Method StartsWith

Bcore/src/main/cpp/Dobby/tests/catch.hpp:2853–2854

struct StartsWith : StringHolder {
  StartsWith(NSString *substr) : StringHolder(substr) {
  }

  bool match(NSString *str) const override {
    return (str != nil || m_substr == nil) && [str rangeOfString:m_substr].location == 0;