状态机学习 解析INI文件

题目来自<系统程序员成长计划>  

作者:李先静.

状态变化如下

#include <string>#include <iostream>using namespace std; string s = "[GRP]/n/name = def /n/data = 2016.11.29 /r/n/; this is a comment /r/n/str = this is a test /n/[zhangshan] /n/;/n/name = pengjun /n/data = 3355456";      enum STATE{    STAT_NONE = 0,    STAT_GROUP,    STAT_KEY,    STAT_VALUE,    STAT_COMMENT};  void IniBufferParse(const string& s){    STATE state = STAT_NONE;    size_t groupStart = 0, groupEnd = 0;    size_t commentStart = 0, commentEnd = 0;    size_t keyStart = 0, keyEnd = 0;    for (size_t i = 0; i < s.size(); i++)    {        switch (state)        {        case STAT_NONE:            if (s[i] == '[')            {                state = STAT_GROUP;                groupStart = i+1;            }else if (s[i] == '/r' || s[i] == '/n')            {                state = STAT_NONE;            }else if (s[i] == ';')            {                state = STAT_COMMENT;                commentStart = i + 1;            }            else if (!isspace( s[i]) )            {                state = STAT_KEY;                keyStart = i;            }            break;        case STAT_GROUP:            if (s[i] == ']')            {                state = STAT_NONE;                groupEnd = i;                cout << "group = " <<  s.substr(groupStart, groupEnd - groupStart) << endl;            }            else if (s[i] == '/r' || s[i] == '/n')            {                state = STAT_NONE;            }            break;        case STAT_COMMENT:            if (s[i] == '/r' || s[i] == '/n')            {                state = STAT_NONE;                commentEnd = i;                cout << "comment = " << s.substr(commentStart, commentEnd - commentStart) << endl;                break;            }            break;        case STAT_KEY:            if (s[i] == '/r' || s[i] == '/n')            {                state = STAT_NONE;                keyEnd = i;                string kvString = s.substr(keyStart, keyEnd - keyStart);                size_t i = kvString.find_first_of('=');                if (i == string::npos)                    break;                cout << "key = " << kvString.substr(0,i-1) << ". value = " << kvString.substr(i+1) <<  endl;                break;            }            break;         default:            break;        }    } }  int main(){    IniBufferParse(s);    return 0;}
　运行结果
group = GRPkey = name. value = defkey = data. value = 2016.11.29comment = this is a commentkey = str. value = this is a testgroup = zhangshancomment =key = name. value = pengjun请按任意键继续. . .