#ifndef CA_UWATERLOO_ALUMNI_DWHARDER_STACK
#define CA_UWATERLOO_ALUMNI_DWHARDER_STACK

// Author:  Douglas Wilhelm Harder
// Copyright (c) 2012 by Douglas Wilhelm Harder.  All rights reserved.

#include <stdlib.h>

struct Stack {
	void **array;
	int size;
	int capacity;
};

void init( struct Stack *s, int n ) {
	// Make sure the array capacity is at least 1 and allocate the memory
	s->capacity = (n > 0) ? n : 1;
	s->array = malloc( (s->capacity)*sizeof( void * ) );
	s->size = 0;
}

void deinit( struct Stack *s ) {
	free( s->array );
}

void *top( struct Stack *s ) {
	return ( s->size == 0 ) ? NULL : s->array[s->size - 1];
}

void push( struct Stack *s, void *ptr ) {
	if ( s->size == s->capacity ) {
		return;
	}

	s->array[s->size] = ptr;
	++(s->size);
}

void pop( struct Stack *s ) {
	if ( s->size != 0 ) {
		--(s->size);
	}
}

#endif