text: /**
   * @cond doxygenLibsbmlInternal
   *
   * @file    Stack.c
   * @brief   Generic (void *) Stack for C structs on the heap
   * @author  Ben Bornstein
   * 
   * <!--------------------------------------------------------------------------
   * This file is part of libSBML.  Please visit http://sbml.org for more
   * information about SBML, and the latest version of libSBML.
   *
   * Copyright (C) 2009-2013 jointly by the following organizations: 
   *     1. California Institute of Technology, Pasadena, CA, USA
   *     2. EMBL European Bioinformatics Institute (EBML-EBI), Hinxton, UK
   *  
   * Copyright (C) 2006-2008 by the California Institute of Technology,
   *     Pasadena, CA, USA 
   *  
   * Copyright (C) 2002-2005 jointly by the following organizations: 
   *     1. California Institute of Technology, Pasadena, CA, USA
   *     2. Japan Science and Technology Agency, Japan
   * 
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation.  A copy of the license agreement is provided
   * in the file named "LICENSE.txt" included with this software distribution and
   * also available online as http://sbml.org/software/libsbml/license.html
   * ---------------------------------------------------------------------- -->*/
  
  
  #include <sbml/common/common.h>
  #include <sbml/util/Stack.h>
  
  LIBSBML_CPP_NAMESPACE_BEGIN
  
  #ifdef DEBUG
  
  /**
   * Reports a message to stderr if n is out of range in Stack_peekAt.
   */
  #define REPORT_STACK_RANGE_ERROR(function, n, size) \
  fprintf( stderr, \
           "Stack.c: %s(Stack_t *s, n = %d): Warning: n must be >= 0 " \
           "and < Stack_size() (%d).  Returning NULL.", \
           function, \
           n, \
           siz );
  
  #else
  
  #define REPORT_STACK_RANGE_ERROR(function, n, size) ;
  
  #endif
  
  
  /**
   * Creates a new Stack and returns a pointer to it.
   */
  LIBSBML_EXTERN
  Stack_t *
  Stack_create (int capacity)
  {
    Stack_t *s;
  
  
    s           = (Stack_t *) safe_calloc( 1       , sizeof(Stack_t) );
    s->stack    = (void   **) safe_calloc( capacity, sizeof(void *)  );
    s->sp       = -1;
    s->capacity = capacity;
  
    return s;
  }
  
  
  /**
   * Free the given Stack.
   *
   * This function does not free individual Stack items.  It frees only the
   * Stack_t structure.
   */
  LIBSBML_EXTERN
  void
  Stack_free (Stack_t *s)
  {
    if (s == NULL) return;
  
    safe_free(s->stack);
    safe_free(s);
  }
  
  
  /**
   * @return the position of the first occurrence of item in the Stack or -1
   * if item cannot be found.  The search begins at the top of the Stack
   * (position 0) and proceeds downward (position 1, 2, etc.).
   *
   * Since ultimately the stack stores pointers, == is used to test for
   * equality.
   */
  LIBSBML_EXTERN
  int
  Stack_find (Stack_t *s, void *item)
  {
    int pos = Stack_size(s);
  
  
    while ((pos-- > 0) && (s->stack[pos] != item)) ;
  
    if (pos >= 0)
    {
      pos = s->sp - pos;
    }
  
    return pos;
  }
  
  
  /**
   * Pushes item onto the top of the Stack.
   */
  LIBSBML_EXTERN
  void
  Stack_push (Stack_t *s, void *item)
  {
    if (s == NULL) return; 
  
    if (Stack_size(s) == s->capacity)
    {
      s->capacity *= 2;
      s->stack     = (void **)
                     safe_realloc(s->stack, s->capacity * sizeof(void *));
                     
    }
  
    s->stack[ ++(s->sp) ] = item;
  }
  
  
  /**
   * @return (and removes) the top item on the Stack.
   */
  LIBSBML_EXTERN
  void *
  Stack_pop (Stack_t *s)
  {
    if (s == NULL) return NULL;
    return s->stack[ (s->sp)-- ];
  }
  
  
  /**
   * Pops the Stack n times.  The last item popped is returned.
   *
   * This function is conceptually simpler (and significantly faster for
   * large N) than calling Stack_pop() in a loop, but assumes you don't need
   * to track or manipulate the intermediate items popped.
   */
  void *
  Stack_popN (Stack_t *s, unsigned int n)
  {
    if (n == 0 || s == NULL || s->sp == -1) return NULL;
  
    s->sp -= n;
  
    if (s->sp < -1)
    {
      s->sp = -1;
    }
  
    return s->stack[ s->sp + 1 ];
  }
  
  
  /**
   * @return (but does not remove) the top item on the Stack.
   */
  LIBSBML_EXTERN
  void *
  Stack_peek (Stack_t *s)
  {
    if (s == NULL) return NULL;
    return s->stack[ s->sp ];
  }
  
  
  /**
   * @return (but does not remove) the nth item from the top of the Stack,
   * starting at zero, i.e. Stack_peekAt(0) is equivalent to Stack_peek().
   * If n is out of range (n < 0 or n >= Stack_size()) returns NULL.
   */
  LIBSBML_EXTERN
  void *
  Stack_peekAt (Stack_t *s, int n)
  {
    int size = Stack_size(s);
  
    if (s == NULL) return NULL;
  
    if (n < 0 || n >= size)
    {
      REPORT_STACK_RANGE_ERROR("Stack_peekAt", n, size);
      return NULL;
    }
  
    return s->stack[ s->sp - n ];
  }
  
  
  /**
   * @return the number of items currently on the Stack.
   */
  LIBSBML_EXTERN
  int
  Stack_size (Stack_t *s)
  {
    if (s == NULL) return 0;
    return s->sp + 1;
  }
  
  
  /**
   * @return the number of items the Stack is capable of holding before it
   * will (automatically) double its storage capacity.
   */
  LIBSBML_EXTERN
  int
  Stack_capacity (Stack_t *s)
  {
    if (s == NULL) return 0;
    return s->capacity;
  }
  
  LIBSBML_CPP_NAMESPACE_END
  
  /** @endcond */
  