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Diffstat (limited to '')
| -rw-r--r-- | xpcom/string/nsTSubstring.cpp | 1706 |
1 files changed, 1706 insertions, 0 deletions
diff --git a/xpcom/string/nsTSubstring.cpp b/xpcom/string/nsTSubstring.cpp new file mode 100644 index 0000000000..b81b845fee --- /dev/null +++ b/xpcom/string/nsTSubstring.cpp @@ -0,0 +1,1706 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "double-conversion/double-conversion.h" +#include "mozilla/CheckedInt.h" +#include "mozilla/MathAlgorithms.h" +#include "mozilla/MemoryReporting.h" +#include "mozilla/Printf.h" +#include "mozilla/ResultExtensions.h" + +#include "nsASCIIMask.h" +#include "nsCharTraits.h" +#include "nsISupports.h" +#include "nsString.h" +#include "nsTArray.h" + +#ifdef DEBUG +# include "nsStringStats.h" +#else +# define STRING_STAT_INCREMENT(_s) +#endif + +// It's not worthwhile to reallocate the buffer and memcpy the +// contents over when the size difference isn't large. With +// power-of-two allocation buckets and 64 as the typical inline +// capacity, considering that above 1000 there performance aspects +// of realloc and memcpy seem to be absorbed, relative to the old +// code, by the performance benefits of the new code being exact, +// we need to choose which transitions of 256 to 128, 512 to 256 +// and 1024 to 512 to allow. As a guess, let's pick the middle +// one as the the largest potential transition that we forgo. So +// we'll shrink from 1024 bucket to 512 bucket but not from 512 +// bucket to 256 bucket. We'll decide by comparing the difference +// of capacities. As bucket differences, the differences are 256 +// and 512. Since the capacities have various overheads, we +// can't compare with 256 or 512 exactly but it's easier to +// compare to some number that's between the two, so it's +// far away from either to ignore the overheads. +const uint32_t kNsStringBufferShrinkingThreshold = 384; + +using double_conversion::DoubleToStringConverter; + +// --------------------------------------------------------------------------- + +static const char16_t gNullChar = 0; + +char* const nsCharTraits<char>::sEmptyBuffer = + (char*)const_cast<char16_t*>(&gNullChar); +char16_t* const nsCharTraits<char16_t>::sEmptyBuffer = + const_cast<char16_t*>(&gNullChar); + +// --------------------------------------------------------------------------- + +static void ReleaseData(void* aData, nsAString::DataFlags aFlags) { + if (aFlags & nsAString::DataFlags::REFCOUNTED) { + nsStringBuffer::FromData(aData)->Release(); + } else if (aFlags & nsAString::DataFlags::OWNED) { + free(aData); + STRING_STAT_INCREMENT(AdoptFree); + // Treat this as destruction of a "StringAdopt" object for leak + // tracking purposes. + MOZ_LOG_DTOR(aData, "StringAdopt", 1); + } + // otherwise, nothing to do. +} + +// --------------------------------------------------------------------------- + +#ifdef XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE +template <typename T> +nsTSubstring<T>::nsTSubstring(char_type* aData, size_type aLength, + DataFlags aDataFlags, ClassFlags aClassFlags) + : ::mozilla::detail::nsTStringRepr<T>(aData, aLength, aDataFlags, + aClassFlags) { + AssertValid(); + + if (aDataFlags & DataFlags::OWNED) { + STRING_STAT_INCREMENT(Adopt); + MOZ_LOG_CTOR(this->mData, "StringAdopt", 1); + } +} +#endif /* XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE */ + +/** + * helper function for down-casting a nsTSubstring to an nsTAutoString. + */ +template <typename T> +inline const nsTAutoString<T>* AsAutoString(const nsTSubstring<T>* aStr) { + return static_cast<const nsTAutoString<T>*>(aStr); +} + +template <typename T> +mozilla::Result<mozilla::BulkWriteHandle<T>, nsresult> +nsTSubstring<T>::BulkWrite(size_type aCapacity, size_type aPrefixToPreserve, + bool aAllowShrinking) { + auto r = StartBulkWriteImpl(aCapacity, aPrefixToPreserve, aAllowShrinking); + if (MOZ_UNLIKELY(r.isErr())) { + return r.propagateErr(); + } + return mozilla::BulkWriteHandle<T>(this, r.unwrap()); +} + +template <typename T> +auto nsTSubstring<T>::StartBulkWriteImpl(size_type aCapacity, + size_type aPrefixToPreserve, + bool aAllowShrinking, + size_type aSuffixLength, + size_type aOldSuffixStart, + size_type aNewSuffixStart) + -> mozilla::Result<size_type, nsresult> { + // Note! Capacity does not include room for the terminating null char. + + MOZ_ASSERT(aPrefixToPreserve <= aCapacity, + "Requested preservation of an overlong prefix."); + MOZ_ASSERT(aNewSuffixStart + aSuffixLength <= aCapacity, + "Requesed move of suffix to out-of-bounds location."); + // Can't assert aOldSuffixStart, because mLength may not be valid anymore, + // since this method allows itself to be called more than once. + + // If zero capacity is requested, set the string to the special empty + // string. + if (MOZ_UNLIKELY(!aCapacity)) { + ReleaseData(this->mData, this->mDataFlags); + SetToEmptyBuffer(); + return 0; + } + + // Note! Capacity() returns 0 when the string is immutable. + const size_type curCapacity = Capacity(); + + bool shrinking = false; + + // We've established that aCapacity > 0. + // |curCapacity == 0| means that the buffer is immutable or 0-sized, so we + // need to allocate a new buffer. We cannot use the existing buffer even + // though it might be large enough. + + if (aCapacity <= curCapacity) { + if (aAllowShrinking) { + shrinking = true; + } else { + char_traits::move(this->mData + aNewSuffixStart, + this->mData + aOldSuffixStart, aSuffixLength); + if (aSuffixLength) { + char_traits::uninitialize(this->mData + aPrefixToPreserve, + XPCOM_MIN(aNewSuffixStart - aPrefixToPreserve, + kNsStringBufferMaxPoison)); + char_traits::uninitialize( + this->mData + aNewSuffixStart + aSuffixLength, + XPCOM_MIN(curCapacity + 1 - aNewSuffixStart - aSuffixLength, + kNsStringBufferMaxPoison)); + } else { + char_traits::uninitialize(this->mData + aPrefixToPreserve, + XPCOM_MIN(curCapacity + 1 - aPrefixToPreserve, + kNsStringBufferMaxPoison)); + } + return curCapacity; + } + } + + char_type* oldData = this->mData; + DataFlags oldFlags = this->mDataFlags; + + char_type* newData; + DataFlags newDataFlags; + size_type newCapacity; + + // If this is an nsTAutoStringN, it's possible that we can use the inline + // buffer. + if ((this->mClassFlags & ClassFlags::INLINE) && + (aCapacity <= AsAutoString(this)->mInlineCapacity)) { + newCapacity = AsAutoString(this)->mInlineCapacity; + newData = (char_type*)AsAutoString(this)->mStorage; + newDataFlags = DataFlags::TERMINATED | DataFlags::INLINE; + } else { + // If |aCapacity > kMaxCapacity|, then our doubling algorithm may not be + // able to allocate it. Just bail out in cases like that. We don't want + // to be allocating 2GB+ strings anyway. + static_assert((sizeof(nsStringBuffer) & 0x1) == 0, + "bad size for nsStringBuffer"); + if (MOZ_UNLIKELY(!this->CheckCapacity(aCapacity))) { + return mozilla::Err(NS_ERROR_OUT_OF_MEMORY); + } + + // We increase our capacity so that the allocated buffer grows + // exponentially, which gives us amortized O(1) appending. Below the + // threshold, we use powers-of-two. Above the threshold, we grow by at + // least 1.125, rounding up to the nearest MiB. + const size_type slowGrowthThreshold = 8 * 1024 * 1024; + + // nsStringBuffer allocates sizeof(nsStringBuffer) + passed size, and + // storageSize below wants extra 1 * sizeof(char_type). + const size_type neededExtraSpace = + sizeof(nsStringBuffer) / sizeof(char_type) + 1; + + size_type temp; + if (aCapacity >= slowGrowthThreshold) { + size_type minNewCapacity = + curCapacity + (curCapacity >> 3); // multiply by 1.125 + temp = XPCOM_MAX(aCapacity, minNewCapacity) + neededExtraSpace; + + // Round up to the next multiple of MiB, but ensure the expected + // capacity doesn't include the extra space required by nsStringBuffer + // and null-termination. + const size_t MiB = 1 << 20; + temp = (MiB * ((temp + MiB - 1) / MiB)) - neededExtraSpace; + } else { + // Round up to the next power of two. + temp = + mozilla::RoundUpPow2(aCapacity + neededExtraSpace) - neededExtraSpace; + } + + newCapacity = XPCOM_MIN(temp, base_string_type::kMaxCapacity); + MOZ_ASSERT(newCapacity >= aCapacity, + "should have hit the early return at the top"); + // Avoid shrinking if the new buffer size is close to the old. Note that + // unsigned underflow is defined behavior. + if ((curCapacity - newCapacity) <= kNsStringBufferShrinkingThreshold && + (this->mDataFlags & DataFlags::REFCOUNTED)) { + MOZ_ASSERT(aAllowShrinking, "How come we didn't return earlier?"); + // We're already close enough to the right size. + newData = oldData; + newCapacity = curCapacity; + } else { + size_type storageSize = (newCapacity + 1) * sizeof(char_type); + // Since we allocate only by powers of 2 we always fit into a full + // mozjemalloc bucket, it's not useful to use realloc, which may spend + // time uselessly copying too much. + nsStringBuffer* newHdr = nsStringBuffer::Alloc(storageSize).take(); + if (newHdr) { + newData = (char_type*)newHdr->Data(); + } else if (shrinking) { + // We're still in a consistent state. + // + // Since shrinking is just a memory footprint optimization, we + // don't propagate OOM if we tried to shrink in order to avoid + // OOM crashes from infallible callers. If we're lucky, soon enough + // a fallible caller reaches OOM and is able to deal or we end up + // disposing of this string before reaching OOM again. + newData = oldData; + newCapacity = curCapacity; + } else { + return mozilla::Err(NS_ERROR_OUT_OF_MEMORY); + } + } + newDataFlags = DataFlags::TERMINATED | DataFlags::REFCOUNTED; + } + + this->mData = newData; + this->mDataFlags = newDataFlags; + + if (oldData == newData) { + char_traits::move(newData + aNewSuffixStart, oldData + aOldSuffixStart, + aSuffixLength); + if (aSuffixLength) { + char_traits::uninitialize(this->mData + aPrefixToPreserve, + XPCOM_MIN(aNewSuffixStart - aPrefixToPreserve, + kNsStringBufferMaxPoison)); + char_traits::uninitialize( + this->mData + aNewSuffixStart + aSuffixLength, + XPCOM_MIN(newCapacity + 1 - aNewSuffixStart - aSuffixLength, + kNsStringBufferMaxPoison)); + } else { + char_traits::uninitialize(this->mData + aPrefixToPreserve, + XPCOM_MIN(newCapacity + 1 - aPrefixToPreserve, + kNsStringBufferMaxPoison)); + } + } else { + char_traits::copy(newData, oldData, aPrefixToPreserve); + char_traits::copy(newData + aNewSuffixStart, oldData + aOldSuffixStart, + aSuffixLength); + ReleaseData(oldData, oldFlags); + } + + return newCapacity; +} + +template <typename T> +void nsTSubstring<T>::FinishBulkWriteImpl(size_type aLength) { + if (aLength) { + FinishBulkWriteImplImpl(aLength); + } else { + ReleaseData(this->mData, this->mDataFlags); + SetToEmptyBuffer(); + } + AssertValid(); +} + +template <typename T> +void nsTSubstring<T>::Finalize() { + ReleaseData(this->mData, this->mDataFlags); + // this->mData, this->mLength, and this->mDataFlags are purposefully left + // dangling +} + +template <typename T> +bool nsTSubstring<T>::ReplacePrep(index_type aCutStart, size_type aCutLength, + size_type aNewLength) { + aCutLength = XPCOM_MIN(aCutLength, this->mLength - aCutStart); + + mozilla::CheckedInt<size_type> newTotalLen = this->Length(); + newTotalLen += aNewLength; + newTotalLen -= aCutLength; + if (!newTotalLen.isValid()) { + return false; + } + + if (aCutStart == this->mLength && Capacity() > newTotalLen.value()) { + this->mDataFlags &= ~DataFlags::VOIDED; + this->mData[newTotalLen.value()] = char_type(0); + this->mLength = newTotalLen.value(); + return true; + } + + return ReplacePrepInternal(aCutStart, aCutLength, aNewLength, + newTotalLen.value()); +} + +template <typename T> +bool nsTSubstring<T>::ReplacePrepInternal(index_type aCutStart, + size_type aCutLen, size_type aFragLen, + size_type aNewLen) { + size_type newSuffixStart = aCutStart + aFragLen; + size_type oldSuffixStart = aCutStart + aCutLen; + size_type suffixLength = this->mLength - oldSuffixStart; + + mozilla::Result<size_type, nsresult> r = StartBulkWriteImpl( + aNewLen, aCutStart, false, suffixLength, oldSuffixStart, newSuffixStart); + if (r.isErr()) { + return false; + } + FinishBulkWriteImpl(aNewLen); + return true; +} + +template <typename T> +typename nsTSubstring<T>::size_type nsTSubstring<T>::Capacity() const { + // return 0 to indicate an immutable or 0-sized buffer + + size_type capacity; + if (this->mDataFlags & DataFlags::REFCOUNTED) { + // if the string is readonly, then we pretend that it has no capacity. + nsStringBuffer* hdr = nsStringBuffer::FromData(this->mData); + if (hdr->IsReadonly()) { + capacity = 0; + } else { + capacity = (size_t(hdr->StorageSize()) / sizeof(char_type)) - 1; + } + } else if (this->mDataFlags & DataFlags::INLINE) { + MOZ_ASSERT(this->mClassFlags & ClassFlags::INLINE); + capacity = AsAutoString(this)->mInlineCapacity; + } else if (this->mDataFlags & DataFlags::OWNED) { + // we don't store the capacity of an adopted buffer because that would + // require an additional member field. the best we can do is base the + // capacity on our length. remains to be seen if this is the right + // trade-off. + capacity = this->mLength; + } else { + capacity = 0; + } + + return capacity; +} + +template <typename T> +bool nsTSubstring<T>::EnsureMutable(size_type aNewLen) { + if (aNewLen == size_type(-1) || aNewLen == this->mLength) { + if (this->mDataFlags & (DataFlags::INLINE | DataFlags::OWNED)) { + return true; + } + if ((this->mDataFlags & DataFlags::REFCOUNTED) && + !nsStringBuffer::FromData(this->mData)->IsReadonly()) { + return true; + } + + aNewLen = this->mLength; + } + return SetLength(aNewLen, mozilla::fallible); +} + +// --------------------------------------------------------------------------- + +// This version of Assign is optimized for single-character assignment. +template <typename T> +void nsTSubstring<T>::Assign(char_type aChar) { + if (MOZ_UNLIKELY(!Assign(aChar, mozilla::fallible))) { + AllocFailed(1); + } +} + +template <typename T> +bool nsTSubstring<T>::Assign(char_type aChar, const fallible_t&) { + auto r = StartBulkWriteImpl(1, 0, true); + if (MOZ_UNLIKELY(r.isErr())) { + return false; + } + *this->mData = aChar; + FinishBulkWriteImpl(1); + return true; +} + +template <typename T> +void nsTSubstring<T>::Assign(const char_type* aData, size_type aLength) { + if (MOZ_UNLIKELY(!Assign(aData, aLength, mozilla::fallible))) { + AllocFailed(aLength == size_type(-1) ? char_traits::length(aData) + : aLength); + } +} + +template <typename T> +bool nsTSubstring<T>::Assign(const char_type* aData, + const fallible_t& aFallible) { + return Assign(aData, size_type(-1), aFallible); +} + +template <typename T> +bool nsTSubstring<T>::Assign(const char_type* aData, size_type aLength, + const fallible_t& aFallible) { + if (!aData || aLength == 0) { + Truncate(); + return true; + } + + if (MOZ_UNLIKELY(aLength == size_type(-1))) { + aLength = char_traits::length(aData); + } + + if (MOZ_UNLIKELY(this->IsDependentOn(aData, aData + aLength))) { + return Assign(string_type(aData, aLength), aFallible); + } + + auto r = StartBulkWriteImpl(aLength, 0, true); + if (MOZ_UNLIKELY(r.isErr())) { + return false; + } + char_traits::copy(this->mData, aData, aLength); + FinishBulkWriteImpl(aLength); + return true; +} + +template <typename T> +void nsTSubstring<T>::AssignASCII(const char* aData, size_type aLength) { + if (MOZ_UNLIKELY(!AssignASCII(aData, aLength, mozilla::fallible))) { + AllocFailed(aLength); + } +} + +template <typename T> +bool nsTSubstring<T>::AssignASCII(const char* aData, size_type aLength, + const fallible_t& aFallible) { + MOZ_ASSERT(aLength != size_type(-1)); + + // A Unicode string can't depend on an ASCII string buffer, + // so this dependence check only applies to CStrings. + if constexpr (std::is_same_v<T, char>) { + if (this->IsDependentOn(aData, aData + aLength)) { + return Assign(string_type(aData, aLength), aFallible); + } + } + + auto r = StartBulkWriteImpl(aLength, 0, true); + if (MOZ_UNLIKELY(r.isErr())) { + return false; + } + char_traits::copyASCII(this->mData, aData, aLength); + FinishBulkWriteImpl(aLength); + return true; +} + +template <typename T> +void nsTSubstring<T>::AssignLiteral(const char_type* aData, size_type aLength) { + ReleaseData(this->mData, this->mDataFlags); + SetData(const_cast<char_type*>(aData), aLength, + DataFlags::TERMINATED | DataFlags::LITERAL); +} + +template <typename T> +void nsTSubstring<T>::Assign(const self_type& aStr) { + if (!Assign(aStr, mozilla::fallible)) { + AllocFailed(aStr.Length()); + } +} + +template <typename T> +bool nsTSubstring<T>::Assign(const self_type& aStr, + const fallible_t& aFallible) { + // |aStr| could be sharable. We need to check its flags to know how to + // deal with it. + + if (&aStr == this) { + return true; + } + + if (!aStr.mLength) { + Truncate(); + this->mDataFlags |= aStr.mDataFlags & DataFlags::VOIDED; + return true; + } + + if (aStr.mDataFlags & DataFlags::REFCOUNTED) { + // nice! we can avoid a string copy :-) + + // |aStr| should be null-terminated + NS_ASSERTION(aStr.mDataFlags & DataFlags::TERMINATED, + "shared, but not terminated"); + + ReleaseData(this->mData, this->mDataFlags); + + SetData(aStr.mData, aStr.mLength, + DataFlags::TERMINATED | DataFlags::REFCOUNTED); + + // get an owning reference to the this->mData + nsStringBuffer::FromData(this->mData)->AddRef(); + return true; + } else if (aStr.mDataFlags & DataFlags::LITERAL) { + MOZ_ASSERT(aStr.mDataFlags & DataFlags::TERMINATED, "Unterminated literal"); + + AssignLiteral(aStr.mData, aStr.mLength); + return true; + } + + // else, treat this like an ordinary assignment. + return Assign(aStr.Data(), aStr.Length(), aFallible); +} + +template <typename T> +void nsTSubstring<T>::Assign(self_type&& aStr) { + if (!Assign(std::move(aStr), mozilla::fallible)) { + AllocFailed(aStr.Length()); + } +} + +template <typename T> +void nsTSubstring<T>::AssignOwned(self_type&& aStr) { + MOZ_ASSERT(aStr.mDataFlags & (DataFlags::REFCOUNTED | DataFlags::OWNED), + "neither shared nor owned"); + + // If they have a REFCOUNTED or OWNED buffer, we can avoid a copy - so steal + // their buffer and reset them to the empty string. + + // |aStr| should be null-terminated + MOZ_ASSERT(aStr.mDataFlags & DataFlags::TERMINATED, + "shared or owned, but not terminated"); + + ReleaseData(this->mData, this->mDataFlags); + + SetData(aStr.mData, aStr.mLength, aStr.mDataFlags); + aStr.SetToEmptyBuffer(); +} + +template <typename T> +bool nsTSubstring<T>::Assign(self_type&& aStr, const fallible_t& aFallible) { + // We're moving |aStr| in this method, so we need to try to steal the data, + // and in the fallback perform a copy-assignment followed by a truncation of + // the original string. + + if (&aStr == this) { + NS_WARNING("Move assigning a string to itself?"); + return true; + } + + if (aStr.mDataFlags & (DataFlags::REFCOUNTED | DataFlags::OWNED)) { + AssignOwned(std::move(aStr)); + return true; + } + + // Otherwise treat this as a normal assignment, and truncate the moved string. + // We don't truncate the source string if the allocation failed. + if (!Assign(aStr, aFallible)) { + return