path: root/Types.h

/*
    This file is part of cpp-ethereum.

    cpp-ethereum 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.

    cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2014
 * Solidity data types
 */

#pragma once

#include <memory>
#include <string>
#include <map>
#include <boost/noncopyable.hpp>
#include <libdevcore/Common.h>
#include <libsolidity/Exceptions.h>
#include <libsolidity/ASTForward.h>
#include <libsolidity/Token.h>
#include <libdevcore/UndefMacros.h>

namespace dev
{
namespace solidity
{

class Type; // forward
class FunctionType; // forward
using TypePointer = std::shared_ptr<Type const>;
using FunctionTypePointer = std::shared_ptr<FunctionType const>;
using TypePointers = std::vector<TypePointer>;


enum class DataLocation { Storage, CallData, Memory };

/**
 * Helper class to compute storage offsets of members of structs and contracts.
 */
class StorageOffsets
{
public:
    /// Resets the StorageOffsets objects and determines the position in storage for each
    /// of the elements of @a _types.
    void computeOffsets(TypePointers const& _types);
    /// @returns the offset of the given member, might be null if the member is not part of storage.
    std::pair<u256, unsigned> const* getOffset(size_t _index) const;
    /// @returns the total number of slots occupied by all members.
    u256 const& getStorageSize() const { return m_storageSize; }

private:
    u256 m_storageSize;
    std::map<size_t, std::pair<u256, unsigned>> m_offsets;
};

/**
 * List of members of a type.
 */
class MemberList
{
public:
    struct Member
    {
        Member(std::string const& _name, TypePointer const& _type, Declaration const* _declaration = nullptr):
            name(_name),
            type(_type),
            declaration(_declaration)
        {
        }

        std::string name;
        TypePointer type;
        Declaration const* declaration = nullptr;
    };

    using MemberMap = std::vector<Member>;

    MemberList() {}
    explicit MemberList(MemberMap const& _members): m_memberTypes(_members) {}
    MemberList& operator=(MemberList&& _other);
    TypePointer getMemberType(std::string const& _name) const
    {
        TypePointer type;
        for (auto const& it: m_memberTypes)
            if (it.name == _name)
            {
                solAssert(!type, "Requested member type by non-unique name.");
                type = it.type;
            }
        return type;
    }
    MemberMap membersByName(std::string const& _name) const
    {
        MemberMap members;
        for (auto const& it: m_memberTypes)
            if (it.name == _name)
                members.push_back(it);
        return members;
    }
    /// @returns the offset of the given member in storage slots and bytes inside a slot or
    /// a nullptr if the member is not part of storage.
    std::pair<u256, unsigned> const* getMemberStorageOffset(std::string const& _name) const;
    /// @returns the number of storage slots occupied by the members.
    u256 const& getStorageSize() const;

    MemberMap::const_iterator begin() const { return m_memberTypes.begin(); }
    MemberMap::const_iterator end() const { return m_memberTypes.end(); }

private:
    MemberMap m_memberTypes;
    mutable std::unique_ptr<StorageOffsets> m_storageOffsets;
};

/**
 * Abstract base class that forms the root of the type hierarchy.
 */
class Type: private boost::noncopyable, public std::enable_shared_from_this<Type>
{
public:
    enum class Category
    {
        Integer, IntegerConstant, Bool, Real, Array,
        FixedBytes, Contract, Struct, Function, Enum,
        Mapping, Void, TypeType, Modifier, Magic
    };

    /// @{
    /// @name Factory functions
    /// Factory functions that convert an AST @ref TypeName to a Type.
    static TypePointer fromElementaryTypeName(Token::Value _typeToken);
    static TypePointer fromElementaryTypeName(std::string const& _name);
    static TypePointer fromUserDefinedTypeName(UserDefinedTypeName const& _typeName);
    static TypePointer fromMapping(ElementaryTypeName& _keyType, TypeName& _valueType);
    static TypePointer fromArrayTypeName(TypeName& _baseTypeName, Expression* _length);
    /// @}

