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gecko-dev/xpcom/string/nsTSubstring.h

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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/. */
// IWYU pragma: private, include "nsString.h"
#ifndef nsTSubstring_h
#define nsTSubstring_h
#include <type_traits>
#include "mozilla/Casting.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/IntegerTypeTraits.h"
#include "mozilla/Result.h"
#include "mozilla/Span.h"
#include "mozilla/Unused.h"
#include "nsTStringRepr.h"
#ifndef MOZILLA_INTERNAL_API
# error "Using XPCOM strings is limited to code linked into libxul."
#endif
// The max number of logically uninitialized code units to
// fill with a marker byte or to mark as unintialized for
// memory checking. (Limited to avoid quadratic behavior.)
const size_t kNsStringBufferMaxPoison = 16;
template <typename T>
class nsTSubstringSplitter;
template <typename T>
class nsTString;
template <typename T>
class nsTSubstring;
namespace mozilla {
/**
* This handle represents permission to perform low-level writes
* the storage buffer of a string in a manner that's aware of the
* actual capacity of the storage buffer allocation and that's
* cache-friendly in the sense that the writing of zero terminator
* for C compatibility can happen in linear memory access order
* (i.e. the zero terminator write takes place after writing
* new content to the string as opposed to the zero terminator
* write happening first causing a non-linear memory write for
* cache purposes).
*
* If you requested a prefix to be preserved when starting
* or restarting the bulk write, the prefix is present at the
* start of the buffer exposed by this handle as Span or
* as a raw pointer, and it's your responsibility to start
* writing after after the preserved prefix (which you
* presumably wanted not to overwrite since you asked for
* it to be preserved).
*
* In a success case, you must call Finish() with the new
* length of the string. In failure cases, it's OK to return
* early from the function whose local variable this handle is.
* The destructor of this class takes care of putting the
* string in a valid and mostly harmless state in that case
* by setting the value of a non-empty string to a single
* REPLACEMENT CHARACTER or in the case of nsACString that's
* too short for a REPLACEMENT CHARACTER to fit, an ASCII
* SUBSTITUTE.
*
* You must not allow this handle to outlive the string you
* obtained it from.
*
* You must not access the string you obtained this handle
* from in any way other than through this handle until
* you call Finish() on the handle or the handle goes out
* of scope.
*
* Once you've called Finish(), you must not call any
* methods on this handle and must not use values previously
* obtained.
*
* Once you call RestartBulkWrite(), you must not use
* values previously obtained from this handle and must
* reobtain the new corresponding values.
*/
template <typename T>
class BulkWriteHandle final {
friend class nsTSubstring<T>;
public:
typedef typename mozilla::detail::nsTStringRepr<T> base_string_type;
typedef typename base_string_type::size_type size_type;
/**
* Pointer to the start of the writable buffer. Never nullptr.
*
* This pointer is valid until whichever of these happens first:
* 1) Finish() is called
* 2) RestartBulkWrite() is called
* 3) BulkWriteHandle goes out of scope
*/
T* Elements() const {
MOZ_ASSERT(mString);
return mString->mData;
}
/**
* How many code units can be written to the buffer.
* (Note: This is not the same as the string's Length().)
*
* This value is valid until whichever of these happens first:
* 1) Finish() is called
* 2) RestartBulkWrite() is called
* 3) BulkWriteHandle goes out of scope
*/
size_type Length() const {
MOZ_ASSERT(mString);
return mCapacity;
}
/**
* Pointer past the end of the buffer.
*
* This pointer is valid until whichever of these happens first:
* 1) Finish() is called
* 2) RestartBulkWrite() is called
* 3) BulkWriteHandle goes out of scope
*/
T* End() const { return Elements() + Length(); }
/**
* The writable buffer as Span.
*
* This Span is valid until whichever of these happens first:
* 1) Finish() is called
* 2) RestartBulkWrite() is called
* 3) BulkWriteHandle goes out of scope
*/
mozilla::Span<T> AsSpan() const {
return mozilla::MakeSpan(Elements(), Length());
}
/**
* Autoconvert to the buffer as writable Span.
*
* This Span is valid until whichever of these happens first:
* 1) Finish() is called
* 2) RestartBulkWrite() is called
* 3) BulkWriteHandle goes out of scope
*/
operator mozilla::Span<T>() const { return AsSpan(); }
/**
* Restart the bulk write with a different capacity.
*
* This method invalidates previous return values
* of the other methods above.
*
* Can fail if out of memory leaving the buffer
* in the state before this call.
*
* @param aCapacity the new requested capacity
* @param aPrefixToPreserve the number of code units at
* the start of the string to
* copy over to the new buffer
* @param aAllowShrinking whether the string is
* allowed to attempt to
* allocate a smaller buffer
* for its content and copy
* the data over.
*/
mozilla::Result<mozilla::Ok, nsresult> RestartBulkWrite(
size_type aCapacity, size_type aPrefixToPreserve, bool aAllowShrinking) {
MOZ_ASSERT(mString);
auto r = mString->StartBulkWriteImpl(aCapacity, aPrefixToPreserve,
aAllowShrinking);
if (MOZ_UNLIKELY(r.isErr())) {
nsresult rv = r.unwrapErr();
// MOZ_TRY or manual unwrapErr() without the intermediate
// assignment complains about an incomplete type.
// andThen() is not enabled on r.
return mozilla::Err(rv);
}
mCapacity = r.unwrap();
return mozilla::Ok();
}
/**
* Indicate that the bulk write finished successfully.
*
* @param aLength the number of code units written;
* must not exceed Length()
* @param aAllowShrinking whether the string is
* allowed to attempt to
* allocate a smaller buffer
* for its content and copy
* the data over.
