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  1. #include <iostream>
  2. #include <map>
  3. #include <string>
  4.  
  5. bool FindVariableString(
  6.     const std::string &str,
  7.     const std::string::size_type pos,
  8.     std::string::size_type &beginVarStringPos,
  9.     std::string::size_type &endVarStringPos,
  10.     std::string::size_type &beginVarNamePos,
  11.     std::string::size_type &endVarNamePos)
  12. {
  13.     const char *TestString = "%$#";
  14.     const char PercentSign = '%';
  15.     const char LeftParenthesis = '(';
  16.     const char LeftSquareBracket = '[';
  17.     const char LeftCurlyBracket = '{';
  18.     const char RightParenthesis = ')';
  19.     const char RightSquareBracket = ']';
  20.     const char RightCurlyBracket = '}';
  21.     beginVarStringPos = std::string::npos;
  22.     endVarStringPos = std::string::npos;
  23.     beginVarNamePos = std::string::npos;
  24.     endVarNamePos = std::string::npos;
  25.     if (str.empty())
  26.     {
  27.         return false;
  28.     }
  29.     beginVarStringPos = str.find_first_of(TestString, pos);
  30.     if (std::string::npos == beginVarStringPos)
  31.     {
  32.         return false;
  33.     }
  34.     if (beginVarStringPos >= str.length() - 1)
  35.     {
  36.         return false;
  37.     }
  38.     char ch = str[beginVarStringPos];
  39.     char ch1 = str[beginVarStringPos + 1];
  40.     if (
  41.        PercentSign == ch
  42.        && LeftParenthesis != ch1 && LeftSquareBracket != ch1
  43.        && LeftCurlyBracket != ch1
  44.        )
  45.     {
  46.         beginVarNamePos = beginVarStringPos + 1;
  47.         endVarStringPos = str.find(PercentSign, beginVarNamePos);
  48.         if (std::string::npos == endVarStringPos)
  49.         {
  50.             return false;
  51.         }
  52.     }
  53.     else if (
  54.        LeftParenthesis != ch1 && LeftSquareBracket != ch1
  55.        && LeftCurlyBracket != ch1
  56.        )
  57.     {
  58.         return false;
  59.     }
  60.     else
  61.     {
  62.         beginVarNamePos = beginVarStringPos + 2;
  63.         char closeChar = 0;
  64.         if (LeftParenthesis == ch1)
  65.         {
  66.             closeChar = RightParenthesis;
  67.         }
  68.         else if (LeftSquareBracket == ch1)
  69.         {
  70.             closeChar = RightSquareBracket;
  71.         }
  72.         else if (LeftCurlyBracket == ch1)
  73.         {
  74.             closeChar = RightCurlyBracket;
  75.         }
  76.         endVarStringPos = str.find(closeChar, beginVarNamePos);
  77.         if (std::string::npos == endVarStringPos)
  78.         {
  79.             return false;
  80.         }
  81.     }
  82.     endVarNamePos = endVarStringPos - 1;
  83.     return true;
  84. }
  85.  
  86. bool StringContainsVariableStrings(const std::string &str)
  87. {
  88.     std::string::size_type beginVarStringPos = 0;
  89.     std::string::size_type endVarStringPos = 0;
  90.     std::string::size_type beginVarNamePos = 0;
  91.     std::string::size_type endVarNamePos = 0;
  92.     bool ret = FindVariableString(str, 0, beginVarStringPos, endVarStringPos, beginVarNamePos, endVarNamePos);
  93.     return ret;
  94. }
  95.  
  96. std::string GetVariableValue(
  97.     const std::string &varName,
  98.     const std::map<std::string, std::string> &env,
  99.     bool &fromEnvMap, bool &valueContainsVariableStrings)
  100. {
  101.     typedef std::map<std::string, std::string> my_map;
  102.     fromEnvMap = false;
  103.     valueContainsVariableStrings = false;
  104.     std::string ret;
  105.     my_map::const_iterator itFind = env.find(varName);
  106.     if (itFind != env.end())
  107.     {
  108.         ret = (*itFind).second;
  109.         if (!ret.empty())
  110.         {
  111.             fromEnvMap = true;
  112.             valueContainsVariableStrings = StringContainsVariableStrings(ret);
  113.         }
  114.     }
  115.     if (ret.empty())
  116.     {
  117.         ret = ::getenv(varName.c_str());
  118.     }
  119.     return ret;
  120. }
  121.  
