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gecko-dev/xpcom/string/nsTSubstring.cpp

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/* -*- 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 "nsASCIIMask.h"
// 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;
template <typename T>
const typename nsTSubstring<T>::size_type nsTSubstring<T>::kMaxCapacity =
(nsTSubstring<T>::size_type(-1) /
2 - sizeof(nsStringBuffer)) /
sizeof(nsTSubstring<T>::char_type) - 2;
#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();
MOZ_RELEASE_ASSERT(CheckCapacity(aLength), "String is too large.");
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::BulkWriteHandle<T>
nsTSubstring<T>::BulkWrite(size_type aCapacity,
size_type aPrefixToPreserve,
bool aAllowShrinking,
nsresult& aRv)
{
auto r = StartBulkWriteImpl(aCapacity,
aPrefixToPreserve,
aAllowShrinking);
if (MOZ_UNLIKELY(r.isErr())) {
aRv = r.unwrapErr();
return mozilla::BulkWriteHandle<T>(nullptr, 0);
}
aRv = NS_OK;
return mozilla::BulkWriteHandle<T>(this, r.unwrap());
}
template<typename T>
mozilla::Result<uint32_t, nsresult>
nsTSubstring<T>::StartBulkWriteImpl(size_type aCapacity,
size_type aPrefixToPreserve,
bool aAllowShrinking,
size_type aSuffixLength,
size_type aOldSuffixStart,
size_type aNewSuffixStart)
{
// 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);
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(!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, 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);
} 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)
{
MOZ_ASSERT(aLength != UINT32_MAX, "OOM magic value passed as length.");
if (aLength) {
this->mData[aLength] = char_type(0);
this->mLength = 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->mLength;
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<uint32_t, 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 = (hdr->StorageSize() / sizeof(char_type)) - 1;
}
} else if (this->mDataFlags & DataFlags::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 (!ReplacePrep(0, this->mLength, 1)) {
AllocFailed(this->mLength);
}
*this->mData = aChar;
}
template <typename T>
bool
nsTSubstring<T>::Assign(char_type aChar, const fallible_t&)
{
if (!ReplacePrep(0, this->mLength, 1)) {
return false;
}
*this->mData = aChar;
return true;
}
template <typename T>
void
nsTSubstring<T>::Assign(const char_type* aData)
{
if (!Assign(aData, mozilla::fallible)) {
AllocFailed(char_traits::length(aData));
}
}
template <typename T>
bool
nsTSubstring<T>::Assign(const char_type* aData, const fallible_t&)
{
return Assign(aData, size_type(-1), mozilla::fallible);
}
template <typename T>
void
nsTSubstring<T>::Assign(const char_type* aData, size_type aLength)
{
if (!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, size_type aLength,
const fallible_t& aFallible)
{
if (!aData || aLength == 0) {
Truncate();
return true;
}
if (aLength == size_type(-1)) {
aLength = char_traits::length(aData);
}
if (this->IsDependentOn(aData, aData + aLength)) {
return Assign(string_type(aData, aLength), aFallible);
}
if (!ReplacePrep(0, this->mLength, aLength)) {
return false;
}
char_traits::copy(this->mData, aData, aLength);
return true;
}
template <typename T>
void
nsTSubstring<T>::AssignASCII(const char* aData, size_type aLength)
{
if (!AssignASCII(aData, aLength, mozilla::fallible)) {
AllocFailed(aLength);
}
}
template <typename T>
bool
nsTSubstring<T>::AssignASCII(const char* aData, size_type aLength,
const fallible_t& aFallible)
{
// A Unicode string can't depend on an ASCII string buffer,
// so this dependence check only applies to CStrings.
