path: root/libsolidity/formal/SymbolicVariables.h

/*
    This file is part of solidity.

    solidity is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    solidity is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with solidity.  If not, see <http://www.gnu.org/licenses/>.
*/

#pragma once

#include <libsolidity/formal/SSAVariable.h>

#include <libsolidity/formal/SolverInterface.h>

#include <libsolidity/ast/Types.h>

#include <memory>

namespace dev
{
namespace solidity
{

class Type;

/**
 * This abstract class represents the symbolic version of a program variable.
 */
class SymbolicVariable
{
public:
    SymbolicVariable(
        TypePointer _type,
        std::string const& _uniqueName,
        smt::SolverInterface& _interface
    );

    virtual ~SymbolicVariable() = default;

    smt::Expression currentValue() const
    {
        return valueAtIndex(m_ssa->index());
    }

    std::string currentName() const;

    virtual smt::Expression valueAtIndex(int _index) const = 0;

    smt::Expression increaseIndex()
    {
        ++(*m_ssa);
        return currentValue();
    }

    unsigned index() const { return m_ssa->index(); }
    unsigned& index() { return m_ssa->index(); }

    /// Sets the var to the default value of its type.
    /// Inherited types must implement.
    virtual void setZeroValue() = 0;
    /// The unknown value is the full range of valid values.
    /// It is sub-type dependent, but not mandatory.
    virtual void setUnknownValue() {}

protected:
    std::string uniqueSymbol(unsigned _index) const;

    TypePointer m_type = nullptr;
    std::string m_uniqueName;
    smt::SolverInterface& m_interface;
    std::shared_ptr<SSAVariable> m_ssa = nullptr;
};

/**
 * Specialization of SymbolicVariable for Bool
 */
class SymbolicBoolVariable: public SymbolicVariable
{
public:
    SymbolicBoolVariable(
        TypePointer _type,
        std::string const& _uniqueName,
        smt::SolverInterface& _interface
    );

    /// Sets the var to false.
    void setZeroValue();
    /// Does nothing since the SMT solver already knows the valid values for Bool.
    void setUnknownValue();

protected:
    smt::Expression valueAtIndex(int _index) const;
};

/**
 * Specialization of SymbolicVariable for Integers
 */
class SymbolicIntVariable: public SymbolicVariable
{
public:
    SymbolicIntVariable(
        TypePointer _type,
        std::string const& _uniqueName,
        smt::SolverInterface& _interface
    );

    /// Sets the var to 0.
    void setZeroValue();
    /// Sets the variable to the full valid value range.
    void setUnknownValue();

protected:
    smt::Expression valueAtIndex(int _index) const;
};

/**
 * Specialization of SymbolicVariable for Address
 */
class SymbolicAddressVariable: public SymbolicIntVariable
{
public:
    SymbolicAddressVariable(
        std::string const& _uniqueName,
        smt::SolverInterface& _interface
    );
};

/**
 * Specialization of SymbolicVariable for FixedBytes
 */
class SymbolicFixedBytesVariable: public SymbolicIntVariable
{
public:
    SymbolicFixedBytesVariable(
        unsigned _numBytes,
        std::string const& _uniqueName,
        smt::SolverInterface& _interface
    );
};

}
}