unit_converter.hh

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/*!
 *
 * Copyright (C) 2015 Technical University of Liberec.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 3 as published by the
 * Free Software Foundation. (http://www.gnu.org/licenses/gpl-3.0.en.html)
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 *
 *
 * @file    unit_converter.hh
 * @brief
 */

#ifndef UNIT_CONVERTER_HH_
#define UNIT_CONVERTER_HH_


#include <map>                       // for map, map<>::value_compare
#include <string>                    // for string
#include <vector>                    // for vector

#include "tools/unit_si.hh"         // for UnitSI
#include "input/input_exception.hh"  // for DECLARE_INPUT_EXCEPTION, Exception
#include "system/asserts.hh"         // for Assert, ASSERT
#include "system/exceptions.hh"      // for operator<<, ExcStream, EI, TYPED...

namespace Input {
    namespace Type {
        class Record;
    }
}

// Declaration of exceptions
TYPEDEF_ERR_INFO(EI_UnitDefinition, std::string);
TYPEDEF_ERR_INFO(EI_ExpectedUnit, std::string);
TYPEDEF_ERR_INFO(EI_UnitError, std::string);
DECLARE_INPUT_EXCEPTION(ExcInvalidUnit,
        << "Invalid definition of unit: " << EI_UnitDefinition::qval << "\n" << EI_UnitError::val << ".\n");
DECLARE_INPUT_EXCEPTION(ExcNoncorrespondingUnit,
        << "Non-corresponding definition of unit: " << EI_UnitDefinition::qval << "\nExpected: unit with base format "
        << EI_ExpectedUnit::qval << ".\n");


/// Store structure given by parser
struct Factor {
    /// Constructor
    Factor() : exponent_(1), basic_(true) {}
    Factor(std::string factor, int exponent, bool basic = true) : factor_(factor), exponent_(exponent), basic_(basic) {}

    std::string factor_;  //!< string represantation of unit or user defined constant
    int exponent_;        //!< exponent
    bool basic_;          //!< unit is basic (strict defined in application) / derived (defined by user as formula)
};
struct Formula {
    /// Constructor
    Formula() : coef_(1.0) {}

    double coef_;                         //!< multiplicative coeficient
    std::vector<struct Factor> factors_;  //!< factors of formula
};
typedef typename std::map<std::string, struct Formula> UnitData;



/**
 * @brief Helper class. Defines basic factors of SI, non-SI and derived units.
 *
 * Class is instantiated as static object of UnitConverter class and provides check
 * of user defined units.
 */
class BasicFactors {
public:
    struct DerivedUnit {
        double coef_;    //!< multiplicative coeficient
        UnitSI unit_;    //!< derived SI unit
    };

    typedef std::map<std::string, struct DerivedUnit> UnitsMap;

    /// Define all base and derived units given by their symbol.
    UnitsMap units_map_;

    /// Constructor
    BasicFactors();

};


class UnitConverter {
public:
    /// Define all base and derived units given by their symbol.
    static const BasicFactors basic_factors;

    /// Constructor
    UnitConverter();

    static const Input::Type::Record & get_input_type();

    /* Compute a multiplicative constant to convert from 'actual_unit' to the SI unit.
     *
     * The 'actual_unit' string convains a unit expression the is parsed and converted to the 'coef_' and 'unit_si_' so that
     * 'actual unit' == coef_ * unit_si_
     *
     * The coefficient coef_ is returned.
     *
     * TODO: pass the actual_unit to the constructor so that we avoid object modifications.
     */
    double convert(std::string actual_unit);

    /// Return @p unit_si_
    inline UnitSI unit_si() const {
        ASSERT(unit_si_.is_def()).error("UnitSI is not defined, first call convert method.");
        return unit_si_;
    }

protected:
    /**
     * @brief Parse and check unit defined in string format.
     *
     * Return data in format \p UnitData
     */
    UnitData read_unit(std::string s);

    /// Calculates UnitSi and coeficient of Factor, recursively calls this method for user defined formula
    void add_converted_unit(Factor factor, UnitData &unit_data, UnitSI &unit_si, double &coef);

    /**
     * Coeficient of unit.
     *
     * Coeficient is used if unit is not in basic format. Example: if the unit is specified
     * in minutes, coeficient has value 60.
     */
    double coef_;

    /**
     * Basic format of converted SI unit
     */
    UnitSI unit_si_;

};


#endif /* UNIT_CONVERTER_HH_ */