// This file is distributed under the BSD License.

// See "license.txt" for details.

// Copyright 2009-2012, Jonathan Turner (jonathan@emptycrate.com)

// Copyright 2009-2016, Jason Turner (jason@emptycrate.com)

// http://www.chaiscript.com

#ifndef CHAISCRIPT_PROXY_FUNCTIONS_HPP_

#define CHAISCRIPT_PROXY_FUNCTIONS_HPP_

#include <cassert>

#include <functional>

#include <memory>

#include <stdexcept>

#include <string>

#include <type_traits>

#include <vector>

#include <iterator>

#include "../chaiscript_defines.hpp"

#include "boxed_cast.hpp"

#include "boxed_value.hpp"

#include "proxy_functions_detail.hpp"

#include "type_info.hpp"

#include "dynamic_object.hpp"

namespace chaiscript {

class Type_Conversions;

namespace exception {

class bad_boxed_cast;

struct arity_error;

} // namespace exception

} // namespace chaiscript

namespace chaiscript

{

class Boxed_Number;

struct AST_Node;

typedef std::shared_ptr<AST_Node> AST_NodePtr;

namespace dispatch

{

template<typename FunctionType>

std::function<FunctionType> functor(std::shared_ptr<const Proxy_Function_Base> func, const Type_Conversions_State *t_conversions);

class Param_Types

{

public:

Param_Types()

: m_has_types(false),

m_doti(user_type<Dynamic_Object>())

{}

Param_Types(std::vector<std::pair<std::string, Type_Info>> t_types)

: m_types(std::move(t_types)),

m_has_types(false),

m_doti(user_type<Dynamic_Object>())

{

update_has_types();

}

void push_front(std::string t_name, Type_Info t_ti)

{

m_types.emplace(m_types.begin(), std::move(t_name), std::move(t_ti));

update_has_types();

}

bool operator==(const Param_Types &t_rhs) const

{

return m_types == t_rhs.m_types;

}

bool match(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &t_conversions) const

{

if (!m_has_types) return true;

if (vals.size() != m_types.size()) return false;

for (size_t i = 0; i < vals.size(); ++i)

{

const auto &name = m_types[i].first;

if (!name.empty()) {

const auto &bv = vals[i];

if (bv.get_type_info().bare_equal(m_doti))

{

try {

const Dynamic_Object &d = boxed_cast<const Dynamic_Object &>(bv, &t_conversions);

return name == "Dynamic_Object" || d.get_type_name() == name;

} catch (const std::bad_cast &) {

return false;

}

} else {

const auto &ti = m_types[i].second;

if (!ti.is_undef())

{

if (!bv.get_type_info().bare_equal(ti)) {

return false;

}

} else {

return false;

}

}

}

}

return true;

}

const std::vector<std::pair<std::string, Type_Info>> &types() const

{

return m_types;

}

private:

void update_has_types()

{

for (const auto &type : m_types)

{

if (!type.first.empty())

{

m_has_types = true;

return;

}

}

m_has_types = false;

}

std::vector<std::pair<std::string, Type_Info>> m_types;

bool m_has_types;

Type_Info m_doti;

};

/**

* Pure virtual base class for all Proxy_Function implementations

* Proxy_Functions are a type erasure of type safe C++

* function calls. At runtime parameter types are expected to be

* tested against passed in types.

* Dispatch_Engine only knows how to work with Proxy_Function, no other

* function classes.

*/

class Proxy_Function_Base

{

public:

virtual ~Proxy_Function_Base() = default;

Boxed_Value operator()(const std::vector<Boxed_Value> &params, const chaiscript::Type_Conversions_State &t_conversions) const

{

if (m_arity < 0 || size_t(m_arity) == params.size()) {

return do_call(params, t_conversions);

} else {

throw exception::arity_error(static_cast<int>(params.size()), m_arity);

}

}

/// Returns a vector containing all of the types of the parameters the function returns/takes

/// if the function is variadic or takes no arguments (arity of 0 or -1), the returned

/// value contains exactly 1 Type_Info object: the return type

/// \returns the types of all parameters.

const std::vector<Type_Info> &get_param_types() const { return m_types; }

virtual bool operator==(const Proxy_Function_Base &) const = 0;

virtual bool call_match(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &t_conversions) const = 0;

virtual bool is_attribute_function() const { return false; }

bool has_arithmetic_param() const

{

return m_has_arithmetic_param;