*/
void Finish(size_type aLength, bool aAllowShrinking) {
MOZ_ASSERT(mString);
MOZ_ASSERT(aLength <= mCapacity);
if (!aLength) {
// Truncate is safe even when the string is in an invalid state
mString->Truncate();
mString = nullptr;
return;
}
if (aAllowShrinking) {
mozilla::Unused << mString->StartBulkWriteImpl(aLength, aLength, true);
}
mString->FinishBulkWriteImpl(aLength);
mString = nullptr;
}
BulkWriteHandle(BulkWriteHandle&& aOther)
: mString(aOther.Forget()), mCapacity(aOther.mCapacity) {}
~BulkWriteHandle() {
if (!mString || !mCapacity) {
return;
}
// The old zero terminator may be gone by now, so we need
// to write a new one somewhere and make length match.
// We can use a length between 1 and self.capacity.
// The contents of the string can be partially uninitialized
// or partially initialized in a way that would be dangerous
// if parsed by some recipient. It's prudent to write something
// same as the contents of the string. U+FFFD is the safest
// placeholder, but when it doesn't fit, let's use ASCII
// substitute. Merely truncating the string to a zero-length
// string might be dangerous in some scenarios. See
// https://www.unicode.org/reports/tr36/#Substituting_for_Ill_Formed_Subsequences
// for closely related scenario.
auto ptr = Elements();
// Cast the pointer below to silence warnings
if (sizeof(T) == 1) {
unsigned char* charPtr = reinterpret_cast<unsigned char*>(ptr);
if (mCapacity >= 3) {
*charPtr++ = 0xEF;
*charPtr++ = 0xBF;
*charPtr++ = 0xBD;
mString->mLength = 3;
} else {
*charPtr++ = 0x1A;
mString->mLength = 1;
}
*charPtr = 0;
} else if (sizeof(T) == 2) {
char16_t* charPtr = reinterpret_cast<char16_t*>(ptr);
*charPtr++ = 0xFFFD;
*charPtr = 0;
mString->mLength = 1;
} else {
MOZ_ASSERT_UNREACHABLE("Only 8-bit and 16-bit code units supported.");
}
}
BulkWriteHandle() = delete;
BulkWriteHandle(const BulkWriteHandle&) = delete;
BulkWriteHandle& operator=(const BulkWriteHandle&) = delete;
private:
BulkWriteHandle(nsTSubstring<T>* aString, size_type aCapacity)
: mString(aString), mCapacity(aCapacity) {}
nsTSubstring<T>* Forget() {
auto string = mString;
mString = nullptr;
return string;
}
nsTSubstring<T>* mString; // nullptr upon finish
size_type mCapacity;
};
} // namespace mozilla
/**
* nsTSubstring is an abstract string class. From an API perspective, this
* class is the root of the string class hierarchy. It represents a single
* contiguous array of characters, which may or may not be null-terminated.
* This type is not instantiated directly. A sub-class is instantiated
* instead. For example, see nsTString.
*
* NAMES:
* nsAString for wide characters
* nsACString for narrow characters
*
*/
template <typename T>
class nsTSubstring : public mozilla::detail::nsTStringRepr<T> {
friend class mozilla::BulkWriteHandle<T>;
public:
typedef nsTSubstring<T> self_type;
typedef nsTString<T> string_type;
typedef typename mozilla::detail::nsTStringRepr<T> base_string_type;
typedef typename base_string_type::substring_type substring_type;
typedef typename base_string_type::fallible_t fallible_t;
typedef typename base_string_type::char_type char_type;
typedef typename base_string_type::char_traits char_traits;
typedef
typename base_string_type::incompatible_char_type incompatible_char_type;
typedef typename base_string_type::substring_tuple_type substring_tuple_type;
typedef typename base_string_type::const_iterator const_iterator;
typedef typename base_string_type::iterator iterator;
typedef typename base_string_type::comparator_type comparator_type;
typedef typename base_string_type::const_char_iterator const_char_iterator;
typedef typename base_string_type::index_type index_type;
typedef typename base_string_type::size_type size_type;
// These are only for internal use within the string classes:
typedef typename base_string_type::DataFlags DataFlags;
typedef typename base_string_type::ClassFlags ClassFlags;
// this acts like a virtual destructor
~nsTSubstring() { Finalize(); }
/**
* writing iterators
*
* BeginWriting() makes the string mutable (if it isn't
* already) and returns (or writes into an outparam) a
* pointer that provides write access to the string's buffer.
*
* Note: Consider if BulkWrite() suits your use case better
* than BeginWriting() combined with SetLength().
*
* Note: Strings autoconvert into writable mozilla::Span,
* which may suit your use case better than calling
* BeginWriting() directly.
*
* When writing via the pointer obtained from BeginWriting(),
* you are allowed to write at most the number of code units
* indicated by Length() or, alternatively, write up to, but
* not including, the position indicated by EndWriting().
*
* In particular, calling SetCapacity() does not affect what
* the above paragraph says.
*/
iterator BeginWriting() {
if (!EnsureMutable()) {
AllocFailed(base_string_type::mLength);
}
return base_string_type::mData;
}
iterator BeginWriting(const fallible_t&) {
return EnsureMutable() ? base_string_type::mData : iterator(0);
}
iterator EndWriting() {
if (!EnsureMutable()) {
AllocFailed(base_string_type::mLength);
}
return base_string_type::mData + base_string_type::mLength;
}
iterator EndWriting(const fallible_t&) {
return EnsureMutable()
? (base_string_type::mData + base_string_type::mLength)
: iterator(0);
}
/**
* Perform string to int conversion.
* @param aErrorCode will contain error if one occurs
* @param aRadix is the radix to use. Only 10 and 16 are supported.
* @return int rep of string value, and possible (out) error code
*/
int32_t ToInteger(nsresult* aErrorCode, uint32_t aRadix = 10) const;
/**
* Perform string to 64-bit int conversion.
* @param aErrorCode will contain error if one occurs
* @param aRadix is the radix to use. Only 10 and 16 are supported.
