chaiscript_eval.hpp

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// This file is distributed under the BSD License.
// See "license.txt" for details.
// Copyright 2009-2012, Jonathan Turner (jonathan@emptycrate.com)
// Copyright 2009-2017, Jason Turner (jason@emptycrate.com)
// http://www.chaiscript.com
 
// This is an open source non-commercial project. Dear PVS-Studio, please check it.
// PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
 
#ifndef CHAISCRIPT_EVAL_HPP_
#define CHAISCRIPT_EVAL_HPP_
 
#include <exception>
#include <functional>
#include <limits>
#include <map>
#include <memory>
#include <ostream>
#include <stdexcept>
#include <string>
#include <vector>
 
#include "../chaiscript_defines.hpp"
#include "../dispatchkit/boxed_cast.hpp"
#include "../dispatchkit/boxed_number.hpp"
#include "../dispatchkit/boxed_value.hpp"
#include "../dispatchkit/dispatchkit.hpp"
#include "../dispatchkit/dynamic_object_detail.hpp"
#include "../dispatchkit/proxy_functions.hpp"
#include "../dispatchkit/proxy_functions_detail.hpp"
#include "../dispatchkit/register_function.hpp"
#include "../dispatchkit/type_info.hpp"
#include "chaiscript_algebraic.hpp"
#include "chaiscript_common.hpp"
 
namespace chaiscript {
namespace exception {
class bad_boxed_cast;
}  // namespace exception
}  // namespace chaiscript
 
namespace chaiscript
{
  namespace eval
  {
    template<typename T> struct AST_Node_Impl;
 
    template<typename T> using AST_Node_Impl_Ptr = typename std::unique_ptr<AST_Node_Impl<T>>;
 
    namespace detail
    {
      template<typename T>
      static Boxed_Value eval_function(chaiscript::detail::Dispatch_Engine &t_ss, const AST_Node_Impl<T> &t_node, const std::vector<std::string> &t_param_names, const std::vector<Boxed_Value> &t_vals, const std::map<std::string, Boxed_Value> *t_locals=nullptr, bool has_this_capture = false) {
        chaiscript::detail::Dispatch_State state(t_ss);
 
        const Boxed_Value *thisobj = [&]() -> const Boxed_Value *{
          auto &stack = t_ss.get_stack_data(state.stack_holder()).back();
          if (!stack.empty() && stack.back().first == "__this") {
            return &stack.back().second;
          } else if (!t_vals.empty()) {
            return &t_vals[0];
          } else {
            return nullptr;
          }
        }();
 
        chaiscript::eval::detail::Stack_Push_Pop tpp(state);
        if (thisobj && !has_this_capture) { state.add_object("this", *thisobj); }
 
        if (t_locals) {
          for (const auto &local : *t_locals) {
            state.add_object(local.first, local.second);
          }
        }
 
        for (size_t i = 0; i < t_param_names.size(); ++i) {
          if (t_param_names[i] != "this") {
            state.add_object(t_param_names[i], t_vals[i]);
          }
        }
 
        try {
          return t_node.eval(state);
        } catch (detail::Return_Value &rv) {
          return std::move(rv.retval);
        } 
      }
 
      inline Boxed_Value clone_if_necessary(Boxed_Value incoming, std::atomic_uint_fast32_t &t_loc, const chaiscript::detail::Dispatch_State &t_ss)
      {
        if (!incoming.is_return_value())
        {
          if (incoming.get_type_info().is_arithmetic()) {
            return Boxed_Number::clone(incoming);
          } else if (incoming.get_type_info().bare_equal_type_info(typeid(bool))) {
            return Boxed_Value(*static_cast<const bool*>(incoming.get_const_ptr()));
          } else {
            return t_ss->call_function("clone", t_loc, {incoming}, t_ss.conversions());
          }
        } else {
          incoming.reset_return_value();
          return incoming;
        }
      }
    }
 
