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Commit aa68d0a1 authored by Ady Abraham's avatar Ady Abraham
Browse files

ftl: add enum_string_full which includes the enum class name 

Bug: 300701739
Test: presubmit
Change-Id: I235275b5d299efea779851434c392ca4e07ca4fd
parent 290dc935

include/ftl/enum.h

+72 −7
Original line number Diff line number Diff line
@@ -25,12 +25,12 @@ 


#include <ftl/string.h>



// Returns the name of enumerator E::V (i.e. "V") as std::optional<std::string_view> by parsing the

// compiler-generated string literal for the signature of this function. The function is defined in

// the global namespace with a short name and inferred return type to reduce bloat in the read-only

// data segment.

template <typename E, E V>

constexpr auto ftl_enum() {

// Returns the name of enumerator E::V and optionally the class (i.e. "E::V" or "V") as

// std::optional<std::string_view> by parsing the compiler-generated string literal for the

// signature of this function. The function is defined in the global namespace with a short name

// and inferred return type to reduce bloat in the read-only data segment.

template <bool S, typename E, E V>

constexpr auto ftl_enum_builder() {

  static_assert(std::is_enum_v<E>);



  using R = std::optional<std::string_view>;
@@ -58,7 +58,9 @@ constexpr auto ftl_enum() { 
  //   V = android::test::Enum::kValue

  //

  view = view.substr(value_begin);

  const auto name_begin = view.rfind("::"sv);

  const auto pos = S ? view.rfind("::"sv) - 2 : view.npos;



  const auto name_begin = view.rfind("::"sv, pos);

  if (name_begin == view.npos) return R{};



  // Chop off the leading "::".
@@ -68,6 +70,18 @@ constexpr auto ftl_enum() { 
  return name.find(')') == view.npos ? R{name} : R{};

}



// Returns the name of enumerator E::V (i.e. "V") as std::optional<std::string_view>

template <typename E, E V>

constexpr auto ftl_enum() {

  return ftl_enum_builder<false, E, V>();

}



// Returns the name of enumerator and class E::V (i.e. "E::V") as std::optional<std::string_view>

template <typename E, E V>

constexpr auto ftl_enum_full() {

  return ftl_enum_builder<true, E, V>();

}



namespace android::ftl {



// Trait for determining whether a type is specifically a scoped enum or not. By definition, a
@@ -191,6 +205,11 @@ struct EnumName { 
  static constexpr auto value = ftl_enum<decltype(V), V>();

};



template <auto V>

struct EnumNameFull {

  static constexpr auto value = ftl_enum_full<decltype(V), V>();

};



template <auto I>

struct FlagName {

  using E = decltype(I);
@@ -230,6 +249,18 @@ constexpr std::string_view enum_name() { 
  return *kName;

}



// Returns a stringified enumerator with class at compile time.

//

//   enum class E { A, B, C };

//   static_assert(ftl::enum_name<E::B>() == "E::B");

//

template <auto V>

constexpr std::string_view enum_name_full() {

  constexpr auto kName = ftl_enum_full<decltype(V), V>();

  static_assert(kName, "Unknown enumerator");

  return *kName;

}



// Returns a stringified enumerator, possibly at compile time.

//

//   enum class E { A, B, C, F = 5, ftl_last = F };
@@ -249,6 +280,25 @@ constexpr std::optional<std::string_view> enum_name(E v) { 
  return kRange.values[value - kBegin];

}



// Returns a stringified enumerator with class, possibly at compile time.

//

//   enum class E { A, B, C, F = 5, ftl_last = F };

//

//   static_assert(ftl::enum_name(E::C).value_or("?") == "E::C");

//   static_assert(ftl::enum_name(E{3}).value_or("?") == "?");

//

template <typename E>

constexpr std::optional<std::string_view> enum_name_full(E v) {

  const auto value = to_underlying(v);



  constexpr auto kBegin = to_underlying(enum_begin_v<E>);

  constexpr auto kLast = to_underlying(enum_last_v<E>);

  if (value < kBegin || value > kLast) return {};



  constexpr auto kRange = details::EnumRange<E, details::EnumNameFull>{};

  return kRange.values[value - kBegin];

}



// Returns a stringified flag enumerator, possibly at compile time.

//

//   enum class F : std::uint16_t { X = 0b1, Y = 0b10, Z = 0b100 };
@@ -282,6 +332,21 @@ inline std::string enum_string(E v) { 
  return to_string(to_underlying(v));

}



// Returns a stringified enumerator with class, or its integral value if not named.

//

//   enum class E { A, B, C, F = 5, ftl_last = F };

//

//   assert(ftl::enum_string(E::C) == "E::C");

//   assert(ftl::enum_string(E{3}) == "3");

//

template <typename E>

inline std::string enum_string_full(E v) {

  if (const auto name = enum_name_full(v)) {

      return std::string(*name);

  }

  return to_string(to_underlying(v));

}



// Returns a stringified flag enumerator, or its integral value if not named.

