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//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose:
//
// $NoKeywords: $
//
//=============================================================================//
/*
*
* Copyright (c) 1998-9
* Dr John Maddock
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Dr John Maddock makes no representations
* about the suitability of this software for any purpose.
* It is provided "as is" without express or implied warranty.
*
*/
/*
* FILE jstack.h
* VERSION 2.12
*/
#ifndef __JSTACH_H
#define __JSTACK_H
#ifndef JM_CFG_H
#include <jm/jm_cfg.h>
#endif
JM_NAMESPACE(__JM)
//
// class jstack
// simplified stack optimised for push/peek/pop
// operations, we could use std::stack<std::vector<T>> instead...
//
template <class T, class Allocator JM_DEF_ALLOC_PARAM(T) >
class jstack
{
private:
typedef JM_MAYBE_TYPENAME REBIND_TYPE(unsigned char, Allocator) alloc_type;
typedef typename REBIND_TYPE(T, Allocator)::size_type size_type;
struct node
{
node* next;
T* start; // first item
T* end; // last item
T* last; // end of storage
};
//
// empty base member optimisation:
struct data : public alloc_type
{
unsigned char buf[sizeof(T)*16];
data(const Allocator& a) : alloc_type(a){}
};
data alloc_inst;
mutable node* stack;
mutable node* unused;
node base;
size_type block_size;
void RE_CALL pop_aux()const;
void RE_CALL push_aux();
public:
jstack(size_type n = 64, const Allocator& a = Allocator());
~jstack();
node* RE_CALL get_node()
{
node* new_stack = (node*)alloc_inst.allocate(sizeof(node) + sizeof(T) * block_size);
new_stack->last = (T*)(new_stack+1);
new_stack->start = new_stack->end = new_stack->last + block_size;
new_stack->next = 0;
return new_stack;
}
bool RE_CALL empty()
{
return (stack->start == stack->end) && (stack->next == 0);
}
bool RE_CALL good()
{
return (stack->start != stack->end) || (stack->next != 0);
}
T& RE_CALL peek()
{
if(stack->start == stack->end)
pop_aux();
return *stack->end;
}
const T& RE_CALL peek()const
{
if(stack->start == stack->end)
pop_aux();
return *stack->end;
}
void RE_CALL pop()
{
if(stack->start == stack->end)
pop_aux();
jm_destroy(stack->end);
++(stack->end);
}
void RE_CALL pop(T& t)
{
if(stack->start == stack->end)
pop_aux();
t = *stack->end;
jm_destroy(stack->end);
++(stack->end);
}
void RE_CALL push(const T& t)
{
if(stack->end == stack->last)
push_aux();
--(stack->end);
jm_construct(stack->end, t);
}
};
template <class T, class Allocator>
jstack<T, Allocator>::jstack(size_type n, const Allocator& a)
: alloc_inst(a)
{
unused = 0;
block_size = n;
stack = &base;
base.last = (T*)alloc_inst.buf;
base.end = base.start = base.last + 16;
base.next = 0;
}
template <class T, class Allocator>
void RE_CALL jstack<T, Allocator>::push_aux()
{
// make sure we have spare space on TOS:
register node* new_node;
if(unused)
{
new_node = unused;
unused = new_node->next;
new_node->next = stack;
stack = new_node;
}
else
{
new_node = get_node();
new_node->next = stack;
stack = new_node;
}
}
template <class T, class Allocator>
void RE_CALL jstack<T, Allocator>::pop_aux()const
{
// make sure that we have a valid item
// on TOS:
jm_assert(stack->next);
register node* p = stack;
stack = p->next;
p->next = unused;
unused = p;
}
template <class T, class Allocator>
jstack<T, Allocator>::~jstack()
{
node* condemned;
while(good())
pop();
while(unused)
{
condemned = unused;
unused = unused->next;
alloc_inst.deallocate((unsigned char*)condemned, sizeof(node) + sizeof(T) * block_size);
}
while(stack != &base)
{
condemned = stack;
stack = stack->next;
alloc_inst.deallocate((unsigned char*)condemned, sizeof(node) + sizeof(T) * block_size);
}
}
JM_END_NAMESPACE
#endif
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