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  1. #include <iostream>
  2. #include <map>
  3. #include <string>
  4. #include <boost/xpressive/xpressive.hpp>
  5.  
  6. bool FindVariableString(
  7.     const std::string &str,
  8.     const std::string::size_type pos,
  9.     std::string::size_type &beginVarStringPos,
  10.     std::string::size_type &endVarStringPos,
  11.     std::string::size_type &beginVarNamePos,
  12.     std::string::size_type &endVarNamePos)
  13. {
  14.     const char *TestString = "%$#";
  15.     const char PercentSign = '%';
  16.     const char LeftParenthesis = '(';
  17.     const char LeftSquareBracket = '[';
  18.     const char LeftCurlyBracket = '{';
  19.     const char RightParenthesis = ')';
  20.     const char RightSquareBracket = ']';
  21.     const char RightCurlyBracket = '}';
  22.     beginVarStringPos = std::string::npos;
  23.     endVarStringPos = std::string::npos;
  24.     beginVarNamePos = std::string::npos;
  25.     endVarNamePos = std::string::npos;
  26.     if (str.empty())
  27.     {
  28.         return false;
  29.     }
  30.     beginVarStringPos = str.find_first_of(TestString, pos);
  31.     if (std::string::npos == beginVarStringPos)
  32.     {
  33.         return false;
  34.     }
  35.     if (beginVarStringPos >= str.length() - 1)
  36.     {
  37.         return false;
  38.     }
  39.     char ch = str[beginVarStringPos];
  40.     char ch1 = str[beginVarStringPos + 1];
  41.     if (
  42.        PercentSign == ch
  43.        && LeftParenthesis != ch1 && LeftSquareBracket != ch1
  44.        && LeftCurlyBracket != ch1
  45.        )
  46.     {
  47.         beginVarNamePos = beginVarStringPos + 1;
  48.         endVarStringPos = str.find(PercentSign, beginVarNamePos);
  49.         if (std::string::npos == endVarStringPos)
  50.         {
  51.             return false;
  52.         }
  53.     }
  54.     else if (
  55.        LeftParenthesis != ch1 && LeftSquareBracket != ch1
  56.        && LeftCurlyBracket != ch1
  57.        )
  58.     {
  59.         return false;
  60.     }
  61.     else
  62.     {
  63.         beginVarNamePos = beginVarStringPos + 2;
  64.         char closeChar = 0;
  65.         if (LeftParenthesis == ch1)
  66.         {
  67.             closeChar = RightParenthesis;
  68.         }
  69.         else if (LeftSquareBracket == ch1)
  70.         {
  71.             closeChar = RightSquareBracket;
  72.         }
  73.         else if (LeftCurlyBracket == ch1)
  74.         {
  75.             closeChar = RightCurlyBracket;
  76.         }
  77.         endVarStringPos = str.find(closeChar, beginVarNamePos);
  78.         if (std::string::npos == endVarStringPos)
  79.         {
  80.             return false;
  81.         }
  82.     }
  83.     endVarNamePos = endVarStringPos - 1;
  84.     return true;
  85. }
  86.  
  87. bool StringContainsVariableStrings(const std::string &str)
  88. {
  89.     std::string::size_type beginVarStringPos = 0;
  90.     std::string::size_type endVarStringPos = 0;
  91.     std::string::size_type beginVarNamePos = 0;
  92.     std::string::size_type endVarNamePos = 0;
  93.     bool ret = FindVariableString(str, 0, beginVarStringPos, endVarStringPos, beginVarNamePos, endVarNamePos);
  94.     return ret;
  95. }
  96.  
  97. std::string GetVariableValue(
  98.     const std::string &varName,
  99.     const std::map<std::string, std::string> &env,
  100.     bool &fromEnvMap, bool &valueContainsVariableStrings)
  101. {
  102.     typedef std::map<std::string, std::string> my_map;
  103.     fromEnvMap = false;
  104.     valueContainsVariableStrings = false;
  105.     std::string ret;
  106.     my_map::const_iterator itFind = env.find(varName);
  107.     if (itFind != env.end())
  108.     {
  109.         ret = (*itFind).second;
  110.         if (!ret.empty())
  111.         {
  112.             fromEnvMap = true;
  113.             valueContainsVariableStrings = StringContainsVariableStrings(ret);
  114.         }
  115.     }
  116.     if (ret.empty())
  117.     {
  118.         ret = ::getenv(varName.c_str());
  119.     }
  120.     return ret;
  121. }
  122.  
