UnitEvaluator.cc

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#include <utl/UnitEvaluator.h>
#include <utl/ErrorLogger.h>
#include <utl/AugerException.h>

#include <boost/version.hpp>
#if BOOST_VERSION >= 103800
#  define BOOST_SPIRIT_USE_OLD_NAMESPACE
#  include <boost/spirit/include/classic_parser.hpp>
#else
#  include <boost/spirit/core/parser.hpp>
#endif

#include <iostream>
#include <iomanip>
#include <sstream>
#include <string>

using namespace std;


namespace utl {

  string
  UnitEvaluator::GetError()
    const
  {
    ostringstream errStream;
    errStream << "Unit parsing failed: ";
    switch (fError) {
    case UnitGrammar::eLookup:
      errStream << "Unknown unit in the expression.";
      break;
    case UnitGrammar::eBracket:
      errStream << "Not a well-formed expression. (e.g.: brackets)";
      break;
    case UnitGrammar::eBadSymbol:
      errStream << "Invalid symbol in the expression. (e.g.: + or -)";
      break;
    case UnitGrammar::eParsing:
      errStream << "Boost spirit parsing error.";
      break;
    default: //Should never reach this.
      errStream << "Unknown error.";
      break;
    }
    errStream << '\n' << fExpression << '\n'
              << setw(fErrPosition) << " "
              << "^ failed at the " << fErrPosition+1 << ". position\n";
    return errStream.str();
  }


  double
  UnitEvaluator::Evaluate(const string& expression)
    const
  {
    fExpression = expression;
    fError = UnitGrammar::eOk;
    fErrPosition = 0;

    string::iterator firstChar = fExpression.begin();
    const string::iterator lastChar = fExpression.end();

    boost::spirit::parse_info<string::iterator> info;

    do {
      info = boost::spirit::parse(
        firstChar,
        lastChar,
        fGrammar,
        boost::spirit::space_p
      );

      if (!info.hit) {                  //not successful parsing
        fError = UnitGrammar::eParsing;
        fErrPosition = info.stop - firstChar;
        const char errChar = fExpression[fErrPosition];
        if (errChar == '-' || errChar == '+')
          fError = UnitGrammar::eBadSymbol;
        if (errChar == '(' || errChar == ')')
          fError = UnitGrammar::eBracket;
        firstChar = info.stop;          //next start point
      } else if (!info.full) {          //ok, but if no full match
        fError = UnitGrammar::eBracket;
        fErrPosition = 0;
      }
    } while(!info.full && info.hit);    //full match and parsing is ok

    if (fError != UnitGrammar::eOk) {
      const string err = GetError();
      ERROR(err);
      throw XMLParseException(err);
    }

    return fValue;
  }

}