    template<typename T>
    struct AST_Node_Impl : AST_Node 
    {
      AST_Node_Impl(std::string t_ast_node_text, AST_Node_Type t_id, Parse_Location t_loc, 
               std::vector<AST_Node_Impl_Ptr<T>> t_children = std::vector<AST_Node_Impl_Ptr<T>>())
        : AST_Node(std::move(t_ast_node_text), t_id, std::move(t_loc)),
          children(std::move(t_children))
      {
      }
 
      static bool get_scoped_bool_condition(const AST_Node_Impl<T> &node, const chaiscript::detail::Dispatch_State &t_ss) {
        chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
        return get_bool_condition(node.eval(t_ss), t_ss);
      }
 
 
      std::vector<std::reference_wrapper<AST_Node>> get_children() const final {
        std::vector<std::reference_wrapper<AST_Node>> retval;
        retval.reserve(children.size());
        for (auto &&child : children) {
          retval.emplace_back(*child);
        }
 
        return retval;
      }
 
      Boxed_Value eval(const chaiscript::detail::Dispatch_State &t_e) const final
      {
        try {
          T::trace(t_e, this);
          return eval_internal(t_e);
        } catch (exception::eval_error &ee) {
          ee.call_stack.push_back(*this);
          throw;
        }
      }
 
      std::vector<AST_Node_Impl_Ptr<T>> children;
 
      protected:
        virtual Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &) const
        {
          throw std::runtime_error("Undispatched ast_node (internal error)");
        }
    };
 
 
    template<typename T>
    struct Compiled_AST_Node : AST_Node_Impl<T> {
        Compiled_AST_Node(AST_Node_Impl_Ptr<T> t_original_node, std::vector<AST_Node_Impl_Ptr<T>> t_children,
            std::function<Boxed_Value (const std::vector<AST_Node_Impl_Ptr<T>> &, const chaiscript::detail::Dispatch_State &t_ss)> t_func) :
          AST_Node_Impl<T>(t_original_node->text, AST_Node_Type::Compiled, t_original_node->location, std::move(t_children)),
          m_func(std::move(t_func)),
          m_original_node(std::move(t_original_node))
        { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          return m_func(this->children, t_ss);
        }
 
        std::function<Boxed_Value (const std::vector<AST_Node_Impl_Ptr<T>> &, const chaiscript::detail::Dispatch_State &t_ss)> m_func;
        AST_Node_Impl_Ptr<T> m_original_node;
    };
 
 
    template<typename T>
    struct Fold_Right_Binary_Operator_AST_Node : AST_Node_Impl<T> {
        Fold_Right_Binary_Operator_AST_Node(const std::string &t_oper, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children, Boxed_Value t_rhs) :
          AST_Node_Impl<T>(t_oper, AST_Node_Type::Binary, std::move(t_loc), std::move(t_children)),
          m_oper(Operators::to_operator(t_oper)),
          m_rhs(std::move(t_rhs))
        { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          return do_oper(t_ss, this->text, this->children[0]->eval(t_ss));
        }
 
      protected:
        Boxed_Value do_oper(const chaiscript::detail::Dispatch_State &t_ss, 
            const std::string &t_oper_string, const Boxed_Value &t_lhs) const
        {
          try {
            if (t_lhs.get_type_info().is_arithmetic())
            {
              // If it's an arithmetic operation we want to short circuit dispatch
              try{
                return Boxed_Number::do_oper(m_oper, t_lhs, m_rhs);
              } catch (const chaiscript::exception::arithmetic_error &) {
                throw;
              } catch (...) {
                throw exception::eval_error("Error with numeric operator calling: " + t_oper_string);
              }
            } else {
              chaiscript::eval::detail::Function_Push_Pop fpp(t_ss);
              fpp.save_params({t_lhs, m_rhs});
              return t_ss->call_function(t_oper_string, m_loc, {t_lhs, m_rhs}, t_ss.conversions());
            }
          }
          catch(const exception::dispatch_error &e){
            throw exception::eval_error("Can not find appropriate '" + t_oper_string + "' operator.", e.parameters, e.functions, false, *t_ss);
          }
        }
 
      private:
        Operators::Opers m_oper;
        Boxed_Value m_rhs;
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
 