}

virtual std::vector<std::shared_ptr<const Proxy_Function_Base> > get_contained_functions() const

{

return std::vector<std::shared_ptr<const Proxy_Function_Base> >();

}

//! Return true if the function is a possible match

//! to the passed in values

bool filter(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &t_conversions) const

{

if (m_arity < 0)

{

return true;

} else if (static_cast<size_t>(m_arity) == vals.size()) {

if (m_arity == 0)

{

return true;

} else if (m_arity > 1) {

return compare_type_to_param(m_types[1], vals[0], t_conversions) && compare_type_to_param(m_types[2], vals[1], t_conversions);

} else {

return compare_type_to_param(m_types[1], vals[0], t_conversions);

}

} else {

return false;

}

}

/// \returns the number of arguments the function takes or -1 if it is variadic

int get_arity() const

{

return m_arity;

}

virtual std::string annotation() const = 0;

static bool compare_type_to_param(const Type_Info &ti, const Boxed_Value &bv, const Type_Conversions_State &t_conversions)

{

if (ti.is_undef()

|| ti.bare_equal(user_type<Boxed_Value>())

|| (!bv.get_type_info().is_undef()

&& ( (ti.bare_equal(user_type<Boxed_Number>()) && bv.get_type_info().is_arithmetic())

|| ti.bare_equal(bv.get_type_info())

|| bv.get_type_info().bare_equal(user_type<std::shared_ptr<const Proxy_Function_Base> >())

|| t_conversions->converts(ti, bv.get_type_info())

)

)

)

{

return true;

} else {

return false;

}

}

virtual bool compare_first_type(const Boxed_Value &bv, const Type_Conversions_State &t_conversions) const

{

return compare_type_to_param(m_types[1], bv, t_conversions);

}

protected:

virtual Boxed_Value do_call(const std::vector<Boxed_Value> &params, const Type_Conversions_State &t_conversions) const = 0;

Proxy_Function_Base(std::vector<Type_Info> t_types, int t_arity)

: m_types(std::move(t_types)), m_arity(t_arity), m_has_arithmetic_param(false)

{

for (size_t i = 1; i < m_types.size(); ++i)

{

if (m_types[i].is_arithmetic())

{

m_has_arithmetic_param = true;

return;

}

}

}

static bool compare_types(const std::vector<Type_Info> &tis, const std::vector<Boxed_Value> &bvs,

const Type_Conversions_State &t_conversions)

{

if (tis.size() - 1 != bvs.size())

{

return false;

} else {

const size_t size = bvs.size();

for (size_t i = 0; i < size; ++i)

{

if (!compare_type_to_param(tis[i + 1], bvs[i], t_conversions)) { return false; }

}

}

return true;

}

std::vector<Type_Info> m_types;

int m_arity;

bool m_has_arithmetic_param;

};

}

/// \brief Common typedef used for passing of any registered function in ChaiScript

typedef std::shared_ptr<dispatch::Proxy_Function_Base> Proxy_Function;

/// \brief Const version of Proxy_Function. Points to a const Proxy_Function. This is how most registered functions

/// are handled internally.

typedef std::shared_ptr<const dispatch::Proxy_Function_Base> Const_Proxy_Function;

namespace exception

{

/// \brief Exception thrown if a function's guard fails

class guard_error : public std::runtime_error

{

public:

guard_error() noexcept

: std::runtime_error("Guard evaluation failed")

{ }

guard_error(const guard_error &) = default;

virtual ~guard_error() noexcept = default;

};

}

namespace dispatch

{

/**

* A Proxy_Function implementation that is not type safe, the called function

* is expecting a vector<Boxed_Value> that it works with how it chooses.

*/

class Dynamic_Proxy_Function : public Proxy_Function_Base

{

public:

Dynamic_Proxy_Function(

int t_arity=-1,

AST_NodePtr t_parsenode = AST_NodePtr(),

Param_Types t_param_types = Param_Types(),

std::string t_description = "",

Proxy_Function t_guard = Proxy_Function())

: Proxy_Function_Base(build_param_type_list(t_param_types), t_arity),

m_param_types(std::move(t_param_types)),

m_guard(std::move(t_guard)), m_parsenode(std::move(t_parsenode)), m_description(std::move(t_description))

{

}

virtual bool operator==(const Proxy_Function_Base &rhs) const override

{

const Dynamic_Proxy_Function *prhs = dynamic_cast<const Dynamic_Proxy_Function *>(&rhs);

return this == &rhs

|| (prhs

&& this->m_arity == prhs->m_arity

&& !this->m_guard && !prhs->m_guard

&& this->m_param_types == prhs->m_param_types);