    /// Auto-detect the proper type for a literal. @returns an empty pointer if the literal does
    /// not fit any type.
    static TypePointer forLiteral(Literal const& _literal);
    /// @returns a pointer to _a or _b if the other is implicitly convertible to it or nullptr otherwise
    static TypePointer commonType(TypePointer const& _a, TypePointer const& _b);

    /// Calculates the

    virtual Category getCategory() const = 0;
    virtual bool isImplicitlyConvertibleTo(Type const& _other) const { return *this == _other; }
    virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const
    {
        return isImplicitlyConvertibleTo(_convertTo);
    }
    /// @returns the resulting type of applying the given unary operator or an empty pointer if
    /// this is not possible.
    /// The default implementation does not allow any unary operator.
    virtual TypePointer unaryOperatorResult(Token::Value) const { return TypePointer(); }
    /// @returns the resulting type of applying the given binary operator or an empty pointer if
    /// this is not possible.
    /// The default implementation allows comparison operators if a common type exists
    virtual TypePointer binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const
    {
        return Token::isCompareOp(_operator) ? commonType(shared_from_this(), _other) : TypePointer();
    }

    virtual bool operator==(Type const& _other) const { return getCategory() == _other.getCategory(); }
    virtual bool operator!=(Type const& _other) const { return !this->operator ==(_other); }

    /// @returns number of bytes used by this type when encoded for CALL, or 0 if the encoding
    /// is not a simple big-endian encoding or the type cannot be stored in calldata.
    /// If @a _padded then it is assumed that each element is padded to a multiple of 32 bytes.
    virtual unsigned getCalldataEncodedSize(bool _padded) const { (void)_padded; return 0; }
    /// @returns the size of this data type in bytes when stored in memory. For memory-reference
    /// types, this is the size of the memory pointer.
    virtual unsigned memoryHeadSize() const { return getCalldataEncodedSize(); }
    /// Convenience version of @see getCalldataEncodedSize(bool)
    unsigned getCalldataEncodedSize() const { return getCalldataEncodedSize(true); }
    /// @returns true if the type is dynamically encoded in calldata
    virtual bool isDynamicallySized() const { return false; }
    /// @returns the number of storage slots required to hold this value in storage.
    /// For dynamically "allocated" types, it returns the size of the statically allocated head,
    virtual u256 getStorageSize() const { return 1; }
    /// Multiple small types can be packed into a single storage slot. If such a packing is possible
    /// this function @returns the size in bytes smaller than 32. Data is moved to the next slot if
    /// it does not fit.
    /// In order to avoid computation at runtime of whether such moving is necessary, structs and
    /// array data (not each element) always start a new slot.
    virtual unsigned getStorageBytes() const { return 32; }
    /// Returns true if the type can be stored in storage.
    virtual bool canBeStored() const { return true; }
    /// Returns false if the type cannot live outside the storage, i.e. if it includes some mapping.
    virtual bool canLiveOutsideStorage() const { return true; }
    /// Returns true if the type can be stored as a value (as opposed to a reference) on the stack,
    /// i.e. it behaves differently in lvalue context and in value context.
    virtual bool isValueType() const { return false; }
    virtual unsigned getSizeOnStack() const { return 1; }
    /// @returns the mobile (in contrast to static) type corresponding to the given type.
    /// This returns the corresponding integer type for IntegerConstantTypes and the pointer type
    /// for storage reference types.
    virtual TypePointer mobileType() const { return shared_from_this(); }
    /// @returns true if this is a non-value type and the data of this type is stored at the
    /// given location.
    virtual bool dataStoredIn(DataLocation) const { return false; }

    /// Returns the list of all members of this type. Default implementation: no members.
    virtual MemberList const& getMembers() const { return EmptyMemberList; }
    /// Convenience method, returns the type of the given named member or an empty pointer if no such member exists.
    TypePointer getMemberType(std::string const& _name) const { return getMembers().getMemberType(_name); }

    virtual std::string toString(bool _short) const = 0;
    std::string toString() const { return toString(false); }
    virtual u256 literalValue(Literal const*) const
    {
        BOOST_THROW_EXCEPTION(
            InternalCompilerError() <<
            errinfo_comment("Literal value requested for type without literals.")
        );
    }