* @return 64-bit int rep of string value, and possible (out) error code
*/
int64_t ToInteger64(nsresult* aErrorCode, uint32_t aRadix = 10) const;
/**
* assignment
*/
void NS_FASTCALL Assign(char_type aChar);
[[nodiscard]] bool NS_FASTCALL Assign(char_type aChar, const fallible_t&);
void NS_FASTCALL Assign(const char_type* aData,
size_type aLength = size_type(-1));
[[nodiscard]] bool NS_FASTCALL Assign(const char_type* aData,
const fallible_t&);
[[nodiscard]] bool NS_FASTCALL Assign(const char_type* aData,
size_type aLength, const fallible_t&);
void NS_FASTCALL Assign(const self_type&);
[[nodiscard]] bool NS_FASTCALL Assign(const self_type&, const fallible_t&);
void NS_FASTCALL Assign(self_type&&);
[[nodiscard]] bool NS_FASTCALL Assign(self_type&&, const fallible_t&);
void NS_FASTCALL Assign(const substring_tuple_type&);
[[nodiscard]] bool NS_FASTCALL Assign(const substring_tuple_type&,
const fallible_t&);
#if defined(MOZ_USE_CHAR16_WRAPPER)
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
void Assign(char16ptr_t aData) {
Assign(static_cast<const char16_t*>(aData));
}
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
void Assign(char16ptr_t aData, size_type aLength) {
Assign(static_cast<const char16_t*>(aData), aLength);
}
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
[[nodiscard]] bool Assign(char16ptr_t aData, size_type aLength,
const fallible_t& aFallible) {
return Assign(static_cast<const char16_t*>(aData), aLength, aFallible);
}
#endif
void NS_FASTCALL AssignASCII(const char* aData, size_type aLength);
[[nodiscard]] bool NS_FASTCALL AssignASCII(const char* aData,
size_type aLength,
const fallible_t&);
void NS_FASTCALL AssignASCII(const char* aData) {
AssignASCII(aData, mozilla::AssertedCast<size_type, size_t>(strlen(aData)));
}
[[nodiscard]] bool NS_FASTCALL AssignASCII(const char* aData,
const fallible_t& aFallible) {
return AssignASCII(aData,
mozilla::AssertedCast<size_type, size_t>(strlen(aData)),
aFallible);
}
// AssignLiteral must ONLY be called with an actual literal string, or
// a character array *constant* of static storage duration declared
// without an explicit size and with an initializer that is a string
// literal or is otherwise null-terminated.
// Use Assign or AssignASCII for other character array variables.
//
// This method does not need a fallible version, because it uses the
// POD buffer of the literal as the string's buffer without allocating.
// The literal does not need to be ASCII. If this a 16-bit string, this
// method takes a u"" literal. (The overload on 16-bit strings that takes
// a "" literal takes only ASCII.)
template <int N>
void AssignLiteral(const char_type (&aStr)[N]) {
AssignLiteral(aStr, N - 1);
}
// AssignLiteral must ONLY be called with an actual literal string, or
// a char array *constant* declared without an explicit size and with an
// initializer that is a string literal or is otherwise null-terminated.
// Use AssignASCII for other char array variables.
//
// This method takes an 8-bit (ASCII-only!) string that is expanded
// into a 16-bit string at run time causing a run-time allocation.
// To avoid the run-time allocation (at the cost of the literal
// taking twice the size in the binary), use the above overload that
// takes a u"" string instead. Using the overload that takes a u""
// literal is generally preferred when working with 16-bit strings.
//
// There is not a fallible version of this method because it only really
// applies to small allocations that we wouldn't want to check anyway.
template <int N, typename Q = T,
typename EnableIfChar16 = typename mozilla::Char16OnlyT<Q>>
void AssignLiteral(const incompatible_char_type (&aStr)[N]) {
AssignASCII(aStr, N - 1);
}
self_type& operator=(char_type aChar) {
Assign(aChar);
return *this;
}
self_type& operator=(const char_type* aData) {
Assign(aData);
return *this;
}
#if defined(MOZ_USE_CHAR16_WRAPPER)
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
self_type& operator=(char16ptr_t aData) {
Assign(aData);
return *this;
}
#endif
self_type& operator=(const self_type& aStr) {
Assign(aStr);
return *this;
}
self_type& operator=(self_type&& aStr) {
Assign(std::move(aStr));
return *this;
}
self_type& operator=(const substring_tuple_type& aTuple) {
Assign(aTuple);
return *this;
}
// Adopt a heap-allocated char sequence for this string; is Voided if aData
// is null. Useful for e.g. converting an strdup'd C string into an
// nsCString. See also getter_Copies(), which is a useful wrapper.
void NS_FASTCALL Adopt(char_type* aData, size_type aLength = size_type(-1));
/**
* buffer manipulation
*/
void NS_FASTCALL Replace(index_type aCutStart, size_type aCutLength,
char_type aChar);
[[nodiscard]] bool NS_FASTCALL Replace(index_type aCutStart,
size_type aCutLength, char_type aChar,
const fallible_t&);
void NS_FASTCALL Replace(index_type aCutStart, size_type aCutLength,
const char_type* aData,
size_type aLength = size_type(-1));
[[nodiscard]] bool NS_FASTCALL Replace(index_type aCutStart,
size_type aCutLength,
const char_type* aData,
size_type aLength, const fallible_t&);
void Replace(index_type aCutStart, size_type aCutLength,
const self_type& aStr) {
Replace(aCutStart, aCutLength, aStr.Data(), aStr.Length());
}
[[nodiscard]] bool Replace(index_type aCutStart, size_type aCutLength,
const self_type& aStr,
const fallible_t& aFallible) {
return Replace(aCutStart, aCutLength, aStr.Data(), aStr.Length(),
aFallible);
}
void NS_FASTCALL Replace(index_type aCutStart, size_type aCutLength,
const substring_tuple_type& aTuple);
// ReplaceLiteral must ONLY be called with an actual literal string, or
// a character array *constant* of static storage duration declared
// without an explicit size and with an initializer that is a string
// literal or is otherwise null-terminated.
