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https://github.com/juce-framework/JUCE.git
synced 2026-02-04 03:40:07 +00:00
String: Avoid using refcount to detect empty strings
This commit is contained in:
reuk
parent
5705a83065
commit
5fcb718ac9
1 changed files with 61 additions and 68 deletions
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@ -45,40 +45,40 @@ static CharPointer_wchar_t castToCharPointer_wchar_t (const void* t) noexcept
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}
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//==============================================================================
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// (Mirrors the structure of StringHolder, but without the atomic member, so can be statically constructed)
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struct EmptyString
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struct StringHolder
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{
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int refCount;
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size_t allocatedBytes;
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String::CharPointerType::CharType text;
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};
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static const EmptyString emptyString { 0x3fffffff, sizeof (String::CharPointerType::CharType), 0 };
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//==============================================================================
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class StringHolder
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{
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public:
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StringHolder() = delete;
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using CharPointerType = String::CharPointerType;
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using CharType = String::CharPointerType::CharType;
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//==============================================================================
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std::atomic<int> refCount { 0 };
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size_t allocatedNumBytes = sizeof (CharType);
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CharType text[1] { 0 };
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};
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constexpr StringHolder emptyString;
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//==============================================================================
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class StringHolderUtils
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{
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public:
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using CharPointerType = StringHolder::CharPointerType;
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using CharType = StringHolder::CharType;
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static CharPointerType createUninitialisedBytes (size_t numBytes)
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{
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numBytes = (numBytes + 3) & ~(size_t) 3;
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auto s = unalignedPointerCast<StringHolder*> (new char [sizeof (StringHolder) - sizeof (CharType) + numBytes]);
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s->refCount.value = 0;
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auto* bytes = new char [sizeof (StringHolder) - sizeof (CharType) + numBytes];
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auto s = unalignedPointerCast<StringHolder*> (bytes);
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s->refCount = 0;
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s->allocatedNumBytes = numBytes;
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return CharPointerType (s->text);
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return CharPointerType (unalignedPointerCast<CharType*> (bytes + offsetof (StringHolder, text)));
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}
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template <class CharPointer>
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static CharPointerType createFromCharPointer (const CharPointer text)
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{
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if (text.getAddress() == nullptr || text.isEmpty())
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return CharPointerType (&(emptyString.text));
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return CharPointerType (emptyString.text);
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auto bytesNeeded = sizeof (CharType) + CharPointerType::getBytesRequiredFor (text);
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auto dest = createUninitialisedBytes (bytesNeeded);
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@ -90,7 +90,7 @@ public:
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static CharPointerType createFromCharPointer (const CharPointer text, size_t maxChars)
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{
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if (text.getAddress() == nullptr || text.isEmpty() || maxChars == 0)
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return CharPointerType (&(emptyString.text));
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return CharPointerType (emptyString.text);
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auto end = text;
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size_t numChars = 0;
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@ -111,7 +111,7 @@ public:
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static CharPointerType createFromCharPointer (const CharPointer start, const CharPointer end)
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{
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if (start.getAddress() == nullptr || start.isEmpty())
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return CharPointerType (&(emptyString.text));
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return CharPointerType (emptyString.text);
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auto e = start;
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int numChars = 0;
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@ -131,7 +131,7 @@ public:
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static CharPointerType createFromCharPointer (const CharPointerType start, const CharPointerType end)
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{
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if (start.getAddress() == nullptr || start.isEmpty())
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return CharPointerType (&(emptyString.text));
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return CharPointerType (emptyString.text);
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auto numBytes = (size_t) (reinterpret_cast<const char*> (end.getAddress())
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- reinterpret_cast<const char*> (start.getAddress()));
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@ -171,7 +171,7 @@ public:
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static int getReferenceCount (const CharPointerType text) noexcept
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{
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return bufferFromText (text)->refCount.get() + 1;
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return bufferFromText (text)->refCount + 1;
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}
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//==============================================================================
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@ -186,7 +186,7 @@ public:
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return newText;
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}
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if (b->allocatedNumBytes >= numBytes && b->refCount.get() <= 0)
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if (b->allocatedNumBytes >= numBytes && b->refCount <= 0)
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return text;
