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

 

 

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#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. . .