#ifdef CharT_is_char
if (this->IsDependentOn(aData, aData + aLength)) {
return Assign(string_type(aData, aLength), aFallible);
}
#endif
if (!ReplacePrep(0, this->mLength, aLength)) {
return false;
}
char_traits::copyASCII(this->mData, aData, 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>
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)) {
// 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
NS_ASSERTION(aStr.mDataFlags & DataFlags::TERMINATED,
"shared or owned, but not terminated");
::ReleaseData(this->mData, this->mDataFlags);
SetData(aStr.mData, aStr.mLength, aStr.mDataFlags);
aStr.SetToEmptyBuffer();
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>::Assign(const substring_tuple_type& aTuple,
const fallible_t& aFallible)
{
if (aTuple.IsDependentOn(this->mData, this->mData + this->mLength)) {
// take advantage of sharing here...
return Assign(string_type(aTuple), aFallible);
}
size_type length = aTuple.Length();
mozilla::Result<uint32_t, nsresult> r = StartBulkWriteImpl(length);
if (r.isErr()) {
return false;
}
aTuple.WriteTo(this->mData, length);
FinishBulkWriteImpl(length);
return true;
}
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);
}
MOZ_RELEASE_ASSERT(CheckCapacity(aLength), "adopting a too-long string");
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>::ReplaceASCII(index_type aCutStart, size_type aCutLength,
const char* aData, size_type aLength)
{
if (!ReplaceASCII(aCutStart, aCutLength, aData, aLength, mozilla::fallible)) {
AllocFailed(this->Length() - aCutLength + 1);
}
}
template <typename T>
bool
nsTSubstring<T>::ReplaceASCII(index_type aCutStart, size_type aCutLength,
const char* aData, size_type aLength,
const fallible_t& aFallible)
{
if (aLength == size_type(-1)) {
aLength = strlen(aData);
}
// A Unicode string can't depend on an ASCII string buffer,
// so this dependence check only applies to CStrings.
#ifdef CharT_is_char
if (this->IsDependentOn(aData, aData + aLength)) {
nsTAutoString_CharT temp(aData, aLength);
return Replace(aCutStart, aCutLength, temp, aFallible);
}
#endif
aCutStart = XPCOM_MIN(aCutStart, this->Length());
bool ok = ReplacePrep(aCutStart, aCutLength, aLength);
if (!ok) {
return false;
}
if (aLength > 0) {
char_traits::copyASCII(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)
{
if (aTuple.IsDependentOn(this->mData, this->mData + this->mLength)) {
nsTAutoString<T> temp(aTuple);
Replace(aCutStart, aCutLength, temp);
return;
}
size_type length = aTuple.Length();
aCutStart = XPCOM_MIN(aCutStart, this->Length());
if (ReplacePrep(aCutStart, aCutLength, length) && length > 0) {
aTuple.WriteTo(this->mData + aCutStart, length);
}
}
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>::SetCapacity(size_type aCapacity)
{
if (!SetCapacity(aCapacity, mozilla::fallible)) {
AllocFailed(aCapacity);
}
}
template <typename T>
bool
nsTSubstring<T>::SetCapacity(size_type aCapacity, const fallible_t&)
{
// capacity does not include room for the terminating null char
// Sadly, existing callers assume that it's valid to
// first call SetCapacity(), then write past mLength
// and then call SetLength() with the assumption that
// SetLength still preserves the written data past
// mLength!!!
size_type preserve;
if (this->mDataFlags & DataFlags::REFCOUNTED) {
nsStringBuffer* hdr = nsStringBuffer::FromData(this->mData);
preserve = (hdr->StorageSize() / sizeof(char_type)) - 1;
} else if (this->mDataFlags & DataFlags::INLINE) {
preserve = AsAutoString(this)->mInlineCapacity;
} else {
preserve = this->mLength;
}
if (preserve > aCapacity) {
preserve = aCapacity;
}
mozilla::Result<uint32_t, nsresult> r = StartBulkWriteImpl(aCapacity, preserve);
if (r.isErr()) {
return false;
}
if (r.unwrap()) {
// In the zero case StartBulkWrite already put the string
// in a valid state.