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auto newText = createUninitialisedBytes (jmax (b->allocatedNumBytes, numBytes));
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@ -201,22 +201,18 @@ public:
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return bufferFromText (text)->allocatedNumBytes;
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}
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//==============================================================================
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Atomic<int> refCount;
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size_t allocatedNumBytes;
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CharType text[1];
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private:
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static StringHolder* bufferFromText (const CharPointerType text) noexcept
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StringHolderUtils() = delete;
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~StringHolderUtils() = delete;
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static StringHolder* bufferFromText (const CharPointerType charPtr) noexcept
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{
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// (Can't use offsetof() here because of warnings about this not being a POD)
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return unalignedPointerCast<StringHolder*> (reinterpret_cast<char*> (text.getAddress())
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- (reinterpret_cast<size_t> (reinterpret_cast<StringHolder*> (128)->text) - 128));
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return unalignedPointerCast<StringHolder*> (unalignedPointerCast<char*> (charPtr.getAddress()) - offsetof (StringHolder, text));
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}
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static bool isEmptyString (StringHolder* other)
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{
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return (other->refCount.get() & 0x30000000) != 0;
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return other == &emptyString;
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}
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void compileTimeChecks()
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@ -231,25 +227,22 @@ private:
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#else
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#error "native wchar_t size is unknown"
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#endif
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static_assert (sizeof (EmptyString) == sizeof (StringHolder),
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"StringHolder is not large enough to hold an empty String");
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}
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};
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//==============================================================================
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String::String() noexcept : text (&(emptyString.text))
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String::String() noexcept : text (emptyString.text)
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{
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}
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String::~String() noexcept
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{
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StringHolder::release (text);
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StringHolderUtils::release (text);
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}
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String::String (const String& other) noexcept : text (other.text)
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{
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StringHolder::retain (text);
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StringHolderUtils::retain (text);
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}
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void String::swapWith (String& other) noexcept
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@ -259,20 +252,20 @@ void String::swapWith (String& other) noexcept
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void String::clear() noexcept
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{
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StringHolder::release (text);
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text = &(emptyString.text);
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StringHolderUtils::release (text);
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text = emptyString.text;
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}
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String& String::operator= (const String& other) noexcept
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{
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StringHolder::retain (other.text);
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StringHolder::release (text.atomicSwap (other.text));
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StringHolderUtils::retain (other.text);
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StringHolderUtils::release (text.atomicSwap (other.text));
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return *this;
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}
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String::String (String&& other) noexcept : text (other.text)
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{
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other.text = &(emptyString.text);
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other.text = emptyString.text;
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}
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String& String::operator= (String&& other) noexcept
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@ -284,23 +277,23 @@ String& String::operator= (String&& other) noexcept
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inline String::PreallocationBytes::PreallocationBytes (const size_t num) noexcept : numBytes (num) {}
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String::String (const PreallocationBytes& preallocationSize)
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: text (StringHolder::createUninitialisedBytes (preallocationSize.numBytes + sizeof (CharPointerType::CharType)))
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: text (StringHolderUtils::createUninitialisedBytes (preallocationSize.numBytes + sizeof (CharPointerType::CharType)))
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{
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}
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void String::preallocateBytes (const size_t numBytesNeeded)
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{
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text = StringHolder::makeUniqueWithByteSize (text, numBytesNeeded + sizeof (CharPointerType::CharType));
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text = StringHolderUtils::makeUniqueWithByteSize (text, numBytesNeeded + sizeof (CharPointerType::CharType));
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}
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int String::getReferenceCount() const noexcept
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{
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return StringHolder::getReferenceCount (text);
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return StringHolderUtils::getReferenceCount (text);
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}
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//==============================================================================
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String::String (const char* const t)
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: text (StringHolder::createFromCharPointer (CharPointer_ASCII (t)))
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: text (StringHolderUtils::createFromCharPointer (CharPointer_ASCII (t)))
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{
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/* If you get an assertion here, then you're trying to create a string from 8-bit data