}

virtual bool call_match(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &t_conversions) const override

{

return (m_arity < 0 || (vals.size() == size_t(m_arity) && m_param_types.match(vals, t_conversions)))

&& test_guard(vals, t_conversions);

}

Proxy_Function get_guard() const

{

return m_guard;

}

AST_NodePtr get_parse_tree() const

{

return m_parsenode;

}

virtual std::string annotation() const override

{

return m_description;

}

protected:

bool test_guard(const std::vector<Boxed_Value> &params, const Type_Conversions_State &t_conversions) const

{

if (m_guard)

{

try {

return boxed_cast<bool>((*m_guard)(params, t_conversions));

} catch (const exception::arity_error &) {

return false;

} catch (const exception::bad_boxed_cast &) {

return false;

}

} else {

return true;

}

}

private:

static std::vector<Type_Info> build_param_type_list(const Param_Types &t_types)

{

// For the return type

std::vector<Type_Info> types{chaiscript::detail::Get_Type_Info<Boxed_Value>::get()};

for (const auto &t : t_types.types())

{

if (t.second.is_undef()) {

types.push_back(chaiscript::detail::Get_Type_Info<Boxed_Value>::get());

} else {

types.push_back(t.second);

}

}

return types;

}

Param_Types m_param_types;

Proxy_Function m_guard;

AST_NodePtr m_parsenode;

std::string m_description;

};

template<typename Callable>

class Dynamic_Proxy_Function_Impl final : public Dynamic_Proxy_Function

{

public:

Dynamic_Proxy_Function_Impl(

Callable t_f,

int t_arity=-1,

AST_NodePtr t_parsenode = AST_NodePtr(),

Param_Types t_param_types = Param_Types(),

std::string t_description = "",

Proxy_Function t_guard = Proxy_Function())

: Dynamic_Proxy_Function(

t_arity,

std::move(t_parsenode),

std::move(t_param_types),

std::move(t_description),

std::move(t_guard)

),

m_f(std::move(t_f))

{

}

protected:

Boxed_Value do_call(const std::vector<Boxed_Value> &params, const Type_Conversions_State &t_conversions) const override

{

if (call_match(params, t_conversions) && test_guard(params, t_conversions))

{

return m_f(params);

} else {

throw exception::guard_error();

}

}

private:

Callable m_f;

};

template<typename Callable, typename ... Arg>

Proxy_Function make_dynamic_proxy_function(Callable &&c, Arg&& ... a)

{

return chaiscript::make_shared<dispatch::Proxy_Function_Base, dispatch::Dynamic_Proxy_Function_Impl<Callable>>(

std::forward<Callable>(c), std::forward<Arg>(a)...);

}

/// An object used by Bound_Function to represent "_" parameters

/// of a binding. This allows for unbound parameters during bind.

struct Placeholder_Object

{

};

/// An implementation of Proxy_Function that takes a Proxy_Function

/// and substitutes bound parameters into the parameter list

/// at runtime, when call() is executed.

/// it is used for bind(function, param1, _, param2) style calls

class Bound_Function final : public Proxy_Function_Base

{

public:

Bound_Function(const Const_Proxy_Function &t_f,

const std::vector<Boxed_Value> &t_args)

: Proxy_Function_Base(build_param_type_info(t_f, t_args), (t_f->get_arity()<0?-1:static_cast<int>(build_param_type_info(t_f, t_args).size())-1)),

m_f(t_f), m_args(t_args)

{

assert(m_f->get_arity() < 0 || m_f->get_arity() == static_cast<int>(m_args.size()));

}

bool operator==(const Proxy_Function_Base &t_f) const override

{

return &t_f == this;

}

bool call_match(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &t_conversions) const override

{

return m_f->call_match(build_param_list(vals), t_conversions);

}

std::vector<Const_Proxy_Function> get_contained_functions() const override

{

return std::vector<Const_Proxy_Function>{m_f};

}

std::vector<Boxed_Value> build_param_list(const std::vector<Boxed_Value> &params) const

{

auto parg = params.begin();

auto barg = m_args.begin();

std::vector<Boxed_Value> args;

while (!(parg == params.end() && barg == m_args.end()))

{

while (barg != m_args.end()

&& !(barg->get_type_info() == chaiscript::detail::Get_Type_Info<Placeholder_Object>::get()))

