[NSE-661] Add trim expression support in WSCG (#664)

* Add trim expression support in WSCG

* Fix a bug

* Format the code

native-sql-engine/cpp/src/codegen/arrow_compute/ext/expression_codegen_visitor.cc

@@ -303,6 +303,37 @@ arrow::Status ExpressionCodegenVisitor::Visit(const gandiva::FunctionNode& node)
     prepare_ss << "if (" << check_str_ << ")" << std::endl;
     prepare_ss << codes_str_ << " = " << ss.str() << ";" << std::endl;
     prepare_str_ += prepare_ss.str();
+  } else if (func_name.compare("btrim") == 0) {
+    codes_str_ = func_name + "_" + std::to_string(cur_func_id);
+    auto validity = codes_str_ + "_validity";
+    real_codes_str_ = codes_str_;
+    real_validity_str_ = validity;
+    std::stringstream prepare_ss;
+    prepare_ss << GetCTypeString(node.return_type()) << " " << codes_str_ << ";"
+               << std::endl;
+    prepare_ss << "bool " << validity << " = " << child_visitor_list[0]->GetPreCheck()
+               << ";" << std::endl;
+    prepare_ss << "if (" << validity << ") {" << std::endl;
+    prepare_ss << "std::string arg = " << child_visitor_list[0]->GetResult() << ";"
+               << std::endl;
+    prepare_ss << "int start_index = 0, end_index = arg.length() - 1;" << std::endl;
+    prepare_ss << "while (start_index <= end_index && arg[start_index] == ' ') {"
+               << std::endl;
+    prepare_ss << "start_index++;" << std::endl;
+    prepare_ss << "}" << std::endl;
+    prepare_ss << "while (end_index >= start_index && arg[end_index] == ' ') {"
+               << std::endl;
+    prepare_ss << "end_index--;" << std::endl;
+    prepare_ss << "}" << std::endl;
+    prepare_ss << codes_str_ << " = arg.substr(start_index, end_index - start_index + 1);"
+               << std::endl;
+    prepare_ss << "}" << std::endl;
+    for (int i = 0; i < 1; i++) {
+      prepare_str_ += child_visitor_list[i]->GetPrepare();
+    }
+    prepare_str_ += prepare_ss.str();
+    check_str_ = validity;
+
   } else if (func_name.compare("upper") == 0) {
     std::stringstream prepare_ss;
     auto child_name = child_visitor_list[0]->GetResult();