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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
#ifndef nsTStringRepr_h
#define nsTStringRepr_h
#include <limits>
#include <string_view>
#include <type_traits> // std::enable_if
#include "mozilla/Char16.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/fallible.h"
#include "nsStringBuffer.h"
#include "nsStringFlags.h"
#include "nsStringFwd.h"
#include "nsStringIterator.h"
#include "nsCharTraits.h"
template <typename T>
class nsTSubstringTuple;
namespace mozilla {
// This is mainly intended to be used in the context of nsTStrings where
// we want to enable a specific function only for a given character class. In
// order for this technique to work the member function needs to be templated
// on something other than `T`. We keep this in the `mozilla` namespace rather
// than `nsTStringRepr` as it's intentionally not dependent on `T`.
//
// The 'T' at the end of `Char[16]OnlyT` is refering to the `::type` portion
// which will only be defined if the character class is correct. This is similar
// to `std::enable_if_t` which is available in C++14, but not C++11.
//
// `CharType` is generally going to be a shadowed type of `T`.
//
// Example usage of a function that will only be defined if `T` == `char`:
//
// template <typename T>
// class nsTSubstring : public nsTStringRepr<T> {
// template <typename Q = T, typename EnableForChar = typename CharOnlyT<Q>>
// int Foo() { return 42; }
// };
//
// Please note that we had to use a separate type `Q` for this to work. You
// will get a semi-decent compiler error if you use `T` directly.
template <typename CharType>
using CharOnlyT =
typename std::enable_if<std::is_same<char, CharType>::value>::type;
template <typename CharType>
using Char16OnlyT =
typename std::enable_if<std::is_same<char16_t, CharType>::value>::type;
namespace detail {
// nsTStringLengthStorage is a helper class which holds the string's length and
// provides getters and setters for converting to and from `size_t`. This is
// done to allow the length to be stored in a `uint32_t` using assertions.
template <typename T>
class nsTStringLengthStorage {
public:
// The maximum byte capacity for a `nsTString` must fit within an `int32_t`,
// with enough room for a trailing null, as consumers often cast `Length()`
// and `Capacity()` to smaller types like `int32_t`.
static constexpr size_t kMax =
size_t{std::numeric_limits<int32_t>::max()} / sizeof(T) - 1;
static_assert(
(kMax + 1) * sizeof(T) <= std::numeric_limits<int32_t>::max(),
"nsTString's maximum length, including the trailing null, must fit "
"within `int32_t`, as callers will cast to `int32_t` occasionally");
static_assert(((CheckedInt<uint32_t>{kMax} + 1) * sizeof(T) +
sizeof(nsStringBuffer))
.isValid(),
"Math required to allocate a nsStringBuffer for a "
"maximum-capacity string must not overflow uint32_t");
// Implicit conversion and assignment from `size_t` which assert that the
// value is in-range.
MOZ_IMPLICIT constexpr nsTStringLengthStorage(size_t aLength)
: mLength(static_cast<uint32_t>(aLength)) {
MOZ_RELEASE_ASSERT(aLength <= kMax, "string is too large");
}
constexpr nsTStringLengthStorage& operator=(size_t aLength) {
MOZ_RELEASE_ASSERT(aLength <= kMax, "string is too large");
mLength = static_cast<uint32_t>(aLength);
return *this;
}
MOZ_IMPLICIT constexpr operator size_t() const { return mLength; }
private:
uint32_t mLength = 0;
};
// nsTStringRepr defines a string's memory layout and some accessor methods.
// This class exists so that nsTLiteralString can avoid inheriting
// nsTSubstring's destructor. All methods on this class must be const because
// literal strings are not writable.
//
// This class is an implementation detail and should not be instantiated
// directly, nor used in any way outside of the string code itself. It is
// buried in a namespace to discourage its use in function parameters.
// If you need to take a parameter, use [const] ns[C]Substring&.
// If you need to instantiate a string, use ns[C]String or descendents.
//
// NAMES:
// nsStringRepr for wide characters
// nsCStringRepr for narrow characters
template <typename T>
class nsTStringRepr {
public:
typedef mozilla::fallible_t fallible_t;
typedef T char_type;
typedef nsCharTraits<char_type> char_traits;
typedef typename char_traits::incompatible_char_type incompatible_char_type;
typedef nsTStringRepr<T> self_type;
typedef self_type base_string_type;
typedef nsTSubstring<T> substring_type;
typedef nsTSubstringTuple<T> substring_tuple_type;
typedef nsReadingIterator<char_type> const_iterator;
typedef char_type* iterator;
typedef nsTStringComparator<char_type> comparator_type;
typedef const char_type* const_char_iterator;
typedef std::basic_string_view<char_type> string_view;
typedef size_t index_type;
typedef size_t size_type;
// These are only for internal use within the string classes:
typedef StringDataFlags DataFlags;
typedef StringClassFlags ClassFlags;
typedef nsTStringLengthStorage<T> LengthStorage;
// Reading iterators.
