Eval.hs

{-# LANGUAGE QuasiQuotes     #-}
{-# LANGUAGE TemplateHaskell #-}
-- |
-- Interface to python's @eval@ and @exec@ which gives programmer
-- control over local and global variables.
module Python.Inline.Eval
  ( -- * Python execution
    eval
  , exec
    -- * Source code
  , PyQuote(..)
  , Code
  , codeFromText
  , codeFromString
  , DictBinder
  , bindVar
    -- * Variable namespaces
  , Namespace(..)
  , Main(..)
  , Temp(..)
  , Dict(..)
  , Module(..)
  ) where

import Data.ByteString.Unsafe     qualified as BS
import Data.Text                  (Text)
import Data.Text.Encoding         qualified as T
import Language.C.Inline          qualified as C
import Language.C.Inline.Unsafe   qualified as CU

import Python.Internal.Types
import Python.Internal.Eval
import Python.Internal.Program
import Python.Inline.Literal


----------------------------------------------------------------
C.context (C.baseCtx <> pyCtx)
C.include "<inline-python.h>"
----------------------------------------------------------------

-- | Bind variable in dictionary
bindVar
  :: (ToPy a)
  => Text -- ^ Variable name
  -> a    -- ^ Variable value
  -> DictBinder
bindVar name a = DictBinder $ \p_dict -> runProgram $ do
  p_key <- progIOBracket $ BS.unsafeUseAsCString (T.encodeUtf8 name)
  p_obj <- takeOwnership =<< progPy (throwOnNULL =<< basicToPy a)
  progPy $ do
    r <- Py [CU.block| int {
      PyObject* p_obj = $(PyObject* p_obj);
      return PyDict_SetItemString($(PyObject* p_dict), $(char* p_key), p_obj);
      } |]
    case r of
      0 -> pure ()
      _ -> mustThrowPyError