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that contains values greater than 127. These can NOT be correctly converted to unicode
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@ -323,7 +316,7 @@ String::String (const char* const t)
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}
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String::String (const char* const t, const size_t maxChars)
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: text (StringHolder::createFromCharPointer (CharPointer_ASCII (t), maxChars))
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: text (StringHolderUtils::createFromCharPointer (CharPointer_ASCII (t), maxChars))
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{
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/* If you get an assertion here, then you're trying to create a string from 8-bit data
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that contains values greater than 127. These can NOT be correctly converted to unicode
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@ -345,23 +338,23 @@ String::String (const char* const t, const size_t maxChars)
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jassert (t == nullptr || CharPointer_ASCII::isValidString (t, (int) maxChars));
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}
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String::String (const wchar_t* const t) : text (StringHolder::createFromCharPointer (castToCharPointer_wchar_t (t))) {}
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String::String (const CharPointer_UTF8 t) : text (StringHolder::createFromCharPointer (t)) {}
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String::String (const CharPointer_UTF16 t) : text (StringHolder::createFromCharPointer (t)) {}
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String::String (const CharPointer_UTF32 t) : text (StringHolder::createFromCharPointer (t)) {}
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String::String (const CharPointer_ASCII t) : text (StringHolder::createFromCharPointer (t)) {}
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String::String (const wchar_t* const t) : text (StringHolderUtils::createFromCharPointer (castToCharPointer_wchar_t (t))) {}
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String::String (const CharPointer_UTF8 t) : text (StringHolderUtils::createFromCharPointer (t)) {}
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String::String (const CharPointer_UTF16 t) : text (StringHolderUtils::createFromCharPointer (t)) {}
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String::String (const CharPointer_UTF32 t) : text (StringHolderUtils::createFromCharPointer (t)) {}
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String::String (const CharPointer_ASCII t) : text (StringHolderUtils::createFromCharPointer (t)) {}
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String::String (CharPointer_UTF8 t, size_t maxChars) : text (StringHolder::createFromCharPointer (t, maxChars)) {}
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String::String (CharPointer_UTF16 t, size_t maxChars) : text (StringHolder::createFromCharPointer (t, maxChars)) {}
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String::String (CharPointer_UTF32 t, size_t maxChars) : text (StringHolder::createFromCharPointer (t, maxChars)) {}
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String::String (const wchar_t* t, size_t maxChars) : text (StringHolder::createFromCharPointer (castToCharPointer_wchar_t (t), maxChars)) {}
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String::String (CharPointer_UTF8 t, size_t maxChars) : text (StringHolderUtils::createFromCharPointer (t, maxChars)) {}
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String::String (CharPointer_UTF16 t, size_t maxChars) : text (StringHolderUtils::createFromCharPointer (t, maxChars)) {}
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String::String (CharPointer_UTF32 t, size_t maxChars) : text (StringHolderUtils::createFromCharPointer (t, maxChars)) {}
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String::String (const wchar_t* t, size_t maxChars) : text (StringHolderUtils::createFromCharPointer (castToCharPointer_wchar_t (t), maxChars)) {}
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String::String (CharPointer_UTF8 start, CharPointer_UTF8 end) : text (StringHolder::createFromCharPointer (start, end)) {}
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String::String (CharPointer_UTF16 start, CharPointer_UTF16 end) : text (StringHolder::createFromCharPointer (start, end)) {}
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String::String (CharPointer_UTF32 start, CharPointer_UTF32 end) : text (StringHolder::createFromCharPointer (start, end)) {}
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String::String (CharPointer_UTF8 start, CharPointer_UTF8 end) : text (StringHolderUtils::createFromCharPointer (start, end)) {}
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String::String (CharPointer_UTF16 start, CharPointer_UTF16 end) : text (StringHolderUtils::createFromCharPointer (start, end)) {}
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String::String (CharPointer_UTF32 start, CharPointer_UTF32 end) : text (StringHolderUtils::createFromCharPointer (start, end)) {}
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String::String (const std::string& s) : text (StringHolder::createFromFixedLength (s.data(), s.size())) {}
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String::String (StringRef s) : text (StringHolder::createFromCharPointer (s.text)) {}
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String::String (const std::string& s) : text (StringHolderUtils::createFromFixedLength (s.data(), s.size())) {}
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String::String (StringRef s) : text (StringHolderUtils::createFromCharPointer (s.text)) {}
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String String::charToString (juce_wchar character)
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{
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@ -487,7 +480,7 @@ namespace NumberToStringConverters
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char buffer [charsNeededForInt];
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auto* end = buffer + numElementsInArray (buffer);
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auto* start = numberToString (end, number);
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return StringHolder::createFromFixedLength (start, (size_t) (end - start - 1));
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return StringHolderUtils::createFromFixedLength (start, (size_t) (end - start - 1));
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}
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static String::CharPointerType createFromDouble (double number, int numberOfDecimalPlaces, bool useScientificNotation)
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@ -495,7 +488,7 @@ namespace NumberToStringConverters
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char buffer [charsNeededForDouble];
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size_t len;
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auto start = doubleToString (buffer, number, numberOfDecimalPlaces, useScientificNotation, len);
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return StringHolder::createFromFixedLength (start, len);
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return StringHolderUtils::createFromFixedLength (start, len);
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}
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}
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@ -1322,7 +1315,7 @@ struct StringCreationHelper
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}
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StringCreationHelper (const String::CharPointerType s)
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: source (s), allocatedBytes (StringHolder::getAllocatedNumBytes (s))
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: source (s), allocatedBytes (StringHolderUtils::getAllocatedNumBytes (s))
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{
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result.preallocateBytes (allocatedBytes);
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dest = result.getCharPointer();
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