gecko-dev/xpcom/string/nsTSubstringTuple.h

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2.8 KiB
C++

/* -*- 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 nsTSubstringTuple_h
#define nsTSubstringTuple_h
#include "mozilla/Attributes.h"
#include "nsTStringRepr.h"
/**
* nsTSubstringTuple
*
* Represents a tuple of string fragments. Built as a recursive binary tree.
* It is used to implement the concatenation of two or more string objects.
*
* NOTE: This class is a private implementation detail and should never be
* referenced outside the string code.
*/
template <typename T>
class MOZ_TEMPORARY_CLASS nsTSubstringTuple {
public:
typedef T char_type;
typedef nsCharTraits<char_type> char_traits;
typedef nsTSubstringTuple<T> self_type;
typedef mozilla::detail::nsTStringRepr<char_type> base_string_type;
typedef size_t size_type;
public:
nsTSubstringTuple(const base_string_type* aStrA,
const base_string_type* aStrB)
: mHead(nullptr), mFragA(aStrA), mFragB(aStrB) {}
nsTSubstringTuple(const self_type& aHead, const base_string_type* aStrB)
: mHead(&aHead),
mFragA(nullptr), // this fragment is ignored when aHead != nullptr
mFragB(aStrB) {}
/**
* computes the aggregate string length
*/
size_type Length() const;
/**
* writes the aggregate string to the given buffer. bufLen is assumed
* to be equal to or greater than the value returned by the Length()
* method. the string written to |buf| is not null-terminated.
*/
void WriteTo(char_type* aBuf, size_type aBufLen) const;
/**
* returns true if this tuple is dependent on (i.e., overlapping with)
* the given char sequence.
*/
bool IsDependentOn(const char_type* aStart, const char_type* aEnd) const;
/**
* returns a pair of the results of IsDependentOn() and Length(). This is more
* efficient than calling both functions subsequently, as this traverses the
* tree only once.
*/
std::pair<bool, size_type> IsDependentOnWithLength(
const char_type* aStart, const char_type* aEnd) const;
private:
const self_type* const mHead;
const base_string_type* const mFragA;
const base_string_type* const mFragB;
};
template <typename T>
inline const nsTSubstringTuple<T> operator+(
const mozilla::detail::nsTStringRepr<T>& aStrA,
const mozilla::detail::nsTStringRepr<T>& aStrB) {
return nsTSubstringTuple<T>(&aStrA, &aStrB);
}
template <typename T>
inline const nsTSubstringTuple<T> operator+(
const nsTSubstringTuple<T>& aHead,
const mozilla::detail::nsTStringRepr<T>& aStrB) {
return nsTSubstringTuple<T>(aHead, &aStrB);
}
#endif