[llvm] 78a26c7 - [ADT] Add new type traits for type pack indexes
Scott Linder via llvm-commits
llvm-commits at lists.llvm.org
Wed Dec 15 11:26:17 PST 2021
Author: Scott Linder
Date: 2021-12-15T19:25:14Z
New Revision: 78a26c7dafc91e5f90e173c5914e374202141293
URL: https://github.com/llvm/llvm-project/commit/78a26c7dafc91e5f90e173c5914e374202141293
DIFF: https://github.com/llvm/llvm-project/commit/78a26c7dafc91e5f90e173c5914e374202141293.diff
LOG: [ADT] Add new type traits for type pack indexes
Similar versions of these already exist, this effectively just just
factors them out into STLExtras. I plan to use these in future patches.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D100672
Added:
Modified:
llvm/include/llvm/ADT/PointerUnion.h
llvm/include/llvm/ADT/STLExtras.h
llvm/unittests/ADT/STLExtrasTest.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/ADT/PointerUnion.h b/llvm/include/llvm/ADT/PointerUnion.h
index 0874f67db3fed..5ce2dbee4b3ad 100644
--- a/llvm/include/llvm/ADT/PointerUnion.h
+++ b/llvm/include/llvm/ADT/PointerUnion.h
@@ -16,6 +16,7 @@
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/PointerIntPair.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/PointerLikeTypeTraits.h"
#include <algorithm>
#include <cassert>
@@ -35,21 +36,6 @@ namespace pointer_union_detail {
return std::min<int>({PointerLikeTypeTraits<Ts>::NumLowBitsAvailable...});
}
- /// Find the index of a type in a list of types. TypeIndex<T, Us...>::Index
- /// is the index of T in Us, or sizeof...(Us) if T does not appear in the
- /// list.
- template <typename T, typename ...Us> struct TypeIndex;
- template <typename T, typename ...Us> struct TypeIndex<T, T, Us...> {
- static constexpr int Index = 0;
- };
- template <typename T, typename U, typename... Us>
- struct TypeIndex<T, U, Us...> {
- static constexpr int Index = 1 + TypeIndex<T, Us...>::Index;
- };
- template <typename T> struct TypeIndex<T> {
- static constexpr int Index = 0;
- };
-
/// Find the first type in a list of types.
template <typename T, typename...> struct GetFirstType {
using type = T;
@@ -116,6 +102,7 @@ namespace pointer_union_detail {
/// P = (float*)0;
/// Y = P.get<float*>(); // ok.
/// X = P.get<int*>(); // runtime assertion failure.
+/// PointerUnion<int*, int*> Q; // compile time failure.
template <typename... PTs>
class PointerUnion
: public pointer_union_detail::PointerUnionMembers<
@@ -124,12 +111,14 @@ class PointerUnion
void *, pointer_union_detail::bitsRequired(sizeof...(PTs)), int,
pointer_union_detail::PointerUnionUIntTraits<PTs...>>,
0, PTs...> {
+ static_assert(TypesAreDistinct<PTs...>::value,
+ "PointerUnion alternative types cannot be repeated");
// The first type is special because we want to directly cast a pointer to a
// default-initialized union to a pointer to the first type. But we don't
// want PointerUnion to be a 'template <typename First, typename ...Rest>'
// because it's much more convenient to have a name for the whole pack. So
// split off the first type here.
- using First = typename pointer_union_detail::GetFirstType<PTs...>::type;
+ using First = TypeAtIndex<0, PTs...>;
using Base = typename PointerUnion::PointerUnionMembers;
public:
@@ -146,10 +135,7 @@ class PointerUnion
/// Test if the Union currently holds the type matching T.
template <typename T> bool is() const {
- constexpr int Index = pointer_union_detail::TypeIndex<T, PTs...>::Index;
- static_assert(Index < sizeof...(PTs),
- "PointerUnion::is<T> given type not in the union");
- return this->Val.getInt() == Index;
+ return this->Val.getInt() == FirstIndexOfType<T, PTs...>::value;
}
/// Returns the value of the specified pointer type.
diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index f9b658ca960a6..2d38e153c79e0 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -144,6 +144,61 @@ template <typename ReturnType, typename... Args>
struct function_traits<ReturnType (&)(Args...), false>
: public function_traits<ReturnType (*)(Args...)> {};
+/// traits class for checking whether type T is one of any of the given
+/// types in the variadic list.
+template <typename T, typename... Ts>
+using is_one_of = disjunction<std::is_same<T, Ts>...>;
+
+/// traits class for checking whether type T is a base class for all
+/// the given types in the variadic list.
+template <typename T, typename... Ts>
+using are_base_of = conjunction<std::is_base_of<T, Ts>...>;
+
+namespace detail {
+template <typename T, typename... Us> struct TypesAreDistinct;
+template <typename T, typename... Us>
+struct TypesAreDistinct
+ : std::integral_constant<bool, !is_one_of<T, Us...>::value &&
+ TypesAreDistinct<Us...>::value> {};
+template <typename T> struct TypesAreDistinct<T> : std::true_type {};
+} // namespace detail
+
+/// Determine if all types in Ts are distinct.
