fix: built-in function: support char_length() and character_length() function

hybridse/src/codegen/udf_ir_builder_test.cc

@@ -1007,6 +1007,13 @@ TEST_F(UdfIRBuilderTest, degrees) {
     CheckUdf<double, double>(udf_name, -90.0, -pi/2);
     CheckUdf<Nullable<double>, Nullable<double>>(udf_name, nullptr, nullptr);
 }
+TEST_F(UdfIRBuilderTest, char_length_udf_test) {
+    auto udf_name = "char_length";
+    CheckUdf<int32_t, StringRef>(udf_name, 10, StringRef("Spark SQL "));
+    CheckUdf<int32_t, StringRef>(udf_name, 10, StringRef("Spark SQL\n"));
+    CheckUdf<int32_t, Nullable<StringRef>>(udf_name, 0, StringRef(""));
+    CheckUdf<int32_t, Nullable<StringRef>>(udf_name, 0, nullptr);
+}
 TEST_F(UdfIRBuilderTest, degree_to_radius_check) {
     auto udf_name = "radians";
     CheckUdf<double, double>(udf_name, 3.141592653589793238463, 180);

hybridse/src/udf/default_udf_library.cc

@@ -895,6 +895,19 @@ void DefaultUdfLibrary::InitStringUdf() {
             @since 0.4.0)");
     RegisterAlias("lower", "lcase");
     RegisterAlias("upper", "ucase");
+    RegisterExternal("char_length")
+        .args<StringRef>(static_cast<int32_t (*)(StringRef*)>(udf::v1::char_length))
+        .doc(R"(
+            @brief Returns the length of the string. It is measured in characters and multibyte character string is not supported.
+
+            Example:
+
+            @code{.sql}
+                SELECT CHAR_LENGTH('Spark SQL ');
+                --output 10
+            @endcode
+            @since 0.6.0)");
+    RegisterAlias("character_length", "char_length");
 }
 
 void DefaultUdfLibrary::InitMathUdf() {

hybridse/src/udf/udf.cc

@@ -157,6 +157,14 @@ int32_t weekofyear(Date *date) {
     }
 }
 
+int32_t char_length(StringRef *str) {
+    if (nullptr == str) {
+        return 0;
+    }
+    int32_t res = str->size_;
+    return res;
+}
+
 float Cotf(float x) { return cosf(x) / sinf(x); }
 
 double degree_to_radius(double degree) {

hybridse/src/udf/udf.h

@@ -224,6 +224,7 @@ int32_t weekofyear(int64_t ts);
 int32_t weekofyear(Timestamp *ts);
 int32_t weekofyear(Date *ts);
 
+int32_t char_length(StringRef *str);
 double degree_to_radius(double degree);
 
 float Cotf(float x);