    /// @returns a type suitable for outside of Solidity, i.e. for contract types it returns address.
    /// If there is no such type, returns an empty shared pointer.
    virtual TypePointer externalType() const { return TypePointer(); }

protected:
    /// Convenience object used when returning an empty member list.
    static const MemberList EmptyMemberList;
};

/**
 * Any kind of integer type (signed, unsigned, address).
 */
class IntegerType: public Type
{
public:
    enum class Modifier
    {
        Unsigned, Signed, Address
    };
    virtual Category getCategory() const override { return Category::Integer; }

    explicit IntegerType(int _bits, Modifier _modifier = Modifier::Unsigned);

    virtual bool isImplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
    virtual TypePointer binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const override;

    virtual bool operator==(Type const& _other) const override;

    virtual unsigned getCalldataEncodedSize(bool _padded = true) const override { return _padded ? 32 : m_bits / 8; }
    virtual unsigned getStorageBytes() const override { return m_bits / 8; }
    virtual bool isValueType() const override { return true; }

    virtual MemberList const& getMembers() const override { return isAddress() ? AddressMemberList : EmptyMemberList; }

    virtual std::string toString(bool _short) const override;

    virtual TypePointer externalType() const override { return shared_from_this(); }

    int getNumBits() const { return m_bits; }
    bool isAddress() const { return m_modifier == Modifier::Address; }
    bool isSigned() const { return m_modifier == Modifier::Signed; }

    static const MemberList AddressMemberList;

private:
    int m_bits;
    Modifier m_modifier;
};

/**
 * Integer constants either literals or computed. Example expressions: 2, 2+10, ~10.
 * There is one distinct type per value.
 */
class IntegerConstantType: public Type
{
public:
    virtual Category getCategory() const override { return Category::IntegerConstant; }

    explicit IntegerConstantType(Literal const& _literal);
    explicit IntegerConstantType(bigint _value): m_value(_value) {}

    virtual bool isImplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
    virtual TypePointer binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const override;

    virtual bool operator==(Type const& _other) const override;

    virtual bool canBeStored() const override { return false; }
    virtual bool canLiveOutsideStorage() const override { return false; }
    virtual unsigned getSizeOnStack() const override { return 1; }

    virtual std::string toString(bool _short) const override;
    virtual u256 literalValue(Literal const* _literal) const override;
    virtual TypePointer mobileType() const override;

    /// @returns the smallest integer type that can hold the value or an empty pointer if not possible.
    std::shared_ptr<IntegerType const> getIntegerType() const;

private:
    bigint m_value;
};

/**
 * Bytes type with fixed length of up to 32 bytes.
 */
class FixedBytesType: public Type
{
public:
    virtual Category getCategory() const override { return Category::FixedBytes; }

    /// @returns the smallest bytes type for the given literal or an empty pointer
    /// if no type fits.
    static std::shared_ptr<FixedBytesType> smallestTypeForLiteral(std::string const& _literal);

    explicit FixedBytesType(int _bytes);

    virtual bool isImplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual bool operator==(Type const& _other) const override;
    virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
    virtual TypePointer binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const override;

    virtual unsigned getCalldataEncodedSize(bool _padded) const override { return _padded && m_bytes > 0 ? 32 : m_bytes; }
    virtual unsigned getStorageBytes() const override { return m_bytes; }
    virtual bool isValueType() const override { return true; }

    virtual std::string toString(bool) const override { return "bytes" + dev::toString(m_bytes); }
    virtual u256 literalValue(Literal const* _literal) const override;
    virtual TypePointer externalType() const override { return shared_from_this(); }

    int getNumBytes() const { return m_bytes; }

private:
    int m_bytes;
};

/**
 * The boolean type.
 */
class BoolType: public Type
{
public:
    BoolType() {}
    virtual Category getCategory() const override { return Category::Bool; }
    virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
    virtual TypePointer binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const override;

    virtual unsigned getCalldataEncodedSize(bool _padded) const override{ return _padded ? 32 : 1; }
    virtual unsigned getStorageBytes() const override { return 1; }
    virtual bool isValueType() const override { return true; }

    virtual std::string toString(bool) const override { return "bool"; }
    virtual u256 literalValue(Literal const* _literal) const override;
    virtual TypePointer externalType() const override { return shared_from_this(); }
};