  122. std::string ExpandVars(
  123.     const std::string &original,
  124.     const std::map<std::string, std::string> &env)
  125. {
  126.     std::string ret = original;
  127.     if (original.empty())
  128.     {
  129.         return ret;
  130.     }
  131.     bool foundVar = false;
  132.     std::string::size_type pos = 0;
  133.     do
  134.     {
  135.         std::string::size_type beginVarStringPos = 0;
  136.         std::string::size_type endVarStringPos = 0;
  137.         std::string::size_type beginVarNamePos = 0;
  138.         std::string::size_type endVarNamePos = 0;
  139.         foundVar = FindVariableString(ret, pos, beginVarStringPos, endVarStringPos, beginVarNamePos, endVarNamePos);
  140.         if (foundVar)
  141.         {
  142.             std::string::size_type varStringLen = endVarStringPos - beginVarStringPos + 1;
  143.             std::string varString = ret.substr(beginVarStringPos, varStringLen);
  144.             std::string::size_type varNameLen = endVarNamePos - beginVarNamePos + 1;
  145.             std::string varName = ret.substr(beginVarNamePos, varNameLen);
  146.             bool fromEnvMap;
  147.             bool valueContainsVariableStrings;
  148.             std::string value = GetVariableValue(varName, env, fromEnvMap, valueContainsVariableStrings);
  149.             if (!value.empty())
  150.             {
  151.                 ret = ret.replace(beginVarStringPos, varStringLen, value);
  152.                 pos = beginVarStringPos;
  153.             }
  154.             else
  155.             {
  156.                 pos = endVarStringPos + 1;
  157.             }
  158.         }
  159.     } while (foundVar);
  160.     return ret;
  161. }
  162.  
  163. std::string GetDateFormatStringExpandVars(const std::string& langCode)
  164. {
  165.     if (
  166.        0 == langCode.compare(0, 2, "en")
  167.        || 0 == langCode.compare(0, 2, "EN")
  168.        )
  169.     {
  170.         return std::string("${month}/${day}/${year}");
  171.     }
  172.     else if (
  173.        0 == langCode.compare(0, 2, "fr")
  174.        || 0 == langCode.compare(0, 2, "FR")
  175.        )
  176.     {
  177.         return std::string("${day}/${month}/${year}");
  178.     }
  179.     else if (
  180.        0 == langCode.compare(0, 2, "ja")
  181.        || 0 == langCode.compare(0, 2, "JA")
  182.        || 0 == langCode.compare(0, 2, "jp")
  183.        || 0 == langCode.compare(0, 2, "JP")
  184.        )
  185.     {
  186.         return std::string("${year}/${day}/${month}");
  187.     }
  188.     return std::string("${month}/${day}/${year}");
  189. }
  190.  
  191. std::string GetDateStringExpandVars(
  192.     const std::string &langCode, int month, int day, int year)
  193. {
  194.     std::string fmt = GetDateFormatStringExpandVars(langCode);
  195.     std::map<std::string,std::string> env{
  196.         {"month", std::to_string(month)},
  197.         {"day", std::to_string(day)},
  198.         {"year", std::to_string(year)}
  199.     };
  200.     std::string ret = ExpandVars(fmt, env);
  201.     return ret;
  202. }
  203.  
  204. int main()
  205. {
  206.     std::cout << GetDateStringExpandVars("en", 11, 7, 2018) << "\n";
  207.     return 0;
  208. }
  209.  
Success #stdin #stdout 0s 15240KB
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11/7/2018
https://ideone.com/LVZWED
Variable Expansion in Strings - Example 8
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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