+///
+/// Useful to statically assert when Ts is intended to describe a non-multi set
+/// of types.
+///
+/// Expensive (currently quadratic in sizeof(Ts...)), and so should only be
+/// asserted once per instantiation of a type which requires it.
+template <typename... Ts> struct TypesAreDistinct;
+template <> struct TypesAreDistinct<> : std::true_type {};
+template <typename... Ts>
+struct TypesAreDistinct
+ : std::integral_constant<bool, detail::TypesAreDistinct<Ts...>::value> {};
+
+/// Find the first index where a type appears in a list of types.
+///
+/// FirstIndexOfType<T, Us...>::value is the first index of T in Us.
+///
+/// Typically only meaningful when it is otherwise statically known that the
+/// type pack has no duplicate types. This should be guaranteed explicitly with
+/// static_assert(TypesAreDistinct<Us...>::value).
+///
+/// It is a compile-time error to instantiate when T is not present in Us, i.e.
+/// if is_one_of<T, Us...>::value is false.
+template <typename T, typename... Us> struct FirstIndexOfType;
+template <typename T, typename U, typename... Us>
+struct FirstIndexOfType<T, U, Us...>
+ : std::integral_constant<size_t, 1 + FirstIndexOfType<T, Us...>::value> {};
+template <typename T, typename... Us>
+struct FirstIndexOfType<T, T, Us...> : std::integral_constant<size_t, 0> {};
+
+/// Find the type at a given index in a list of types.
+///
+/// TypeAtIndex<I, Ts...> is the type at index I in Ts.
+template <size_t I, typename... Ts>
+using TypeAtIndex = std::tuple_element_t<I, std::tuple<Ts...>>;
+
//===----------------------------------------------------------------------===//
// Extra additions to <functional>
//===----------------------------------------------------------------------===//
diff --git a/llvm/unittests/ADT/STLExtrasTest.cpp b/llvm/unittests/ADT/STLExtrasTest.cpp
index c286cd5263a4d..f7079d2e706d2 100644
--- a/llvm/unittests/ADT/STLExtrasTest.cpp
+++ b/llvm/unittests/ADT/STLExtrasTest.cpp
@@ -905,4 +905,39 @@ TEST(STLExtrasTest, AllOfZip) {
all_of_zip(v1, v2, v_short, [](int, int, int) { return true; }));
}
+TEST(STLExtrasTest, TypesAreDistinct) {
+ EXPECT_TRUE((llvm::TypesAreDistinct<>::value));
+ EXPECT_TRUE((llvm::TypesAreDistinct<int>::value));
+ EXPECT_FALSE((llvm::TypesAreDistinct<int, int>::value));
+ EXPECT_TRUE((llvm::TypesAreDistinct<int, float>::value));
+ EXPECT_FALSE((llvm::TypesAreDistinct<int, float, int>::value));
+ EXPECT_TRUE((llvm::TypesAreDistinct<int, float, double>::value));
+ EXPECT_FALSE((llvm::TypesAreDistinct<int, float, double, float>::value));
+ EXPECT_TRUE((llvm::TypesAreDistinct<int, int *>::value));
+ EXPECT_TRUE((llvm::TypesAreDistinct<int, int &>::value));
+ EXPECT_TRUE((llvm::TypesAreDistinct<int, int &&>::value));
+ EXPECT_TRUE((llvm::TypesAreDistinct<int, const int>::value));
+}
+
+TEST(STLExtrasTest, FirstIndexOfType) {
+ EXPECT_EQ((llvm::FirstIndexOfType<int, int>::value), 0u);
+ EXPECT_EQ((llvm::FirstIndexOfType<int, int, int>::value), 0u);
+ EXPECT_EQ((llvm::FirstIndexOfType<int, float, int>::value), 1u);
+ EXPECT_EQ((llvm::FirstIndexOfType<int const *, float, int, int const *,
+ const int>::value),
+ 2u);
+}
+
+TEST(STLExtrasTest, TypeAtIndex) {
+ EXPECT_TRUE((std::is_same<int, llvm::TypeAtIndex<0, int>>::value));
+ EXPECT_TRUE((std::is_same<int, llvm::TypeAtIndex<0, int, float>>::value));
+ EXPECT_TRUE((std::is_same<float, llvm::TypeAtIndex<1, int, float>>::value));
+ EXPECT_TRUE(
+ (std::is_same<float, llvm::TypeAtIndex<1, int, float, double>>::value));
+ EXPECT_TRUE(
+ (std::is_same<float, llvm::TypeAtIndex<1, int, float, double>>::value));
+ EXPECT_TRUE(
+ (std::is_same<double, llvm::TypeAtIndex<2, int, float, double>>::value));
+}
+
} // namespace
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