/**
 * Base class used by types which are not value types and can be stored either in storage, memory
 * or calldata. This is currently used by arrays and structs.
 */
class ReferenceType: public Type
{
public:
    explicit ReferenceType(DataLocation _location): m_location(_location) {}
    DataLocation location() const { return m_location; }

    virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
    virtual unsigned memoryHeadSize() const override { return 32; }

    /// @returns a copy of this type with location (recursively) changed to @a _location,
    /// whereas isPointer is only shallowly changed - the deep copy is always a bound reference.
    virtual TypePointer copyForLocation(DataLocation _location, bool _isPointer) const = 0;

    virtual TypePointer mobileType() const override { return copyForLocation(m_location, true); }
    virtual bool dataStoredIn(DataLocation _location) const override { return m_location == _location; }

    /// Storage references can be pointers or bound references. In general, local variables are of
    /// pointer type, state variables are bound references. Assignments to pointers or deleting
    /// them will not modify storage (that will only change the pointer). Assignment from
    /// non-storage objects to a variable of storage pointer type is not possible.
    bool isPointer() const { return m_isPointer; }

    bool operator==(ReferenceType const& _other) const
    {
        return location() == _other.location() && isPointer() == _other.isPointer();
    }

    /// @returns a copy of @a _type having the same location as this (and is not a pointer type)
    /// if _type is a reference type and an unmodified copy of _type otherwise.
    /// This function is mostly useful to modify inner types appropriately.
    static TypePointer copyForLocationIfReference(DataLocation _location, TypePointer const& _type);

protected:
    TypePointer copyForLocationIfReference(TypePointer const& _type) const;
    /// @returns a human-readable description of the reference part of the type.
    std::string stringForReferencePart() const;

    DataLocation m_location = DataLocation::Storage;
    bool m_isPointer = true;
};

/**
 * The type of an array. The flavours are byte array (bytes), statically- (<type>[<length>])
 * and dynamically-sized array (<type>[]).
 * In storage, all arrays are packed tightly (as long as more than one elementary type fits in
 * one slot). Dynamically sized arrays (including byte arrays) start with their size as a uint and
 * thus start on their own slot.
 */
class ArrayType: public ReferenceType
{
public:
    virtual Category getCategory() const override { return Category::Array; }

    /// Constructor for a byte array ("bytes") and string.
    explicit ArrayType(DataLocation _location, bool _isString = false):
        ReferenceType(_location),
        m_arrayKind(_isString ? ArrayKind::String : ArrayKind::Bytes),
        m_baseType(std::make_shared<FixedBytesType>(1))
    {
    }
    /// Constructor for a dynamically sized array type ("type[]")
    ArrayType(DataLocation _location, TypePointer const& _baseType):
        ReferenceType(_location),
        m_baseType(copyForLocationIfReference(_baseType))
    {
    }
    /// Constructor for a fixed-size array type ("type[20]")
    ArrayType(DataLocation _location, TypePointer const& _baseType, u256 const& _length):
        ReferenceType(_location),
        m_baseType(copyForLocationIfReference(_baseType)),
        m_hasDynamicLength(false),
        m_length(_length)
    {}

    virtual bool isImplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual bool operator==(const Type& _other) const override;
    virtual unsigned getCalldataEncodedSize(bool _padded) const override;
    virtual bool isDynamicallySized() const override { return m_hasDynamicLength; }
    virtual u256 getStorageSize() const override;
    virtual bool canLiveOutsideStorage() const override { return m_baseType->canLiveOutsideStorage(); }
    virtual unsigned getSizeOnStack() const override;
    virtual std::string toString(bool _short) const override;
    virtual MemberList const& getMembers() const override
    {
        return isString() ? EmptyMemberList : s_arrayTypeMemberList;
    }
    virtual TypePointer externalType() const override;

