libConfiguration.h

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#ifndef __LIBCONFIGURATION_H__
#define __LIBCONFIGURATION_H__

#include "HashTable.h"
#include "String.h"

class Configuration
{
  static String g_sfl;
  static bool g_bRead;
  static HashSS g_h;

private:
  static bool IsWhitespace(char ch)
  {
    return ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t';
  }

  static void ReadConfigFile()
  {
    UD("READING CONFIGURATION FILE: %s", g_sfl.V());
    g_bRead = true;

    FILE *pfl = fopen(g_sfl, "r");
    char s[4096];
    while (fgets(s, sizeof(s) - 1, pfl) != NULL)
      {
      // trim off trailing whitespace
      int nch = strlen(s) - 1;
      while (nch >= 0 && IsWhitespace(s[nch]))
        {
        nch--;
        }
      s[nch + 1] = 0;

      // split
      char sParam[4096];
      int cch;
      if (sscanf(s, " %4095s %n", sParam, &cch) == 1)
        {
        if (sParam[0] != '#')
          {
          String sKey = ConfigEvalString(sParam);
          String sVar = ConfigEvalString(&s[cch]);
          g_h.Set(sKey, sVar);
          }
        }
      }
    fclose(pfl);
  }

  static String ConfigEvalStringInternal(const char *&pch) __attribute__((noinline))
  {
    // TODO: consider speeding this up using strrchr to quickly jump through the string
    VectorOf<char> vecch;
    while (*pch != 0)
      {
      if (*pch == '{')
        {
        pch++;
        String sT = ConfigEvalStringInternal(pch);
        if (sT.V()[0] == '$')
          {
          sT = g_h.Get(String(&sT.V()[1]), "");
          }
        else if (sT.V()[0] == '+')
          {
          ASSERT(sT.V()[1] == '+'); // assume ++
          String sVal = g_h.Get(String(&sT.V()[2]), "");
          sVal = String(sVal.AsInt() + 1);
          g_h.Set(String(&sT.V()[2]), sVal);
          sT = sVal + "";
          }
        /*
         TODO: implement functionals

         else if (sT.V()[0]=='+'){
         vecs=ListFromString(String(&sT.V()[1]));
         Real r=0;
         for (int n=0; n<vecs.C(); n++){
         r=r+AsNumber(vecs[n]);
         }
         sT=String(r);
         }
         */
        vecch.Append(sT.V(), sT.C());
        }
      else if (*pch == '}')
        {
        vecch.Append('\0');
        return String(vecch.V());
        }
      else
        {
        vecch.Append(*pch);
        }
      pch++;
      }
    vecch.Append('\0');
    return String(vecch.V());
  }

  static String ConfigEvalString(const char *pch)
  {
    return ConfigEvalStringInternal(pch);
  }

public:
  static String Describe()
  {
    if (!g_bRead)
      {
      ReadConfigFile();
      }

    String s;
    String sKey;
    String sVal;

    forhash(sKey,sVal,g_h)
      {
      s+=_LINE + StringF("%60s",sKey.V()) + " := " + sVal + LINE_;
      }

    return s;
  }

  static void SetConfigFile(String sfl)
  {
    g_sfl = sfl;
    g_bRead = false;
  }

  static String GetConfigFile()
  {
    return g_sfl;
  }

  static const char* ConfigValue(const char *s, const char* sDefault)
  {
    if (!g_bRead)
      {
      ReadConfigFile();
      }

    String sOut;

    if (g_h.GetInto(s, &sOut))
      {
      return sOut;
      }
    return sDefault;
  }

  static Real ConfigValue(const char *s, const double& rDefault)
  {
    if (!g_bRead)
      {
      ReadConfigFile();
      }

    String sOut;

    if (g_h.GetInto(s, &sOut))
      {
      return sOut.AsReal();
      }
    return rDefault;
  }

  static Real ConfigValue(const char *s, const float& rDefault)
  {
    if (!g_bRead)
      {
      ReadConfigFile();
      }

    String sOut;

    if (g_h.GetInto(s, &sOut))
      {
      return sOut.AsReal();
      }
    return rDefault;
  }

  static int ConfigValue(const char *s, const int& zDefault)
  {
    if (!g_bRead)
      {
      ReadConfigFile();
      }

    String sOut;

    if (g_h.GetInto(s, &sOut))
      {
      return sOut.AsInt();
      }
    return zDefault;
  }

  static bool ConfigValue(const char *s, const bool& bDefault)
  {
    if (!g_bRead)
      {
      ReadConfigFile();
      }

    String sOut;

    if (g_h.GetInto(s, &sOut))
      {
      return sOut == "true" || sOut == "yes";
      }
    return bDefault;
  }
};

inline void SetConfigFile(String sfl)
{
  Configuration::SetConfigFile(sfl);
}

inline String GetConfigFile()
{
  return Configuration::GetConfigFile();
}

inline String DescribeConfiguration()
{
  return Configuration::Describe();
}

inline const char* ConfigValue(const char *s, const char* tDefault)
{
  return Configuration::ConfigValue(s, tDefault);
}
template<class T>
inline T ConfigValue(const char *s, const T& tDefault)
{
  return Configuration::ConfigValue(s, tDefault);
}

#endif //__LIBCONFIGURATION_H__