{

args.push_back(*barg);

++barg;

}

if (parg != params.end())

{

args.push_back(*parg);

++parg;

}

if (barg != m_args.end()

&& barg->get_type_info() == chaiscript::detail::Get_Type_Info<Placeholder_Object>::get())

{

++barg;

}

}

return args;

}

virtual std::string annotation() const override

{

return "Bound: " + m_f->annotation();

}

protected:

static std::vector<Type_Info> build_param_type_info(const Const_Proxy_Function &t_f,

const std::vector<Boxed_Value> &t_args)

{

assert(t_f->get_arity() < 0 || t_f->get_arity() == static_cast<int>(t_args.size()));

if (t_f->get_arity() < 0) { return std::vector<Type_Info>(); }

const auto types = t_f->get_param_types();

assert(types.size() == t_args.size() + 1);

// this analysis warning is invalid in MSVC12 and doesn't exist in MSVC14

std::vector<Type_Info> retval{types[0]};

for (size_t i = 0; i < types.size() - 1; ++i)

{

if (t_args[i].get_type_info() == chaiscript::detail::Get_Type_Info<Placeholder_Object>::get())

{

retval.push_back(types[i+1]);

}

}

return retval;

}

virtual Boxed_Value do_call(const std::vector<Boxed_Value> &params, const Type_Conversions_State &t_conversions) const override

{

return (*m_f)(build_param_list(params), t_conversions);

}

private:

Const_Proxy_Function m_f;

std::vector<Boxed_Value> m_args;

};

class Proxy_Function_Impl_Base : public Proxy_Function_Base

{

public:

Proxy_Function_Impl_Base(const std::vector<Type_Info> &t_types)

: Proxy_Function_Base(t_types, static_cast<int>(t_types.size()) - 1)

{

}

std::string annotation() const override

{

return "";

}

bool call_match(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &t_conversions) const override

{

return static_cast<int>(vals.size()) == get_arity()

&& (compare_types(m_types, vals, t_conversions) && compare_types_with_cast(vals, t_conversions));

}

virtual bool compare_types_with_cast(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &t_conversions) const = 0;

};

/// For any callable object

template<typename Func, typename Callable>

class Proxy_Function_Callable_Impl final : public Proxy_Function_Impl_Base

{

public:

Proxy_Function_Callable_Impl(Callable f)

: Proxy_Function_Impl_Base(detail::build_param_type_list(static_cast<Func *>(nullptr))),

m_f(std::move(f))

{

}

bool compare_types_with_cast(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &t_conversions) const override

{

return detail::compare_types_cast(static_cast<Func *>(nullptr), vals, t_conversions);

}

bool operator==(const Proxy_Function_Base &t_func) const override

{

return dynamic_cast<const Proxy_Function_Callable_Impl<Func, Callable> *>(&t_func) != nullptr;

}

protected:

Boxed_Value do_call(const std::vector<Boxed_Value> &params, const Type_Conversions_State &t_conversions) const override

{

typedef typename detail::Function_Signature<Func>::Return_Type Return_Type;

return detail::Do_Call<Return_Type>::template go<Func>(m_f, params, t_conversions);

}

private:

Callable m_f;

};

class Assignable_Proxy_Function : public Proxy_Function_Impl_Base

{

public:

Assignable_Proxy_Function(const std::vector<Type_Info> &t_types)

: Proxy_Function_Impl_Base(t_types)

{

}

virtual void assign(const std::shared_ptr<const Proxy_Function_Base> &t_rhs) = 0;

};

template<typename Func>

class Assignable_Proxy_Function_Impl final : public Assignable_Proxy_Function

{

public:

Assignable_Proxy_Function_Impl(std::reference_wrapper<std::function<Func>> t_f, std::shared_ptr<std::function<Func>> t_ptr)

: Assignable_Proxy_Function(detail::build_param_type_list(static_cast<Func *>(nullptr))),

m_f(std::move(t_f)), m_shared_ptr_holder(std::move(t_ptr))

{

assert(!m_shared_ptr_holder || m_shared_ptr_holder.get() == &m_f.get());

}

bool compare_types_with_cast(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &t_conversions) const override

{

return detail::compare_types_cast(static_cast<Func *>(nullptr), vals, t_conversions);

}

bool operator==(const Proxy_Function_Base &t_func) const override

{

return dynamic_cast<const Assignable_Proxy_Function_Impl<Func> *>(&t_func) != nullptr;