// Otherwise, instead of calling FinishBulkWrite,
// intentionally replicate the legacy semantics of
// this method:
// If requested capacity was smaller than the pre-existing
// length, set length to the requested capacity and
// zero-terminate there. Otherwise, zero-terminate at
// the requested capacity. (This latter behavior was
// designated as a legacy compatibility measure by the
// previous implementation of this method.)
if (aCapacity < this->mLength) {
// aCapacity not capacity for legacy reasons;
// maybe capacity would work, too.
this->mLength = aCapacity;
}
// Note that we can't write a terminator at
// mData[mLength], because doing so would overwrite
// data when this method is called from SetLength.
this->mData[aCapacity] = char_type(0);
}
return true;
}
template <typename T>
void
nsTSubstring<T>::SetLength(size_type aLength)
{
SetCapacity(aLength);
this->mLength = aLength;
}
template <typename T>
bool
nsTSubstring<T>::SetLength(size_type aLength, const fallible_t& aFallible)
{
if (!SetCapacity(aLength, aFallible)) {
return false;
}
this->mLength = aLength;
return true;
}
template <typename T>
void
nsTSubstring<T>::SetIsVoid(bool aVal)
{
if (aVal) {
Truncate();
this->mDataFlags |= DataFlags::VOIDED;
} else {
this->mDataFlags &= ~DataFlags::VOIDED;
}
}
namespace mozilla {
namespace detail {
template <typename T>
typename nsTStringRepr<T>::char_type
nsTStringRepr<T>::First() const
{
MOZ_RELEASE_ASSERT(this->mLength > 0, "|First()| called on an empty string");
return this->mData[0];
}
template <typename T>
typename nsTStringRepr<T>::char_type
nsTStringRepr<T>::Last() const
{
MOZ_RELEASE_ASSERT(this->mLength > 0, "|Last()| called on an empty string");
return this->mData[this->mLength - 1];
}
template <typename T>
bool
nsTStringRepr<T>::Equals(const self_type& aStr) const
{
return this->mLength == aStr.mLength &&
char_traits::compare(this->mData, aStr.mData, this->mLength) == 0;
}
template <typename T>
bool
nsTStringRepr<T>::Equals(const self_type& aStr,
const comparator_type& aComp) const
{
return this->mLength == aStr.mLength &&
aComp(this->mData, aStr.mData, this->mLength, aStr.mLength) == 0;
}
template <typename T>
bool
nsTStringRepr<T>::Equals(const substring_tuple_type& aTuple) const
{
return Equals(substring_type(aTuple));
}
template <typename T>
bool
nsTStringRepr<T>::Equals(const substring_tuple_type& aTuple,
const comparator_type& aComp) const
{
return Equals(substring_type(aTuple), aComp);
}
template <typename T>
bool
nsTStringRepr<T>::Equals(const char_type* aData) const
{
// unfortunately, some callers pass null :-(
if (!aData) {
MOZ_ASSERT_UNREACHABLE("null data pointer");
return this->mLength == 0;
}
// XXX avoid length calculation?
size_type length = char_traits::length(aData);
return this->mLength == length &&
char_traits::compare(this->mData, aData, this->mLength) == 0;
}
template <typename T>
bool
nsTStringRepr<T>::Equals(const char_type* aData,
const comparator_type& aComp) const
{
// unfortunately, some callers pass null :-(
if (!aData) {
MOZ_ASSERT_UNREACHABLE("null data pointer");
return this->mLength == 0;
}
// XXX avoid length calculation?
