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 <liblangutil/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, CONFLICTING, ERROR
};

enum class Kind
{
    Int,
    Bool,
    Function,
    Array
};

struct Sort
{
    Sort(Kind _kind):
        kind(_kind) {}
    virtual ~Sort() = default;
    bool operator==(Sort const& _other) const { return kind == _other.kind; }

    Kind const kind;
};
using SortPointer = std::shared_ptr<Sort>;

struct FunctionSort: public Sort
{
    FunctionSort(std::vector<SortPointer> _domain, SortPointer _codomain):
        Sort(Kind::Function), domain(std::move(_domain)), codomain(std::move(_codomain)) {}
    bool operator==(FunctionSort const& _other) const
    {
        if (!std::equal(
            domain.begin(),
            domain.end(),
            _other.domain.begin(),
            [&](SortPointer _a, SortPointer _b) { return *_a == *_b; }
        ))
            return false;
        return Sort::operator==(_other) && *codomain == *_other.codomain;
    }

    std::vector<SortPointer> domain;
    SortPointer codomain;
};

struct ArraySort: public Sort
{
    /// _domain is the sort of the indices
    /// _range is the sort of the values
    ArraySort(SortPointer _domain, SortPointer _range):
        Sort(Kind::Array), domain(std::move(_domain)), range(std::move(_range)) {}
    bool operator==(ArraySort const& _other) const
    {
        return Sort::operator==(_other) && *domain == *_other.domain && *range == *_other.range;
    }

    SortPointer domain;
    SortPointer range;
};

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

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

    bool hasCorrectArity() const
    {
        static std::map<std::string, unsigned> const operatorsArity{
            {"ite", 3},
            {"not", 1},
            {"and", 2},
            {"or", 2},
            {"=", 2},
            {"<", 2},
            {"<=", 2},
            {">", 2},
            {">=", 2},
            {"+", 2},
            {"-", 2},
            {"*", 2},
            {"/", 2},
            {"select", 2},
            {"store", 3}
        };
        return operatorsArity.count(name) && operatorsArity.at(name) == arguments.size();
    }

    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);
    }

    /// select is the SMT representation of an array index access.
    static Expression select(Expression _array, Expression _index)
    {
        solAssert(_array.sort->kind == Kind::Array, "");
        auto const& arraySort = dynamic_cast<ArraySort const*>(_array.sort.get());
        solAssert(arraySort, "");
        solAssert(*arraySort->domain == *_index.sort, "");
        return Expression(
            "select",
            std::vector<Expression>{std::move(_array), std::move(_index)},
            arraySort->range
        );
    }

    /// store is the SMT representation of an assignment to array index.
    /// The function is pure and returns the modified array.
    static Expression store(Expression _array, Expression _index, Expression _element)
    {
        solAssert(_array.sort->kind == Kind::Array, "");
        auto const& arraySort = dynamic_cast<ArraySort const*>(_array.sort.get());
        solAssert(arraySort, "");
        solAssert(*arraySort->domain == *_index.sort, "");
        solAssert(*arraySort->range == *_element.sort, "");
        return Expression(
            "store",
            std::vector<Expression>{std::move(_array), std::move(_index), std::move(_element)},
            _array.sort
        );
    }

    friend Expression operator!(Expression _a)
    {
        return Expression("not", std::move(_a), Kind::Bool);
    }
    friend Expression operator&&(Expression _a, Expression _b)
    {
        return Expression("and", std::move(_a), std::move(_b), Kind::Bool);
    }
    friend Expression operator||(Expression _a, Expression _b)
    {
        return Expression("or", std::move(_a), std::move(_b), Kind::Bool);
    }
    friend Expression operator==(Expression _a, Expression _b)
    {
        return Expression("=", std::move(_a), std::move(_b), Kind::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), Kind::Bool);
    }
    friend Expression operator<=(Expression _a, Expression _b)
    {
        return Expression("<=", std::move(_a), std::move(_b), Kind::Bool);
    }
    friend Expression operator>(Expression _a, Expression _b)
    {
        return Expression(">", std::move(_a), std::move(_b), Kind::Bool);
    }
    friend Expression operator>=(Expression _a, Expression _b)
    {
        return Expression(">=", std::move(_a), std::move(_b), Kind::Bool);
    }
    friend Expression operator+(Expression _a, Expression _b)
    {
        return Expression("+", std::move(_a), std::move(_b), Kind::Int);
    }
    friend Expression operator-(Expression _a, Expression _b)
    {
        return Expression("-", std::move(_a), std::move(_b), Kind::Int);
    }
    friend Expression operator*(Expression _a, Expression _b)
    {
        return Expression("*", std::move(_a), std::move(_b), Kind::Int);
    }
    friend Expression operator/(Expression _a, Expression _b)
    {
        return Expression("/", std::move(_a), std::move(_b), Kind::Int);
    }
    Expression operator()(std::vector<Expression> _arguments) const
    {
        solAssert(
            sort->kind == Kind::Function,
            "Attempted function application to non-function."
        );
        auto fSort = dynamic_cast<FunctionSort const*>(sort.get());
        solAssert(fSort, "");
        return Expression(name, std::move(_arguments), fSort->codomain);
    }

    std::string name;
    std::vector<Expression> arguments;
    SortPointer sort;

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

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

DEV_SIMPLE_EXCEPTION(SolverError);

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

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

    virtual void declareVariable(std::string const& _name, Sort const& _sort) = 0;
    Expression newVariable(std::string _name, SortPointer _sort)
    {
        // Subclasses should do something here
        declareVariable(_name, *_sort);
        return Expression(std::move(_name), {}, std::move(_sort));
    }

    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;

    /// @returns a list of queries that the system was not able to respond to.
    virtual std::vector<std::string> unhandledQueries() { return {}; }

protected:
    // SMT query timeout in milliseconds.
    static int const queryTimeout = 10000;
};

}
}
}