valueParser.hpp

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#ifndef _Wolframe_CONFIG_VALUE_PARSER_HPP_INCLUDED
#define _Wolframe_CONFIG_VALUE_PARSER_HPP_INCLUDED

#include "logger-v1.hpp"
#include "types/propertyTree.hpp"
#include <stdexcept>
#include <boost/type_traits.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/algorithm/string.hpp>
#include <boost/utility/value_init.hpp>
#include <boost/type_traits/is_enum.hpp>
#include <boost/utility.hpp>
#include <boost/limits.hpp>
#include <string>
#include <ostream>
#include <utility>

namespace _Wolframe {
namespace config {

namespace traits {
template <typename T> typename boost::enable_if<boost::is_enum<T>, T>::type increment( const T& i) { return (T)((int)i + 1); }
template <typename T> typename boost::disable_if<boost::is_enum<T>, T>::type increment( const T& i) { T rt = i; return ++rt; }
}//namespace


class Parser
{
public:
        typedef std::string string;

        //
        //  All domains have to implement a check(ValueType&,string&) and a parse(ValueType&,const string&,string&) method
        //
        struct BaseTypeDomain
        {
                BaseTypeDomain(){}

                template <typename ValueType>
                bool check( const ValueType&, string&) const
                {
                        return true;
                }

                template <typename ValueType>
                bool parse( ValueType& value, const string& token, string& explanation) const
                {
                        using boost::bad_lexical_cast;
                        try
                        {
                                value = boost::lexical_cast<ValueType>( token);
                        }
                        catch (bad_lexical_cast& e)
                        {
                                explanation = e.what();
                                return false;
                        };
                        return true;
                }
        };

        template <typename DomainValueType>
        struct RangeDomain :public BaseTypeDomain
        {
                RangeDomain( const DomainValueType& min_, const DomainValueType& max_=std::numeric_limits<DomainValueType>::max()) :m_min(min_),m_max(max_){}

                string getDomainDescription() const
                {
                        string rt( "[ ");
                        rt.append( boost::lexical_cast<string>(m_min));
                        rt.append( ", ");
                        rt.append( boost::lexical_cast<string>(m_max));
                        rt.append( " ]");
                        return rt;
                }

                template <typename ValueType>
                bool check( const ValueType& val, string& explanation) const
                {
                        if (val < m_min || val > m_max)
                        {
                                explanation = "value out of range, expected value in the range of ";
                                explanation.append( getDomainDescription());
                                return false;
                        }
                        return true;
                }
        private:
                DomainValueType m_min;          //< minimal allowed value of the range
                DomainValueType m_max;          //< maximal allowed value of the range
        };

        template <typename DomainValueType>
        struct NonEmptyDomain :public BaseTypeDomain
        {
                NonEmptyDomain(){}

                template <typename ValueType>
                bool check( const ValueType& val, string& explanation) const
                {
                        ValueType empty = boost::value_initialized<ValueType>();
                        if (val == empty)
                        {
                                explanation = "value expected to be other than '";
                                explanation.append( boost::lexical_cast<std::string>( empty));
                                explanation.append( "'");
                                return false;
                        }
                        return true;
                }
        };

        struct EnumDomain :public BaseTypeDomain
        {
                EnumDomain( unsigned int nofelems, const char** elems) :m_size(nofelems),m_ar(elems){}

                string getDomainDescription() const
                {
                        string rt( "{");
                        unsigned int ii;
                        for (ii=0; ii<m_size; ii++)
                        {
                                if (ii>0) rt.append( ", ");
                                rt.append( "'");
                                rt.append( boost::lexical_cast<string>(m_ar[ii]));
                                rt.append( "'");
                        }
                        rt.append( "}");
                        return rt;
                }

                template <typename ValueType>
                bool parse( ValueType& value, const string& token, string& explanation) const
                {
                        unsigned int ii;
                        value = boost::value_initialized<ValueType>();

