Listing 2: table.cpp — cross-reference table implementation

#include <stdio.h>
#include <string.h>

#include "table.h"

struct list_node
    {
    unsigned number;
    list_node *next;
    };

struct cross_reference_table::tree_node
    {
    char *word;
    list_node *first, *last;
    tree_node *left, *right;
    };

cross_reference_table::tree_node *
cross_reference_table::add_tree
    (tree_node *t, char const *w,
     unsigned n)
    {
    int cmp;
    if (t == NULL)
        {
        t = new tree_node;
        t->word = new char [strlen(w) + 1];
        strcpy(t->word, w);
        t->first = new list_node;
        t->first->number = n;
        t->first->next = NULL;
        t->last = t->first;
        t->left = t->right = NULL;
        }
    else if((cmp = strcmp(w, t->word))<0)
        t->left = add_tree(t->left, w, n);
    else if (cmp > 0)
        t->right =
            add_tree(t->right, w, n);
    else if (n != t->last->number)
        {
        t->last->next = new list_node;
        t->last = t->last->next;
        t->last->number = n;
        t->last->next = NULL;
        }
    return t;
    }

void
cross_reference_table::put_tree
    (tree_node const *t)
    {
    if (t != NULL)
        {
        put_tree(t->left);
        printf("%12s:", t->word);
        list_node const *p;
        for (p = t->first; 
             p != NULL; 
             p = p->next)
            printf(" %4d", p->number);
        printf("\n");
        put_tree(t->right);
        }
    }