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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/. */
#ifndef nsTStringRepr_h
#define nsTStringRepr_h
#include <type_traits> // std::enable_if
#include "mozilla/Char16.h"
#include "mozilla/fallible.h"
#include "nsStringFlags.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 {
// 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 uint32_t index_type;
typedef uint32_t size_type;
// These are only for internal use within the string classes:
typedef StringDataFlags DataFlags;
typedef StringClassFlags ClassFlags;
// 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 const typename raw_type<T, int>::type Data() const { return mData; }
constexpr size_type Length() const { return mLength; }
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 < mLength, "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;
size_type NS_FASTCALL CountChar(char_type) const;
int32_t NS_FASTCALL FindChar(char_type, index_type aOffset = 0) const;
bool Contains(char_type aChar) 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;
/**
* Compares a given string to this string.
*
* @param aString is the string to be compared
* @param aIgnoreCase tells us how to treat case
* @param aCount tells us how many chars to compare
* @return -1,0,1
*/
template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
int32_t Compare(const char_type* aString, bool aIgnoreCase = false,
int32_t aCount = -1) const;
/**
* Equality check between given string and this string.
*
* @param aString is the string to check
* @param aIgnoreCase tells us how to treat case
* @param aCount tells us how many chars to compare
* @return boolean
*/
template <typename Q = T, typename EnableIfChar = mozilla::CharOnlyT<Q>>
bool EqualsIgnoreCase(const char_type* aString, int32_t aCount = -1) const {
return Compare(aString, true, aCount) == 0;
}
template <typename Q = T, typename EnableIfChar16 = mozilla::Char16OnlyT<Q>>
bool EqualsIgnoreCase(const incompatible_char_type* aString,
int32_t aCount = -1) const;
#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));
}
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) {}
char_type* mData;
size_type 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