548 lines
14 KiB
C++
548 lines
14 KiB
C++
// This file is distributed under the BSD License.
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// See "license.txt" for details.
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// Copyright 2009-2010, Jonathan Turner (jturner@minnow-lang.org)
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// and Jason Turner (lefticus@gmail.com)
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// http://www.chaiscript.com
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#ifndef __proxy_functions_hpp__
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#define __proxy_functions_hpp__
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#include "boxed_value.hpp"
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#include "type_info.hpp"
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#include <string>
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#include <boost/function.hpp>
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#include <boost/type_traits/add_reference.hpp>
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#include <stdexcept>
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#include <vector>
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#include "proxy_functions_detail.hpp"
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namespace chaiscript
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{
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/**
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* Helper for building a list of parameters for calling a Proxy_Function
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* it does automatic conversion to Boxed_Value types via operator<<
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*
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* example usage:
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* Boxed_Value retval = dispatch(dispatchengine.get_function("+"),
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* chaiscript::Param_List_Builder() << 5 << 6);
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*/
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struct Param_List_Builder
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{
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Param_List_Builder &operator<<(const Boxed_Value &so)
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{
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objects.push_back(so);
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return *this;
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}
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template<typename T>
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Param_List_Builder &operator<<(T t)
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{
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objects.push_back(Boxed_Value(t));
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return *this;
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}
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operator const std::vector<Boxed_Value> &() const
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{
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return objects;
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}
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std::vector<Boxed_Value> objects;
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};
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/**
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* Pure virtual base class for all Proxy_Function implementations
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* Proxy_Functions are a type erasure of type safe C++
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* function calls. At runtime parameter types are expected to be
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* tested against passed in types.
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* Dispatch_Engine only knows how to work with Proxy_Function, no other
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* function classes.
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*/
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class Proxy_Function_Base
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{
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public:
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virtual ~Proxy_Function_Base() {}
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virtual Boxed_Value operator()(const std::vector<Boxed_Value> ¶ms) const = 0;
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std::vector<Type_Info> get_param_types() const { return m_types; }
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virtual bool operator==(const Proxy_Function_Base &) const = 0;
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virtual bool call_match(const std::vector<Boxed_Value> &vals) const = 0;
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//! Return true if the function is a possible match
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//! to the passed in values
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bool filter(const std::vector<Boxed_Value> &vals) const
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{
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int arity = get_arity();
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if (arity < 0)
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{
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return true;
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} else if (size_t(arity) == vals.size()) {
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if (arity == 0)
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{
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return true;
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} else {
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const std::vector<Type_Info> &types = get_param_types();
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if (types.size() < 2)
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{
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return true;
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}
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const Type_Info &ti = types[1];
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if (ti.is_undef() || vals[0].get_type_info().is_undef()
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|| ti.bare_equal(user_type<Boxed_Value>())
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|| ti.bare_equal(user_type<Boxed_POD_Value>())
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|| ti.bare_equal(vals[0].get_type_info()))
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{
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return true;
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} else {
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return false;
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}
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}
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} else {
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return false;
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}
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}
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virtual int get_arity() const = 0;
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virtual std::string annotation() const = 0;
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protected:
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Proxy_Function_Base(const std::vector<Type_Info> &t_types)
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: m_types(t_types)
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{
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}
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bool compare_types(const std::vector<Type_Info> &tis, const std::vector<Boxed_Value> &bvs) const
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{
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if (tis.size() - 1 != bvs.size())
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{
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return false;
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} else {
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const int size = bvs.size();
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for (int i = 0; i < size; ++i)
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{
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if (!(tis[i+1].bare_equal(bvs[i].get_type_info()) && tis[i+1].is_const() >= bvs[i].get_type_info().is_const() ))
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{
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return false;
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}
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}
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}
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return true;
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}
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std::vector<Type_Info> m_types;
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};
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typedef boost::shared_ptr<Proxy_Function_Base> Proxy_Function;
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typedef boost::shared_ptr<const Proxy_Function_Base> Const_Proxy_Function;
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/**
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* Exception thrown if a function's guard fails to execute
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*/
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class guard_error : public std::runtime_error
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{
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public:
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guard_error() throw()
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: std::runtime_error("Guard evaluation failed")
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{ }
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virtual ~guard_error() throw()
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{ }
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};
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/**
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* A Proxy_Function implementation that is not type safe, the called function
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* is expecting a vector<Boxed_Value> that it works with how it chooses.