    template<typename T>
    struct Binary_Operator_AST_Node : AST_Node_Impl<T> {
        Binary_Operator_AST_Node(const std::string &t_oper, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(t_oper, AST_Node_Type::Binary, std::move(t_loc), std::move(t_children)),
          m_oper(Operators::to_operator(t_oper))
        { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          auto lhs = this->children[0]->eval(t_ss);
          auto rhs = this->children[1]->eval(t_ss);
          return do_oper(t_ss, m_oper, this->text, lhs, rhs);
        }
 
      protected:
        Boxed_Value do_oper(const chaiscript::detail::Dispatch_State &t_ss, 
            Operators::Opers t_oper, const std::string &t_oper_string, const Boxed_Value &t_lhs, const Boxed_Value &t_rhs) const
        {
          try {
            if (t_oper != Operators::Opers::invalid && t_lhs.get_type_info().is_arithmetic() && t_rhs.get_type_info().is_arithmetic())
            {
              // If it's an arithmetic operation we want to short circuit dispatch
              try{
                return Boxed_Number::do_oper(t_oper, t_lhs, t_rhs);
              } catch (const chaiscript::exception::arithmetic_error &) {
                throw;
              } catch (...) {
                throw exception::eval_error("Error with numeric operator calling: " + t_oper_string);
              }
            } else {
              chaiscript::eval::detail::Function_Push_Pop fpp(t_ss);
              fpp.save_params({t_lhs, t_rhs});
              return t_ss->call_function(t_oper_string, m_loc, {t_lhs, t_rhs}, t_ss.conversions());
            }
          }
          catch(const exception::dispatch_error &e){
            throw exception::eval_error("Can not find appropriate '" + t_oper_string + "' operator.", e.parameters, e.functions, false, *t_ss);
          }
        }
 
      private:
        Operators::Opers m_oper;
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
 
    template<typename T>
    struct Constant_AST_Node final : AST_Node_Impl<T> {
      Constant_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, Boxed_Value t_value)
        : AST_Node_Impl<T>(t_ast_node_text, AST_Node_Type::Constant, std::move(t_loc)),
          m_value(std::move(t_value))
      {
      }
 
      explicit Constant_AST_Node(Boxed_Value t_value)
        : AST_Node_Impl<T>("", AST_Node_Type::Constant, Parse_Location()),
          m_value(std::move(t_value))
      {
      }
 
      Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &) const override {
        return m_value;
      }
 
      Boxed_Value m_value;
    };
 
    template<typename T>
    struct Id_AST_Node final : AST_Node_Impl<T> {
        Id_AST_Node(const std::string &t_ast_node_text, Parse_Location t_loc) :
          AST_Node_Impl<T>(t_ast_node_text, AST_Node_Type::Id, std::move(t_loc))
        { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          try {
            return t_ss.get_object(this->text, m_loc);
          }
          catch (std::exception &) {
            throw exception::eval_error("Can not find object: " + this->text);
          }
        }
 
      private:
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
    template<typename T>
    struct Fun_Call_AST_Node : AST_Node_Impl<T> {
        Fun_Call_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Fun_Call, std::move(t_loc), std::move(t_children)) { 
            assert(!this->children.empty());
          }
 
        template<bool Save_Params>
        Boxed_Value do_eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const
        {
          chaiscript::eval::detail::Function_Push_Pop fpp(t_ss);
 
          std::vector<Boxed_Value> params;
 
          params.reserve(this->children[1]->children.size());
          for (const auto &child : this->children[1]->children) {
            params.push_back(child->eval(t_ss));
          }
 
          if (Save_Params) {
            fpp.save_params(params);
          }
 
          Boxed_Value fn(this->children[0]->eval(t_ss));
 
