Block constructor

Block(Function function)

Creating a Block from a Function.

NOTE: The arguments of function should be wrapper class which can represent native type, such as unsigned_int or custom wrapper class with the same name. When you create a Block, you release it using Block_release after use.

Implementation

factory Block(Function function) {
  List<String> dartTypes = dartTypeStringForFunction(function);
  bool shouldReturnAsync = dartTypes.first.startsWith('Future');
  // block receives results from dart function asynchronously by appending a callback function to arguments.
  if (shouldReturnAsync) {
    dartTypes.add('Function');
  }
  List<String> nativeTypes = nativeTypeStringForDartTypes(dartTypes);
  Pointer<Utf8> typeStringPtr = nativeTypes.join(', ').toNativeUtf8();
  Pointer<Void> blockPtr = blockCreate(
      typeStringPtr, _callbackPtr, shouldReturnAsync ? 1 : 0, nativePort);
  assert(blockPtr != nullptr);
  if (blockPtr == nullptr) {
    return nilBlock;
  }
  int sequence = _blockSequence(blockPtr);
  Block result = Block.fromPointer(blockPtr, function: function);
  calloc.free(typeStringPtr);
  result.types = dartTypes;
  result.shouldReturnAsync = shouldReturnAsync;
  result.typeEncodingsPtrPtr = _blockTypeEncodings(blockPtr);
  result.sequence = sequence;
  if (blockForSequence[sequence] != null) {
    throw 'Already exists a block on sequence $sequence';
  }
  blockForSequence[sequence] = result;
  return result;
}