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*/
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class Dynamic_Proxy_Function : public Proxy_Function_Base
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{
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public:
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Dynamic_Proxy_Function(
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const boost::function<Boxed_Value (const std::vector<Boxed_Value> &)> &t_f,
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int t_arity=-1,
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const std::string &t_description = "",
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const Proxy_Function &t_guard = Proxy_Function())
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: Proxy_Function_Base(build_param_type_list(t_arity)),
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m_f(t_f), m_arity(t_arity), m_description(t_description), m_guard(t_guard)
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{
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}
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virtual bool operator==(const Proxy_Function_Base &) const
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{
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return false;
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}
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virtual bool call_match(const std::vector<Boxed_Value> &vals) const
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{
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return (m_arity < 0 || vals.size() == size_t(m_arity))
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&& test_guard(vals);
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}
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virtual ~Dynamic_Proxy_Function() {}
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virtual Boxed_Value operator()(const std::vector<Boxed_Value> ¶ms) const
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{
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if (m_arity < 0 || params.size() == size_t(m_arity))
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{
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if (test_guard(params))
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{
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return m_f(params);
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} else {
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throw guard_error();
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}
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} else {
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throw arity_error(params.size(), m_arity);
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}
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}
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virtual int get_arity() const
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{
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return m_arity;
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}
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virtual std::string annotation() const
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{
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return m_description;
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}
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private:
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bool test_guard(const std::vector<Boxed_Value> ¶ms) const
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{
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if (m_guard)
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{
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try {
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return boxed_cast<bool>((*m_guard)(params));
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} catch (const arity_error &) {
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return false;
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} catch (const bad_boxed_cast &) {
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return false;
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}
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} else {
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return true;
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}
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}
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static std::vector<Type_Info> build_param_type_list(int arity)
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{
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std::vector<Type_Info> types;
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types.push_back(detail::Get_Type_Info<Boxed_Value>::get());
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if (arity >= 0)
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{
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for (int i = 0; i < arity; ++i)
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{
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types.push_back(detail::Get_Type_Info<Boxed_Value>::get());
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}
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} else {
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types.push_back(detail::Get_Type_Info<std::vector<Boxed_Value> >::get());
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}
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return types;
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}
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boost::function<Boxed_Value (const std::vector<Boxed_Value> &)> m_f;
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int m_arity;
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std::string m_description;
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Proxy_Function m_guard;
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};
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/**
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* An object used by Bound_Function to represent "_" parameters
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* of a binding. This allows for unbound parameters during bind.
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*/
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struct Placeholder_Object
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{
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};
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/**
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* An implementation of Proxy_Function that takes a Proxy_Function
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* and substitutes bound parameters into the parameter list
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* at runtime, when call() is executed.
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* it is used for bind(function, param1, _, param2) style calls
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*/
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class Bound_Function : public Proxy_Function_Base
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{
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public:
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Bound_Function(const Const_Proxy_Function &t_f,
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const std::vector<Boxed_Value> &t_args)
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: Proxy_Function_Base(std::vector<Type_Info>()),
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m_f(t_f), m_args(t_args), m_arity(m_f->get_arity()<0?-1:(m_f->get_arity() - m_args.size()))
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{
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}
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virtual bool operator==(const Proxy_Function_Base &) const
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{
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return false;
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}
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virtual ~Bound_Function() {}
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virtual bool call_match(const std::vector<Boxed_Value> &vals) const
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{
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return m_f->call_match(build_param_list(vals));
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}
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virtual Boxed_Value operator()(const std::vector<Boxed_Value> ¶ms) const
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{
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return (*m_f)(build_param_list(params));
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}
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std::vector<Boxed_Value> build_param_list(const std::vector<Boxed_Value> ¶ms) const
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{
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typedef std::vector<Boxed_Value>::const_iterator pitr;
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pitr parg = params.begin();
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pitr barg = m_args.begin();
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std::vector<Boxed_Value> args;
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while (!(parg == params.end() && barg == m_args.end()))
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{
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while (barg != m_args.end()
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&& !(barg->get_type_info() == detail::Get_Type_Info<Placeholder_Object>::get()))
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{
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args.push_back(*barg);
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++barg;
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}
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if (parg != params.end())
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{
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args.push_back(*parg);
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++parg;
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}
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if (barg != m_args.end()
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&& barg->get_type_info() == detail::Get_Type_Info<Placeholder_Object>::get())
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{
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++barg;
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}
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}
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return args;
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}
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virtual int get_arity() const
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{
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return m_arity;
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}
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virtual std::string annotation() const
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{
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return "";
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}
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private:
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Const_Proxy_Function m_f;
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std::vector<Boxed_Value> m_args;
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int m_arity;
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};
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/**
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* The standard typesafe function call implementation of Proxy_Function
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* It takes a boost::function<> object and performs runtime
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* type checking of Boxed_Value parameters, in a type safe manner
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*/
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template<typename Func>
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class Proxy_Function_Impl : public Proxy_Function_Base
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{
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public:
