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construct/include/ircd/buffer/parse_buffer.h

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// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_BUFFER_PARSE_BUFFER_H
/// The parse_buffer is the const version of a window_buffer. It is basically
/// the same idea with the underlying data is being read rather than written.
///
struct ircd::buffer::parse_buffer
:const_buffer
{
using closure = std::function<size_t (const const_buffer &)>;
using closure_cbuf = std::function<const_buffer (const const_buffer &)>;
using closure_spirit = std::function<bool (const char *&, const char *const &)>;
const_buffer base;
size_t remaining() const;
size_t consumed() const;
const_buffer completed() const;
const_buffer operator()(const closure &);
const_buffer operator()(const closure_cbuf &);
const_buffer operator()(const closure_spirit &);
const_buffer rewind(const size_t &n = 1);
parse_buffer(const const_buffer &base);
parse_buffer(const window_buffer &base);
parse_buffer() = default;
};
inline
ircd::buffer::parse_buffer::parse_buffer(const const_buffer &buf)
:const_buffer{buf}
,base{buf}
{}
inline ircd::buffer::const_buffer
ircd::buffer::parse_buffer::rewind(const size_t &n)
{
const size_t nmax
{
std::min(n, consumed())
};
static_cast<const_buffer &>(*this).begin() -= nmax;
assert(base.begin() <= begin());
assert(begin() <= base.end());
return completed();
}
inline ircd::buffer::const_buffer
ircd::buffer::parse_buffer::operator()(const closure_spirit &closure)
{
return operator()([&closure]
(const const_buffer &buf) -> size_t
{
const char *start(data(buf));
const char *const stop(start + size(buf));
if(!closure(start, stop))
return 0;
assert(start <= stop);
assert(start >= data(buf));
return start - data(buf);
});
}
inline ircd::buffer::const_buffer
ircd::buffer::parse_buffer::operator()(const closure_cbuf &closure)
{
return operator()([&closure]
(const const_buffer &buf)
{
return size(closure(buf));
});
}
inline ircd::buffer::const_buffer
ircd::buffer::parse_buffer::operator()(const closure &closure)
{
consume(*this, closure(*this));
return completed();
}
inline ircd::buffer::const_buffer
ircd::buffer::parse_buffer::completed()
const
{
assert(base.begin() <= begin());
assert(base.begin() + consumed() <= base.end());
return
{
base.begin(), base.begin() + consumed()
};
}
inline size_t
ircd::buffer::parse_buffer::consumed()
const
{
assert(begin() >= base.begin());
assert(begin() <= base.end());
return std::distance(base.begin(), begin());
}
inline size_t
ircd::buffer::parse_buffer::remaining()
const
{
assert(begin() <= base.end());
const size_t ret(std::distance(begin(), base.end()));
assert(ret == size(*this));
return ret;
}