                        for (ii=0; ii<m_size; ii++, value=traits::increment(value))
                        {
                                if (boost::algorithm::iequals( token, m_ar[ii]))
                                {
                                        return true;
                                }
                        }
                        explanation = "must be one of ";
                        explanation.append( getDomainDescription());
                        return false;
                }
        private:
                unsigned int m_size;    //< number of elements in the enumeration
                const char** m_ar;      //< string representation of the elements in the enumeration
        };

        struct BoolDomain :public EnumDomain
        {
        private:
                enum {NofBooleanEnum=10};

                static const char** booleanEnum()
                {
                        static const char* ar[ NofBooleanEnum ] = {"false", "true", "0", "1", "off", "on", "no", "yes", "deny", "allow"};
                        return ar;
                }
                static bool getBooleanValue( unsigned int booleanEnumIdx)
                {
                        return (booleanEnumIdx & 0x01);
                }

        public:
                BoolDomain() :EnumDomain( NofBooleanEnum, booleanEnum()){}

                bool parse( bool& value, const string& token, string& explanation) const
                {
                        unsigned int enumval = 0;
                        bool rt = EnumDomain::parse( enumval, token, explanation);
                        value = getBooleanValue( enumval);
                        return rt;
                }
        };

        //  If the flag is set when the method is called an error message is logged and the command fails.
        template <typename Value, class Domain>
        static bool getValue( const char* module, const char* name, const string& token, Value& value, const Domain& domain, bool* isDefined=0)
        {
                using std::bad_alloc;
                using std::exception;
                try
                {
                        if (isDefined)
                        {
                                if (*isDefined)
                                {
                                        LOG_ERROR << loggingScope(module) << "duplicate definition of configuration element '" << name << "'";
                                        return false;
                                }
                        }
                        string errorExplanation;
                        if (domain.parse( value, token, errorExplanation) && domain.check( value, errorExplanation))
                        {
                                if (isDefined) *isDefined = true;
                                return true;
                        }
                        LOG_ERROR << loggingScope(module) << "invalid value '" << token << "' for configuration element '" << name << "' (" << errorExplanation << ")";
                        return false;
                }
                catch (bad_alloc&)
                {
                        LOG_ERROR << loggingScope(module) << "out of memory when parsing configuration element '" << name << "'";
                        return false;
                }
                catch (exception& e)
                {
                        LOG_ERROR << loggingScope(module) << "illegal value for configuration element '" << name << "' (" << e.what() << ")";
                        return false;
                }
        }

        //  If the flag is set when the method is called an error message is logged and the command fails.
        template <typename Value>
        static bool getValue( const char* module, const char* name, const string& token, Value& value, bool* isDefined=0)
        {
                return getValue<Value,BaseTypeDomain>( module, name, token, value, BaseTypeDomain(), isDefined);
        }

        //   See definition of getValue(const char*,const std::pair<const std::string,const std::string>&,Value&,const Domain&,bool*).
        //   Only difference is that we convert the decl structure from a property tree element and check if it is a name value assignement.
        //  If the flag is set when the method is called an error message is logged and the command fails.
        template <typename Value, class Domain>
        static bool getValue( const char* module, const std::pair<const std::string, const types::PropertyTree::Node>& decl, Value& value, const Domain& domain, bool* isDefined=0)
        {
                try
                {
                        if (decl.second.begin() != decl.second.end())
                        {
                                LOG_ERROR << loggingScope(module) << "atomic value expected for configuration element '" << decl.first.c_str() << "'";
                                return false;
                        }
                        return getValue( module, decl.first.c_str(), decl.second.data(), value, domain, isDefined);
                }
                catch (std::bad_alloc&)
                {
                        LOG_ERROR << loggingScope(module) << "out of memory when parsing configuration element '" << decl.first.c_str() << "'";
                        return false;
                };
        }

        //   See definition of getValue(const char*,const std::pair<const std::string,const std::string>&,Value&,bool*).
        //   Only difference is that we convert the decl structure from a property tree element and check if it is a name value assignement.
        //  If the flag is set when the method is called an error message is logged and the command fails.
        template <typename Value>
        static bool getValue( const char* module, const std::pair<const std::string, const types::PropertyTree::Node>& decl, Value& value, bool* isDefined=0)
        {
                return getValue<Value,BaseTypeDomain>( module, decl, value, BaseTypeDomain(), isDefined);
        }

private:
        static const std::string loggingScope( const char* scope)
        {
                std::string rt;
                if (scope && *scope)
                {
                        rt.append( scope);
                        rt.append( ": ");
                }
                return rt;
        }
};

}} // namespace _Wolframe::config

#endif // _Wolframe_CONFIG_VALUE_PARSER_HPP_INCLUDED