// Use Replace for other character array variables.
template <int N>
void ReplaceLiteral(index_type aCutStart, size_type aCutLength,
const char_type (&aStr)[N]) {
ReplaceLiteral(aCutStart, aCutLength, aStr, N - 1);
}
void Append(char_type aChar);
[[nodiscard]] bool Append(char_type aChar, const fallible_t& aFallible);
void Append(const char_type* aData, size_type aLength = size_type(-1));
[[nodiscard]] bool Append(const char_type* aData, size_type aLength,
const fallible_t& aFallible);
#if defined(MOZ_USE_CHAR16_WRAPPER)
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
void Append(char16ptr_t aData, size_type aLength = size_type(-1)) {
Append(static_cast<const char16_t*>(aData), aLength);
}
#endif
void Append(const self_type& aStr);
[[nodiscard]] bool Append(const self_type& aStr, const fallible_t& aFallible);
void Append(const substring_tuple_type& aTuple);
[[nodiscard]] bool Append(const substring_tuple_type& aTuple,
const fallible_t& aFallible);
void AppendASCII(const char* aData, size_type aLength = size_type(-1));
[[nodiscard]] bool AppendASCII(const char* aData,
const fallible_t& aFallible);
[[nodiscard]] bool AppendASCII(const char* aData, size_type aLength,
const fallible_t& aFallible);
// Appends a literal string ("" literal in the 8-bit case and u"" literal
// in the 16-bit case) to the string.
//
// AppendLiteral must ONLY be called with an actual literal string, or
// a character array *constant* of static storage duration declared
// without an explicit size and with an initializer that is a string
// literal or is otherwise null-terminated.
// Use Append or AppendASCII for other character array variables.
template <int N>
void AppendLiteral(const char_type (&aStr)[N]) {
// The case where base_string_type::mLength is zero is intentionally
// left unoptimized (could be optimized as call to AssignLiteral),
// because it's rare/nonexistent. If you add that optimization,
// please be sure to also check that
// !(base_string_type::mDataFlags & DataFlags::REFCOUNTED)
// to avoid undoing the effects of SetCapacity().
Append(aStr, N - 1);
}
template <int N>
void AppendLiteral(const char_type (&aStr)[N], const fallible_t& aFallible) {
// The case where base_string_type::mLength is zero is intentionally
// left unoptimized (could be optimized as call to AssignLiteral),
// because it's rare/nonexistent. If you add that optimization,
// please be sure to also check that
// !(base_string_type::mDataFlags & DataFlags::REFCOUNTED)
// to avoid undoing the effects of SetCapacity().
return Append(aStr, N - 1, aFallible);
}
// Only enable for T = char16_t
//
// Appends an 8-bit literal string ("" literal) to a 16-bit string by
// expanding it. The literal must only contain ASCII.
//
// Using u"" literals with 16-bit strings is generally preferred.
template <int N, typename Q = T,
typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
void AppendLiteral(const incompatible_char_type (&aStr)[N]) {
AppendASCII(aStr, N - 1);
}
// Only enable for T = char16_t
template <int N, typename Q = T,
typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
[[nodiscard]] bool AppendLiteral(const incompatible_char_type (&aStr)[N],
const fallible_t& aFallible) {
return AppendASCII(aStr, N - 1, aFallible);
}
/**
* Append a formatted string to the current string. Uses the
* standard printf format codes. This uses NSPR formatting, which will be
* locale-aware for floating-point values. You probably don't want to use
* this with floating-point values as a result.
*/
void AppendPrintf(const char* aFormat, ...) MOZ_FORMAT_PRINTF(2, 3);
void AppendPrintf(const char* aFormat, va_list aAp) MOZ_FORMAT_PRINTF(2, 0);
void AppendInt(int32_t aInteger) { AppendIntDec(aInteger); }
void AppendInt(int32_t aInteger, int aRadix) {
if (aRadix == 10) {
AppendIntDec(aInteger);
} else if (aRadix == 8) {
AppendIntOct(static_cast<uint32_t>(aInteger));
} else {
AppendIntHex(static_cast<uint32_t>(aInteger));
}
}
void AppendInt(uint32_t aInteger) { AppendIntDec(aInteger); }
void AppendInt(uint32_t aInteger, int aRadix) {
if (aRadix == 10) {
AppendIntDec(aInteger);
} else if (aRadix == 8) {
AppendIntOct(aInteger);
} else {
AppendIntHex(aInteger);
}
}
void AppendInt(int64_t aInteger) { AppendIntDec(aInteger); }
void AppendInt(int64_t aInteger, int aRadix) {
if (aRadix == 10) {
AppendIntDec(aInteger);
} else if (aRadix == 8) {
AppendIntOct(static_cast<uint64_t>(aInteger));
} else {
AppendIntHex(static_cast<uint64_t>(aInteger));
}
}
void AppendInt(uint64_t aInteger) { AppendIntDec(aInteger); }
void AppendInt(uint64_t aInteger, int aRadix) {
if (aRadix == 10) {
AppendIntDec(aInteger);
} else if (aRadix == 8) {
AppendIntOct(aInteger);
} else {
AppendIntHex(aInteger);
}
}
private:
void AppendIntDec(int32_t);
void AppendIntDec(uint32_t);
void AppendIntOct(uint32_t);
void AppendIntHex(uint32_t);
void AppendIntDec(int64_t);
void AppendIntDec(uint64_t);
void AppendIntOct(uint64_t);
void AppendIntHex(uint64_t);
public:
/**
* Append the given float to this string
*/
void NS_FASTCALL AppendFloat(float aFloat);
void NS_FASTCALL AppendFloat(double aFloat);
self_type& operator+=(char_type aChar) {
Append(aChar);
return *this;
}
self_type& operator+=(const char_type* aData) {
Append(aData);
return *this;
}
#if defined(MOZ_USE_CHAR16_WRAPPER)
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
self_type& operator+=(char16ptr_t aData) {
Append(aData);
return *this;
}
#endif
self_type& operator+=(const self_type& aStr) {
Append(aStr);
return *this;
}
self_type& operator+=(const substring_tuple_type& aTuple) {
Append(aTuple);
return *this;
}
void Insert(char_type aChar, index_type aPos) { Replace(aPos, 0, aChar); }
void Insert(const char_type* aData, index_type aPos,
size_type aLength = size_type(-1)) {
Replace(aPos, 0, aData, aLength);
}
#if defined(MOZ_USE_CHAR16_WRAPPER)
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
void Insert(char16ptr_t aData, index_type aPos,
size_type aLength = size_type(-1)) {
Insert(static_cast<const char16_t*>(aData), aPos, aLength);
}
#endif
void Insert(const self_type& aStr, index_type aPos) {
Replace(aPos, 0, aStr);
}
void Insert(const substring_tuple_type& aTuple, index_type aPos) {
Replace(aPos, 0, aTuple);
}
// InsertLiteral must ONLY be called with an actual literal string, or
// a character array *constant* of static storage duration declared
// without an explicit size and with an initializer that is a string
// literal or is otherwise null-terminated.
