Test sample for HString stuff

HStringReference.cpp

// References:
// https://docs.microsoft.com/en-us/cpp/cppcx/wrl/how-to-activate-and-use-a-windows-runtime-component-using-wrl?view=vs-2019
// https://chromium.googlesource.com/chromium/src/+/master/base/win/hstring_reference_unittest.cc

// This is compiled by: `$HOME/.mozbuild/clang/bin/clang-cl.exe HStringReference.cpp`
// or `cl.exe HStringReference.cpp runtimeobject.lib` in `Developer Command Prompt`

#include <assert.h>                     // assert
#include <wchar.h>                      // wcscmp
#include <wrl\wrappers\corewrappers.h>  // HStringReference

#pragma comment(lib, "runtimeobject.lib")

// To shorten the Microsoft::WRL::Wrappers::HStringReference:
using namespace Microsoft::WRL::Wrappers;

constexpr wchar_t kTestString[] = L"123";
constexpr wchar_t kEmptyString[] = L"";

int main() {
    unsigned int length = 0;
    const wchar_t* raw = nullptr;

    // normal string
    const HStringReference string(kTestString);
    assert(string.Get() != nullptr); // HSTRING
    raw = string.GetRawBuffer(&length);
    wprintf(L"kTestString(%s): raw: %s, length: %d\n", kTestString, raw, length);
    assert(raw != nullptr);
    assert(wcscmp(raw, kTestString) == 0);
    assert(length == 3);

    // empty string
    const HStringReference empty_string(kEmptyString);
    assert(empty_string.Get() == nullptr); // HSTRING
    raw = empty_string.GetRawBuffer(&length);
    wprintf(L"kEmptyString(%s): raw: %s, length: %d\n", kEmptyString, raw, length);
    assert(raw != nullptr);
    assert(wcscmp(raw, kEmptyString) == 0);
    assert(length == 0);

    // null string
    // const HStringReference null_string(nullptr); // Segmentation fault
    // HSTRING null_string(nullptr); // This is ok.

    return 0;
}