我爱分享----百万商业圈C语言实现的倒排索引算法(含全部源码)

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最新推荐文章于 2025-04-29 14:26:00 发布

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文章标签：语言 c 算法 file path traversal

本文链接：https://blog.youkuaiyun.com/sooch/article/details/6734277

这篇博客分享了C语言实现的倒排索引算法，包括百万商业圈小型企业云ERP的开发规划和开源搜索引擎项目。内容涵盖完全自主研发的搜索引擎源代码，实现了单机400万网页的高速检索。此外，还提到了基于.NET开发框架的并行采集器，以及C语言的WEB文件上传框架源码。

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我爱分享----百万商业圈C语言实现的倒排索引算法(含全部源码)

#include <stdio.h>

#include <stdlib.h>

char chr_legal[] = "abcdefghijklmnopqrstuvwxyz0123456789_-./";
int chr_idx[256] = {0};
char idx_chr[256] = {0};

#define FNAME 0
typedef struct trie_t *trie, trie_t;
struct trie_t {
   trie next[sizeof(chr_legal)]; /* next letter; slot 0 is for file name */
   int eow;
};

trie trie_new() { return calloc(sizeof(trie_t), 1); }

#define find_word(r, w) trie_trav(r, w, 1)
/* tree traversal: returns node if end of word and matches string, optionally
* create node if doesn't exist
*/
trie trie_trav(trie root, char * str, int no_create)
{
   int c;
   while (root) {
       if ((c = str[0]) == '\0') {
           if (!root->eow && no_create) return 0;
           break;
       }
       if (! (c = chr_idx[c]) ) {
           str++;
           continue;
       }

       if (!root->next[c]) {
           if (no_create) return 0;
           root->next[c] = trie_new();
       }
       root = root->next[c];
       str++;
   }
   return root;
}

/* complete traversal of whole tree, calling callback at each end of word node.
* similar method can be used to free nodes, had we wanted to do that.
*/
int trie_all(trie root, char path[], int depth, int (*callback)(char *))
{
   int i;
   if (root->eow && !callback(path)) return 0;

   for (i = 1; i < sizeof(chr_legal); i++) {
       if (!root->next[i]) continue;

       path[depth] = idx_chr[i];
       path[depth + 1] = '\0';
       if (!trie_all(root->next[i], path, depth + 1, callback))
           return 0;
   }
   return 1;
}

void add_index(trie root, char *word, char *fname)
{
   trie x = trie_trav(root, word, 0);
   x->eow = 1;

   if (!x->next[FNAME])
       x->next[FNAME] = trie_new();
   x = trie_trav(x->next[FNAME], fname, 0);
   x->eow = 1;
}

int print_path(char *path)
{
   printf(" %s", path);
   return 1;
}

/* pretend we parsed text files and got lower cased words: dealing     *
* with text file is a whole other animal and would make code too long */
char *files[] = { "f1.txt", "source/f2.txt", "other_file" };
char *text[][5] ={{ "it", "is", "what", "it", "is" },
       { "what", "is", "it", 0 },
       { "it", "is", "a", "banana", 0 }};

trie init_tables()
{
   int i, j;
   trie root = trie_new();
   for (i = 0; i < sizeof(chr_legal); i++) {
       chr_idx[(int)chr_legal[i]] = i + 1;
       idx_chr[i + 1] = chr_legal[i];
   }

/* Enable USE_ADVANCED_FILE_HANDLING to use advanced file handling.
* You need to have files named like above files[], with words in them
* like in text[][]. Case doesn't matter (told you it's advanced).
*/
#define USE_ADVANCED_FILE_HANDLING 0
#if USE_ADVANCED_FILE_HANDLING
   void read_file(char * fname) {
       char cmd[1024];
       char word[1024];
       sprintf(cmd, "perl -p -e 'while(/(\\w+)/g) {print lc($1),\"\\n\"}' %s", fname);
       FILE *in = popen(cmd, "r");
       while (!feof(in)) {
           fscanf(in, "%1000s", word);
           add_index(root, word, fname);
       }
       pclose(in);
   };

   read_file("f1.txt");
   read_file("source/f2.txt");
   read_file("other_file");
#else
   for (i = 0; i < 3; i++) {
       for (j = 0; j < 5; j++) {
           if (!text[i][j]) break;
           add_index(root, text[i][j], files[i]);
       }
   }
#endif /*USE_ADVANCED_FILE_HANDLING*/

   return root;
}

void search_index(trie root, char *word)
{
   char path[1024];
   printf("Search for \"%s\": ", word);
   trie found = find_word(root, word);

   if (!found) printf("not found\n");
   else {
       trie_all(found->next[FNAME], path, 0, print_path);
       printf("\n");
   }
}

int main()
{
   trie root = init_tables();

   search_index(root, "what");
   search_index(root, "is");
   search_index(root, "banana");
   search_index(root, "boo");
   return 0;

}

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