path: root/libsolidity/interface/GasEstimator.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/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2015
 * Gas consumption estimator working alongside the AST.
 */

#pragma once

#include <libsolidity/interface/EVMVersion.h>

#include <libevmasm/GasMeter.h>
#include <libevmasm/Assembly.h>

#include <vector>
#include <map>
#include <array>

namespace dev
{
namespace solidity
{

class ASTNode;
class FunctionDefinition;

struct GasEstimator
{
public:
    using GasConsumption = eth::GasMeter::GasConsumption;
    using ASTGasConsumption = std::map<ASTNode const*, GasConsumption>;
    using ASTGasConsumptionSelfAccumulated =
        std::map<ASTNode const*, std::array<GasConsumption, 2>>;

    explicit GasEstimator(EVMVersion _evmVersion): m_evmVersion(_evmVersion) {}

    /// Estimates the gas consumption for every assembly item in the given assembly and stores
    /// it by source location.
    /// @returns a mapping from each AST node to a pair of its particular and syntactically accumulated gas costs.
    ASTGasConsumptionSelfAccumulated structuralEstimation(
        eth::AssemblyItems const& _items,
        std::vector<ASTNode const*> const& _ast
    ) const;
    /// @returns a mapping from nodes with non-overlapping source locations to gas consumptions such that
    /// the following source locations are part of the mapping:
    /// 1. source locations of statements that do not contain other statements
    /// 2. maximal source locations that do not overlap locations coming from the first rule
    static ASTGasConsumption breakToStatementLevel(
        ASTGasConsumptionSelfAccumulated const& _gasCosts,
        std::vector<ASTNode const*> const& _roots
    );

    /// @returns the estimated gas consumption by the (public or external) function with the
    /// given signature. If no signature is given, estimates the maximum gas usage.
    GasConsumption functionalEstimation(
        eth::AssemblyItems const& _items,
        std::string const& _signature = ""
    ) const;

    /// @returns the estimated gas consumption by the given function which starts at the given
    /// offset into the list of assembly items.
    /// @note this does not work correctly for recursive functions.
    GasConsumption functionalEstimation(
        eth::AssemblyItems const& _items,
        size_t const& _offset,
        FunctionDefinition const& _function
    ) const;

private:
    /// @returns the set of AST nodes which are the finest nodes at their location.
    static std::set<ASTNode const*> finestNodesAtLocation(std::vector<ASTNode const*> const& _roots);
    EVMVersion m_evmVersion;
};

}
}