Pseudocode for class and algorithms implementing a queue using 2 stacks)

Implementing Queue Using 2 Stacks
(Queue Class and Algorithms in Pseudocode)

Interface

macro guard
make stack available
make assert() available
class queue:
public:
... // others (constructors, destructer, etc.) as needed
void push(item)
void pop()
item front()
bool empty()
private:
stack inStack
stack outStack

Algorithms for Implementation

Assumptions:
(1) capacity of stack is limited only by system resources
(2) interface for key stack operations as shown below:
void push(item)
void pop()
item top()
bool empty()

void push(item):
inStack.push(item)

void pop():
   assert( !inStack.empty() || !outStack.empty() )
   if ( outStack.empty() )
      while ( !inStack.empty() )
         outStack.push( inStack.top() )
         inStack.pop()
   outStack.pop()

item front():
   assert( !inStack.empty() || !outStack.empty() )
   if ( outStack.empty() )
      while ( !inStack.empty() )
         outStack.push( inStack.top() )
         inStack.pop()
   return outStack.top()

bool empty():
return outStack.empty() && inStack.empty()