size_type length = char_traits::length(aData);
return this->mLength == length && aComp(this->mData, aData, this->mLength, length) == 0;
}
template <typename T>
bool
nsTStringRepr<T>::EqualsASCII(const char* aData, size_type aLen) const
{
return this->mLength == aLen &&
char_traits::compareASCII(this->mData, aData, aLen) == 0;
}
template <typename T>
bool
nsTStringRepr<T>::EqualsASCII(const char* aData) const
{
return char_traits::compareASCIINullTerminated(this->mData, this->mLength, aData) == 0;
}
template <typename T>
bool
nsTStringRepr<T>::LowerCaseEqualsASCII(const char* aData,
size_type aLen) const
{
return this->mLength == aLen &&
char_traits::compareLowerCaseToASCII(this->mData, aData, aLen) == 0;
}
template <typename T>
bool
nsTStringRepr<T>::LowerCaseEqualsASCII(const char* aData) const
{
return char_traits::compareLowerCaseToASCIINullTerminated(this->mData,
this->mLength,
aData) == 0;
}
template <typename T>
typename nsTStringRepr<T>::size_type
nsTStringRepr<T>::CountChar(char_type aChar) const
{
const char_type* start = this->mData;
const char_type* end = this->mData + this->mLength;
return NS_COUNT(start, end, aChar);
}
template <typename T>
int32_t
nsTStringRepr<T>::FindChar(char_type aChar, index_type aOffset) const
{
if (aOffset < this->mLength) {
const char_type* result = char_traits::find(this->mData + aOffset,
this->mLength - aOffset, aChar);
if (result) {
return result - this->mData;
}
}
return -1;
}
} // namespace detail
} // namespace mozilla
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;
}
if (!EnsureMutable()) {
AllocFailed(this->mLength);
}
char_type* to = this->mData;
char_type* from = this->mData;
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>::AppendPrintf(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");
}
}
// 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::EMIT_POSITIVE_EXPONENT_SIGN,
"Infinity",
"NaN",
'e',
-6, 21,
6, 1);
double_conversion::StringBuilder builder(aBuf, sizeof(aBuf));
bool exponential_notation = false;
converter.ToPrecision(aDouble, aPrecision, &exponential_notation, &builder);
int length = builder.position();
char* formattedDouble = builder.Finalize();
// If we have a shorter string than aPrecision, it means we have a special
// value (NaN or Infinity). All other numbers will be formatted with at
// least aPrecision digits.
if (length <= aPrecision) {
return length;
}
char* end = formattedDouble + length;
char* decimalPoint = strchr(aBuf, '.');
// No trailing zeros to remove.
if (!decimalPoint) {
return length;
}
if (MOZ_UNLIKELY(exponential_notation)) {
// We need to check for cases like 1.00000e-10 (yes, this is
// disgusting).
char* exponent = end - 1;
for (; ; --exponent) {
if (*exponent == 'e') {
break;
}
}
char* zerosBeforeExponent = exponent - 1;
for (; zerosBeforeExponent != decimalPoint; --zerosBeforeExponent) {
if (*zerosBeforeExponent != '0') {
break;
}
}
if (zerosBeforeExponent == decimalPoint) {
--zerosBeforeExponent;
}
// Slide the exponent to the left over the trailing zeros. Don't
// worry about copying the trailing NUL character.
size_t exponentSize = end - exponent;
memmove(zerosBeforeExponent + 1, exponent, exponentSize);
length -= exponent - (zerosBeforeExponent + 1);
} else {
char* trailingZeros = end - 1;
for (; trailingZeros != decimalPoint; --trailingZeros) {
if (*trailingZeros != '0') {
break;
}
}
if (trailingZeros == decimalPoint) {
--trailingZeros;
}
length -= end - (trailingZeros + 1);
}
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>
inline
nsTSubstringSplitter<T>::nsTSubstringSplitter(
const nsTSubstring<T>* aStr, char_type aDelim)
: mStr(aStr)
, mArray(nullptr)
, mDelim(aDelim)
{
if (mStr->IsEmpty()) {
mArraySize = 0;
return;
}
size_type delimCount = mStr->CountChar(aDelim);
mArraySize = delimCount + 1;
mArray.reset(new nsTDependentSubstring<T>[mArraySize]);
size_t seenParts = 0;
size_type start = 0;
do {
MOZ_ASSERT(seenParts < mArraySize);
int32_t offset = mStr->FindChar(aDelim, start);
if (offset != -1) {
size_type length = static_cast<size_type>(offset) - start;
mArray[seenParts++].Rebind(mStr->Data() + start, length);
start = static_cast<size_type>(offset) + 1;
} else {
// Get the remainder
mArray[seenParts++].Rebind(mStr->Data() + start, mStr->Length() - start);
break;
}
} while (start < mStr->Length());
}
template <typename T>
nsTSubstringSplitter<T>
nsTSubstring<T>::Split(const char_type aChar) const
{
return nsTSubstringSplitter<T>(this, aChar);
}
template <typename T>
const nsTDependentSubstring<T>&
nsTSubstringSplitter<T>::nsTSubstringSplit_Iter::operator* () const
{
return mObj.Get(mPos);
}
// 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);
}
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