通过状态机实现的一个配置读取函数

完整代码：

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

char IS_CHAR(char x)
{
    return (x >= 'A' && x <= 'Z') || (x >= 'a' && x <= 'z')? true:false;
}

char *strtrim(char *s)
{
    char *p = NULL,*right = s,*left = s;

    while(isspace(*left)) left++;
    p = left;
    while(*right != '\0') right++;
    for(right--;isspace(*right);right--);
    *(right+1) = '\0';
    strcpy(s,p);
    return s;
}

void parse_body(const char *s,
                char *section,
                char *key,
                char *value)
{
    typedef enum _body_state body_state;
    enum _body_state
    {
        STATE_NONE = 0,
        STATE_SECTION,
        STATE_KEY,
        STATE_SPLIT,
        STATE_IN_SECTION,
        STATE_VALUE,
        STATE_COMMENT
    };

    char *p_section_start;
    char *p_key_start;
    char *p_value_start;

    char *p = NULL;

    body_state state = STATE_NONE;
    char *tmp = (char*)malloc(strlen(s) + 1);
    memset(tmp,'\0',strlen(s) + 1);
    strncpy(tmp,s,strlen(s));

    for(p = tmp;
        *p != '\0';
        p++)
    {
        switch(state)
        {
        case STATE_NONE:
            if(IS_CHAR(*p))
            {
                state = STATE_SECTION;
                p_section_start = p;
            }
            if((*p) == '#')
            {
                state = STATE_COMMENT;
            }
            break;
        case STATE_COMMENT:
            if(*p == '\n')
            {
                state = STATE_NONE;
            }

            break;
        case STATE_SECTION:
            if((*p) == '{')
            {
                *p = '\0';
                state = STATE_IN_SECTION;

            }

            break;
        case STATE_KEY:
            if(*p == '=')
            {
                *p = '\0';
                p_value_start = p+1;
                state = STATE_VALUE;
            }
            break;
        case STATE_VALUE:
            if(*p == ';')
            {
                *p = '\0';

                strtrim(p_section_start);
                strtrim(p_key_start);
                strtrim(p_value_start);
                if(strcmp(p_section_start,section) == 0 &&
                   strcmp(p_key_start ,key) == 0)
                {
                    strcpy(value,p_value_start);
                }
                state = STATE_IN_SECTION;
            }
            break;
        case STATE_SPLIT:
            if(IS_CHAR(*p))
            {
                state = STATE_VALUE;
            }
            break;
        case STATE_IN_SECTION:
            if(IS_CHAR(*p))
            {
                p_key_start = p;
                state = STATE_KEY;
            }
            if((*p) == '}')
            {
                state = STATE_NONE;
            }
            break;
        }
    }

    free(tmp);
}

int main()
{
    char value[16] = {0};
    FILE *f = NULL;
    char *buff = NULL;
    fpos_t pos = 0;
    f = fopen("d:\\my.conf","r");
    fseek(f,0,SEEK_END);
    fgetpos(f,&pos);
    buff = (char*)malloc(pos);
    memset(buff,0,pos);
    fseek(f,0,SEEK_SET);
    fread(buff,pos,1,f);


    parse_body(buff,"people","name",value);
    printf("value:%s",value);

    free(buff);
    return 0;
}

my.conf:

#test title
#this is a comment
#

people
{
    name=ligang;
    age=20;
    sex=1;
}

box
{
    widget=20;
    height=30;
    color=blue;
}

seller
{
    n73 =    590;
    N900 =      1500;
}

学习了李先静老师的系统程序员成长计划，自己实现了个简单的状态机，感觉真是威力无穷啊。。

 配合词法树就可以实现词法解析处理了，嘿嘿，年底也可以写个简单的解释语言玩玩咯