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

#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. . .