stream_match.c

#include "stream_match.h"

Matcher *matcher_init(const char *match_target)
{
    Matcher *matcher = (Matcher *)malloc(sizeof(Matcher));
    if (matcher == NULL)
    {
        perror("malloc failed");
        exit(EXIT_FAILURE);
    }
    
    matcher->target_length = strlen(match_target);

    matcher->match_target = (char *)malloc((matcher->target_length + 1) * sizeof(char));
    if (matcher->match_target == NULL)
    {
        perror("malloc failed");
        free(matcher);
        exit(EXIT_FAILURE);
    }

    strcpy(matcher->match_target, match_target);


    matcher->buffer = NULL;

    return matcher;
}

void matcher_resize_buffer(Matcher *matcher, size_t n)
{
    size_t old_len = strlen(matcher->buffer);

    if (old_len <= n)
    {
        // 不需要缩小
        return;
    }

    char *new_buffer = (char *)malloc((n + 1) * sizeof(char));
    if (new_buffer == NULL)
    {
        perror("malloc failed");
        exit(EXIT_FAILURE);
    }

    // 将原始数据的后n个字节复制到新缓冲区
    memcpy(new_buffer, matcher->buffer + (old_len - n), n);
    new_buffer[n] = '\0'; // 添加字符串结尾的空字符

    // 释放原始缓冲区，并更新matcher->buffer指向新缓冲区
    free(matcher->buffer);
    matcher->buffer = new_buffer;
}

MatchResult matcher_receive(Matcher *matcher, const char *new_content)
{
    if (matcher->buffer == NULL)
    {
        matcher->buffer = (char *)malloc((strlen(new_content) + 1) * sizeof(char));
        if (matcher->buffer == NULL)
        {
            perror("malloc failed");
            exit(EXIT_FAILURE);
        }

        strcpy(matcher->buffer, new_content);
    }
    else
    {
        size_t old_len = strlen(matcher->buffer);
        size_t new_len = strlen(new_content);
        matcher->buffer = realloc(matcher->buffer, old_len + new_len + 1);
        if (matcher->buffer == NULL)
        {
            perror("realloc failed");
            exit(EXIT_FAILURE);
        }
        strcat(matcher->buffer, new_content);
    }

    if (strstr(matcher->buffer, matcher->match_target) != NULL)
    {
        return MATCH;
    }
    else
    {
        // not match. we shrink the buffer to the size of target.
        matcher_resize_buffer(matcher, matcher->target_length - 1);

        return NOT_MATCH;
    }
}

void matcher_destroy(Matcher *matcher)
{
    // 这里不释放match_target，因为match target谁知道是哪来的！反正不归我管。
    // free(matcher->match_target);
    free(matcher->buffer);
    free(matcher);
}