFFI.
foreign import ccall "wrapper"
    mallocBotanViewBinCallback
        :: BotanViewBinFn ctx
        -> IO (BotanViewBinCallback ctx)

freeBotanViewBinCallback :: BotanViewBinCallback ctx -> IO ()
freeBotanViewBinCallback = freeHaskellFunPtr

{-------------------------------------------------------------------------------
  View string
-------------------------------------------------------------------------------}

type BotanViewStrFn ctx
    =   BotanViewContext ctx    -- ^ __view_ctx__: some application context
    ->  ConstPtr CChar          -- ^ __str__: the null terminated string
    ->  CSize                   -- ^ __len__: the length of string *including* the null terminator
    ->  CInt

type BotanViewStrCallback ctx = FunPtr (BotanViewStrFn ctx)

-- NOTE: Wrapper stubs can't be used with CApiFFI.
foreign import ccall "wrapper"
    mallocBotanViewStrCallback
        :: BotanViewStrFn ctx
        -> IO (BotanViewStrCallback ctx)

freeBotanViewStrCallback :: BotanViewStrCallback ctx -> IO ()
freeBotanViewStrCallback = freeHaskellFunPtr