constexpr const_char_iterator BeginReading() const { return mData; }
constexpr const_char_iterator EndReading() const { return mData + mLength; }
// Deprecated reading iterators.
const_iterator& BeginReading(const_iterator& aIter) const {
aIter.mStart = mData;
aIter.mEnd = mData + mLength;
aIter.mPosition = aIter.mStart;
return aIter;
}
const_iterator& EndReading(const_iterator& aIter) const {
aIter.mStart = mData;
aIter.mEnd = mData + mLength;
aIter.mPosition = aIter.mEnd;
return aIter;
}
const_char_iterator& BeginReading(const_char_iterator& aIter) const {
return aIter = mData;
}
const_char_iterator& EndReading(const_char_iterator& aIter) const {
return aIter = mData + mLength;
}
// Accessors.
template <typename U, typename Dummy>
struct raw_type {
typedef const U* type;
};
#if defined(MOZ_USE_CHAR16_WRAPPER)
template <typename Dummy>
struct raw_type<char16_t, Dummy> {
typedef char16ptr_t type;
};
#endif
// Returns pointer to string data (not necessarily null-terminated)
constexpr typename raw_type<T, int>::type Data() const { return mData; }
constexpr size_type Length() const { return static_cast<size_type>(mLength); }
constexpr string_view View() const { return string_view(Data(), Length()); }
constexpr operator string_view() const { return View(); }
constexpr DataFlags GetDataFlags() const { return mDataFlags; }
constexpr bool IsEmpty() const { return mLength == 0; }
constexpr bool IsLiteral() const {
return !!(mDataFlags & DataFlags::LITERAL);
}
constexpr bool IsVoid() const { return !!(mDataFlags & DataFlags::VOIDED); }
constexpr bool IsTerminated() const {
return !!(mDataFlags & DataFlags::TERMINATED);
}
constexpr char_type CharAt(index_type aIndex) const {
NS_ASSERTION(aIndex < Length(), "index exceeds allowable range");
return mData[aIndex];
}
constexpr char_type operator[](index_type aIndex) const {
return CharAt(aIndex);
}
char_type First() const;
char_type Last() const;
// Equality.
bool NS_FASTCALL Equals(const self_type&) const;
bool NS_FASTCALL Equals(const self_type&, comparator_type) const;
bool NS_FASTCALL Equals(const substring_tuple_type& aTuple) const;
bool NS_FASTCALL Equals(const substring_tuple_type& aTuple,
comparator_type) const;
bool NS_FASTCALL Equals(const char_type* aData) const;
bool NS_FASTCALL Equals(const char_type* aData, comparator_type) const;
/**
* Compare this string and another ASCII-case-insensitively.
*
* This method is similar to `LowerCaseEqualsASCII` however both strings are
* lowercased, meaning that `aString` need not be all lowercase.
*
* @param aString is the string to check
* @return boolean
*/
bool EqualsIgnoreCase(const std::string_view& aString) const;
#ifdef __cpp_char8_t
template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
bool NS_FASTCALL Equals(const char8_t* aData) const {
return Equals(reinterpret_cast<const char*>(aData));
}
template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
bool NS_FASTCALL Equals(const char8_t* aData, comparator_type aComp) const {
return Equals(reinterpret_cast<const char*>(aData), aComp);
}
#endif
#if defined(MOZ_USE_CHAR16_WRAPPER)
template <typename Q = T, typename EnableIfChar16 = Char16OnlyT<Q>>
bool NS_FASTCALL Equals(char16ptr_t aData) const {
return Equals(static_cast<const char16_t*>(aData));
}
template <typename Q = T, typename EnableIfChar16 = Char16OnlyT<Q>>
bool NS_FASTCALL Equals(char16ptr_t aData, comparator_type aComp) const {
return Equals(static_cast<const char16_t*>(aData), aComp);
}
#endif
// An efficient comparison with ASCII that can be used even
// for wide strings. Call this version when you know the
// length of 'data'.
bool NS_FASTCALL EqualsASCII(const char* aData, size_type aLen) const;
// An efficient comparison with ASCII that can be used even
// for wide strings. Call this version when 'data' is
// null-terminated.
bool NS_FASTCALL EqualsASCII(const char* aData) const;
// An efficient comparison with Latin1 characters that can be used even for
// wide strings.
bool EqualsLatin1(const char* aData, size_type aLength) const;
// EqualsLiteral 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 EqualsASCII for other char array variables.
// (Although this method may happen to produce expected results for other
// char arrays that have bound one greater than the sequence of interest,
// such use is discouraged for reasons of readability and maintainability.)
