message: Check for a constant BLOB value and return ConstantExpression with BLOB.
diff: @@ -14,21 +14,15 @@ unique_ptr<ParsedExpression> Transformer::TransformTypeCast(PGTypeCast *root) {
  auto type_name = root->typeName;
  SQLType target_type = TransformTypeName(type_name);
  - //check by a constant BLOB value, then change PGAConstant value type to T_PGBitString
  + //check for a constant BLOB value, then return ConstantExpression with BLOB
  if(target_type == SQLType::BLOB && root->arg->type == T_PGAConst) {
  PGAConst *c = reinterpret_cast<PGAConst *>(root->arg);
  - c->val.type = T_PGBitString;
  + return make_unique<ConstantExpression>(SQLType::BLOB, Value::BLOB(string(c->val.val.str)));
  }
  // transform the expression node
  auto expression = TransformExpression(root->arg);
  -// //check by a constant VARCHAR value
  -// if(expression->type == ExpressionType::VALUE_CONSTANT && target_type == SQLType::VARCHAR) {
  -// auto constant_expression_ptr = static_cast<ConstantExpression*>(expression.get());
  -// //validating VARCHAR and scape BLOB strings
  -// constant_expression_ptr->value.ValidateString();
  -// }
  // now create a cast operation
  return make_unique<CastExpression>(target_type, move(expression));
  }
  