const void*
StreamBuffer::peek(UInt32 n)
{
assert(n <= m_size);
// if requesting no data then return NULL so we don't try to access
// an empty list.
if (n == 0) {
return NULL;
}
// reserve space in first chunk
ChunkList::iterator head = m_chunks.begin();
head->reserve(n + m_headUsed);
// consolidate chunks into the first chunk until it has n bytes
ChunkList::iterator scan = head;
++scan;
while (head->size() - m_headUsed < n && scan != m_chunks.end()) {
head->insert(head->end(), scan->begin(), scan->end());
scan = m_chunks.erase(scan);
}
return reinterpret_cast<const void*>(&(head->begin()[m_headUsed]));
}