// The template trick to acquire the array bound at compile time without
// using a macro is due to Corey Kosak, with much thanks.
template <int N>
inline bool EqualsLiteral(const char (&aStr)[N]) const {
return EqualsASCII(aStr, N - 1);
}
// EqualsLiteral 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 EqualsASCII for other char array variables.
// (Although this method may happen to produce expected results for other
// char arrays that have bound one greater than the sequence of interest,
// such use is discouraged for reasons of readability and maintainability.)
// The template trick to acquire the array bound at compile time without
// using a macro is due to Corey Kosak, with much thanks.
template <size_t N, typename = std::enable_if_t<!std::is_same_v<
const char (&)[N], const char_type (&)[N]>>>
inline bool EqualsLiteral(const char_type (&aStr)[N]) const {
return *this == nsTLiteralString<char_type>(aStr);
}
// The LowerCaseEquals methods compare the ASCII-lowercase version of
// this string (lowercasing only ASCII uppercase characters) to some
// ASCII/Literal string. The ASCII string is *not* lowercased for
// you. If you compare to an ASCII or literal string that contains an
// uppercase character, it is guaranteed to return false. We will
// throw assertions too.
bool NS_FASTCALL LowerCaseEqualsASCII(const char* aData,
size_type aLen) const;
bool NS_FASTCALL LowerCaseEqualsASCII(const char* aData) const;
// LowerCaseEqualsLiteral 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 LowerCaseEqualsASCII for other char array variables.
// (Although this method may happen to produce expected results for other
// char arrays that have bound one greater than the sequence of interest,
// such use is discouraged for reasons of readability and maintainability.)
template <int N>
bool LowerCaseEqualsLiteral(const char (&aStr)[N]) const {
return LowerCaseEqualsASCII(aStr, N - 1);
}
// Returns true if this string overlaps with the given string fragment.
bool IsDependentOn(const char_type* aStart, const char_type* aEnd) const {
// If it _isn't_ the case that one fragment starts after the other ends,
// or ends before the other starts, then, they conflict:
//
// !(f2.begin >= f1.aEnd || f2.aEnd <= f1.begin)
//
// Simplified, that gives us (To avoid relying on Undefined Behavior
// from comparing pointers from different allocations (which in
// principle gives the optimizer the permission to assume elsewhere
// that the pointers are from the same allocation), the comparisons
// are done on integers, which merely relies on implementation-defined
// behavior of converting pointers to integers. std::less and
// std::greater implementations don't actually provide the guarantees
// that they should.):
return (reinterpret_cast<uintptr_t>(aStart) <
reinterpret_cast<uintptr_t>(mData + mLength) &&
reinterpret_cast<uintptr_t>(aEnd) >
reinterpret_cast<uintptr_t>(mData));
}
/**
* Search for the given substring within this string.
*
* @param aString is substring to be sought in this
* @param aOffset tells us where in this string to start searching
* @return offset in string, or kNotFound
*/
int32_t Find(const string_view& aString, index_type aOffset = 0) const;
// Previously there was an overload of `Find()` which took a bool second
// argument. Avoid issues by explicitly preventing that overload.
// TODO: Remove this at some point.
template <typename I,
typename = std::enable_if_t<!std::is_same_v<I, index_type> &&
std::is_convertible_v<I, index_type>>>
int32_t Find(const string_view& aString, I aOffset) const {
static_assert(!std::is_same_v<I, bool>, "offset must not be `bool`");
return Find(aString, static_cast<index_type>(aOffset));
}
/**
* Search for the given ASCII substring within this string, ignoring case.
*
* @param aString is substring to be sought in this
* @param aOffset tells us where in this string to start searching
* @return offset in string, or kNotFound
*/
int32_t LowerCaseFindASCII(const std::string_view& aString,
index_type aOffset = 0) const;
/**
* Scan the string backwards, looking for the given substring.
*
* @param aString is substring to be sought in this
* @return offset in string, or kNotFound
*/
int32_t RFind(const string_view& aString) const;
size_type CountChar(char_type) const;
bool Contains(char_type aChar) const { return FindChar(aChar) != kNotFound; }
/**
* Search for the first instance of a given char within this string
*
* @param aChar is the character to search for
* @param aOffset tells us where in this string to start searching
* @return offset in string, or kNotFound
*/
int32_t FindChar(char_type aChar, index_type aOffset = 0) const;
/**
* Search for the last instance of a given char within this string
*
* @param aChar is the character to search for
* @param aOffset tells us where in this string to start searching
* @return offset in string, or kNotFound
*/
int32_t RFindChar(char_type aChar, int32_t aOffset = -1) const;
/**
* This method searches this string for the first character found in
* the given string.
