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#include "config.h"
#include <stdio.h>
#include <string.h>
/**
* btree - Efficient sorted associative container based on B-trees.
*
* This module provides an efficient in-memory lookup container that keeps a
* set of pointers sorted using a user-defined search function.
*
* This module supports insertion, removal, lookup, and traversal using an
* iterator system. Note that insertion and removal into/from a btree will
* invalidate all iterators pointing to it (including the one passed to the
* insertion or removal function).
*
* A B-tree (not to be confused with a binary tree) is a data structure that
* performs insertion, removal, and lookup in O(log n) time per operation.
* Although B-trees are typically used for databases and filesystems, this is
* an in-memory implementation.
*
* Unlike functions like qsort, bsearch, and tsearch, btree does not take a
* comparison function. It takes a binary search function, which is
* theoretically equivalent but faster. Writing a binary search function
* is more difficult than writing a comparison function, so a macro is provided
* to make it much easier than doing either manually.
*
* Example:
* #include <ccan/btree/btree.h>
*
* #include <errno.h>
* #include <stdlib.h>
* #include <stdio.h>
* #include <string.h>
*
* struct word {
* char *word;
* char *letter_set;
* };
*
* //Define the ordering function order_by_letter_set
* static btree_search_implement
* (
* order_by_letter_set,
* struct word *,
* int c = strcmp(a->letter_set, b->letter_set),
* c == 0,
* c < 0
* )
*
* struct word *new_word(const char *line);
* char *chomp(char *str);
* char *make_letter_set(char *str);
*
* static void insert_word(struct btree *btree, struct word *word)
* {
* btree_iterator iter;
*
* //Position iterator after existing words with this letter set.
* btree_find_last(btree, word, iter);
*
* //Insert new word at iterator position.
* btree_insert_at(iter, word);
* }
*
* static void print_anagrams(struct btree *btree, char *line)
* {
* btree_iterator iter, end;
* struct word key = {
* NULL,
* make_letter_set(line)
* };
*
* //Find first matching word.
* if (!btree_find_first(btree, &key, iter)) {
* printf("\t(none)\n");
* return;
* }
*
* btree_find_last(btree, &key, end);
*
* //Traverse matching words.
* for (; btree_deref(iter) && btree_cmp_iters(iter, end) < 0;
* btree_next(iter))
* {
* struct word *word = iter->item;
* printf("\t%s\n", word->word);
* }
* }
*
* static int destroy_word(struct word *word, void *ctx)
* {
* (void) ctx;
*
* free(word->word);
* free(word->letter_set);
* free(word);
*
* return 1;
* }
*
* static struct btree *read_dictionary(const char *filename)
* {
* FILE *f;
* char line[256];
*
* //Construct new btree with the ordering function order_by_letter_set .
* struct btree *btree = btree_new(order_by_letter_set);
*
* f = fopen(filename, "r");
* if (!f)
* goto fail;
*
* //Set the destroy callback so btree_free will automatically
* //free our items. Setting btree->destroy is optional.
* btree->destroy = (btree_action_t)destroy_word;
*
* while (fgets(line, sizeof(line), f)) {
* struct word *word = new_word(line);
* if (!word)
* continue;
* insert_word(btree, word);
* }
*
* if (ferror(f)) {
* fclose(f);
* goto fail;
* }
* if (fclose(f))
* goto fail;
*
* return btree;
*
* fail:
* btree_delete(btree);
* fprintf(stderr, "%s: %s\n", filename, strerror(errno));
* return NULL;
* }
*
* int main(int argc, char *argv[])
* {
* struct btree *btree;
* char line[256];
*
* if (argc != 2) {
* fprintf(stderr,
* "Usage: %s dictionary-file\n"
* "Example:\n"
* "\t%s /usr/share/dict/words\n"
* "\n"
* , argv[0], argv[0]);
* return 1;
* }
*
* printf("Indexing...\n");
* btree = read_dictionary(argv[1]);
* printf("Dictionary has %ld words\n", (long)btree->count);
*
* for (;;) {
* printf("> ");
* if (!fgets(line, sizeof(line), stdin))
* break;
* chomp(line);
* if (!*line)
* break;
*
* printf("Anagrams of \"%s\":\n", line);
* print_anagrams(btree, line);
* }
*
* printf("Cleaning up...\n");
* btree_delete(btree);
*
* return 0;
* }
*
* struct word *new_word(const char *line)
* {
* struct word *word;
* char *letter_set = make_letter_set(strdup(line));
*
* //Discard lines with no letters
* if (!*letter_set) {
* free(letter_set);
* return NULL;
* }
*
* word = malloc(sizeof(struct word));
* word->word = chomp(strdup(line));
* word->letter_set = letter_set;
*
* return word;
* }
*
* //Remove trailing newline (if present).
* char *chomp(char *str)
* {
* char *end = strchr(str, '\0') - 1;
* if (*str && *end == '\n')
* *end = 0;
* return str;
* }
*
* //Remove all characters but letters, make letters lowercase, and sort them.
* char *make_letter_set(char *str)
* {
* size_t count[26] = {0};
* size_t i, j;
* char *o = str;
*
* for (i=0; str[i]; i++) {
* char c = str[i];
* if (c >= 'A' && c <= 'Z')
* c += 'a'-'A';
* if (c >= 'a' && c <= 'z')
* count[c - 'a']++;
* }
*
* for (i = 0; i < 26; i++) {
* for (j = 0; j < count[i]; j++)
* *o++ = 'a' + i;
* }
* *o = '\0';
*
* return str;
* }
*
* Author: Joey Adams <joeyadams3.14159@gmail.com>
* License: MIT
* Version: 0.2
*/
int main(int argc, char *argv[])
{
/* Expect exactly one argument */
if (argc != 2)
return 1;
if (strcmp(argv[1], "depends") == 0) {
/* Nothing */
return 0;
}
return 1;
}
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