    /// @returns true if this is a byte array or a string
    bool isByteArray() const { return m_arrayKind != ArrayKind::Ordinary; }
    /// @returns true if this is a string
    bool isString() const { return m_arrayKind == ArrayKind::String; }
    TypePointer const& getBaseType() const { solAssert(!!m_baseType, ""); return m_baseType;}
    u256 const& getLength() const { return m_length; }

    TypePointer copyForLocation(DataLocation _location, bool _isPointer) const override;

private:
    /// String is interpreted as a subtype of Bytes.
    enum class ArrayKind { Ordinary, Bytes, String };

    ///< Byte arrays ("bytes") and strings have different semantics from ordinary arrays.
    ArrayKind m_arrayKind = ArrayKind::Ordinary;
    TypePointer m_baseType;
    bool m_hasDynamicLength = true;
    u256 m_length;
    static const MemberList s_arrayTypeMemberList;
};

/**
 * The type of a contract instance, there is one distinct type for each contract definition.
 */
class ContractType: public Type
{
public:
    virtual Category getCategory() const override { return Category::Contract; }
    explicit ContractType(ContractDefinition const& _contract, bool _super = false):
        m_contract(_contract), m_super(_super) {}
    /// Contracts can be implicitly converted to super classes and to addresses.
    virtual bool isImplicitlyConvertibleTo(Type const& _convertTo) const override;
    /// Contracts can be converted to themselves and to integers.
    virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
    virtual bool operator==(Type const& _other) const override;
    virtual unsigned getCalldataEncodedSize(bool _padded ) const override
    {
        return externalType()->getCalldataEncodedSize(_padded);
    }
    virtual unsigned getStorageBytes() const override { return 20; }
    virtual bool canLiveOutsideStorage() const override { return true; }
    virtual bool isValueType() const override { return true; }
    virtual std::string toString(bool _short) const override;

    virtual MemberList const& getMembers() const override;
    virtual TypePointer externalType() const override
    {
        return std::make_shared<IntegerType>(160, IntegerType::Modifier::Address);
    }

    bool isSuper() const { return m_super; }
    ContractDefinition const& getContractDefinition() const { return m_contract; }

    /// Returns the function type of the constructor. Note that the location part of the function type
    /// is not used, as this type cannot be the type of a variable or expression.
    FunctionTypePointer const& getConstructorType() const;

    /// @returns the identifier of the function with the given name or Invalid256 if such a name does
    /// not exist.
    u256 getFunctionIdentifier(std::string const& _functionName) const;

    /// @returns a list of all state variables (including inherited) of the contract and their
    /// offsets in storage.
    std::vector<std::tuple<VariableDeclaration const*, u256, unsigned>> getStateVariables() const;

private:
    ContractDefinition const& m_contract;
    /// If true, it is the "super" type of the current contract, i.e. it contains only inherited
    /// members.
    bool m_super;
    /// Type of the constructor, @see getConstructorType. Lazily initialized.
    mutable FunctionTypePointer m_constructorType;
    /// List of member types, will be lazy-initialized because of recursive references.
    mutable std::unique_ptr<MemberList> m_members;
};

/**
 * The type of a struct instance, there is one distinct type per struct definition.
 */
class StructType: public ReferenceType
{
public:
    virtual Category getCategory() const override { return Category::Struct; }
    explicit StructType(StructDefinition const& _struct):
        ReferenceType(DataLocation::Storage), m_struct(_struct) {}
    virtual bool isImplicitlyConvertibleTo(const Type& _convertTo) const override;
    virtual bool operator==(Type const& _other) const override;
    virtual unsigned getCalldataEncodedSize(bool _padded) const override;
    u256 memorySize() const;
    virtual u256 getStorageSize() const override;
    virtual bool canLiveOutsideStorage() const override;
    virtual unsigned getSizeOnStack() const override;
    virtual std::string toString(bool _short) const override;

    virtual MemberList const& getMembers() const override;

    TypePointer copyForLocation(DataLocation _location, bool _isPointer) const override;

