format_helpers.hpp

/*
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relinquishment in perpetuity of all present and future rights to this
software under copyright law.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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*/

#pragma once

#include "stack_format.hpp"

namespace fmt
{
template<typename C, typename BeginIt, typename EndIt>
struct separated_formatter
{
	BeginIt begin;
	EndIt end;
	const C * separator;
};
template<typename BeginIt, typename EndIt, typename C>
separated_formatter<C, BeginIt, EndIt> with_separator(BeginIt begin, EndIt end, const C * separator)
{
	return { begin, end, separator };
}
template<typename T, typename C>
separated_formatter<C, typename T::const_iterator, typename T::const_iterator> with_separator(const T & range, const C * separator)
{
	return { range.begin(), range.end(), separator };
}
template<typename C, typename It, typename BeginIt, typename EndIt>
format_it<C, It> format(format_it<C, It> it, separated_formatter<C, BeginIt, EndIt> format)
{
	if (format.begin != format.end)
	{
		*it++ = *format.begin;
		for (++format.begin; format.begin != format.end; ++format.begin)
		{
			*it++ = format.separator;
			*it++ = *format.begin;
		}
	}
	return it;
}
namespace detail
{
template<typename C, typename It, typename T>
struct separator_it : std::iterator<std::output_iterator_tag, void, void, void, void>
{
	separator_it(format_it<C, It> it, T separator)
		: it(std::move(it)), separator(std::move(separator))
	{
	}

	separator_it & operator*()
	{
		return *this;
	}
	separator_it & operator++()
	{
		return *this;
	}
	separator_it & operator++(int)
	{
		return *this;
	}
	template<typename U>
	separator_it & operator=(const U & value)
	{
		if (first) first = false;
		else it.print(separator);
		it.print(value);
		return *this;
	}

	format_it<C, It> it;
	bool first = true;
	T separator;
};
}
template<typename C, typename It, typename T>
detail::separator_it<C, format_it<C, It>, T> with_separator(format_it<C, It> it, T separator)
{
	return detail::separator_it<C, format_it<C, It>, T>(std::move(it), std::move(separator));
}

namespace detail
{
template<typename V, typename C>
struct padded_formatter
{
	padded_formatter(const V & value, int num_padding, C padding)
		: value(value), num_padding(num_padding), padding(padding)
	{
	}
	const V & value;
	int num_padding;
	C padding;
};
}
template<typename V, typename C>
struct left_padded_formatter : detail::padded_formatter<V, C>
{
	using detail::padded_formatter<V, C>::padded_formatter;
};
template<typename V, typename C = char>
left_padded_formatter<V, C> pad_left(const V & value, int num_padding, C padding = C(' '))
{
	return { value, num_padding, padding };
}
template<typename C, typename It, typename V>
format_it<C, It> format(format_it<C, It> it, const left_padded_formatter<V, C> & padding)
{
	stack_print<1024> print_value(padding.value);
	it = std::fill_n(it, std::max(0, padding.num_padding - int(print_value.end() - print_value.begin())), padding.padding);
	return std::copy(print_value.begin(), print_value.end(), it);
}
template<typename V, typename C>
struct right_padded_formatter : detail::padded_formatter<V, C>
{
	using detail::padded_formatter<V, C>::padded_formatter;
};
template<typename V, typename C = char>
right_padded_formatter<V, C> pad_right(const V & value, int num_padding, C padding = C(' '))
{
	return { value, num_padding, padding };
}
template<typename C, typename It, typename V>
format_it<C, It> format(format_it<C, It> it, const right_padded_formatter<V, C> & padding)
{
	// the temporary storage isn't really needed for the right_padded_formatter
	// but it is needed for padding on the left, and I think they should be similar
	// in terms of both code and performance
	stack_print<1024> print_value(padding.value);
	it = std::copy(print_value.begin(), print_value.end(), it);
	return std::fill_n(it, std::max(0, padding.num_padding - int(print_value.end() - print_value.begin())), padding.padding);
}
template<typename V, typename C>
struct both_padded_formatter : detail::padded_formatter<V, C>
{
	using detail::padded_formatter<V, C>::padded_formatter;
};
template<typename V, typename C = char>
both_padded_formatter<V, C> pad_both(const V & value, int num_padding, C padding = C(' '))
{
	return { value, num_padding, padding };
}
template<typename C, typename It, typename V>
format_it<C, It> format(format_it<C, It> it, const both_padded_formatter<V, C> & padding)
{
	stack_print<1024> print_value(padding.value);
	int to_pad = std::max(0, padding.num_padding - int(print_value.end() - print_value.begin()));
	int right_half = to_pad / 2;
	it = std::fill_n(it, to_pad - right_half, padding.padding);
	it = std::copy(print_value.begin(), print_value.end(), it);
	return std::fill_n(it, right_half, padding.padding);
}
template<typename V, typename C>
struct int_padded_formatter : detail::padded_formatter<V, C>
{
	using detail::padded_formatter<V, C>::padded_formatter;
};
template<typename V, typename C = char>
int_padded_formatter<V, C> pad_int(const V & value, int num_padding, C padding = C('0'))
{
	return { value, num_padding, padding };
}
template<typename C, typename It, typename V>
format_it<C, It> format(format_it<C, It> it, const int_padded_formatter<V, C> & padding)
{
	if (padding.value < 0)
	{
		*it++ = '-';
		return it.print(pad_left(-padding.value, padding.num_padding - 1, padding.padding));
	}
	else return it.print(pad_left(padding.value, padding.num_padding, padding.padding));
}
}