LookupTableMap.h

/* Copyright 2017 Kristofer Björnson
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


#ifndef COM_DAFER45_TBTK_LOOKUP_TABLE_MAP
#define COM_DAFER45_TBTK_LOOKUP_TABLE_MAP

#include "TBTK/FockStateMap/FockStateMap.h"
#include "TBTK/BitRegister.h"
#include "TBTK/ExtensiveBitRegister.h"

namespace TBTK{
namespace FockStateMap{

template<typename BIT_REGISTER>
class LookupTableMap : public FockStateMap<BIT_REGISTER>{
public:
    LookupTableMap(unsigned int exponentialDimension);

    virtual ~LookupTableMap();

    virtual unsigned int getBasisSize() const;

    virtual unsigned int getBasisIndex(
        const FockState<BIT_REGISTER> &fockState
    ) const;

    virtual FockState<BIT_REGISTER> getFockState(unsigned int index) const;

    void addState(const FockState<BIT_REGISTER> &fockState);
private:
    std::vector<FockState<BIT_REGISTER>> states;
};

template<typename BIT_REGISTER>
LookupTableMap<BIT_REGISTER>::LookupTableMap(
    unsigned int exponentialDimension
) :
    FockStateMap<BIT_REGISTER>(exponentialDimension)
{
}

template<typename BIT_REGISTER>
LookupTableMap<BIT_REGISTER>::~LookupTableMap(){
}

template<typename BIT_REGISTER>
unsigned int LookupTableMap<BIT_REGISTER>::getBasisSize() const{
    return states.size();
}

template<typename BIT_REGISTER>
unsigned int LookupTableMap<BIT_REGISTER>::getBasisIndex(
    const FockState<BIT_REGISTER> &fockState
) const{
    unsigned int min = 0;
    unsigned int max = states.size()-1;
    while(min <= max){
        unsigned int currentState = (min+max)/2;
        if(fockState.getBitRegister() > states.at(currentState).getBitRegister())
            min = currentState + 1;
        else if(fockState.getBitRegister() < states.at(currentState).getBitRegister())
            max = currentState - 1;
        else if(fockState.getBitRegister() == states.at(currentState).getBitRegister())
            return currentState;
    }
    TBTKExit(
        "LookupTableFockStateMap<BIT_REGISTER>::getBasisIndex()",
        "FockState not found.",
        ""
    );
}

template<typename BIT_REGISTER>
FockState<BIT_REGISTER> LookupTableMap<BIT_REGISTER>::getFockState(
    unsigned int index
) const{
    return states.at(index);
}

template<typename BIT_REGISTER>
void LookupTableMap<BIT_REGISTER>::addState(
    const FockState<BIT_REGISTER> &fockState
){
    if(
        states.size() == 0
        || states.back().getBitRegister() < fockState.getBitRegister()
    ){
        states.push_back(fockState);
    }
    else{
        unsigned int min = 0;
        unsigned int max = states.size()-1;
        while(min <= max){
            unsigned int currentState = (min+max)/2;
            if(
                fockState.getBitRegister()
                > states.at(currentState).getBitRegister()
            ){
                min = currentState + 1;
            }
            else if(
                fockState.getBitRegister()
                < states.at(currentState).getBitRegister()
            ){
                max = currentState - 1;
            }

            if(min >= max){
                if(
                    fockState.getBitRegister()
                        < states.at(
                            currentState
                        ).getBitRegister()
                ){
                    states.insert(
                        states.begin() + currentState,
                        fockState
                    );
                }
                else{
                    states.insert(
                        states.begin() + currentState
                            + 1,
                        fockState
                    );
                }
                break;
            }
        }
    }
}

};  //End of namespace FockStateMap
};  //End of namespace TBTK

#endif