Recommit r334887: [SmallSet] Add SmallSetIterator.

Spell out destructor, copy/move constructor and assignment operators for
MSVC STL, where set<T>::const_iterator is not trivially copy constructible.

llvm-svn: 337292
This commit is contained in:
Florian Hahn 2018-07-17 15:24:19 +00:00
parent 4ab5731973
commit c491c2b955
2 changed files with 156 additions and 0 deletions
llvm
include/llvm/ADT
unittests/ADT

View File

@ -17,14 +17,102 @@
#include "llvm/ADT/None.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/iterator.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/type_traits.h"
#include <cstddef>
#include <functional>
#include <set>
#include <type_traits>
#include <utility>
namespace llvm {
/// SmallSetIterator - This class implements a const_iterator for SmallSet by
/// delegating to the underlying SmallVector or Set iterators.
template <typename T, unsigned N, typename C>
class SmallSetIterator
: public iterator_facade_base<SmallSetIterator<T, N, C>,
std::forward_iterator_tag, T> {
private:
using SetIterTy = typename std::set<T, C>::const_iterator;
using VecIterTy = typename SmallVector<T, N>::const_iterator;
using SelfTy = SmallSetIterator<T, N, C>;
/// Iterators to the parts of the SmallSet containing the data. They are set
/// depending on isSmall.
union {
SetIterTy SetIter;
VecIterTy VecIter;
};
bool isSmall;
public:
SmallSetIterator(SetIterTy SetIter) : SetIter(SetIter), isSmall(false) {}
SmallSetIterator(VecIterTy VecIter) : VecIter(VecIter), isSmall(true) {}
// Spell out destructor, copy/move constructor and assignment operators for
// MSVC STL, where set<T>::const_iterator is not trivially copy constructible.
~SmallSetIterator() {
if (isSmall)
VecIter.~VecIterTy();
else
SetIter.~SetIterTy();
}
SmallSetIterator(const SmallSetIterator &Other) : isSmall(Other.isSmall) {
if (isSmall)
VecIter = Other.VecIter;
else
SetIter = Other.SetIter;
}
SmallSetIterator(SmallSetIterator &&Other) : isSmall(Other.isSmall) {
if (isSmall)
VecIter = std::move(Other.VecIter);
else
SetIter = std::move(Other.SetIter);
}
SmallSetIterator& operator=(const SmallSetIterator& Other) {
isSmall = Other.isSmall;
if (isSmall)
VecIter = Other.VecIter;
else
SetIter = Other.SetIter;
return *this;
}
SmallSetIterator& operator=(SmallSetIterator&& Other) {
isSmall = Other.isSmall;
if (isSmall)
VecIter = std::move(Other.VecIter);
else
SetIter = std::move(Other.SetIter);
return *this;
}
bool operator==(const SmallSetIterator &RHS) const {
if (isSmall != RHS.isSmall)
return false;
if (isSmall)
return VecIter == RHS.VecIter;
return SetIter == RHS.SetIter;
}
SmallSetIterator &operator++() { // Preincrement
if (isSmall)
VecIter++;
else
SetIter++;
return *this;
}
const T &operator*() const { return isSmall ? *VecIter : *SetIter; }
};
/// SmallSet - This maintains a set of unique values, optimizing for the case
/// when the set is small (less than N). In this case, the set can be
/// maintained with no mallocs. If the set gets large, we expand to using an
@ -50,6 +138,7 @@ class SmallSet {
public:
using size_type = size_t;
using const_iterator = SmallSetIterator<T, N, C>;
SmallSet() = default;
@ -121,6 +210,18 @@ public:
Set.clear();
}
const_iterator begin() const {
if (isSmall())
return {Vector.begin()};
return {Set.begin()};
}
const_iterator end() const {
if (isSmall())
return {Vector.end()};
return {Set.end()};
}
private:
bool isSmall() const { return Set.empty(); }

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@ -13,6 +13,7 @@
#include "llvm/ADT/SmallSet.h"
#include "gtest/gtest.h"
#include <string>
using namespace llvm;
@ -68,3 +69,57 @@ TEST(SmallSetTest, Erase) {
EXPECT_EQ(0u, s1.count(8));
}
TEST(SmallSetTest, IteratorInt) {
SmallSet<int, 4> s1;
// Test the 'small' case.
for (int i = 0; i < 3; i++)
s1.insert(i);
std::vector<int> V(s1.begin(), s1.end());
// Make sure the elements are in the expected order.
std::sort(V.begin(), V.end());
for (int i = 0; i < 3; i++)
EXPECT_EQ(i, V[i]);
// Test the 'big' case by adding a few more elements to switch to std::set
// internally.
for (int i = 3; i < 6; i++)
s1.insert(i);
V.assign(s1.begin(), s1.end());
// Make sure the elements are in the expected order.
std::sort(V.begin(), V.end());
for (int i = 0; i < 6; i++)
EXPECT_EQ(i, V[i]);
}
TEST(SmallSetTest, IteratorString) {
// Test SmallSetIterator for SmallSet with a type with non-trivial
// ctors/dtors.
SmallSet<std::string, 2> s1;
s1.insert("str 1");
s1.insert("str 2");
s1.insert("str 1");
std::vector<std::string> V(s1.begin(), s1.end());
std::sort(V.begin(), V.end());
EXPECT_EQ(2u, s1.size());
EXPECT_EQ("str 1", V[0]);
EXPECT_EQ("str 2", V[1]);
s1.insert("str 4");
s1.insert("str 0");
s1.insert("str 4");
V.assign(s1.begin(), s1.end());
// Make sure the elements are in the expected order.
std::sort(V.begin(), V.end());
EXPECT_EQ(4u, s1.size());
EXPECT_EQ("str 0", V[0]);
EXPECT_EQ("str 1", V[1]);
EXPECT_EQ("str 2", V[2]);
EXPECT_EQ("str 4", V[3]);
}