    /// @returns a function that peforms the type conversion between a list of struct members
    /// and a memory struct of this type.
    FunctionTypePointer constructorType() const;

    std::pair<u256, unsigned> const& getStorageOffsetsOfMember(std::string const& _name) const;
    u256 memoryOffsetOfMember(std::string const& _name) const;

    StructDefinition const& structDefinition() const { return m_struct; }

private:
    StructDefinition const& m_struct;
    /// List of member types, will be lazy-initialized because of recursive references.
    mutable std::unique_ptr<MemberList> m_members;
};

/**
 * The type of an enum instance, there is one distinct type per enum definition.
 */
class EnumType: public Type
{
public:
    virtual Category getCategory() const override { return Category::Enum; }
    explicit EnumType(EnumDefinition const& _enum): m_enum(_enum) {}
    virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
    virtual bool operator==(Type const& _other) const override;
    virtual unsigned getCalldataEncodedSize(bool _padded) const override
    {
        return externalType()->getCalldataEncodedSize(_padded);
    }
    virtual unsigned getSizeOnStack() const override { return 1; }
    virtual unsigned getStorageBytes() const override;
    virtual bool canLiveOutsideStorage() const override { return true; }
    virtual std::string toString(bool _short) const override;
    virtual bool isValueType() const override { return true; }

    virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
    virtual TypePointer externalType() const override
    {
        return std::make_shared<IntegerType>(8 * int(getStorageBytes()));
    }

    EnumDefinition const& getEnumDefinition() const { return m_enum; }
    /// @returns the value that the string has in the Enum
    unsigned int getMemberValue(ASTString const& _member) const;

private:
    EnumDefinition const& m_enum;
    /// List of member types, will be lazy-initialized because of recursive references.
    mutable std::unique_ptr<MemberList> m_members;
};

/**
 * The type of a function, identified by its (return) parameter types.
 * @todo the return parameters should also have names, i.e. return parameters should be a struct
 * type.
 */
class FunctionType: public Type
{
public:
    /// How this function is invoked on the EVM.
    /// @todo This documentation is outdated, and Location should rather be named "Type"
    enum class Location
    {
        Internal, ///< stack-call using plain JUMP
        External, ///< external call using CALL
        CallCode, ///< extercnal call using CALLCODE, i.e. not exchanging the storage
        Bare, ///< CALL without function hash
        BareCallCode, ///< CALLCODE without function hash
        Creation, ///< external call using CREATE
        Send, ///< CALL, but without data and gas
        SHA3, ///< SHA3
        Suicide, ///< SUICIDE
        ECRecover, ///< CALL to special contract for ecrecover
        SHA256, ///< CALL to special contract for sha256
        RIPEMD160, ///< CALL to special contract for ripemd160
        Log0,
        Log1,
        Log2,
        Log3,
        Log4,
        Event, ///< syntactic sugar for LOG*
        SetGas, ///< modify the default gas value for the function call
        SetValue, ///< modify the default value transfer for the function call
        BlockHash ///< BLOCKHASH
    };

    virtual Category getCategory() const override { return Category::Function; }

    /// @returns TypePointer of a new FunctionType object. All input/return parameters are an
    /// appropriate external types of input/return parameters of current function.
    /// Returns an empty shared pointer if one of the input/return parameters does not have an
    /// external type.
    FunctionTypePointer externalFunctionType() const;
    virtual TypePointer externalType() const override { return externalFunctionType(); }

    /// Creates the type of a function.
    explicit FunctionType(FunctionDefinition const& _function, bool _isInternal = true);
    /// Creates the accessor function type of a state variable.
    explicit FunctionType(VariableDeclaration const& _varDecl);
    /// Creates the function type of an event.
    explicit FunctionType(EventDefinition const& _event);
    FunctionType(
        strings const& _parameterTypes,
        strings const& _returnParameterTypes,
        Location _location = Location::Internal,
        bool _arbitraryParameters = false
    ): FunctionType(
        parseElementaryTypeVector(_parameterTypes),
        parseElementaryTypeVector(_returnParameterTypes),
        strings(),
        strings(),
        _location,
        _arbitraryParameters
    )
    {
    }
    FunctionType(
        TypePointers const& _parameterTypes,
        TypePointers const& _returnParameterTypes,
        strings _parameterNames = strings(),
        strings _returnParameterNames = strings(),
        Location _location = Location::Internal,
        bool _arbitraryParameters = false,
        Declaration const* _declaration = nullptr,
        bool _gasSet = false,
        bool _valueSet = false
    ):
        m_parameterTypes(_parameterTypes),
        m_returnParameterTypes(_returnParameterTypes),
        m_parameterNames(_parameterNames),
        m_returnParameterNames(_returnParameterNames),
        m_location(_location),
        m_arbitraryParameters(_arbitraryParameters),
        m_gasSet(_gasSet),
        m_valueSet(_valueSet),
        m_declaration(_declaration)
    {}

