std::deque help...

[Cactus_Hugger]

Edit: Solved. Posted, saw the "const" in the error, and then it hit me: const. Peek() is const (as peeking a buffer shouldn't change it). Change the iterator to a const_iterator, and everything works. Good day, thank you CBoard for sparking my mind.. (That's what I get for trying to be const-correct...)
Edit II: Sorry for the ... width ... of the original post.

Can't seem to get iterators for deques working. This is probably a simple error somewhere. Sorry about the length - tried to make a smaller example but it worked. (And I've no clue how it differs...)
The sole error perplexing me:

BufferImpl.cpp: In member function `unsigned int Net::BufferImpl::Peek(void*, unsigned int, unsigned int) const':
BufferImpl.cpp:90: error: no match for 'operator=' in
  'i = (((const std::deque<Net::DataChunk, std::allocator<Net::DataChunk> >*)
    ((const Net::BufferImpl*)this)) + 4u)->std::deque<_Tp, _Alloc>::begin
  [with _Tp = Net::DataChunk, _Alloc = std::allocator<Net::DataChunk>]()'
N:/MINGW/include/c++/3.4.2/bits/stl_deque.h:101: note:
  candidates are:
  std::_Deque_iterator<Net::DataChunk, Net::DataChunk&, Net::DataChunk*>& 
  std::_Deque_iterator<Net::DataChunk, Net::DataChunk&, Net::DataChunk*>::operator=
    (const std::_Deque_iterator<Net::DataChunk, Net::DataChunk&, Net::DataChunk*>&)

Header file:

#ifndef _INET_PIMPL_H
#define _INET_PIMPL_H

#include <stdint.h>
#include <deque>
#include <boost/shared_array.hpp>

namespace Net
{
	struct DataChunk
	{
		// Snipped
	};

	class BufferImpl
	{
		std::deque<DataChunk> m_datalist;

	public:
		BufferImpl();
		BufferImpl(const BufferImpl &b);
		virtual ~BufferImpl();
		BufferImpl &operator = (const BufferImpl &b);

		unsigned int Read(void *buffer, unsigned int length);
		unsigned int Write(const void *buffer, unsigned int length);
		unsigned int Peek(void *buffer, unsigned int length, unsigned int pos = 0) const;
		unsigned int Pop(unsigned int length);
		unsigned int GetSize() const;
	};
}

#endif

Code file:

#include <stdint.h>
#include <string.h>	// For memcpy()
#include <deque>
#include <boost/shared_array.hpp>
#include "inet_pimpl.h"

using namespace Net;

// Snip

unsigned int BufferImpl::Peek(void *buffer, unsigned int length, unsigned int pos) const
{
	uint8_t *ubuf = (uint8_t *) buffer;
	unsigned int read = 0, seeked = 0;
	std::deque<DataChunk>::iterator i;

	for(i = m_datalist.begin(); i != m_datalist.end(); ++i)
	{
		if(seeked < pos)
		{
			// Are we at our chunk yet?
			seeked += (*i).GetDataSize();
			if(seeked <= pos) continue;

			// We're done seeking, but _some_ data in this chunk must be copied.
			// (We've "ought seeked")
			read = (*i).Peek(ubuf, length, pos - (seeked - (*i).GetDataSize()));
		}
		else
		{
			// Continue reading
			read += (*i).Peek(ubuf + read, length - read);
		}
	}

	return read;
}
// Snip