// Use Insert for other character array variables.
template <int N>
void InsertLiteral(const char_type (&aStr)[N], index_type aPos) {
ReplaceLiteral(aPos, 0, aStr, N - 1);
}
void Cut(index_type aCutStart, size_type aCutLength) {
Replace(aCutStart, aCutLength, char_traits::sEmptyBuffer, 0);
}
nsTSubstringSplitter<T> Split(const char_type aChar) const;
/**
* buffer sizing
*/
/**
* Attempts to set the capacity to the given size in number of
* code units without affecting the length of the string in
* order to avoid reallocation during a subsequent sequence of
* appends.
*
* This method is appropriate to use before a sequence of multiple
* operations from the following list (without operations that are
* not on the list between the SetCapacity() call and operations
* from the list):
*
* Append()
* AppendASCII()
* AppendLiteral() (except if the string is empty: bug 1487606)
* AppendPrintf()
* AppendInt()
* AppendFloat()
* LossyAppendUTF16toASCII()
* AppendASCIItoUTF16()
*
* DO NOT call SetCapacity() if the subsequent operations on the
* string do not meet the criteria above. Operations that undo
* the benefits of SetCapacity() include but are not limited to:
*
* SetLength()
* Truncate()
* Assign()
* AssignLiteral()
* Adopt()
* CopyASCIItoUTF16()
* LossyCopyUTF16toASCII()
* AppendUTF16toUTF8()
* AppendUTF8toUTF16()
* CopyUTF16toUTF8()
* CopyUTF8toUTF16()
*
* If your string is an nsAuto[C]String and you are calling
* SetCapacity() with a constant N, please instead declare the
* string as nsAuto[C]StringN<N+1> without calling SetCapacity().
*
* There is no need to include room for the null terminator: it is
* the job of the string class.
*
* Note: Calling SetCapacity() does not give you permission to
* use the pointer obtained from BeginWriting() to write
* past the current length (as returned by Length()) of the
* string. Please use either BulkWrite() or SetLength()
* instead.
*
* Note: SetCapacity() won't make the string shorter if
* called with an argument smaller than the length of the
* string.
*
* Note: You must not use previously obtained iterators
* or spans after calling SetCapacity().
*/
void NS_FASTCALL SetCapacity(size_type aNewCapacity);
[[nodiscard]] bool NS_FASTCALL SetCapacity(size_type aNewCapacity,
const fallible_t&);
/**
* Changes the logical length of the string, potentially
* allocating a differently-sized buffer for the string.
*
* When making the string shorter, this method never
* reports allocation failure.
*
* Exposes uninitialized memory if the string got longer.
*
* If called with the argument 0, releases the
* heap-allocated buffer, if any. (But the no-argument
* overload of Truncate() is a more idiomatic and efficient
* option than SetLength(0).)
*
* Note: You must not use previously obtained iterators
* or spans after calling SetLength().
*/
void NS_FASTCALL SetLength(size_type aNewLength);
[[nodiscard]] bool NS_FASTCALL SetLength(size_type aNewLength,
const fallible_t&);
/**
* Like SetLength() but asserts in that the string
* doesn't become longer. Never fails, so doesn't need a
* fallible variant.
*
* Note: You must not use previously obtained iterators
* or spans after calling Truncate().
*/
void Truncate(size_type aNewLength) {
MOZ_RELEASE_ASSERT(aNewLength <= base_string_type::mLength,
"Truncate cannot make string longer");
mozilla::DebugOnly<bool> success = SetLength(aNewLength, mozilla::fallible);
MOZ_ASSERT(success);
}
/**
* A more efficient overload for Truncate(0). Releases the
* heap-allocated buffer if any.
*/
void Truncate();
/**
* buffer access
*/
/**
* Get a const pointer to the string's internal buffer. The caller
* MUST NOT modify the characters at the returned address.
*
* @returns The length of the buffer in characters.
*/
inline size_type GetData(const char_type** aData) const {
*aData = base_string_type::mData;
return base_string_type::mLength;
}
/**
* Get a pointer to the string's internal buffer, optionally resizing
* the buffer first. If size_type(-1) is passed for newLen, then the
* current length of the string is used. The caller MAY modify the
* characters at the returned address (up to but not exceeding the
* length of the string).
*
* @returns The length of the buffer in characters or 0 if unable to
* satisfy the request due to low-memory conditions.
