/****
 *
 * This module defines a list specialization for nested lists of integers.  It
 * does so by defining a specialized list element data type, and specialized
 * list construction and access functions.
 *
 * The specialized list element has the following concrete structure:
 *
 *              |-------------------------------|
 *              |            int data           |
 *              |-------------------------------|
 *              |         List* sublist         |
 *              |-------------------------------|
 *
 * The value of the sublist field serves as the tag for the type of data that's
 * in an element.  Namely, if the sublist field is null, then the int data
 * field holds an integer value.  If the sublist field is non-null, then it
 * points to a sublist.
 * 
 */
#ifndef nestedIntListIncluded
#define nestedIntListIncluded
#include "list.h"

/*
 * NestedIntListElemData is the two-element struct that represents the data
 * stored in each list element.
 */
typedef struct {
    int data;
    List* sublist;
} NestedIntListElemData;

/*
 * NewIntDatum allocates a new integer-valued list element.  I.e., it wraps a
 * plain int with a NestedIntListElemData.
 */
NestedIntListElemData* NewIntDatum(int i);

/*
 * NewSubListDatum allocates a new list-valued element.  I.e., it wraps a
 * sublist pointer with a NestedIntListElemData.
 */
NestedIntListElemData* NewSubListDatum(List* l);

/*
 * EqualsFunc compares two wrapped list elements for equality.  If the sublist
 * fields are both null, then it compares the int data values.  Otherwise in
 * recursively compares two sublist values.
 */
bool EqualsFunc(void* d1, void* d2);

/*
 * PrintFunc is used as the second arg to PrintList to print out nested int
 * lists.  As above, it uses the value of sublist data field to figure out what
 * to do.  If sublist is null, it prints the element value as an int.
 * Otherwise it recursively prints the element as a sublist.
 */
void PrintFunc(void* d);

/*
 * CopyFunc is used as the second arg to CopyList.  It has the same
 * base/recurse logic as EqualsFunc and PrintFunc.
 */
void* CopyFunc(void* d);

#endif