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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 nsStringIterator_h___
#define nsStringIterator_h___
#include "nsCharTraits.h"
#include "nsAlgorithm.h"
#include "nsDebug.h"
/**
* @see nsTAString
*/
template <class CharT>
class nsReadingIterator {
public:
typedef nsReadingIterator<CharT> self_type;
typedef ptrdiff_t difference_type;
typedef size_t size_type;
typedef CharT value_type;
typedef const CharT* pointer;
typedef const CharT& reference;
private:
friend class mozilla::detail::nsTStringRepr<CharT>;
// unfortunately, the API for nsReadingIterator requires that the
// iterator know its start and end positions. this was needed when
// we supported multi-fragment strings, but now it is really just
// extra baggage. we should remove mStart and mEnd at some point.
const CharT* mStart;
const CharT* mEnd;
const CharT* mPosition;
public:
nsReadingIterator() : mStart(nullptr), mEnd(nullptr), mPosition(nullptr) {}
// clang-format off
// nsReadingIterator( const nsReadingIterator<CharT>& ); // auto-generated copy-constructor OK
// nsReadingIterator<CharT>& operator=( const nsReadingIterator<CharT>& ); // auto-generated copy-assignment operator OK
// clang-format on
pointer get() const { return mPosition; }
CharT operator*() const { return *get(); }
self_type& operator++() {
++mPosition;
return *this;
}
self_type operator++(int) {
self_type result(*this);
++mPosition;
return result;
}
self_type& operator--() {
--mPosition;
return *this;
}
self_type operator--(int) {
self_type result(*this);
--mPosition;
return result;
}
self_type& advance(difference_type aN) {
if (aN > 0) {
difference_type step = XPCOM_MIN(aN, mEnd - mPosition);
NS_ASSERTION(
step > 0,
"can't advance a reading iterator beyond the end of a string");
mPosition += step;
} else if (aN < 0) {
difference_type step = XPCOM_MAX(aN, -(mPosition - mStart));
NS_ASSERTION(step < 0,
"can't advance (backward) a reading iterator beyond the end "
"of a string");
mPosition += step;
}
return *this;
}
// We return an unsigned type here (with corresponding assert) rather than
// the more usual difference_type because we want to make this class go
// away in favor of mozilla::RangedPtr. Since RangedPtr has the same
// requirement we are enforcing here, the transition ought to be much
// smoother.
size_type operator-(const self_type& aOther) const {
MOZ_ASSERT(mPosition >= aOther.mPosition);
return mPosition - aOther.mPosition;
}
};
template <class CharT>
inline bool operator==(const nsReadingIterator<CharT>& aLhs,
const nsReadingIterator<CharT>& aRhs) {
return aLhs.get() == aRhs.get();
}
template <class CharT>
inline bool operator!=(const nsReadingIterator<CharT>& aLhs,
const nsReadingIterator<CharT>& aRhs) {
return aLhs.get() != aRhs.get();
}
#endif /* !defined(nsStringIterator_h___) */
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