/***********************************************************************/
/*                        String List Utilities                        */
/*                               Solutions                             */
/*                                                                     */
/*       Author:  Mark A. Sheldon, Tufts University, Fall 2012         */
/***********************************************************************/

#include <iostream>

using std::cout;

#include "StringList.h"
#include "StringListUtils.h"


/*
 * Can use a while or for loop. 
 */
void print(StringListNode *list)
{
	cout << "[";
	while (!isEmpty(list)) {
		cout << first(list);
		if (!isEmpty(rest(list)))
			cout << ", ";
		list = rest(list);
	}
	cout << "]";
}

// 	4 ~> 3 ~> ()
void printArtistically(StringListNode *list)
{
	if (isEmpty(list))
		cout << "()";
	else {
		cout << first(list) << " ~> ";
		printArtistically(rest(list));
	}
}

// Return the length (number of non-empty nodes in) list.
int length(StringListNode *list)
{
	return isEmpty(list) ? 0 : 1 + length(rest(list));
}

string concat_all(StringListNode *list)
{
        if (isEmpty(list))
                return "";
        else
                return first(list) + concat_all(rest(list));
}

StringListNode *copy(StringListNode *list)
{
        if (isEmpty(list))
                return empty();
        else
                return prepend(first(list), copy(rest(list)));
}

StringListNode *mapPluralize(StringListNode *words)
{
        if (isEmpty(words))
                return empty();
        else
                return prepend(first(words) + "s",
                               mapPluralize(rest(words)));
}

StringListNode *pairwiseConcat(StringListNode *a, StringListNode *b)
{
        if (isEmpty(a) and isEmpty(b))
                return empty();
        else if (isEmpty(a) and not isEmpty(b))
                return prepend(first(b), pairwiseConcat(a, rest(b)));
        else if (not isEmpty(a) and isEmpty(b))
                return prepend(first(a), pairwiseConcat(rest(a), b));
        else
                // both a and b are non-empty
                return prepend(first(a) + first(b),
                               pairwiseConcat(rest(a), rest(b)));
}

void deleteList(StringListNode **p_list)
{
        while (not isEmpty(*p_list))
                *p_list = deleteFirst(*p_list);
        // *p_list now contains the empty list.
}