capitalize() should match first character regardless of whether it is alphanumeric

Author: waybeforenow

src/string_converter_filter.cpp

@@ -304,15 +304,18 @@ InternalValue StringConverter::Filter(const InternalValue& baseVal, RenderContex
         result = Apply<UrlStringEncoder>(baseVal);
         break;
     case CapitalMode:
-        result = ApplyStringConverter<GenericStringEncoder>(baseVal, [isFirstChar = true, &isAlNum](auto ch, auto&& fn) mutable {
-            if (isFirstChar && isAlNum(ch)) {
-                isFirstChar = false;
-                fn(std::toupper(ch, std::locale()));
-            } else if (isAlNum(ch)) {
-                fn(std::tolower(ch, std::locale()));
+        result = ApplyStringConverter<GenericStringEncoder>(baseVal, [isFirstChar = true, &isAlpha](auto ch, auto&& fn) mutable {
+            if (isAlpha(ch)) {
+                if (isFirstChar) {
+                    fn(std::toupper(ch, std::locale()));
+                } else {
+                    fn(std::tolower(ch, std::locale()));
+                }
             } else {
                 fn(ch);
             }
+
+            isFirstChar = false;
         });
         break;
     default:

test/filters_test.cpp

@@ -473,6 +473,7 @@ INSTANTIATE_TEST_CASE_P(Capitalize, FilterGenericTest, ::testing::Values(
                             InputOutputPair{"'1234string' | capitalize | pprint", "'1234string'"},
                             InputOutputPair{"'1234String' | capitalize | pprint", "'1234string'"},
                             InputOutputPair{"'Hello World' | capitalize | pprint", "'Hello world'"},
+                            InputOutputPair{"' Hello World' | capitalize | pprint", "' hello world'"},
                             InputOutputPair{"'Hello123OOO, World!' | capitalize | pprint", "'Hello123ooo, world!'"}
                             ));