//

//   enum class F : std::uint16_t { X = 0b1, Y = 0b10, Z = 0b100 };

libs/ftl/enum_test.cpp

+38 −0
Original line number Diff line number Diff line
@@ -33,6 +33,11 @@ static_assert(ftl::enum_name<E::ftl_last>() == "F"); 
static_assert(ftl::enum_name(E::C).value_or("?") == "C");

static_assert(ftl::enum_name(E{3}).value_or("?") == "?");



static_assert(ftl::enum_name_full<E::B>() == "E::B");

static_assert(ftl::enum_name_full<E::ftl_last>() == "E::F");

static_assert(ftl::enum_name_full(E::C).value_or("?") == "E::C");

static_assert(ftl::enum_name_full(E{3}).value_or("?") == "?");



enum class F : std::uint16_t { X = 0b1, Y = 0b10, Z = 0b100 };



static_assert(ftl::enum_begin_v<F> == F{0});
@@ -60,6 +65,10 @@ static_assert(ftl::enum_name<Flags::kNone>() == "kNone"); 
static_assert(ftl::enum_name<Flags::kFlag4>() == "kFlag4");

static_assert(ftl::enum_name<Flags::kFlag7>() == "kFlag7");



static_assert(ftl::enum_name_full<Flags::kNone>() == "Flags::kNone");

static_assert(ftl::enum_name_full<Flags::kFlag4>() == "Flags::kFlag4");

static_assert(ftl::enum_name_full<Flags::kFlag7>() == "Flags::kFlag7");



// Though not flags, the enumerators are within the implicit range of bit indices.

enum class Planet : std::uint8_t {

  kMercury,
@@ -81,6 +90,9 @@ static_assert(ftl::enum_size_v<Planet> == 8); 
static_assert(ftl::enum_name<Planet::kMercury>() == "kMercury");

static_assert(ftl::enum_name<Planet::kSaturn>() == "kSaturn");



static_assert(ftl::enum_name_full<Planet::kMercury>() == "Planet::kMercury");

static_assert(ftl::enum_name_full<Planet::kSaturn>() == "Planet::kSaturn");



// Unscoped enum must define explicit range, even if the underlying type is fixed.

enum Temperature : int {

  kRoom = 20,
@@ -122,16 +134,28 @@ TEST(Enum, Name) { 
    EXPECT_EQ(ftl::enum_name(Planet::kEarth), "kEarth");

    EXPECT_EQ(ftl::enum_name(Planet::kNeptune), "kNeptune");



    EXPECT_EQ(ftl::enum_name_full(Planet::kEarth), "Planet::kEarth");

    EXPECT_EQ(ftl::enum_name_full(Planet::kNeptune), "Planet::kNeptune");



    EXPECT_EQ(ftl::enum_name(kPluto), std::nullopt);

    EXPECT_EQ(ftl::enum_name_full(kPluto), std::nullopt);

  }

  {

    EXPECT_EQ(ftl::enum_name(kRoom), "kRoom");

    EXPECT_EQ(ftl::enum_name(kFridge), "kFridge");

    EXPECT_EQ(ftl::enum_name(kFreezer), "kFreezer");



    EXPECT_EQ(ftl::enum_name(kRoom), "kRoom");

    EXPECT_EQ(ftl::enum_name(kFridge), "kFridge");

    EXPECT_EQ(ftl::enum_name(kFreezer), "kFreezer");



    EXPECT_EQ(ftl::enum_name(static_cast<Temperature>(-30)), std::nullopt);

    EXPECT_EQ(ftl::enum_name(static_cast<Temperature>(0)), std::nullopt);

    EXPECT_EQ(ftl::enum_name(static_cast<Temperature>(100)), std::nullopt);



    EXPECT_EQ(ftl::enum_name_full(static_cast<Temperature>(-30)), std::nullopt);

    EXPECT_EQ(ftl::enum_name_full(static_cast<Temperature>(0)), std::nullopt);

    EXPECT_EQ(ftl::enum_name_full(static_cast<Temperature>(100)), std::nullopt);

  }

}
@@ -158,16 +182,30 @@ TEST(Enum, String) { 
    EXPECT_EQ(ftl::enum_string(Planet::kEarth), "kEarth");

    EXPECT_EQ(ftl::enum_string(Planet::kNeptune), "kNeptune");



    EXPECT_EQ(ftl::enum_string_full(Planet::kEarth), "Planet::kEarth");

    EXPECT_EQ(ftl::enum_string_full(Planet::kNeptune), "Planet::kNeptune");



    EXPECT_EQ(ftl::enum_string(kPluto), "8");



    EXPECT_EQ(ftl::enum_string_full(kPluto), "8");



  }

  {

    EXPECT_EQ(ftl::enum_string(kRoom), "kRoom");

    EXPECT_EQ(ftl::enum_string(kFridge), "kFridge");

    EXPECT_EQ(ftl::enum_string(kFreezer), "kFreezer");



    EXPECT_EQ(ftl::enum_string_full(kRoom), "20");

    EXPECT_EQ(ftl::enum_string_full(kFridge), "4");

    EXPECT_EQ(ftl::enum_string_full(kFreezer), "-18");



    EXPECT_EQ(ftl::enum_string(static_cast<Temperature>(-30)), "-30");

    EXPECT_EQ(ftl::enum_string(static_cast<Temperature>(0)), "0");

    EXPECT_EQ(ftl::enum_string(static_cast<Temperature>(100)), "100");



    EXPECT_EQ(ftl::enum_string_full(static_cast<Temperature>(-30)), "-30");

    EXPECT_EQ(ftl::enum_string_full(static_cast<Temperature>(0)), "0");

    EXPECT_EQ(ftl::enum_string_full(static_cast<Temperature>(100)), "100");

  }

}