false; + } + aStr.Truncate(); + return true; +} + +template <typename T> +void nsTSubstring<T>::Assign(const substring_tuple_type& aTuple) { + if (!Assign(aTuple, mozilla::fallible)) { + AllocFailed(aTuple.Length()); + } +} + +template <typename T> +bool nsTSubstring<T>::AssignNonDependent(const substring_tuple_type& aTuple, + size_type aTupleLength, + const mozilla::fallible_t& aFallible) { + NS_ASSERTION(aTuple.Length() == aTupleLength, "wrong length passed"); + + auto r = StartBulkWriteImpl(aTupleLength); + if (r.isErr()) { + return false; + } + + aTuple.WriteTo(this->mData, aTupleLength); + + FinishBulkWriteImpl(aTupleLength); + return true; +} + +template <typename T> +bool nsTSubstring<T>::Assign(const substring_tuple_type& aTuple, + const fallible_t& aFallible) { + const auto [isDependentOnThis, tupleLength] = + aTuple.IsDependentOnWithLength(this->mData, this->mData + this->mLength); + if (isDependentOnThis) { + string_type temp; + self_type& tempSubstring = temp; + if (!tempSubstring.AssignNonDependent(aTuple, tupleLength, aFallible)) { + return false; + } + AssignOwned(std::move(temp)); + return true; + } + + return AssignNonDependent(aTuple, tupleLength, aFallible); +} + +template <typename T> +void nsTSubstring<T>::Adopt(char_type* aData, size_type aLength) { + if (aData) { + ReleaseData(this->mData, this->mDataFlags); + + if (aLength == size_type(-1)) { + aLength = char_traits::length(aData); + } + + SetData(aData, aLength, DataFlags::TERMINATED | DataFlags::OWNED); + + STRING_STAT_INCREMENT(Adopt); + // Treat this as construction of a "StringAdopt" object for leak + // tracking purposes. + MOZ_LOG_CTOR(this->mData, "StringAdopt", 1); + } else { + SetIsVoid(true); + } +} + +// This version of Replace is optimized for single-character replacement. +template <typename T> +void nsTSubstring<T>::Replace(index_type aCutStart, size_type aCutLength, + char_type aChar) { + aCutStart = XPCOM_MIN(aCutStart, this->Length()); + + if (ReplacePrep(aCutStart, aCutLength, 1)) { + this->mData[aCutStart] = aChar; + } +} + +template <typename T> +bool nsTSubstring<T>::Replace(index_type aCutStart, size_type aCutLength, + char_type aChar, const fallible_t&) { + aCutStart = XPCOM_MIN(aCutStart, this->Length()); + + if (!ReplacePrep(aCutStart, aCutLength, 1)) { + return false; + } + + this->mData[aCutStart] = aChar; + + return true; +} + +template <typename T> +void nsTSubstring<T>::Replace(index_type aCutStart, size_type aCutLength, + const char_type* aData, size_type aLength) { + if (!Replace(aCutStart, aCutLength, aData, aLength, mozilla::fallible)) { + AllocFailed(this->Length() - aCutLength + 1); + } +} + +template <typename T> +bool nsTSubstring<T>::Replace(index_type aCutStart, size_type aCutLength, + const char_type* aData, size_type aLength, + const fallible_t& aFallible) { + // unfortunately, some callers pass null :-( + if (!aData) { + aLength = 0; + } else { + if (aLength == size_type(-1)) { + aLength = char_traits::length(aData); + } + + if (this->IsDependentOn(aData, aData + aLength)) { + nsTAutoString<T> temp(aData, aLength); + return Replace(aCutStart, aCutLength, temp, aFallible); + } + } + + aCutStart = XPCOM_MIN(aCutStart, this->Length()); + + bool ok = ReplacePrep(aCutStart, aCutLength, aLength); + if (!ok) { + return false; + } + + if (aLength > 0) { + char_traits::copy(this->mData + aCutStart, aData, aLength); + } + + return true; +} + +template <typename T> +void nsTSubstring<T>::Replace(index_type aCutStart, size_type aCutLength, + const substring_tuple_type& aTuple) { + const auto [isDependentOnThis, tupleLength] = + aTuple.IsDependentOnWithLength(this->mData, this->mData + this->mLength); + + if (isDependentOnThis) { + nsTAutoString<T> temp; + if (!temp.AssignNonDependent(aTuple, tupleLength, mozilla::fallible)) { + AllocFailed(tupleLength); + } + Replace(aCutStart, aCutLength, temp); + return; + } + + aCutStart = XPCOM_MIN(aCutStart, this->Length()); + + if (ReplacePrep(aCutStart, aCutLength, tupleLength) && tupleLength > 0) { + aTuple.WriteTo(this->mData + aCutStart, tupleLength); + } +} + +template <typename T> +void nsTSubstring<T>::ReplaceLiteral(index_type aCutStart, size_type aCutLength, + const char_type* aData, + size_type aLength) { + aCutStart = XPCOM_MIN(aCutStart, this->Length()); + + if (!aCutStart && aCutLength == this->Length() && + !(this->mDataFlags & DataFlags::REFCOUNTED)) { + // Check for REFCOUNTED above to avoid undoing the effect of + // SetCapacity(). + AssignLiteral(aData, aLength); + } else if (ReplacePrep(aCutStart, aCutLength, aLength) && aLength > 0) { + char_traits::copy(this->mData + aCutStart, aData, aLength); + } +} + +template <typename T> +void nsTSubstring<T>::Append(char_type aChar) { + if (MOZ_UNLIKELY(!Append(aChar, mozilla::fallible))) { + AllocFailed(this->mLength + 1); + } +} + +template <typename T> +bool nsTSubstring<T>::Append(char_type aChar, const fallible_t& aFallible) { + size_type oldLen = this->mLength; + size_type newLen = oldLen + 1; // Can't overflow + auto r = StartBulkWriteImpl(newLen, oldLen, false); + if (MOZ_UNLIKELY(r.isErr())) { + return false; + } + this->mData[oldLen] = aChar; + FinishBulkWriteImpl(newLen); + return true; +} + +template <typename T> +void nsTSubstring<T>::Append(const char_type* aData, size_type aLength) { + if (MOZ_UNLIKELY(!Append(aData, aLength, mozilla::fallible))) { + AllocFailed(this->mLength + (aLength == size_type(-1) + ? char_traits::length(aData) + : aLength)); + } +} + +template <typename T> +bool nsTSubstring<T>::Append(const char_type* aData, size_type aLength, + const fallible_t& aFallible) { + if (MOZ_UNLIKELY(aLength == size_type(-1))) { + aLength = char_traits::length(aData); + } + + if (MOZ_UNLIKELY(!aLength)) { + // Avoid undoing the effect of SetCapacity() if both + // mLength and aLength are zero. + return true; + } + + if (MOZ_UNLIKELY(this->IsDependentOn(aData, aData + aLength))) { + return Append(string_type(aData, aLength), mozilla::fallible); + } + size_type oldLen = this->mLength; + mozilla::CheckedInt<size_type> newLen(oldLen); + newLen += aLength; + if (MOZ_UNLIKELY(!newLen.isValid())) { + return false; + } + auto r = StartBulkWriteImpl(newLen.value(), oldLen, false); + if (MOZ_UNLIKELY(r.isErr())) { + return false; + } + char_traits::copy(this->mData + oldLen, aData, aLength); + FinishBulkWriteImpl(newLen.value()); + return true; +} + +template <typename T> +void nsTSubstring<T>::AppendASCII(const char* aData, size_type aLength) { + if (MOZ_UNLIKELY(!AppendASCII(aData, aLength, mozilla::fallible))) { + AllocFailed(this->mLength + + (aLength == size_type(-1) ? strlen(aData) : aLength)); + } +} + +template <typename T> +bool nsTSubstring<T>::AppendASCII(const char* aData, + const fallible_t& aFallible) { + return AppendASCII(aData, size_type(-1), aFallible); +} + +template <typename T> +bool nsTSubstring<T>::AppendASCII(const char* aData, size_type aLength, + const fallible_t& aFallible) { + if (MOZ_UNLIKELY(aLength == size_type(-1))) { + aLength = strlen(aData); + } + + if (MOZ_UNLIKELY(!aLength)) { + // Avoid undoing the effect of SetCapacity() if both + // mLength and aLength are zero. + return true; + } + + if constexpr (std::is_same_v<T, char>) { + // 16-bit string can't depend on an 8-bit buffer + if (MOZ_UNLIKELY(this->IsDependentOn(aData, aData + aLength))) { + return Append(string_type(aData, aLength), mozilla::fallible); + } + } + + size_type oldLen = this->mLength; + mozilla::CheckedInt<size_type> newLen(oldLen); + newLen += aLength; + if (MOZ_UNLIKELY(!newLen.isValid())) { + return false; + } + auto r = StartBulkWriteImpl(newLen.value(), oldLen, false); + if (MOZ_UNLIKELY(r.isErr())) { + return false; + } + char_traits::copyASCII(this->mData + oldLen, aData, aLength); + FinishBulkWriteImpl(newLen.value()); + return true; +} + +template <typename T> +void nsTSubstring<T>::Append(const self_type& aStr) { + if (MOZ_UNLIKELY(!Append(aStr, mozilla::fallible))) { + AllocFailed(this->mLength + aStr.Length()); + } +} + +template <typename T> +bool nsTSubstring<T>::Append(const self_type& aStr, + const fallible_t& aFallible) { + // Check refcounted to avoid undoing the effects of SetCapacity(). + if (MOZ_UNLIKELY(!this->mLength && + !(this->mDataFlags & DataFlags::REFCOUNTED))) { + return Assign(aStr, mozilla::fallible); + } + return Append(aStr.BeginReading(), aStr.Length(), mozilla::fallible); +} + +template <typename T> +void nsTSubstring<T>::Append(const substring_tuple_type& aTuple) { + if (MOZ_UNLIKELY(!Append(aTuple, mozilla::fallible))) { + AllocFailed(this->mLength + aTuple.Length()); + } +} + +template <typename T> +bool nsTSubstring<T>::Append(const substring_tuple_type& aTuple, + const fallible_t& aFallible) { + const auto [isDependentOnThis, tupleLength] = + aTuple.IsDependentOnWithLength(this->mData, this->mData + this->mLength); + + if (MOZ_UNLIKELY(!tupleLength)) { + // Avoid undoing the effect of SetCapacity() if both + // mLength and tupleLength are zero. + return true; + } + + if (MOZ_UNLIKELY(isDependentOnThis)) { + return Append(string_type(aTuple), aFallible); + } + + size_type oldLen = this->mLength; + mozilla::CheckedInt<size_type> newLen(oldLen); + newLen += tupleLength; + if (MOZ_UNLIKELY(!newLen.isValid())) { + return false; + } + auto r = StartBulkWriteImpl(newLen.value(), oldLen, false); + if (MOZ_UNLIKELY(r.isErr())) { + return false; + } + aTuple.WriteTo(this->mData + oldLen, tupleLength); + FinishBulkWriteImpl(newLen.value()); + return true; +} + +template <typename T> +void nsTSubstring<T>::SetCapacity(size_type aCapacity) { + if (!SetCapacity(aCapacity, mozilla::fallible)) { + AllocFailed(aCapacity); + } +} + +template <typename T> +bool nsTSubstring<T>::SetCapacity(size_type aCapacity, const fallible_t&) { + size_type length = this->mLength; + // This method can no longer be used to shorten the + // logical length. + size_type capacity = XPCOM_MAX(aCapacity, length); + + auto r = StartBulkWriteImpl(capacity, length, true); + if (r.isErr()) { + return false; + } + + if (MOZ_UNLIKELY(!capacity)) { + // Zero capacity was requested on a zero-length + // string. In this special case, we are pointing + // to the special empty buffer, which is already + // zero-terminated and not writable, so we must + // not attempt to zero-terminate it. + AssertValid(); + return true; + } + + // FinishBulkWriteImpl with argument zero releases + // the heap-allocated buffer. However, SetCapacity() + // is a special case that allows mLength to be zero + // while a heap-allocated buffer exists. + // By calling FinishBulkWriteImplImpl, we skip the + // zero case handling that's inappropriate in the + // SetCapacity() case. + FinishBulkWriteImplImpl(length); + return true; +} + +template <typename T> +void nsTSubstring<T>::SetLength(size_type aLength) { + if (!SetLength(aLength, mozilla::fallible)) { + AllocFailed(aLength); + } +} + +template <typename T> +bool nsTSubstring<T>::SetLength(size_type aLength, + const fallible_t& aFallible) { + size_type preserve = XPCOM_MIN(aLength, this->Length()); + auto r = StartBulkWriteImpl(aLength, preserve, true); + if (r.isErr()) { + return false; + } + + FinishBulkWriteImpl(aLength); + + return true; +} + +template <typename T> +void nsTSubstring<T>::Truncate() { + ReleaseData(this->mData, this->mDataFlags); + SetToEmptyBuffer(); + AssertValid(); +} + +template <typename T> +void nsTSubstring<T>::SetIsVoid(bool aVal) { + if (aVal) { + Truncate(); + this->mDataFlags |= DataFlags::VOIDED; + } else { + this->mDataFlags &= ~DataFlags::VOIDED; + } +} + +template <typename T> +void nsTSubstring<T>::StripChar(char_type aChar) { + if (this->mLength == 0) { + return; + } + + if (!EnsureMutable()) { // XXX do this lazily? + AllocFailed(this->mLength); + } + + // XXX(darin): this code should defer writing until necessary. + + char_type* to = this->mData; + char_type* from = this->mData; + char_type* end = this->mData + this->mLength; + + while (from < end) { + char_type theChar = *from++; + if (aChar != theChar) { + *to++ = theChar; + } + } + *to = char_type(0); // add the null + this->mLength = to - this->mData; +} + +template <typename T> +void nsTSubstring<T>::StripChars(const char_type* aChars) { + if (this->mLength == 0) { + return; + } + + if (!EnsureMutable()) { // XXX do this lazily? + AllocFailed(this->mLength); + } + + // XXX(darin): this code should defer writing until necessary. + + char_type* to = this->mData; + char_type* from = this->mData; + char_type* end = this->mData + this->mLength; + + while (from < end) { + char_type theChar = *from++; + const char_type* test = aChars; + + for (; *test && *test != theChar; ++test) + ; + + if (!