////   This file contains the C++ code from Program 13.6 of//   "Data Structures and Algorithms//    with Object-Oriented Design Patterns in C++"//   by Bruno R. Preiss.////   Copyright (c) 1998 by Bruno R. Preiss, P.Eng.  All rights reserved.////   http://www.pads.uwaterloo.ca/Bruno.Preiss/books/opus4/programs/pgm13_06.cpp//void SinglyLinkedPool::Release (void* arg){    Block& block = *reinterpret_cast<Block*> (	reinterpret_cast<Header*> (arg) - 1U);        if (&block < pool || &block >= pool + numberOfBlocks)	throw invalid_argument ("invalid block");    Block* prevPtr = &sentinel;    Block* ptr = prevPtr->next;    while (ptr != 0 && ptr < &block)    {	prevPtr = ptr;	ptr = ptr->next;    }    if (ptr != 0 && &block + block.length == ptr)    {	block.length += ptr->length;	block.next = ptr->next;    }    else	block.next = ptr;    if (prevPtr + prevPtr->length == &block)    {	prevPtr->length += block.length;	prevPtr->next = block.next;    }    else	prevPtr->next = &block;}