path: root/libsolidity/formal/SolverInterface.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/interface/Exceptions.h>
#include <libsolidity/interface/ReadFile.h>

#include <libdevcore/Common.h>
#include <libdevcore/Exceptions.h>

#include <boost/noncopyable.hpp>

#include <map>
#include <string>
#include <vector>
#include <cstdio>

namespace dev
{
namespace solidity
{
namespace smt
{

enum class CheckResult
{
    SATISFIABLE, UNSATISFIABLE, UNKNOWN, ERROR
};

enum class Sort
{
    Int,
    Bool,
    IntIntFun // Function of one Int returning a single Int
};

/// C++ representation of an SMTLIB2 expression.
class Expression
{
    friend class SolverInterface;
public:
    explicit Expression(bool _v): name(_v ? "true" : "false"), sort(Sort::Bool) {}
    Expression(size_t _number): name(std::to_string(_number)), sort(Sort::Int) {}
    Expression(u256 const& _number): name(_number.str()), sort(Sort::Int) {}
    Expression(bigint const& _number): name(_number.str()), sort(Sort::Int) {}

    Expression(Expression const&) = default;
    Expression(Expression&&) = default;
    Expression& operator=(Expression const&) = default;
    Expression& operator=(Expression&&) = default;

    static Expression ite(Expression _condition, Expression _trueValue, Expression _falseValue)
    {
        solAssert(_trueValue.sort == _falseValue.sort, "");
        return Expression("ite", std::vector<Expression>{
            std::move(_condition), std::move(_trueValue), std::move(_falseValue)
        }, _trueValue.sort);
    }

    static Expression implies(Expression _a, Expression _b)
    {
        return !std::move(_a) || std::move(_b);
    }

    friend Expression operator!(Expression _a)
    {
        return Expression("not", std::move(_a), Sort::Bool);
    }
    friend Expression operator&&(Expression _a, Expression _b)
    {
        return Expression("and", std::move(_a), std::move(_b), Sort::Bool);
    }
    friend Expression operator||(Expression _a, Expression _b)
    {
        return Expression("or", std::move(_a), std::move(_b), Sort::Bool);
    }
    friend Expression operator==(Expression _a, Expression _b)
    {
        return Expression("=", std::move(_a), std::move(_b), Sort::Bool);
    }
    friend Expression operator!=(Expression _a, Expression _b)
    {
        return !(std::move(_a) == std::move(_b));
    }
    friend Expression operator<(Expression _a, Expression _b)
    {
        return Expression("<", std::move(_a), std::move(_b), Sort::Bool);
    }
    friend Expression operator<=(Expression _a, Expression _b)
    {
        return Expression("<=", std::move(_a), std::move(_b), Sort::Bool);
    }
    friend Expression operator>(Expression _a, Expression _b)
    {
        return Expression(">", std::move(_a), std::move(_b), Sort::Bool);
    }
    friend Expression operator>=(Expression _a, Expression _b)
    {
        return Expression(">=", std::move(_a), std::move(_b), Sort::Bool);
    }
    friend Expression operator+(Expression _a, Expression _b)
    {
        return Expression("+", std::move(_a), std::move(_b), Sort::Int);
    }
    friend Expression operator-(Expression _a, Expression _b)
    {
        return Expression("-", std::move(_a), std::move(_b), Sort::Int);
    }
    friend Expression operator*(Expression _a, Expression _b)
    {
        return Expression("*", std::move(_a), std::move(_b), Sort::Int);
    }
    friend Expression operator/(Expression _a, Expression _b)
    {
        return Expression("/", std::move(_a), std::move(_b), Sort::Int);
    }
    Expression operator()(Expression _a) const
    {
        solAssert(
            sort == Sort::IntIntFun && arguments.empty(),
            "Attempted function application to non-function."
        );
        return Expression(name, _a, Sort::Int);
    }

    std::string const name;
    std::vector<Expression> const arguments;
    Sort sort;

private:
    /// Manual constructor, should only be used by SolverInterface and this class itself.
    Expression(std::string _name, std::vector<Expression> _arguments, Sort _sort):
        name(std::move(_name)), arguments(std::move(_arguments)), sort(_sort) {}

    explicit Expression(std::string _name, Sort _sort):
        Expression(std::move(_name), std::vector<Expression>{}, _sort) {}
    Expression(std::string _name, Expression _arg, Sort _sort):
        Expression(std::move(_name), std::vector<Expression>{std::move(_arg)}, _sort) {}
    Expression(std::string _name, Expression _arg1, Expression _arg2, Sort _sort):
        Expression(std::move(_name), std::vector<Expression>{std::move(_arg1), std::move(_arg2)}, _sort) {}
};

DEV_SIMPLE_EXCEPTION(SolverError);

class SolverInterface
{
public:
    virtual void reset() = 0;

    virtual void push() = 0;
    virtual void pop() = 0;

    virtual Expression newFunction(std::string _name, Sort _domain, Sort _codomain)
    {
        solAssert(_domain == Sort::Int && _codomain == Sort::Int, "Function sort not supported.");
        // Subclasses should do something here
        return Expression(std::move(_name), {}, Sort::IntIntFun);
    }
    virtual Expression newInteger(std::string _name)
    {
        // Subclasses should do something here
        return Expression(std::move(_name), {}, Sort::Int);
    }
    virtual Expression newBool(std::string _name)
    {
        // Subclasses should do something here
        return Expression(std::move(_name), {}, Sort::Bool);
    }

    virtual void addAssertion(Expression const& _expr) = 0;

    /// Checks for satisfiability, evaluates the expressions if a model
    /// is available. Throws SMTSolverError on error.
    virtual std::pair<CheckResult, std::vector<std::string>>
    check(std::vector<Expression> const& _expressionsToEvaluate) = 0;
};


}
}
}