CSWAP.cpp

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/*
Created on Fri Jun 26 14:13:26 2020
Copyright 2020 Peter Rakyta, Ph.D.

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.

@author: Peter Rakyta, Ph.D.
*/
#include "CSWAP.h"

using namespace std;

CSWAP::CSWAP() : SWAP() {

    // A string labeling the gate operation
    name = "CSWAP";

    // A string describing the type of the gate
    type = CSWAP_OPERATION;

    // Clear control qubits for nullary constructor
    control_qbits.clear();
}

CSWAP::CSWAP(int qbit_num_in, const std::vector<int>& target_qbits_in, const std::vector<int>& control_qbits_in)
    : SWAP(qbit_num_in, target_qbits_in) {

    // A string labeling the gate operation
    name = "CSWAP";

    // A string describing the type of the gate
    type = CSWAP_OPERATION;

    // Validate that we have exactly 1 control qubit
    if (control_qbits_in.size() != 1) {
        std::stringstream sstream;
        sstream << "CSWAP gate requires exactly 1 control qubit, got " << control_qbits_in.size() << std::endl;
        print(sstream, 0);
        throw sstream.str();
    }

    // Validate control qubit index
    if (control_qbits_in[0] >= qbit_num_in) {
        std::stringstream sstream;
        sstream << "Control qubit index " << control_qbits_in[0] << " is larger than or equal to the number of qubits" << std::endl;
        print(sstream, 0);
        throw sstream.str();
    }

    // Check that control qubit doesn't overlap with target qubits
    for (int tq : target_qbits_in) {
        if (control_qbits_in[0] == tq) {
            std::stringstream sstream;
            sstream << "The control qubit cannot be the same as any target qubit" << std::endl;
            print(sstream, 0);
            throw sstream.str();
        }
    }

    // Store control qubit
    control_qbits = control_qbits_in;
    control_qbit = control_qbits[0];  // For backward compatibility
}

CSWAP::~CSWAP() {
}

CSWAP* CSWAP::clone() {

    CSWAP* ret = new CSWAP(qbit_num, target_qbits, control_qbits);

    ret->set_parameter_start_idx(get_parameter_start_idx());
    ret->set_parents(parents);
    ret->set_children(children);

    return ret;
}