/*******************************************************************************
 * Copyright IBM Corp. and others 2020
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution
 * and is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License, v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception [1] and GNU General Public
 * License, version 2 with the OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
 * [2] https://openjdk.org/legal/assembly-exception.html
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0 OR GPL-2.0-only WITH OpenJDK-assembly-exception-1.0
 *******************************************************************************/

#ifndef ABS_OP_STACK_INCL
#define ABS_OP_STACK_INCL

#include "env/Region.hpp"
#include "infra/vector.hpp"
#include "optimizer/abstractinterpreter/AbsValue.hpp"

namespace TR {

/**
 * Abstract representation of the operand stack.
 */
class AbsOpStack {
public:
    explicit AbsOpStack(TR::Region &region)
        : _container(region)
    {}

    /**
     * @brief Clone an operand stack
     *
     * @param region The memory region where the cloned operand stack should be allocated.
     * @return the cloned operand stack
     */
    TR::AbsOpStack *clone(TR::Region &region) const;

    /**
     * @brief Perform an in-place merge another operand stack.
     * The merge operation does not modify the state of another state
     * or store any references of abstract values from another state to be merged with
     *
     * @param other the operand stack to be merged with
     */
    void merge(const TR::AbsOpStack *other, TR::Region &region);

    /**
     * @brief Push an abstract value onto the operand stack.
     *
     * @param value the value to be pushed
     */
    void push(TR::AbsValue *value) { _container.push_back(value); }

    /**
     * @brief Peek the top value on the operand stack (stack top; not lattice top).
     * @note the stack must not be empty
     *
     * @return the abstract value
     */
    TR::AbsValue *peek() const
    {
        TR_ASSERT_FATAL(size() > 0, "Peek an empty stack!");
        return _container.back();
    }

    /**
     * @brief Get and pop a value off of the operand stack.
     * @note the stack must not be empty.
     *
     * @return the abstract value
     */
    TR::AbsValue *pop();

    bool empty() const { return _container.empty(); }

    size_t size() const { return _container.size(); }

    void print(TR::Compilation *comp) const;

private:
    TR::vector<TR::AbsValue *, TR::Region &> _container;
};

} // namespace TR

#endif