*
* @param aSet contains set of chars to be found
* @param aOffset tells us where in this string to start searching
* (counting from left)
* @return offset in string, or kNotFound
*/
int32_t FindCharInSet(const string_view& aSet, index_type aOffset = 0) const;
/**
* This method searches this string for the last character found in
* the given string.
*
* @param aSet contains set of chars to be found
* @param aOffset tells us where in this string to start searching
* (counting from left)
* @return offset in string, or kNotFound
*/
int32_t RFindCharInSet(const string_view& aSet, int32_t aOffset = -1) const;
/**
* Perform locale-independent string to double-precision float conversion.
*
* Leading spaces in the string will be ignored. The returned value will be
* finite unless aErrorCode is set to a failed status.
*
* @param aErrorCode will contain error if one occurs
* @return double-precision float rep of string value
*/
double ToDouble(nsresult* aErrorCode) const;
/**
* Perform locale-independent string to single-precision float conversion.
*
* Leading spaces in the string will be ignored. The returned value will be
* finite unless aErrorCode is set to a failed status.
*
* @param aErrorCode will contain error if one occurs
* @return single-precision float rep of string value
*/
float ToFloat(nsresult* aErrorCode) const;
/**
* Similar to above ToDouble and ToFloat but allows trailing characters that
* are not converted.
*/
double ToDoubleAllowTrailingChars(nsresult* aErrorCode) const;
float ToFloatAllowTrailingChars(nsresult* aErrorCode) const;
protected:
nsTStringRepr() = delete; // Never instantiate directly
constexpr nsTStringRepr(char_type* aData, size_type aLength,
DataFlags aDataFlags, ClassFlags aClassFlags)
: mData(aData),
mLength(aLength),
mDataFlags(aDataFlags),
mClassFlags(aClassFlags) {}
static constexpr size_type kMaxCapacity = LengthStorage::kMax;
/**
* Checks if the given capacity is valid for this string type.
*/
[[nodiscard]] static constexpr bool CheckCapacity(size_type aCapacity) {
return aCapacity <= kMaxCapacity;
}
char_type* mData;
LengthStorage mLength;
DataFlags mDataFlags;
ClassFlags const mClassFlags;
};
extern template class nsTStringRepr<char>;
extern template class nsTStringRepr<char16_t>;
} // namespace detail
} // namespace mozilla
template <typename T>
int NS_FASTCALL Compare(const mozilla::detail::nsTStringRepr<T>& aLhs,
const mozilla::detail::nsTStringRepr<T>& aRhs,
nsTStringComparator<T> = nsTDefaultStringComparator<T>);
extern template int NS_FASTCALL Compare<char>(
const mozilla::detail::nsTStringRepr<char>&,
const mozilla::detail::nsTStringRepr<char>&, nsTStringComparator<char>);
extern template int NS_FASTCALL
Compare<char16_t>(const mozilla::detail::nsTStringRepr<char16_t>&,
const mozilla::detail::nsTStringRepr<char16_t>&,
nsTStringComparator<char16_t>);
template <typename T>
inline constexpr bool operator!=(
const mozilla::detail::nsTStringRepr<T>& aLhs,
const mozilla::detail::nsTStringRepr<T>& aRhs) {
return !aLhs.Equals(aRhs);
}
template <typename T>
inline constexpr bool operator!=(const mozilla::detail::nsTStringRepr<T>& aLhs,
const T* aRhs) {
return !aLhs.Equals(aRhs);
}
template <typename T>
inline bool operator<(const mozilla::detail::nsTStringRepr<T>& aLhs,
const mozilla::detail::nsTStringRepr<T>& aRhs) {
return Compare(aLhs, aRhs) < 0;
}
template <typename T>
inline bool operator<=(const mozilla::detail::nsTStringRepr<T>& aLhs,
const mozilla::detail::nsTStringRepr<T>& aRhs) {
return Compare(aLhs, aRhs) <= 0;
}
template <typename T>
inline bool operator==(const mozilla::detail::nsTStringRepr<T>& aLhs,
const mozilla::detail::nsTStringRepr<T>& aRhs) {
return aLhs.Equals(aRhs);
}
template <typename T>
inline bool operator==(const mozilla::detail::nsTStringRepr<T>& aLhs,
const T* aRhs) {
return aLhs.Equals(aRhs);
}
template <typename T>
inline bool operator>=(const mozilla::detail::nsTStringRepr<T>& aLhs,
const mozilla::detail::nsTStringRepr<T>& aRhs) {
return Compare(aLhs, aRhs) >= 0;
}
template <typename T>
inline bool operator>(const mozilla::detail::nsTStringRepr<T>& aLhs,
const mozilla::detail::nsTStringRepr<T>& aRhs) {
return Compare(aLhs, aRhs) > 0;
}
#endif