*/
size_type GetMutableData(char_type** aData,
size_type aNewLen = size_type(-1)) {
if (!EnsureMutable(aNewLen)) {
AllocFailed(aNewLen == size_type(-1) ? base_string_type::mLength
: aNewLen);
}
*aData = base_string_type::mData;
return base_string_type::mLength;
}
size_type GetMutableData(char_type** aData, size_type aNewLen,
const fallible_t&) {
if (!EnsureMutable(aNewLen)) {
*aData = nullptr;
return 0;
}
*aData = base_string_type::mData;
return base_string_type::mLength;
}
#if defined(MOZ_USE_CHAR16_WRAPPER)
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
size_type GetMutableData(wchar_t** aData, size_type aNewLen = size_type(-1)) {
return GetMutableData(reinterpret_cast<char16_t**>(aData), aNewLen);
}
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
size_type GetMutableData(wchar_t** aData, size_type aNewLen,
const fallible_t& aFallible) {
return GetMutableData(reinterpret_cast<char16_t**>(aData), aNewLen,
aFallible);
}
#endif
/**
* Span integration
*/
operator mozilla::Span<char_type>() {
return mozilla::MakeSpan(BeginWriting(), base_string_type::Length());
}
operator mozilla::Span<const char_type>() const {
return mozilla::MakeSpan(base_string_type::BeginReading(),
base_string_type::Length());
}
void Append(mozilla::Span<const char_type> aSpan) {
auto len = aSpan.Length();
MOZ_RELEASE_ASSERT(len <= std::numeric_limits<size_type>::max());
Append(aSpan.Elements(), len);
}
[[nodiscard]] bool Append(mozilla::Span<const char_type> aSpan,
const fallible_t& aFallible) {
auto len = aSpan.Length();
if (len > std::numeric_limits<size_type>::max()) {
return false;
}
return Append(aSpan.Elements(), len, aFallible);
}
void NS_FASTCALL AssignASCII(mozilla::Span<const char> aData) {
AssignASCII(aData.Elements(), aData.Length());
}
[[nodiscard]] bool NS_FASTCALL AssignASCII(mozilla::Span<const char> aData,
const fallible_t& aFallible) {
return AssignASCII(aData.Elements(), aData.Length(), aFallible);
}
void AppendASCII(mozilla::Span<const char> aData) {
AppendASCII(aData.Elements(), aData.Length());
}
template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
operator mozilla::Span<uint8_t>() {
return mozilla::MakeSpan(reinterpret_cast<uint8_t*>(BeginWriting()),
base_string_type::Length());
}
template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
operator mozilla::Span<const uint8_t>() const {
return mozilla::MakeSpan(
reinterpret_cast<const uint8_t*>(base_string_type::BeginReading()),
base_string_type::Length());
}
template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
void Append(mozilla::Span<const uint8_t> aSpan) {
auto len = aSpan.Length();
MOZ_RELEASE_ASSERT(len <= std::numeric_limits<size_type>::max());
Append(reinterpret_cast<const char*>(aSpan.Elements()), len);
}
template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
[[nodiscard]] bool Append(mozilla::Span<const uint8_t> aSpan,
const fallible_t& aFallible) {
auto len = aSpan.Length();
if (len > std::numeric_limits<size_type>::max()) {
return false;
}
return Append(reinterpret_cast<const char*>(aSpan.Elements()), len,
aFallible);
}
/**
* string data is never null, but can be marked void. if true, the
* string will be truncated. @see nsTSubstring::IsVoid
*/
void NS_FASTCALL SetIsVoid(bool);
/**
* This method is used to remove all occurrences of aChar from this
* string.
*
* @param aChar -- char to be stripped
*/
void StripChar(char_type aChar);
/**
* This method is used to remove all occurrences of aChars from this
* string.
*
* @param aChars -- chars to be stripped
*/
void StripChars(const char_type* aChars);
/**
* This method is used to remove all occurrences of some characters this
* from this string. The characters removed have the corresponding
* entries in the bool array set to true; we retain all characters
* with code beyond 127.
* THE CALLER IS RESPONSIBLE for making sure the complete boolean
* array, 128 entries, is properly initialized.
*
* See also: ASCIIMask class.
*
* @param aToStrip -- Array where each entry is true if the
* corresponding ASCII character is to be stripped. All
* characters beyond code 127 are retained. Note that this
* parameter is of ASCIIMaskArray type, but we expand the typedef
* to avoid having to include nsASCIIMask.h in this include file
* as it brings other includes.
*/
void StripTaggedASCII(const std::array<bool, 128>& aToStrip);
/**
* A shortcut to strip \r and \n.
*/
void StripCRLF();
/**
* If the string uses a shared buffer, this method
* clears the pointer without releasing the buffer.
*/
void ForgetSharedBuffer() {
if (base_string_type::mDataFlags & DataFlags::REFCOUNTED) {
SetToEmptyBuffer();
}
}
protected:
void AssertValid() {
MOZ_ASSERT(!(this->mClassFlags & ClassFlags::NULL_TERMINATED) ||
(this->mDataFlags & DataFlags::TERMINATED),
"String classes whose static type guarantees a null-terminated "
"buffer must not be assigned a non-null-terminated buffer.");
}
public:
/**
* this is public to support automatic conversion of tuple to string
* base type, which helps avoid converting to nsTAString.
*/
MOZ_IMPLICIT nsTSubstring(const substring_tuple_type& aTuple)
: base_string_type(nullptr, 0, DataFlags(0), ClassFlags(0)) {
AssertValid();
Assign(aTuple);
}
size_t SizeOfExcludingThisIfUnshared(
mozilla::MallocSizeOf aMallocSizeOf) const;
size_t SizeOfIncludingThisIfUnshared(
mozilla::MallocSizeOf aMallocSizeOf) const;
/**
* WARNING: Only use these functions if you really know what you are
* doing, because they can easily lead to double-counting strings. If
* you do use them, please explain clearly in a comment why it's safe
* and won't lead to double-counting.
