xls-r-300m-sv-robust / kenlm /util /proxy_iterator.hh

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	#ifndef UTIL_PROXY_ITERATOR_H
	#define UTIL_PROXY_ITERATOR_H

	#include <cstddef>
	#include <iterator>

	/* This is a RandomAccessIterator that uses a proxy to access the underlying
	* data. Useful for packing data at bit offsets but still using STL
	* algorithms.
	*
	* Normally I would use boost::iterator_facade but some people are too lazy to
	* install boost and still want to use my language model. It's amazing how
	* many operators an iterator has.
	*
	* The Proxy needs to provide:
	* class InnerIterator;
	* InnerIterator &Inner();
	* const InnerIterator &Inner() const;
	*
	* InnerIterator has to implement:
	* operator==(InnerIterator)
	* operator<(InnerIterator)
	* operator+=(std::ptrdiff_t)
	* operator-(InnerIterator)
	* and of course whatever Proxy needs to dereference it.
	*
	* It's also a good idea to specialize std::swap for Proxy.
	*/

	namespace util {
	template <class Proxy> class ProxyIterator {
	private:
	// Self.
	typedef ProxyIterator<Proxy> S;
	typedef typename Proxy::InnerIterator InnerIterator;

	public:
	typedef std::random_access_iterator_tag iterator_category;
	typedef typename Proxy::value_type value_type;
	typedef std::ptrdiff_t difference_type;
	typedef Proxy reference;
	typedef ProxyIterator<Proxy> * pointer;

	ProxyIterator() {}

	// For cast from non const to const.
	template <class AlternateProxy> ProxyIterator(const ProxyIterator<AlternateProxy> &in) : p_(*in) {}
	explicit ProxyIterator(const Proxy &p) : p_(p) {}

	/* // p_'s swap does value swapping, but here we want iterator swapping
	friend inline void swap(ProxyIterator<Proxy> &first, ProxyIterator<Proxy> &second) {
	swap(first.I(), second.I());
	}*/

	// p_'s operator= does value copying, but here we want iterator copying.
	S &operator=(const S &other) {
	I() = other.I();
	return *this;
	}

	bool operator==(const S &other) const { return I() == other.I(); }
	bool operator!=(const S &other) const { return !(*this == other); }
	bool operator<(const S &other) const { return I() < other.I(); }
	bool operator>(const S &other) const { return other < *this; }
	bool operator<=(const S &other) const { return !(*this > other); }
	bool operator>=(const S &other) const { return !(*this < other); }

	S &operator++() { return *this += 1; }
	S operator++(int) { S ret(this); ++this; return ret; }
	S &operator+=(std::ptrdiff_t amount) { I() += amount; return *this; }
	S operator+(std::ptrdiff_t amount) const { S ret(*this); ret += amount; return ret; }

	S &operator--() { return *this -= 1; }
	S operator--(int) { S ret(this); --this; return ret; }
	S &operator-=(std::ptrdiff_t amount) { I() += (-amount); return *this; }
	S operator-(std::ptrdiff_t amount) const { S ret(*this); ret -= amount; return ret; }

	std::ptrdiff_t operator-(const S &other) const { return I() - other.I(); }

	Proxy operator*() const { return p_; }
	Proxy *operator->() { return &p_; }
	const Proxy *operator->() const { return &p_; }
	Proxy operator[](std::ptrdiff_t amount) const { return (this + amount); }

	const InnerIterator &Inner() { return p_.Inner(); }

	private:
	InnerIterator &I() { return p_.Inner(); }
	const InnerIterator &I() const { return p_.Inner(); }

	Proxy p_;
	};

	template <class Proxy> ProxyIterator<Proxy> operator+(std::ptrdiff_t amount, const ProxyIterator<Proxy> &it) {
	return it + amount;
	}

	} // namespace util

	#endif // UTIL_PROXY_ITERATOR_H