          using ConstFunctionTypePtr = const dispatch::Proxy_Function_Base *;
          try {
            return (*t_ss->boxed_cast<ConstFunctionTypePtr>(fn))(params, t_ss.conversions());
          }
          catch(const exception::dispatch_error &e){
            throw exception::eval_error(std::string(e.what()) + " with function '" + this->children[0]->text + "'", e.parameters, e.functions, false, *t_ss);
          }
          catch(const exception::bad_boxed_cast &){
            try {
              using ConstFunctionTypeRef = const Const_Proxy_Function &;
              Const_Proxy_Function f = t_ss->boxed_cast<ConstFunctionTypeRef>(fn);
              // handle the case where there is only 1 function to try to call and dispatch fails on it
              throw exception::eval_error("Error calling function '" + this->children[0]->text + "'", params, {f}, false, *t_ss);
            } catch (const exception::bad_boxed_cast &) {
              throw exception::eval_error("'" + this->children[0]->pretty_print() + "' does not evaluate to a function.");
            }
          }
          catch(const exception::arity_error &e){
            throw exception::eval_error(std::string(e.what()) + " with function '" + this->children[0]->text + "'");
          }
          catch(const exception::guard_error &e){
            throw exception::eval_error(std::string(e.what()) + " with function '" + this->children[0]->text + "'");
          }
          catch(detail::Return_Value &rv) {
            return rv.retval;
          }
        }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override
        {
          return do_eval_internal<true>(t_ss);
        }
 
    };
 
 
    template<typename T>
    struct Unused_Return_Fun_Call_AST_Node final : Fun_Call_AST_Node<T> {
        Unused_Return_Fun_Call_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          Fun_Call_AST_Node<T>(std::move(t_ast_node_text), std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override
        {
          return this->template do_eval_internal<false>(t_ss);
        }
    };
 
 
 
 
 
    template<typename T>
    struct Arg_AST_Node final : AST_Node_Impl<T> {
        Arg_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Arg_List, std::move(t_loc), std::move(t_children)) { }
 
    };
 
    template<typename T>
    struct Arg_List_AST_Node final : AST_Node_Impl<T> {
        Arg_List_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Arg_List, std::move(t_loc), std::move(t_children)) { }
 
 
        static std::string get_arg_name(const AST_Node_Impl<T> &t_node) {
          if (t_node.children.empty())
          {
            return t_node.text;
          } else if (t_node.children.size() == 1) {
            return t_node.children[0]->text;
          } else {
            return t_node.children[1]->text;
          }
        }
 
        static std::vector<std::string> get_arg_names(const AST_Node_Impl<T> &t_node) {
          std::vector<std::string> retval;
 
          for (const auto &node : t_node.children)
          {
            retval.push_back(get_arg_name(*node));
          }
 
          return retval;
        }
 
        static std::pair<std::string, Type_Info> get_arg_type(const AST_Node_Impl<T> &t_node, const chaiscript::detail::Dispatch_State &t_ss) 
        {
          if (t_node.children.size() < 2)
          {
            return {};
          } else {
            return {t_node.children[0]->text, t_ss->get_type(t_node.children[0]->text, false)};
          }
        }
 
        static dispatch::Param_Types get_arg_types(const AST_Node_Impl<T> &t_node, const chaiscript::detail::Dispatch_State &t_ss) {
          std::vector<std::pair<std::string, Type_Info>> retval;
 
          for (const auto &child : t_node.children)
          {
            retval.push_back(get_arg_type(*child, t_ss));
          }
 
          return dispatch::Param_Types(std::move(retval));
        }
    };
 
    template<typename T>
    struct Equation_AST_Node final : AST_Node_Impl<T> {
        Equation_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Equation, std::move(t_loc), std::move(t_children)), 
          m_oper(Operators::to_operator(this->text))
        { assert(this->children.size() == 2); }
 
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          chaiscript::eval::detail::Function_Push_Pop fpp(t_ss);
          Boxed_Value rhs = this->children[1]->eval(t_ss); 
          Boxed_Value lhs = this->children[0]->eval(t_ss);
 
          if (lhs.is_return_value()) {
            throw exception::eval_error("Error, cannot assign to temporary value.");
          } else if (lhs.is_const()) {
            throw exception::eval_error("Error, cannot assign to constant value.");
          }
 
 
          if (m_oper != Operators::Opers::invalid && lhs.get_type_info().is_arithmetic() &&
              rhs.get_type_info().is_arithmetic())
          {
            try {
              return Boxed_Number::do_oper(m_oper, lhs, rhs);
            } catch (const std::exception &) {
              throw exception::eval_error("Error with unsupported arithmetic assignment operation.");
            }
          } else if (m_oper == Operators::Opers::assign) {
            try {
 
              if (lhs.is_undef()) {
                if (!this->children.empty()
                     && ((this->children[0]->identifier == AST_Node_Type::Reference)
                         || (!this->children[0]->children.empty()
                              && this->children[0]->children[0]->identifier == AST_Node_Type::Reference)
                       )
                   )
 