*/
size_t SizeOfExcludingThisEvenIfShared(
mozilla::MallocSizeOf aMallocSizeOf) const;
size_t SizeOfIncludingThisEvenIfShared(
mozilla::MallocSizeOf aMallocSizeOf) const;
template <class N>
void NS_ABORT_OOM(T) {
struct never {}; // a compiler-friendly way to do static_assert(false)
static_assert(
std::is_same_v<N, never>,
"In string classes, use AllocFailed to account for sizeof(char_type). "
"Use the global ::NS_ABORT_OOM if you really have a count of bytes.");
}
MOZ_ALWAYS_INLINE void AllocFailed(size_t aLength) {
::NS_ABORT_OOM(aLength * sizeof(char_type));
}
protected:
// default initialization
nsTSubstring()
: base_string_type(char_traits::sEmptyBuffer, 0, DataFlags::TERMINATED,
ClassFlags(0)) {
AssertValid();
}
// copy-constructor, constructs as dependent on given object
// (NOTE: this is for internal use only)
nsTSubstring(const self_type& aStr)
: base_string_type(aStr.base_string_type::mData,
aStr.base_string_type::mLength,
aStr.base_string_type::mDataFlags &
(DataFlags::TERMINATED | DataFlags::VOIDED),
ClassFlags(0)) {
AssertValid();
}
// initialization with ClassFlags
explicit nsTSubstring(ClassFlags aClassFlags)
: base_string_type(char_traits::sEmptyBuffer, 0, DataFlags::TERMINATED,
aClassFlags) {
AssertValid();
}
/**
* allows for direct initialization of a nsTSubstring object.
*/
nsTSubstring(char_type* aData, size_type aLength, DataFlags aDataFlags,
ClassFlags aClassFlags)
// XXXbz or can I just include nscore.h and use NS_BUILD_REFCNT_LOGGING?
#if defined(DEBUG) || defined(FORCE_BUILD_REFCNT_LOGGING)
# define XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE
;
#else
# undef XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE
: base_string_type(aData, aLength, aDataFlags, aClassFlags) {
AssertValid();
MOZ_RELEASE_ASSERT(CheckCapacity(aLength), "String is too large.");
}
#endif /* DEBUG || FORCE_BUILD_REFCNT_LOGGING */
void SetToEmptyBuffer() {
base_string_type::mData = char_traits::sEmptyBuffer;
base_string_type::mLength = 0;
base_string_type::mDataFlags = DataFlags::TERMINATED;
AssertValid();
}
void SetData(char_type* aData, size_type aLength, DataFlags aDataFlags) {
base_string_type::mData = aData;
base_string_type::mLength = aLength;
base_string_type::mDataFlags = aDataFlags;
AssertValid();
}
/**
* this function releases mData and does not change the value of
* any of its member variables. in other words, this function acts
* like a destructor.
*/
void NS_FASTCALL Finalize();
public:
/**
* Starts a low-level write transaction to the string.
*
* Prepares the string for mutation such that the capacity
* of the string is at least aCapacity. The returned handle
* exposes the actual, potentially larger, capacity.
*
* If meeting the capacity or mutability requirement requires
* reallocation, aPrefixToPreserve code units are copied from the
* start of the old buffer to the start of the new buffer.
* aPrefixToPreserve must not be greater than the string's current
* length or greater than aCapacity.
*
* aAllowShrinking indicates whether an allocation may be
* performed when the string is already mutable and the requested
* capacity is smaller than the current capacity.
*
* aRv takes a reference to an nsresult that will be set to
* NS_OK on success or to NS_ERROR_OUT_OF_MEMORY on failure,
* because mozilla::Result cannot wrap move-only types at
* this time.
*
* If this method returns successfully, you must not access
* the string except through the returned BulkWriteHandle
* until either the BulkWriteHandle goes out of scope or
* you call Finish() on the BulkWriteHandle.
*
* Compared to SetLength() and BeginWriting(), this more
* complex API accomplishes two things:
* 1) It exposes the actual capacity which may be larger
* than the requested capacity, which is useful in some
* multi-step write operations that don't allocate for
* the worst case up front.
* 2) It writes the zero terminator after the string
* content has been written, which results in a
* cache-friendly linear write pattern.
*/
mozilla::BulkWriteHandle<T> NS_FASTCALL BulkWrite(size_type aCapacity,
size_type aPrefixToPreserve,
bool aAllowShrinking,
nsresult& aRv);
/**
* THIS IS NOT REALLY A PUBLIC METHOD! DO NOT CALL FROM OUTSIDE
* THE STRING IMPLEMENTATION. (It's public only because friend
* declarations don't allow extern or static and this needs to
* be called from Rust FFI glue.)
*
* Prepares mData to be mutated such that the capacity of the string
* (not counting the zero-terminator) is at least aCapacity.
* Returns the actual capacity, which may be larger than what was
* requested or Err(NS_ERROR_OUT_OF_MEMORY) on allocation failure.
*
* mLength is ignored by this method. If the buffer is reallocated,
* aUnitsToPreserve specifies how many code units to copy over to
* the new buffer. The old buffer is freed if applicable.
*
* Unless the return value is Err(NS_ERROR_OUT_OF_MEMORY) to signal
* failure or 0 to signal that the string has been set to
* the special empty state, this method leaves the string in an
* invalid state! The caller is responsible for calling
* FinishBulkWrite() (or in Rust calling
* nsA[C]StringBulkWriteHandle::finish()), which put the string
* into a valid state by setting mLength and zero-terminating.
* This method sets the flag to claim that the string is
* zero-terminated before it actually is.
*
* Once this method has been called and before FinishBulkWrite()
* has been called, only accessing mData or calling this method
* again are valid operations. Do not call any other methods or
* access other fields between calling this method and
* FinishBulkWrite().
*
* @param aCapacity The requested capacity. The return value
* will be greater than or equal to this value.
* @param aPrefixToPreserve The number of code units at the start
* of the old buffer to copy into the
* new buffer.
* @parem aAllowShrinking If true, an allocation may be performed
* if the requested capacity is smaller
* than the current capacity.
* @param aSuffixLength The length, in code units, of a suffix
* to move.
* @param aOldSuffixStart The old start index of the suffix to
* move.
* @param aNewSuffixStart The new start index of the suffix to
* move.
