状态机学习（二）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

100

101

#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 = GRP
key = name. value = def
key = data. value = 2016.11.29
comment = this is a comment
key = str. value = this is a test
group = zhangshan
comment =
key = name. value = pengjun
请按任意键继续. . .