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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
// ArrayStack: A stack, implemented as a growable array
template <class T>
class ArrayStack
{
static const int builtinSize = 8;
public:
ArrayStack(Compiler *comp, int initialSize = builtinSize)
{
compiler = comp;
if (initialSize > builtinSize)
{
maxIndex = initialSize;
data = new(compiler, CMK_ArrayStack) T[initialSize];
}
else
{
maxIndex = builtinSize;
data = builtinData;
}
tosIndex = 0;
}
void Push(T item)
{
if (tosIndex == maxIndex)
Realloc();
data[tosIndex] = item;
tosIndex++;
}
void Realloc()
{
// get a new chunk 2x the size of the old one
// and copy over
T* oldData = data;
noway_assert(maxIndex*2 > maxIndex);
data = new(compiler, CMK_ArrayStack) T[maxIndex*2];
for (int i=0; i<maxIndex; i++)
{
data[i] = oldData[i];
}
maxIndex *= 2;
}
// reverse the top N in the stack
void ReverseTop(int number)
{
if (number < 2)
return;
assert(number <= tosIndex);
int start = tosIndex - number;
int offset = 0;
while (offset < number/2)
{
T temp;
int index = start+offset;
int otherIndex = tosIndex - 1 - offset;
temp = data[index];
data[index] = data[otherIndex];
data[otherIndex] = temp;
offset++;
}
}
T Pop()
{
assert(tosIndex > 0);
tosIndex--;
return data[tosIndex];
}
T Top()
{
assert(tosIndex > 0);
return data[tosIndex-1];
}
T& TopRef()
{
assert(tosIndex > 0);
return data[tosIndex-1];
}
// return the i'th from the top
T Index(int idx)
{
assert(tosIndex > idx);
return data[tosIndex - 1 - idx];
}
int Height()
{
return tosIndex;
}
// return the bottom of the stack
T Bottom()
{
assert(tosIndex > 0);
return data[0];
}
// return the i'th from the bottom
T Bottom(int indx)
{
assert(tosIndex > indx);
return data[indx];
}
void Reset()
{
tosIndex = 0;
}
private:
Compiler *compiler; // needed for allocation
int tosIndex; // first free location
int maxIndex;
T* data;
// initial allocation
T builtinData[builtinSize];
};
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