*test) { + // Not stripped, copy this char. + *to++ = theChar; + } + } + *to = char_type(0); // add the null + this->mLength = to - this->mData; +} + +template <typename T> +void nsTSubstring<T>::StripTaggedASCII(const ASCIIMaskArray& aToStrip) { + if (this->mLength == 0) { + return; + } + + size_t untaggedPrefixLength = 0; + for (; untaggedPrefixLength < this->mLength; ++untaggedPrefixLength) { + uint32_t theChar = (uint32_t)this->mData[untaggedPrefixLength]; + if (mozilla::ASCIIMask::IsMasked(aToStrip, theChar)) { + break; + } + } + + if (untaggedPrefixLength == this->mLength) { + return; + } + + if (!EnsureMutable()) { + AllocFailed(this->mLength); + } + + char_type* to = this->mData + untaggedPrefixLength; + char_type* from = to; + char_type* end = this->mData + this->mLength; + + while (from < end) { + uint32_t theChar = (uint32_t)*from++; + // Replacing this with a call to ASCIIMask::IsMasked + // regresses performance somewhat, so leaving it inlined. + if (!mozilla::ASCIIMask::IsMasked(aToStrip, theChar)) { + // Not stripped, copy this char. + *to++ = (char_type)theChar; + } + } + *to = char_type(0); // add the null + this->mLength = to - this->mData; +} + +template <typename T> +void nsTSubstring<T>::StripCRLF() { + // Expanding this call to copy the code from StripTaggedASCII + // instead of just calling it does somewhat help with performance + // but it is not worth it given the duplicated code. + StripTaggedASCII(mozilla::ASCIIMask::MaskCRLF()); +} + +template <typename T> +struct MOZ_STACK_CLASS PrintfAppend : public mozilla::PrintfTarget { + explicit PrintfAppend(nsTSubstring<T>* aString) : mString(aString) {} + + bool append(const char* aStr, size_t aLen) override { + if (aLen == 0) { + return true; + } + + mString->AppendASCII(aStr, aLen); + return true; + } + + private: + nsTSubstring<T>* mString; +}; + +template <typename T> +void nsTSubstring<T>::AppendPrintf(const char* aFormat, ...) { + PrintfAppend<T> appender(this); + va_list ap; + va_start(ap, aFormat); + bool r = appender.vprint(aFormat, ap); + if (!r) { + MOZ_CRASH("Allocation or other failure in PrintfTarget::print"); + } + va_end(ap); +} + +template <typename T> +void nsTSubstring<T>::AppendVprintf(const char* aFormat, va_list aAp) { + PrintfAppend<T> appender(this); + bool r = appender.vprint(aFormat, aAp); + if (!r) { + MOZ_CRASH("Allocation or other failure in PrintfTarget::print"); + } +} + +template <typename T> +void nsTSubstring<T>::AppendIntDec(int32_t aInteger) { + PrintfAppend<T> appender(this); + bool r = appender.appendIntDec(aInteger); + if (MOZ_UNLIKELY(!r)) { + MOZ_CRASH("Allocation or other failure while appending integers"); + } +} + +template <typename T> +void nsTSubstring<T>::AppendIntDec(uint32_t aInteger) { + PrintfAppend<T> appender(this); + bool r = appender.appendIntDec(aInteger); + if (MOZ_UNLIKELY(!r)) { + MOZ_CRASH("Allocation or other failure while appending integers"); + } +} + +template <typename T> +void nsTSubstring<T>::AppendIntOct(uint32_t aInteger) { + PrintfAppend<T> appender(this); + bool r = appender.appendIntOct(aInteger); + if (MOZ_UNLIKELY(!r)) { + MOZ_CRASH("Allocation or other failure while appending integers"); + } +} + +template <typename T> +void nsTSubstring<T>::AppendIntHex(uint32_t aInteger) { + PrintfAppend<T> appender(this); + bool r = appender.appendIntHex(aInteger); + if (MOZ_UNLIKELY(!r)) { + MOZ_CRASH("Allocation or other failure while appending integers"); + } +} + +template <typename T> +void nsTSubstring<T>::AppendIntDec(int64_t aInteger) { + PrintfAppend<T> appender(this); + bool r = appender.appendIntDec(aInteger); + if (MOZ_UNLIKELY(!r)) { + MOZ_CRASH("Allocation or other failure while appending integers"); + } +} + +template <typename T> +void nsTSubstring<T>::AppendIntDec(uint64_t aInteger) { + PrintfAppend<T> appender(this); + bool r = appender.appendIntDec(aInteger); + if (MOZ_UNLIKELY(!r)) { + MOZ_CRASH("Allocation or other failure while appending integers"); + } +} + +template <typename T> +void nsTSubstring<T>::AppendIntOct(uint64_t aInteger) { + PrintfAppend<T> appender(this); + bool r = appender.appendIntOct(aInteger); + if (MOZ_UNLIKELY(!r)) { + MOZ_CRASH("Allocation or other failure while appending integers"); + } +} + +template <typename T> +void nsTSubstring<T>::AppendIntHex(uint64_t aInteger) { + PrintfAppend<T> appender(this); + bool r = appender.appendIntHex(aInteger); + if (MOZ_UNLIKELY(!r)) { + MOZ_CRASH("Allocation or other failure while appending integers"); + } +} + +// Returns the length of the formatted aDouble in aBuf. +static int FormatWithoutTrailingZeros(char (&aBuf)[40], double aDouble, + int aPrecision) { + static const DoubleToStringConverter converter( + DoubleToStringConverter::UNIQUE_ZERO | + DoubleToStringConverter::NO_TRAILING_ZERO | + DoubleToStringConverter::EMIT_POSITIVE_EXPONENT_SIGN, + "Infinity", "NaN", 'e', -6, 21, 6, 1); + double_conversion::StringBuilder builder(aBuf, sizeof(aBuf)); + converter.ToPrecision(aDouble, aPrecision, &builder); + int length = builder.position(); + builder.Finalize(); + return length; +} + +template <typename T> +void nsTSubstring<T>::AppendFloat(float aFloat) { + char buf[40]; + int length = FormatWithoutTrailingZeros(buf, aFloat, 6); + AppendASCII(buf, length); +} + +template <typename T> +void nsTSubstring<T>::AppendFloat(double aFloat) { + char buf[40]; + int length = FormatWithoutTrailingZeros(buf, aFloat, 15); + AppendASCII(buf, length); +} + +template <typename T> +size_t nsTSubstring<T>::SizeOfExcludingThisIfUnshared( + mozilla::MallocSizeOf aMallocSizeOf) const { + if (this->mDataFlags & DataFlags::REFCOUNTED) { + return nsStringBuffer::FromData(this->mData) + ->SizeOfIncludingThisIfUnshared(aMallocSizeOf); + } + if (this->mDataFlags & DataFlags::OWNED) { + return aMallocSizeOf(this->mData); + } + + // If we reach here, exactly one of the following must be true: + // - DataFlags::VOIDED is set, and this->mData points to sEmptyBuffer; + // - DataFlags::INLINE is set, and this->mData points to a buffer within a + // string object (e.g. nsAutoString); + // - None of DataFlags::REFCOUNTED, DataFlags::OWNED, DataFlags::INLINE is + // set, and this->mData points to a buffer owned by something else. + // + // In all three cases, we don't measure it. + return 0; +} + +template <typename T> +size_t nsTSubstring<T>::SizeOfExcludingThisEvenIfShared( + mozilla::MallocSizeOf aMallocSizeOf) const { + // This is identical to SizeOfExcludingThisIfUnshared except for the + // DataFlags::REFCOUNTED case. + if (this->mDataFlags & DataFlags::REFCOUNTED) { + return nsStringBuffer::FromData(this->mData) + ->SizeOfIncludingThisEvenIfShared(aMallocSizeOf); + } + if (this->mDataFlags & DataFlags::OWNED) { + return aMallocSizeOf(this->mData); + } + return 0; +} + +template <typename T> +size_t nsTSubstring<T>::SizeOfIncludingThisIfUnshared( + mozilla::MallocSizeOf aMallocSizeOf) const { + return aMallocSizeOf(this) + SizeOfExcludingThisIfUnshared(aMallocSizeOf); +} + +template <typename T> +size_t nsTSubstring<T>::SizeOfIncludingThisEvenIfShared( + mozilla::MallocSizeOf aMallocSizeOf) const { + return aMallocSizeOf(this) + SizeOfExcludingThisEvenIfShared(aMallocSizeOf); +} + +template <typename T> +nsTSubstringSplitter<T> nsTSubstring<T>::Split(const char_type aChar) const { + return nsTSubstringSplitter<T>( + nsTCharSeparatedTokenizerTemplate< + NS_TokenizerIgnoreNothing, T, + nsTokenizerFlags::IncludeEmptyTokenAtEnd>(*this, aChar)); +} + +// Common logic for nsTSubstring<T>::ToInteger and nsTSubstring<T>::ToInteger64. +template <typename T, typename int_type> +int_type ToIntegerCommon(const nsTSubstring<T>& aSrc, nsresult* aErrorCode, + uint32_t aRadix) { + MOZ_ASSERT(aRadix == 10 || aRadix == 16); + + // Initial value, override if we find an integer. + *aErrorCode = NS_ERROR_ILLEGAL_VALUE; + + // Begin by skipping over leading chars that shouldn't be part of the number. + auto cp = aSrc.BeginReading(); + auto endcp = aSrc.EndReading(); + bool negate = false; + bool done = false; + + // NB: For backwards compatibility I'm not going to change this logic but + // it seems really odd. Previously there was logic to auto-detect the + // radix if kAutoDetect was passed in. In practice this value was never + // used, so it pretended to auto detect and skipped some preceding + // letters (excluding valid hex digits) but never used the result. + // + // For example if you pass in "Get the number: 10", aRadix = 10 we'd + // skip the 'G', and then fail to parse "et the number: 10". If aRadix = + // 16 we'd skip the 'G', and parse just 'e' returning 14. + while ((cp < endcp) && (!done)) { + switch (*cp++) { + // clang-format off + case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': + case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': + case '0': case '1': case '2': case '3': case '4': + case '5': case '6': case '7': case '8': case '9': + done = true; + break; + // clang-format on + case '-': + negate = true; + break; + default: + break; + } + } + + if (!done) { + // No base 16 or base 10 digits were found. + return 0; + } + + // Step back. + cp--; + + mozilla::CheckedInt<int_type> result; + + // Now iterate the numeric chars and build our result. + while (cp < endcp) { + auto theChar = *cp++; + if (('0' <= theChar) && (theChar <= '9')) { + result = (aRadix * result) + (theChar - '0'); + } else if ((theChar >= 'A') && (theChar <= 'F')) { + if (10 == aRadix) { + // Invalid base 10 digit, error out. + return 0; + } else { + result = (aRadix * result) + ((theChar - 'A') + 10); + } + } else if ((theChar >= 'a') && (theChar <= 'f')) { + if (10 == aRadix) { + // Invalid base 10 digit, error out. + return 0; + } else { + result = (aRadix * result) + ((theChar - 'a') + 10); + } + } else if ((('X' == theChar) || ('x' == theChar)) && result == 0) { + // For some reason we support a leading 'x' regardless of radix. For + // example: "000000x500", aRadix = 10 would be parsed as 500 rather + // than 0. + continue; + } else { + // We've encountered a char that's not a legal number or sign and we can + // terminate processing. + break; + } + + if (!result.isValid()) { + // Overflow! + return 0; + } + } + + // Integer found. + *aErrorCode = NS_OK; + + if (negate) { + result = -result; + } + + return result.value(); +} + +template <typename T> +int32_t nsTSubstring<T>::ToInteger(nsresult* aErrorCode, + uint32_t aRadix) const { + return ToIntegerCommon<T, int32_t>(*this, aErrorCode, aRadix); +} + +/** + * nsTSubstring::ToInteger64 + */ +template <typename T> +int64_t nsTSubstring<T>::ToInteger64(nsresult* aErrorCode, + uint32_t aRadix) const { + return ToIntegerCommon<T, int64_t>(*this, aErrorCode, aRadix); +} + +/** + * nsTSubstring::Mid + */ +template <typename T> +typename nsTSubstring<T>::size_type nsTSubstring<T>::Mid( + self_type& aResult, index_type aStartPos, size_type aLengthToCopy) const { + if (aStartPos == 0 && aLengthToCopy >= this->mLength) { + aResult = *this; + } else { + aResult = Substring(*this, aStartPos, aLengthToCopy); + } + + return aResult.mLength; +} + +/** + * nsTSubstring::StripWhitespace + */ + +template <typename T> +void nsTSubstring<T>::StripWhitespace() { + if (!StripWhitespace(mozilla::fallible)) { + this->AllocFailed(this->mLength); + } +} + +template <typename T> +bool nsTSubstring<T>::StripWhitespace(const fallible_t&) { + if (!this->EnsureMutable()) { + return false; + } + + this->StripTaggedASCII(mozilla::ASCIIMask::MaskWhitespace()); + return true; +} + +/** + * nsTSubstring::ReplaceChar,ReplaceSubstring + */ + +template <typename T> +void nsTSubstring<T>::ReplaceChar(char_type aOldChar, char_type aNewChar) { + int32_t i = this->FindChar(aOldChar); + if (i == kNotFound) { + return; + } + + if (!this->EnsureMutable()) { + this->AllocFailed(this->mLength); + } + for (; i != kNotFound; i = this->FindChar(aOldChar, i + 1)) { + this->mData[i] = aNewChar; + } +} + +template <typename T> +void nsTSubstring<T>::ReplaceChar(const string_view& aSet, char_type aNewChar) { + int32_t i = this->FindCharInSet(aSet); + if (i == kNotFound) { + return; + } + + if (!this->EnsureMutable()) { + this->AllocFailed(this->mLength); + } + for (; i != kNotFound; i = this->FindCharInSet(aSet, i + 1)) { + this->mData[i] = aNewChar; + } +} + +template <typename T> +void nsTSubstring<T>::ReplaceSubstring(const char_type* aTarget, + const char_type* aNewValue) { + ReplaceSubstring(nsTDependentString<T>(aTarget), + nsTDependentString<T>(aNewValue)); +} + +template <typename T> +bool nsTSubstring<T>::ReplaceSubstring(const char_type* aTarget, + const char_type* aNewValue, + const fallible_t& aFallible) { + return ReplaceSubstring(nsTDependentString<T>(aTarget), + nsTDependentString<T>(aNewValue), aFallible); +} + +template <typename T> +void nsTSubstring<T>::ReplaceSubstring(const self_type& aTarget, + const self_type& aNewValue) { + if (!ReplaceSubstring(aTarget, aNewValue, mozilla::fallible)) { + // Note that this may wildly underestimate the allocation that failed, as + // we could have been replacing multiple copies of aTarget. + this->AllocFailed(this->mLength + (aNewValue.Length() - aTarget.Length())); + } +} + +template <typename T> +bool nsTSubstring<T>::ReplaceSubstring(const self_type& aTarget, + const self_type& aNewValue, + const fallible_t&) { + struct Segment { + uint32_t mBegin, mLength; + Segment(uint32_t aBegin, uint32_t aLength) + : mBegin(aBegin), mLength(aLength) {} + }; + + if (aTarget.Length() == 0) { + return true; + } + + // Remember all of the non-matching parts. + AutoTArray<Segment, 16> nonMatching; + uint32_t i = 0; + mozilla::CheckedUint32 newLength; + while (true) { + int32_t r = this->Find(aTarget, i); + int32_t until = (r == kNotFound) ? this->Length() - i : r - i; + nonMatching.AppendElement(Segment(i, until)); + newLength += until; + if (r == kNotFound) { + break; + } + + newLength += aNewValue.Length(); + i = r + aTarget.Length(); + if (i >= this->Length()) { + // Add an auxiliary entry at the end of the list to help as an edge case + // for the algorithms below. + nonMatching.AppendElement(Segment(this->Length(), 0)); + break; + } + } + + if (!newLength.isValid()) { + return false; + } + + // If there's only one non-matching segment, then the target string was not + // found, and there's nothing to do. + if (nonMatching.Length() == 1) { + MOZ_ASSERT( + nonMatching[0].mBegin == 0 && nonMatching[0].mLength == this->Length(), + "We should have the correct non-matching segment."); + return true; + } + + // Make sure that we can mutate our buffer. + // Note that we always allocate at least an this->mLength sized buffer, + // because the rest of the algorithm relies on having access to all of the + // original string. In other words, we over-allocate in the shrinking case. + uint32_t oldLen = this->Length(); + auto r = + this->StartBulkWriteImpl(XPCOM_MAX(oldLen, newLength.value()), oldLen); + if (r.isErr()) { + return false; + } + + if (aTarget.Length() >= aNewValue.Length()) { + // In the shrinking case, start filling the buffer from the beginning. + const uint32_t delta = (aTarget.Length() - aNewValue.Length()); + for (i = 1; i < nonMatching.Length(); ++i) { + // When we move the i'th non-matching segment into position, we need to + // account for the characters deleted by the previous |i| replacements by + // subtracting |i * delta|. + const char_type* sourceSegmentPtr = this->mData + nonMatching[i].mBegin; + char_type* destinationSegmentPtr = + this->mData + nonMatching[i].mBegin - i * delta; + // Write the i'th replacement immediately before the new i'th non-matching + // segment. + char_traits::copy(destinationSegmentPtr - aNewValue.Length(), + aNewValue.Data(), aNewValue.Length()); + char_traits::move(destinationSegmentPtr, sourceSegmentPtr, + nonMatching[i].mLength); + } + } else { + // In the growing case, start filling the buffer from the end. + const uint32_t delta = (aNewValue.Length() - aTarget.Length()); + for (i = nonMatching.Length() - 1; i > 0; --i) { + // When we move the i'th non-matching segment into position, we need to + // account for the characters added by the previous |i| replacements by + // adding |i * delta|. + const char_type* sourceSegmentPtr = this->mData + nonMatching[i].mBegin; + char_type* destinationSegmentPtr = + this->mData + nonMatching[i].mBegin + i * delta; + char_traits::move(destinationSegmentPtr, sourceSegmentPtr, + nonMatching[i].mLength); + // Write the i'th replacement immediately before the new i'th non-matching + // segment. + char_traits::copy(destinationSegmentPtr - aNewValue.Length(), + aNewValue.Data(), aNewValue.Length()); + } + } + + // Adjust the length and make sure the string is null terminated. + this->FinishBulkWriteImpl(newLength.value()); + + return true; +} + +/** + * nsTSubstring::Trim + */ + +template <typename T> +void nsTSubstring<T>::Trim(const std::string_view& aSet, bool aTrimLeading, + bool aTrimTrailing, bool aIgnoreQuotes) { + char_type* start = this->mData; + char_type* end = this->mData + this->mLength; + + // skip over quotes if requested + if (aIgnoreQuotes && this->mLength > 2 && + this->mData[0] == this->mData[this->mLength - 1] && + (this->mData[0] == '\'' || this->mData[0] == '"')) { + ++start; + --end; + } + + if (aTrimLeading) { + uint32_t cutStart = start - this->mData; + uint32_t cutLength = 0; + + // walk forward from start to end + for (; start != end; ++start, ++cutLength) { + if ((*start & ~0x7F) || // non-ascii + aSet.find(char(*start)) == std::string_view::npos) { + break; + } + } + + if (cutLength) { + this->Cut(cutStart, cutLength); + + // reset iterators + start = this->mData + cutStart; + end = this->mData + this->mLength - cutStart; + } + } + + if (aTrimTrailing) { + uint32_t cutEnd = end - this->mData; + uint32_t cutLength = 0; + + // walk backward from end to start + --end; + for (; end >= start; --end, ++cutLength) { + if ((*end & ~0x7F) || // non-ascii + aSet.find(char(*end)) == std::string_view::npos) { + break; + } + } + + if (cutLength) { + this->Cut(cutEnd - cutLength, cutLength); + } + } +} + +/** + * nsTSubstring::CompressWhitespace. + */ + +template <typename T> +void nsTSubstring<T>::CompressWhitespace(bool aTrimLeading, + bool aTrimTrailing) { + // Quick exit + if (this->mLength == 0) { + return; + } + + if (!this->EnsureMutable()) { + this->AllocFailed(this->mLength); + } + + const ASCIIMaskArray& mask = mozilla::ASCIIMask::MaskWhitespace(); + + char_type* to = this->mData; + char_type* from = this->mData; + char_type* end = this->mData + this->mLength; + + // Compresses runs of whitespace down to a normal space ' ' and convert + // any whitespace to a normal space. This assumes that whitespace is + // all standard 7-bit ASCII. + bool skipWS = aTrimLeading; + while (from < end) { + uint32_t theChar = *from++; + if (mozilla::ASCIIMask::IsMasked(mask, theChar)) { + if (!skipWS) { + *to++ = ' '; + skipWS = true; + } + } else { + *to++ = theChar; + skipWS = false; + } + } + + // If we need to trim the trailing whitespace, back up one character. + if (aTrimTrailing && skipWS && to > this->mData) { + to--; + } + + *to = char_type(0); // add the null + this->mLength = to - this->mData; +} + +template class nsTSubstring<char>; +template class nsTSubstring<char16_t>; |