}

std::function<Func> internal_function() const

{

return m_f.get();

}

void assign(const std::shared_ptr<const Proxy_Function_Base> &t_rhs) override {

m_f.get() = dispatch::functor<Func>(t_rhs, nullptr);

}

protected:

Boxed_Value do_call(const std::vector<Boxed_Value> &params, const Type_Conversions_State &t_conversions) const override

{

return detail::Do_Call<typename std::function<Func>::result_type>::template go<Func>(m_f.get(), params, t_conversions);

}

private:

std::reference_wrapper<std::function<Func>> m_f;

std::shared_ptr<std::function<Func>> m_shared_ptr_holder;

};

/// Attribute getter Proxy_Function implementation

template<typename T, typename Class>

class Attribute_Access final : public Proxy_Function_Base

{

public:

Attribute_Access(T Class::* t_attr)

: Proxy_Function_Base(param_types(), 1),

m_attr(t_attr)

{

}

bool is_attribute_function() const override { return true; }

bool operator==(const Proxy_Function_Base &t_func) const override

{

const Attribute_Access<T, Class> * aa

= dynamic_cast<const Attribute_Access<T, Class> *>(&t_func);

if (aa) {

return m_attr == aa->m_attr;

} else {

return false;

}

}

bool call_match(const std::vector<Boxed_Value> &vals, const Type_Conversions_State &) const override

{

if (vals.size() != 1)

{

return false;

}

return vals[0].get_type_info().bare_equal(user_type<Class>());

}

std::string annotation() const override

{

return "";

}

protected:

Boxed_Value do_call(const std::vector<Boxed_Value> &params, const Type_Conversions_State &t_conversions) const override

{

const Boxed_Value &bv = params[0];

if (bv.is_const())

{

const Class *o = boxed_cast<const Class *>(bv, &t_conversions);

return do_call_impl<T>(o);

} else {

Class *o = boxed_cast<Class *>(bv, &t_conversions);

return do_call_impl<T>(o);

}

}

private:

template<typename Type>

auto do_call_impl(Class *o) const -> std::enable_if_t<std::is_pointer<Type>::value, Boxed_Value>

{

return detail::Handle_Return<Type>::handle(o->*m_attr);

}

template<typename Type>

auto do_call_impl(const Class *o) const -> std::enable_if_t<std::is_pointer<Type>::value, Boxed_Value>

{

return detail::Handle_Return<const Type>::handle(o->*m_attr);

}

template<typename Type>

auto do_call_impl(Class *o) const -> std::enable_if_t<!std::is_pointer<Type>::value, Boxed_Value>

{

return detail::Handle_Return<const typename std::add_lvalue_reference<Type>::type>::handle(o->*m_attr);

}

template<typename Type>

auto do_call_impl(const Class *o) const -> std::enable_if_t<!std::is_pointer<Type>::value, Boxed_Value>

{

return detail::Handle_Return<const typename std::add_lvalue_reference<Type>::type>::handle(o->*m_attr);

}

static std::vector<Type_Info> param_types()

{

return {user_type<T>(), user_type<Class>()};

}

T Class::* m_attr;

};

}

namespace exception

{

/// \brief Exception thrown in the case that a method dispatch fails

/// because no matching function was found

///

/// May be thrown due to an arity_error, a guard_error or a bad_boxed_cast

/// exception

class dispatch_error : public std::runtime_error

{

public:

dispatch_error(std::vector<Boxed_Value> t_parameters,

std::vector<Const_Proxy_Function> t_functions)

: std::runtime_error("Error with function dispatch"), parameters(std::move(t_parameters)), functions(std::move(t_functions))

{

}

dispatch_error(std::vector<Boxed_Value> t_parameters,

std::vector<Const_Proxy_Function> t_functions,

const std::string &t_desc)

: std::runtime_error(t_desc), parameters(std::move(t_parameters)), functions(std::move(t_functions))

{

}

dispatch_error(const dispatch_error &) = default;

virtual ~dispatch_error() noexcept = default;

std::vector<Boxed_Value> parameters;

std::vector<Const_Proxy_Function> functions;

};

}

namespace dispatch

{

namespace detail

{

template<typename FuncType>

bool types_match_except_for_arithmetic(const FuncType &t_func, const std::vector<Boxed_Value> &plist,

const Type_Conversions_State &t_conversions)