*
*/
mozilla::Result<uint32_t, nsresult> NS_FASTCALL StartBulkWriteImpl(
size_type aCapacity, size_type aPrefixToPreserve = 0,
bool aAllowShrinking = true, size_type aSuffixLength = 0,
size_type aOldSuffixStart = 0, size_type aNewSuffixStart = 0);
private:
/**
* Do not call this except from within FinishBulkWriteImpl() and
* SetCapacity().
*/
MOZ_ALWAYS_INLINE void NS_FASTCALL
FinishBulkWriteImplImpl(size_type aLength) {
base_string_type::mData[aLength] = char_type(0);
base_string_type::mLength = aLength;
#ifdef DEBUG
// ifdefed in order to avoid the call to Capacity() in non-debug
// builds.
//
// Our string is mutable, so Capacity() doesn't return zero.
// Capacity() doesn't include the space for the zero terminator,
// but we want to unitialize that slot, too. Since we start
// counting after the zero terminator the we just wrote above,
// we end up overwriting the space for terminator not reflected
// in the capacity number.
char_traits::uninitialize(
base_string_type::mData + aLength + 1,
XPCOM_MIN(size_t(Capacity() - aLength), kNsStringBufferMaxPoison));
#endif
}
protected:
/**
* Restores the string to a valid state after a call to StartBulkWrite()
* that returned a non-error result. The argument to this method
* must be less than or equal to the value returned by the most recent
* StartBulkWrite() call.
*/
void NS_FASTCALL FinishBulkWriteImpl(size_type aLength);
/**
* this function prepares a section of mData to be modified. if
* necessary, this function will reallocate mData and possibly move
* existing data to open up the specified section.
*
* @param aCutStart specifies the starting offset of the section
* @param aCutLength specifies the length of the section to be replaced
* @param aNewLength specifies the length of the new section
*
* for example, suppose mData contains the string "abcdef" then
*
* ReplacePrep(2, 3, 4);
*
* would cause mData to look like "ab____f" where the characters
* indicated by '_' have an unspecified value and can be freely
* modified. this function will null-terminate mData upon return.
*
* this function returns false if is unable to allocate sufficient
* memory.
*/
[[nodiscard]] bool ReplacePrep(index_type aCutStart, size_type aCutLength,
size_type aNewLength);
[[nodiscard]] bool NS_FASTCALL ReplacePrepInternal(index_type aCutStart,
size_type aCutLength,
size_type aNewFragLength,
size_type aNewTotalLength);
/**
* returns the number of writable storage units starting at mData.
* the value does not include space for the null-terminator character.
*
* NOTE: this function returns 0 if mData is immutable (or the buffer
* is 0-sized).
*/
size_type NS_FASTCALL Capacity() const;
/**
* this helper function can be called prior to directly manipulating
* the contents of mData. see, for example, BeginWriting.
*/
[[nodiscard]] bool NS_FASTCALL
EnsureMutable(size_type aNewLen = size_type(-1));
/**
* Checks if the given capacity is valid for this string type.
*/
[[nodiscard]] static bool CheckCapacity(size_type aCapacity) {
if (aCapacity > kMaxCapacity) {
// Also assert for |aCapacity| equal to |size_type(-1)|, since we used to
// use that value to flag immutability.
NS_ASSERTION(aCapacity != size_type(-1), "Bogus capacity");
return false;
}
return true;
}
void NS_FASTCALL ReplaceLiteral(index_type aCutStart, size_type aCutLength,
const char_type* aData, size_type aLength);
static const size_type kMaxCapacity;
public:
// NOTE: this method is declared public _only_ for convenience for
// callers who don't have access to the original nsLiteralString_CharT.
void NS_FASTCALL AssignLiteral(const char_type* aData, size_type aLength);
};
extern template class nsTSubstring<char>;
extern template class nsTSubstring<char16_t>;
static_assert(sizeof(nsTSubstring<char>) ==
sizeof(mozilla::detail::nsTStringRepr<char>),
"Don't add new data fields to nsTSubstring_CharT. "
"Add to nsTStringRepr<T> instead.");
// You should not need to instantiate this class directly.
// Use nsTSubstring::Split instead.
template <typename T>
class nsTSubstringSplitter {
typedef typename nsTSubstring<T>::size_type size_type;
typedef typename nsTSubstring<T>::char_type char_type;
class nsTSubstringSplit_Iter {
public:
nsTSubstringSplit_Iter(const nsTSubstringSplitter<T>& aObj, size_type aPos)
: mObj(aObj), mPos(aPos) {}
bool operator!=(const nsTSubstringSplit_Iter& other) const {
return mPos != other.mPos;
}
const nsTDependentSubstring<T>& operator*() const;
const nsTSubstringSplit_Iter& operator++() {
++mPos;
return *this;
}
private:
const nsTSubstringSplitter<T>& mObj;
size_type mPos;
};
private:
const nsTSubstring<T>* const mStr;
mozilla::UniquePtr<nsTDependentSubstring<T>[]> mArray;
size_type mArraySize;
const char_type mDelim;
public:
nsTSubstringSplitter(const nsTSubstring<T>* aStr, char_type aDelim);
nsTSubstringSplit_Iter begin() const {
return nsTSubstringSplit_Iter(*this, 0);
}
nsTSubstringSplit_Iter end() const {
return nsTSubstringSplit_Iter(*this, mArraySize);
}
const nsTDependentSubstring<T>& Get(const size_type index) const {
MOZ_ASSERT(index < mArraySize);
return mArray[index];
}
};
extern template class nsTSubstringSplitter<char>;
extern template class nsTSubstringSplitter<char16_t>;
/**
* Span integration
*/
namespace mozilla {
inline Span<char> MakeSpan(nsTSubstring<char>& aString) { return aString; }
inline Span<const char> MakeSpan(const nsTSubstring<char>& aString) {
return aString;
}
inline Span<char16_t> MakeSpan(nsTSubstring<char16_t>& aString) {
return aString;
}
inline Span<const char16_t> MakeSpan(const nsTSubstring<char16_t>& aString) {
return aString;
}
} // namespace mozilla
#endif
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