    TypePointers const& getParameterTypes() const { return m_parameterTypes; }
    std::vector<std::string> const& getParameterNames() const { return m_parameterNames; }
    std::vector<std::string> const getParameterTypeNames() const;
    TypePointers const& getReturnParameterTypes() const { return m_returnParameterTypes; }
    std::vector<std::string> const& getReturnParameterNames() const { return m_returnParameterNames; }
    std::vector<std::string> const getReturnParameterTypeNames() const;

    virtual bool operator==(Type const& _other) const override;
    virtual std::string toString(bool _short) const override;
    virtual bool canBeStored() const override { return false; }
    virtual u256 getStorageSize() const override;
    virtual bool canLiveOutsideStorage() const override { return false; }
    virtual unsigned getSizeOnStack() const override;
    virtual MemberList const& getMembers() const override;

    /// @returns true if this function can take the given argument types (possibly
    /// after implicit conversion).
    bool canTakeArguments(TypePointers const& _arguments) const;
    /// @returns true if the types of parameters are equal (does't check return parameter types)
    bool hasEqualArgumentTypes(FunctionType const& _other) const;

    /// @returns true if the ABI is used for this call (only meaningful for external calls)
    bool isBareCall() const;
    Location const& getLocation() const { return m_location; }
    /// @returns the external signature of this function type given the function name
    /// If @a _name is not provided (empty string) then the @c m_declaration member of the
    /// function type is used
    std::string externalSignature(std::string const& _name = "") const;
    /// @returns the external identifier of this function (the hash of the signature).
    u256 externalIdentifier() const;
    Declaration const& getDeclaration() const
    {
        solAssert(m_declaration, "Requested declaration from a FunctionType that has none");
        return *m_declaration;
    }
    bool hasDeclaration() const { return !!m_declaration; }
    bool isConstant() const { return m_isConstant; }
    /// @return A shared pointer of an ASTString.
    /// Can contain a nullptr in which case indicates absence of documentation
    ASTPointer<ASTString> getDocumentation() const;

    /// true iff arguments are to be padded to multiples of 32 bytes for external calls
    bool padArguments() const { return !(m_location == Location::SHA3 || m_location == Location::SHA256 || m_location == Location::RIPEMD160); }
    bool takesArbitraryParameters() const { return m_arbitraryParameters; }
    bool gasSet() const { return m_gasSet; }
    bool valueSet() const { return m_valueSet; }

    /// @returns a copy of this type, where gas or value are set manually. This will never set one
    /// of the parameters to fals.
    TypePointer copyAndSetGasOrValue(bool _setGas, bool _setValue) const;

    /// @returns a copy of this function type where all return parameters of dynamic size are
    /// removed and the location of reference types is changed from CallData to Memory.
    /// This is needed if external functions are called on other contracts, as they cannot return
    /// dynamic values.
    FunctionTypePointer asMemberFunction() const;

private:
    static TypePointers parseElementaryTypeVector(strings const& _types);

    TypePointers m_parameterTypes;
    TypePointers m_returnParameterTypes;
    std::vector<std::string> m_parameterNames;
    std::vector<std::string> m_returnParameterNames;
    Location const m_location;
    /// true if the function takes an arbitrary number of arguments of arbitrary types
    bool const m_arbitraryParameters = false;
    bool const m_gasSet = false; ///< true iff the gas value to be used is on the stack
    bool const m_valueSet = false; ///< true iff the value to be sent is on the stack
    bool m_isConstant = false;
    mutable std::unique_ptr<MemberList> m_members;
    Declaration const* m_declaration = nullptr;
};