{

const std::vector<Type_Info> &types = t_func->get_param_types();

if (t_func->get_arity() == -1) return false;

assert(plist.size() == types.size() - 1);

return std::mismatch(plist.begin(), plist.end(),

types.begin()+1,

[&](const Boxed_Value &bv, const Type_Info &ti) {

return Proxy_Function_Base::compare_type_to_param(ti, bv, t_conversions)

|| (bv.get_type_info().is_arithmetic() && ti.is_arithmetic());

}

) == std::make_pair(plist.end(), types.end());

}

template<typename InItr, typename Funcs>

Boxed_Value dispatch_with_conversions(InItr begin, const InItr &end, const std::vector<Boxed_Value> &plist,

const Type_Conversions_State &t_conversions, const Funcs &t_funcs)

{

InItr matching_func(end);

while (begin != end)

{

if (types_match_except_for_arithmetic(begin->second, plist, t_conversions))

{

if (matching_func == end)

{

matching_func = begin;

} else {

// handle const members vs non-const member, which is not really ambiguous

const auto &mat_fun_param_types = matching_func->second->get_param_types();

const auto &next_fun_param_types = begin->second->get_param_types();

if (plist[0].is_const() && !mat_fun_param_types[1].is_const() && next_fun_param_types[1].is_const()) {

matching_func = begin; // keep the new one, the const/non-const matchup is correct

} else if (!plist[0].is_const() && !mat_fun_param_types[1].is_const() && next_fun_param_types[1].is_const()) {

// keep the old one, it has a better const/non-const matchup

} else {

// ambiguous function call

throw exception::dispatch_error(plist, std::vector<Const_Proxy_Function>(t_funcs.begin(), t_funcs.end()));

}

}

}

++begin;

}

if (matching_func == end)

{

// no appropriate function to attempt arithmetic type conversion on

throw exception::dispatch_error(plist, std::vector<Const_Proxy_Function>(t_funcs.begin(), t_funcs.end()));

}

std::vector<Boxed_Value> newplist;

newplist.reserve(plist.size());

const std::vector<Type_Info> &tis = matching_func->second->get_param_types();

std::transform(tis.begin() + 1, tis.end(),

plist.begin(),

std::back_inserter(newplist),

[](const Type_Info &ti, const Boxed_Value &param) -> Boxed_Value {

if (ti.is_arithmetic() && param.get_type_info().is_arithmetic()) {

return Boxed_Number(param).get_as(ti).bv;

} else {

return param;

}

}

);

try {

return (*(matching_func->second))(newplist, t_conversions);

} catch (const exception::bad_boxed_cast &) {

//parameter failed to cast

} catch (const exception::arity_error &) {

//invalid num params

} catch (const exception::guard_error &) {

//guard failed to allow the function to execute

}

throw exception::dispatch_error(plist, std::vector<Const_Proxy_Function>(t_funcs.begin(), t_funcs.end()));

}

}

/**

* Take a vector of functions and a vector of parameters. Attempt to execute

* each function against the set of parameters, in order, until a matching

* function is found or throw dispatch_error if no matching function is found

*/

template<typename Funcs>

Boxed_Value dispatch(const Funcs &funcs,

const std::vector<Boxed_Value> &plist, const Type_Conversions_State &t_conversions)

{

std::vector<std::pair<size_t, const Proxy_Function_Base *>> ordered_funcs;

ordered_funcs.reserve(funcs.size());

for (const auto &func : funcs)

{

const auto arity = func->get_arity();

if (arity == -1)

{

ordered_funcs.emplace_back(plist.size(), func.get());

} else if (arity == static_cast<int>(plist.size())) {

size_t numdiffs = 0;

for (size_t i = 0; i < plist.size(); ++i)

{

if (!func->get_param_types()[i+1].bare_equal(plist[i].get_type_info()))

{

++numdiffs;

}

}

ordered_funcs.emplace_back(numdiffs, func.get());

}

}

for (size_t i = 0; i <= plist.size(); ++i)

{

for (const auto &func : ordered_funcs )

{

try {

if (func.first == i && func.second->filter(plist, t_conversions))

{

return (*(func.second))(plist, t_conversions);

}

} catch (const exception::bad_boxed_cast &) {

//parameter failed to cast, try again

} catch (const exception::arity_error &) {

//invalid num params, try again

} catch (const exception::guard_error &) {

//guard failed to allow the function to execute,

//try again

}

}

}

return detail::dispatch_with_conversions(ordered_funcs.cbegin(), ordered_funcs.cend(), plist, t_conversions, funcs);

}

}

}

#endif