发信人: zhch (zhch), 信区: BBSDev
标  题: 一个粗略的BBS快速全站全文离线搜索程序
发信站: 南京大学小百合站 (Sun Jun 23 13:28:23 2002), 站内信件


这是一个很粗略的代码。和一般web全文搜索引擎算法差不多，以空间换时间，把所有
的可能先穷尽一遍，关键字长度2-12字节。可以快速全文搜索全站文章。缺点是占用
空间太大，数据大小会膨胀100倍，添加数据速度也很慢，算法还有待改进。

程序1: 添加数据.

#include "/home/bbs/bbssrc/include/bbs.h"
struct dir2 {
        char board[24];
        char title[60];
        int filetime;
};

int main(int n, char *cmd[]) {
        int i;
        if(n<2) {
                printf("usage: add3 board\n");
                exit(0);
        }
        chdir(BBSHOME);
        add_dir(cmd[1]);
}

int strsncpy(char *s, char *s2, int len) {
        if(len<0) len=0;
        strncpy(s, s2, len);
        if(len-1>0) s[len-1]=0;
}

int add_dir(char *board) {
        FILE *fp, *fp2;
        struct fileheader x;
        struct dir2 x2;
        char path[256];
        sprintf(path, "boards/%s/.DIR", board);
        fp=fopen(path, "r");
        if(!fp) exit(0);
        printf("add_dir: %s\n", board);
        fp2=fopen("/search/.DIR2", "a");
        while(1) {
                int i, pos;
                char file[256];
                if(fread(&x, sizeof(struct fileheader), 1, fp)<=0) break;
                bzero(&x2, sizeof(struct dir2));
                strsncpy(x2.board, board, 24);
                strsncpy(x2.title, x.title, 60);
                x2.filetime=atoi(x.filename+2);
                pos=ftell(fp2)/sizeof(struct dir2);
                fwrite(&x2, sizeof(struct dir2), 1, fp2);
                sprintf(file, "boards/%s/%s", board, x.filename);
                for(i=2; i<=12; i++) {
                        aaa(pos, file, i);
                }
        }
        fclose(fp);
        fclose(fp2);
}

int hash(unsigned char *s) {
        unsigned int z=0;
        int i;
        for(i=0; s[i]; i++) {
                int xx=toupper(s[i]);
                z=z*79+xx;
        }
        return z%852;
}

int aaa(int pos, char *file, int len) {
        FILE *fp, *fp2;
        char path[256], buf[256];
        int flag[1000];
        struct fileheader x;
        bzero(flag, 4000);
        fp=fopen(file, "r");
        if(!fp) exit(0);
        printf("aa %d %s %d\n", pos, file, len);
        while(1) {
                int i, j;
                if(fgets(buf, 255, fp)==0) break;
                for(i=0; buf[i]; i++) {
                        if(buf[i]==10 || buf[i]==13) buf[i]=0;
                        if(buf[i]>0 && buf[i]<32) buf[i]=' ';
                }
                if(buf[0]==':' && buf[1]==' ') continue;
                for(i=0; buf[i]; i++) {
                        char path2[256], tmp[20], out[80];
                        int h;
                        bzero(tmp, 20);
                        for(j=0; j<len; j++) if(buf[i+j]==0) goto L;
                        strncpy(tmp, buf+i, len);
                        h=hash(tmp);
                        if(flag[h]) continue;
                        flag[h]=1;
                        sprintf(path2, "/search/%d/%d", len, h);
                        fp2=fopen(path2, "a");
                        fwrite(&pos, sizeof(int), 1, fp2);
                        fwrite(tmp, 1, len, fp2);
                        fclose(fp2);
                }
L:
        }
        fclose(fp);
}

程序2: 查找数据.

#include "/home/bbs/bbssrc/include/bbs.h"
struct dir2 {
        char board[24];
        char title[60];
        int filetime;
};

int main(int n, char *cmd[]) {
        if(n<=1) {
                printf("usage: find3 xxx\n");
                exit(0);
        }
        if(strlen(cmd[1])<2 || strlen(cmd[1])>12) {
                printf("len must > 1 and <13\n");
                exit(0);
        }
        find3(cmd[1]);
}

int hash(unsigned char *s) {
        unsigned int z=0;
        int i;
        for(i=0; s[i]; i++) {
                int xx=toupper(s[i]);
                z=z*79+xx;
        }
        return z%852;
}

int find3(char *s) {
        FILE *fp;
        char file[256];
        char tmp[80];
        int pos, last=-1;
        int len=strlen(s);
        sprintf(file, "/search/%d/%d", len, hash(s));
        printf("len=%d\n", len);
        printf("hash=%d\n", hash(s));
        printf("s=%s\n", s);
        fp=fopen(file, "r");
        if(!fp) {
                printf("not found!\n");
                exit(0);
        }
        while(1) {
                if(fread(&pos, sizeof(int), 1, fp)<=0) break;
                if(fread(tmp, len, 1, fp)<=0) break;
                if(!strncasecmp(s, tmp, len)) {
                        show(pos);
                        last=pos;
                }
        }
        fclose(fp);
}

int show(int pos) {
        FILE *fp;
        struct dir2 x;
        bzero(&x, sizeof(struct dir2));
        fp=fopen("/search/.DIR2", "r");
        if(!fp) exit(0);
        fseek(fp, pos*sizeof(struct dir2), SEEK_SET);
        fread(&x, sizeof(struct dir2), 1, fp);
        printf("file=%d, url=http://bbs.nju.edu.cn/bbscon?board=%s&file=M.%d.
A\n", pos+1, x.board, x.filetime);
        fclose(fp);
}
--
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