  123. ::boost::xpressive::sregex GetRegex()
  124. {
  125.     namespace xpr = ::boost::xpressive;
  126.     xpr::sregex ret =
  127.         "%" >> (xpr::s1 = +(xpr::_w | xpr::_s | "(" | ")")) >> '%'
  128.         | "%(" >> (xpr::s1 = +(xpr::_w | xpr::_s)) >> ')'
  129.         | "%[" >> (xpr::s1 = +(xpr::_w | xpr::_s | "(" | ")")) >> ']'
  130.         | "%{" >> (xpr::s1 = +(xpr::_w | xpr::_s | "(" | ")")) >> '}'
  131.         | "$(" >> (xpr::s1 = +(xpr::_w | xpr::_s)) >> ')'
  132.         | "$[" >> (xpr::s1 = +(xpr::_w | xpr::_s | "(" | ")")) >> ']'
  133.         | "${" >> (xpr::s1 = +(xpr::_w | xpr::_s | "(" | ")")) >> '}'
  134.         | "#(" >> (xpr::s1 = +(xpr::_w | xpr::_s)) >> ')'
  135.         | "#[" >> (xpr::s1 = +(xpr::_w | xpr::_s | "(" | ")")) >> ']'
  136.         | "#{" >> (xpr::s1 = +(xpr::_w | xpr::_s | "(" | ")")) >> '}';
  137.     return ret;
  138. }
  139.  
  140. struct string_formatter
  141. {
  142.     typedef std::map<std::string, std::string> env_map;
  143.     env_map env;
  144.     mutable bool valueContainsVariables;
  145.     string_formatter()
  146.     {
  147.         valueContainsVariables = false;
  148.     }
  149.     template<typename Out>
  150.     Out operator()(::boost::xpressive::smatch const& what, Out out) const
  151.     {
  152.         bool fromEnvMap;
  153.         bool valueContainsVariableStrings;
  154.         std::string value = GetVariableValue(
  155.             what.str(1), env, fromEnvMap, valueContainsVariableStrings);
  156.         if (fromEnvMap && !value.empty() && valueContainsVariableStrings)
  157.         {
  158.             valueContainsVariables = true;
  159.         }
  160.         if (value.empty())
  161.         {
  162.             value = what[0];
  163.         }
  164.         if (!value.empty())
  165.         {
  166.             out = std::copy(value.begin(), value.end(), out);
  167.         }
  168.         return out;
  169.     }
  170. };
  171.  
  172. std::string ExpandVarsR(
  173.     const std::string &original,
  174.     const std::map<std::string, std::string> &env)
  175. {
  176.     std::string ret = original;
  177.     if (original.empty())
  178.     {
  179.         return ret;
  180.     }
  181.     string_formatter fmt;
  182.     fmt.env = env;
  183.     fmt.valueContainsVariables = false;
  184.     ::boost::xpressive::sregex envar = GetRegex();
  185.     ret = ::boost::xpressive::regex_replace(original, envar, fmt);
  186.     if (fmt.valueContainsVariables)
  187.     {
  188.         std::string newValue;
  189.         std::string prevValue = ret;
  190.         do
  191.         {
  192.             fmt.valueContainsVariables = false;
  193.             newValue = ::boost::xpressive::regex_replace(prevValue, envar, fmt);
  194.             if (0 == prevValue.compare(newValue))
  195.             {
  196.                 break;
  197.             }
  198.             prevValue.erase();
  199.             prevValue = newValue;
  200.         }
  201.         while (fmt.valueContainsVariables);
  202.         if (0 != ret.compare(newValue))
  203.         {
  204.             ret = newValue;
  205.         }
  206.     }
  207.     return ret;
  208. }
  209.  
  210. std::string GetDateFormatStringExpandVars(const std::string& langCode)
  211. {
  212.     if (
  213.        0 == langCode.compare(0, 2, "en")
  214.        || 0 == langCode.compare(0, 2, "EN")
  215.        )
  216.     {
  217.         return std::string("${month}/${day}/${year}");
  218.     }
  219.     else if (
  220.        0 == langCode.compare(0, 2, "fr")
  221.        || 0 == langCode.compare(0, 2, "FR")
  222.        )
  223.     {
  224.         return std::string("${day}/${month}/${year}");
  225.     }
  226.     else if (
  227.        0 == langCode.compare(0, 2, "ja")
  228.        || 0 == langCode.compare(0, 2, "JA")
  229.        || 0 == langCode.compare(0, 2, "jp")
  230.        || 0 == langCode.compare(0, 2, "JP")
  231.        )
  232.     {
  233.         return std::string("${year}/${day}/${month}");
  234.     }
  235.     return std::string("${month}/${day}/${year}");
  236. }
  237.  
  238. std::string GetDateStringExpandVarsR(
  239.     const std::string &langCode, int month, int day, int year)
  240. {
  241.     std::string fmt = GetDateFormatStringExpandVars(langCode);
  242.     std::map<std::string,std::string> env{
  243.         {"month", std::to_string(month)},
  244.         {"day", std::to_string(day)},
  245.         {"year", std::to_string(year)}
  246.     };
  247.     std::string ret = ExpandVarsR(fmt, env);
  248.     return ret;
  249. }
  250.  
  251. int main()
  252. {
  253.     std::cout << GetDateStringExpandVarsR("en", 11, 7, 2018) << "\n";
  254.     return 0;
  255. }
  256.  
Success #stdin #stdout 0s 15360KB
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Standard input is empty
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11/7/2018
https://ideone.com/nhAJqe
Variable Expansion in Strings - Example 9
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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