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Proxy_Function_Impl(const boost::function<Func> &f)
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: Proxy_Function_Base(build_param_type_list(static_cast<Func *>(0))),
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m_f(f), m_dummy_func(0)
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{
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}
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virtual ~Proxy_Function_Impl() {}
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virtual bool operator==(const Proxy_Function_Base &t_func) const
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{
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try {
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dynamic_cast<const Proxy_Function_Impl<Func> &>(t_func);
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return true;
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} catch (const std::bad_cast &) {
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return false;
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}
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}
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virtual Boxed_Value operator()(const std::vector<Boxed_Value> ¶ms) const
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{
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return Do_Call<typename boost::function<Func>::result_type>::go(m_f, params);
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}
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virtual int get_arity() const
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{
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return m_types.size() - 1;
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}
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virtual bool call_match(const std::vector<Boxed_Value> &vals) const
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{
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if (int(vals.size()) != get_arity())
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{
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return false;
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}
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return compare_types(m_types, vals) || compare_types_cast(m_dummy_func, vals);
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}
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virtual std::string annotation() const
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{
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return "";
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}
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private:
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boost::function<Func> m_f;
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Func *m_dummy_func;
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};
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/**
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* Attribute getter Proxy_Function implementation
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*/
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template<typename T, typename Class>
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class Attribute_Access : public Proxy_Function_Base
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{
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public:
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Attribute_Access(T Class::* t_attr)
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: Proxy_Function_Base(param_types()),
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m_attr(t_attr)
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{
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}
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virtual ~Attribute_Access() {}
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virtual bool operator==(const Proxy_Function_Base &t_func) const
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{
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try {
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const Attribute_Access<T, Class> &aa
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= dynamic_cast<const Attribute_Access<T, Class> &>(t_func);
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return m_attr == aa.m_attr;
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} catch (const std::bad_cast &) {
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return false;
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}
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}
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virtual Boxed_Value operator()(const std::vector<Boxed_Value> ¶ms) const
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{
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if (params.size() == 1)
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{
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const Boxed_Value &bv = params[0];
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if (bv.is_const())
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{
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const Class *o = boxed_cast<const Class *>(bv);
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return Handle_Return<typename boost::add_reference<T>::type>::handle(o->*m_attr);
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} else {
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Class *o = boxed_cast<Class *>(bv);
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return Handle_Return<typename boost::add_reference<T>::type>::handle(o->*m_attr);
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}
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} else {
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throw arity_error(params.size(), 1);
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}
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}
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virtual int get_arity() const
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{
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return 1;
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}
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virtual bool call_match(const std::vector<Boxed_Value> &vals) const
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{
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if (vals.size() != 1)
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{
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return false;
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}
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return vals[0].get_type_info().bare_equal(user_type<Class>());
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}
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virtual std::string annotation() const
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{
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return "";
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}
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private:
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static std::vector<Type_Info> param_types()
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{
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std::vector<Type_Info> v;
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v.push_back(user_type<T>());
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v.push_back(user_type<Class>());
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return v;
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}
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T Class::* m_attr;
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};
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/**
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* Exception thrown in the case that a multi method dispatch fails
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* because no matching function was found
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* at runtime due to either an arity_error, a guard_error or a bad_boxed_cast
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* exception
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*/
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struct dispatch_error : std::runtime_error
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{
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dispatch_error() throw()
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: std::runtime_error("No matching function to dispatch to")
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{
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}
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dispatch_error(bool is_const) throw()
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: std::runtime_error(std::string("No matching function to dispatch to") + (is_const?", parameter is const":""))
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{
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}
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virtual ~dispatch_error() throw() {}
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};
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/**
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* Take a vector of functions and a vector of parameters. Attempt to execute
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* each function against the set of parameters, in order, until a matching
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* function is found or throw dispatch_error if no matching function is found
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*/
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template<typename InItr>
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Boxed_Value dispatch(InItr begin, InItr end,
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const std::vector<Boxed_Value> &plist)
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{
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while (begin != end)
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{
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try {
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if (begin->second->filter(plist))
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{
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return (*begin->second)(plist);
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}
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} catch (const bad_boxed_cast &) {
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//parameter failed to cast, try again
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} catch (const arity_error &) {
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//invalid num params, try again
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} catch (const guard_error &) {
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//guard failed to allow the function to execute,
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//try again
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}
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++begin;
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}
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throw dispatch_error(plist.empty()?false:plist[0].is_const());
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}
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/**
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* Take a vector of functions and a vector of parameters. Attempt to execute
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* each function against the set of parameters, in order, until a matching
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* function is found or throw dispatch_error if no matching function is found
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*/
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template<typename Funcs>
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Boxed_Value dispatch(const Funcs &funcs,
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const std::vector<Boxed_Value> &plist)
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{
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return dispatch(funcs.begin(), funcs.end(), plist);
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}
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}
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#endif
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