DartType? getExpectedType()

in lib/src/rules/unnecessary_null_checks.dart [39:83]

• 44 lines of code
• 17 McCabe index (conditional complexity)

DartType? getExpectedType(PostfixExpression node) {
  var realNode =
      node.thisOrAncestorMatching((e) => e.parent is! ParenthesizedExpression);
  var parent = realNode?.parent;

  // in return value
  if (parent is ReturnStatement || parent is ExpressionFunctionBody) {
    var parentExpression = parent?.thisOrAncestorOfType<FunctionExpression>();
    if (parentExpression == null) {
      return null;
    }
    var staticType = parentExpression.staticType;
    return staticType is FunctionType ? staticType.returnType : null;
  }
  // assignment
  if (parent is AssignmentExpression &&
      parent.operator.type == TokenType.EQ &&
      (parent.leftHandSide is! Identifier ||
          node.operand is! Identifier ||
          (parent.leftHandSide as Identifier).name !=
              (node.operand as Identifier).name)) {
    return parent.writeType;
  }
  // in variable declaration
  if (parent is VariableDeclaration) {
    return parent.declaredElement?.type;
  }
  // as right member of binary operator
  if (parent is BinaryExpression && parent.rightOperand == realNode) {
    var parentElement = parent.staticElement;
    if (parentElement == null) {
      return null;
    }
    return parentElement.parameters.first.type;
  }
  // as parameter of function
  if (parent is NamedExpression) {
    realNode = parent;
    parent = parent.parent;
  }
  if (parent is ArgumentList && realNode is Expression) {
    return realNode.staticParameterElement?.type;
  }
  return null;
}