/**
 * The type of a mapping, there is one distinct type per key/value type pair.
 * Mappings always occupy their own storage slot, but do not actually use it.
 */
class MappingType: public Type
{
public:
    virtual Category getCategory() const override { return Category::Mapping; }
    MappingType(TypePointer const& _keyType, TypePointer const& _valueType):
        m_keyType(_keyType), m_valueType(_valueType) {}

    virtual bool operator==(Type const& _other) const override;
    virtual std::string toString(bool _short) const override;
    virtual unsigned getSizeOnStack() const override { return 2; }
    virtual bool canLiveOutsideStorage() const override { return false; }

    TypePointer const& getKeyType() const { return m_keyType; }
    TypePointer const& getValueType() const { return m_valueType; }

private:
    TypePointer m_keyType;
    TypePointer m_valueType;
};

/**
 * The void type, can only be implicitly used as the type that is returned by functions without
 * return parameters.
 */
class VoidType: public Type
{
public:
    virtual Category getCategory() const override { return Category::Void; }
    VoidType() {}

    virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
    virtual std::string toString(bool) const override { return "void"; }
    virtual bool canBeStored() const override { return false; }
    virtual u256 getStorageSize() const override;
    virtual bool canLiveOutsideStorage() const override { return false; }
    virtual unsigned getSizeOnStack() const override { return 0; }
};

/**
 * The type of a type reference. The type of "uint32" when used in "a = uint32(2)" is an example
 * of a TypeType.
 */
class TypeType: public Type
{
public:
    virtual Category getCategory() const override { return Category::TypeType; }
    explicit TypeType(TypePointer const& _actualType, ContractDefinition const* _currentContract = nullptr):
        m_actualType(_actualType), m_currentContract(_currentContract) {}
    TypePointer const& getActualType() const { return m_actualType; }

    virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
    virtual bool operator==(Type const& _other) const override;
    virtual bool canBeStored() const override { return false; }
    virtual u256 getStorageSize() const override;
    virtual bool canLiveOutsideStorage() const override { return false; }
    virtual unsigned getSizeOnStack() const override { return 0; }
    virtual std::string toString(bool _short) const override { return "type(" + m_actualType->toString(_short) + ")"; }
    virtual MemberList const& getMembers() const override;

private:
    TypePointer m_actualType;
    /// Context in which this type is used (influences visibility etc.), can be nullptr.
    ContractDefinition const* m_currentContract;
    /// List of member types, will be lazy-initialized because of recursive references.
    mutable std::unique_ptr<MemberList> m_members;
};


/**
 * The type of a function modifier. Not used for anything for now.
 */
class ModifierType: public Type
{
public:
    virtual Category getCategory() const override { return Category::Modifier; }
    explicit ModifierType(ModifierDefinition const& _modifier);

    virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
    virtual bool canBeStored() const override { return false; }
    virtual u256 getStorageSize() const override;
    virtual bool canLiveOutsideStorage() const override { return false; }
    virtual unsigned getSizeOnStack() const override { return 0; }
    virtual bool operator==(Type const& _other) const override;
    virtual std::string toString(bool _short) const override;

private:
    TypePointers m_parameterTypes;
};


/**
 * Special type for magic variables (block, msg, tx), similar to a struct but without any reference
 * (it always references a global singleton by name).
 */
class MagicType: public Type
{
public:
    enum class Kind { Block, Message, Transaction };
    virtual Category getCategory() const override { return Category::Magic; }

    explicit MagicType(Kind _kind);

    virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override
    {
        return TypePointer();
    }

    virtual bool operator==(Type const& _other) const override;
    virtual bool canBeStored() const override { return false; }
    virtual bool canLiveOutsideStorage() const override { return true; }
    virtual unsigned getSizeOnStack() const override { return 0; }
    virtual MemberList const& getMembers() const override { return m_members; }

    virtual std::string toString(bool _short) const override;

private:
    Kind m_kind;

    MemberList m_members;
};

}
}