/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

#include "atn/SingletonPredictionContext.h"

#include "atn/EmptyPredictionContext.h"

using namespace antlr4::atn;

SingletonPredictionContext::SingletonPredictionContext(
    Ref<PredictionContext> const& parent, size_t returnState)
    : PredictionContext(parent ? calculateHashCode(parent, returnState) : calculateEmptyHashCode()),
      parent(parent), returnState(returnState) {
    assert(returnState != ATNState::INVALID_STATE_NUMBER);
}

SingletonPredictionContext::~SingletonPredictionContext() {}

Ref<SingletonPredictionContext> SingletonPredictionContext::create(
    Ref<PredictionContext> const& parent, size_t returnState) {

    if (returnState == EMPTY_RETURN_STATE && parent) {
        // someone can pass in the bits of an array ctx that mean $
        return std::dynamic_pointer_cast<SingletonPredictionContext>(EMPTY);
    }
    return std::make_shared<SingletonPredictionContext>(parent, returnState);
}

size_t SingletonPredictionContext::size() const {
    return 1;
}

Ref<PredictionContext> SingletonPredictionContext::getParent(size_t index) const {
    assert(index == 0);
    ((void)(index)); // Make Release build happy.
    return parent;
}

size_t SingletonPredictionContext::getReturnState(size_t index) const {
    assert(index == 0);
    ((void)(index)); // Make Release build happy.
    return returnState;
}

bool SingletonPredictionContext::operator==(const PredictionContext& o) const {
    if (this == &o) {
        return true;
    }

    const SingletonPredictionContext* other = dynamic_cast<const SingletonPredictionContext*>(&o);
    if (other == nullptr) {
        return false;
    }

    if (this->hashCode() != other->hashCode()) {
        return false; // can't be same if hash is different
    }

    if (returnState != other->returnState)
        return false;

    if (!parent && !other->parent)
        return true;
    if (!parent || !other->parent)
        return false;

    return *parent == *other->parent;
}

std::string SingletonPredictionContext::toString() const {
    // std::string up = !parent.expired() ? parent.lock()->toString() : "";
    std::string up = parent != nullptr ? parent->toString() : "";
    if (up.length() == 0) {
        if (returnState == EMPTY_RETURN_STATE) {
            return "$";
        }
        return std::to_string(returnState);
    }
    return std::to_string(returnState) + " " + up;
}
