154 lines
3.4 KiB
C++
154 lines
3.4 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsHtml5String_h
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#define nsHtml5String_h
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#include "nsString.h"
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#include "nsIAtom.h"
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class nsHtml5TreeBuilder;
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/**
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* A pass-by-value type that can represent
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* * nullptr
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* * empty string
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* * Non-empty string as exactly-sized (capacity is length) `nsStringBuffer*`
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* * Non-empty string as an nsIAtom*
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*
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* Holding or passing this type is as unsafe as holding or passing
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* `nsStringBuffer*`/`nsIAtom*`.
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*/
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class nsHtml5String final
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{
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private:
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static const uintptr_t kKindMask = uintptr_t(3);
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static const uintptr_t kPtrMask = ~kKindMask;
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enum Kind : uintptr_t {
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eNull = 0,
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eEmpty = 1,
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eStringBuffer = 2,
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eAtom = 3,
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};
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inline Kind GetKind() const { return (Kind)(mBits & kKindMask); }
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inline nsStringBuffer* AsStringBuffer() const
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{
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MOZ_ASSERT(GetKind() == eStringBuffer);
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return reinterpret_cast<nsStringBuffer*>(mBits & kPtrMask);
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}
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inline nsIAtom* AsAtom() const
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{
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MOZ_ASSERT(GetKind() == eAtom);
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return reinterpret_cast<nsIAtom*>(mBits & kPtrMask);
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}
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inline const char16_t* AsPtr() const
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{
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switch (GetKind()) {
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case eStringBuffer:
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return reinterpret_cast<char16_t*>(AsStringBuffer()->Data());
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case eAtom:
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return AsAtom()->GetUTF16String();
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default:
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return nullptr;
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}
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}
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public:
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/**
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* Default constructor.
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*/
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inline nsHtml5String()
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: nsHtml5String(nullptr)
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{
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}
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/**
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* Constructor from nullptr.
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*/
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inline MOZ_IMPLICIT nsHtml5String(decltype(nullptr))
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: mBits(eNull)
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{
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}
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inline uint32_t Length() const
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{
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switch (GetKind()) {
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case eStringBuffer:
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return (AsStringBuffer()->StorageSize()/sizeof(char16_t) - 1);
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case eAtom:
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return AsAtom()->GetLength();
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default:
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return 0;
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}
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}
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/**
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* False iff the string is logically null
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*/
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inline MOZ_IMPLICIT operator bool() const { return mBits; }
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/**
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* Get the underlying nsIAtom* or nullptr if this nsHtml5String
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* does not hold an atom.
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*/
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inline nsIAtom* MaybeAsAtom()
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{
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if (GetKind() == eAtom) {
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return AsAtom();
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}
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return nullptr;
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}
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void ToString(nsAString& aString);
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void CopyToBuffer(char16_t* aBuffer) const;
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bool LowerCaseEqualsASCII(const char* aLowerCaseLiteral) const;
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bool EqualsASCII(const char* aLiteral) const;
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bool LowerCaseStartsWithASCII(const char* aLowerCaseLiteral) const;
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bool Equals(nsHtml5String aOther) const;
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nsHtml5String Clone();
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void Release();
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static nsHtml5String FromBuffer(char16_t* aBuffer,
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int32_t aLength,
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nsHtml5TreeBuilder* aTreeBuilder);
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static nsHtml5String FromLiteral(const char* aLiteral);
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static nsHtml5String FromString(const nsAString& aString);
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static nsHtml5String FromAtom(already_AddRefed<nsIAtom> aAtom);
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static nsHtml5String EmptyString();
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private:
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/**
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* Constructor from raw bits.
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*/
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explicit nsHtml5String(uintptr_t aBits) : mBits(aBits) {};
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/**
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* Zero if null, one if empty, otherwise tagged pointer
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* to either nsIAtom or nsStringBuffer. The two least-significant
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* bits are tag bits.
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*/
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uintptr_t mBits;
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};
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#endif // nsHtml5String_h
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