                {
                  lhs.assign(rhs);
                  lhs.reset_return_value();
                  return rhs;
                } else {
                  rhs = detail::clone_if_necessary(std::move(rhs), m_clone_loc, t_ss);
                }
              }
 
              try {
                return t_ss->call_function(this->text, m_loc, {std::move(lhs), rhs}, t_ss.conversions());
              }
              catch(const exception::dispatch_error &e){
                throw exception::eval_error("Unable to find appropriate'" + this->text + "' operator.", e.parameters, e.functions, false, *t_ss);
              }
            }
            catch(const exception::dispatch_error &e){
              throw exception::eval_error("Missing clone or copy constructor for right hand side of equation", e.parameters, e.functions, false, *t_ss);
            }
          }
          else if (this->text == ":=") {
            if (lhs.is_undef() || Boxed_Value::type_match(lhs, rhs)) {
              lhs.assign(rhs);
              lhs.reset_return_value();
            } else {
              throw exception::eval_error("Mismatched types in equation");
            }
          }
          else {
            try {
              return t_ss->call_function(this->text, m_loc, {std::move(lhs), rhs}, t_ss.conversions());
            } catch(const exception::dispatch_error &e){
              throw exception::eval_error("Unable to find appropriate'" + this->text + "' operator.", e.parameters, e.functions, false, *t_ss);
            }
          }
 
          return rhs;
        }
 
      private:
        Operators::Opers m_oper;
        mutable std::atomic_uint_fast32_t m_loc = {0};
        mutable std::atomic_uint_fast32_t m_clone_loc = {0};
    };
 
    template<typename T>
    struct Global_Decl_AST_Node final : AST_Node_Impl<T> {
        Global_Decl_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Global_Decl, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          const std::string &idname =
            [&]()->const std::string & {
              if (this->children[0]->identifier == AST_Node_Type::Reference) {
                return this->children[0]->children[0]->text;
              } else {
                return this->children[0]->text;
              }
            }();
 
          return t_ss->add_global_no_throw(Boxed_Value(), idname);
 
        }
    };
 
 
    template<typename T>
    struct Var_Decl_AST_Node final : AST_Node_Impl<T> {
        Var_Decl_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Var_Decl, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          const std::string &idname = this->children[0]->text;
 
          try {
            Boxed_Value bv;
            t_ss.add_object(idname, bv);
            return bv;
          } catch (const exception::name_conflict_error &e) {
            throw exception::eval_error("Variable redefined '" + e.name() + "'");
          }
        }
    };
 
    template<typename T>
    struct Assign_Decl_AST_Node final : AST_Node_Impl<T> {
        Assign_Decl_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Assign_Decl, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          const std::string &idname = this->children[0]->text;
 
          try {
            Boxed_Value bv(detail::clone_if_necessary(this->children[1]->eval(t_ss), m_loc, t_ss));
            bv.reset_return_value();
            t_ss.add_object(idname, bv);
            return bv;
          } catch (const exception::name_conflict_error &e) {
            throw exception::eval_error("Variable redefined '" + e.name() + "'");
          }
        }
      private:
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
 
    template<typename T>
    struct Array_Call_AST_Node final : AST_Node_Impl<T> {
        Array_Call_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Array_Call, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          chaiscript::eval::detail::Function_Push_Pop fpp(t_ss);
 
          const std::vector<Boxed_Value> params{this->children[0]->eval(t_ss), this->children[1]->eval(t_ss)};
 
          try {
            fpp.save_params(params);
            return t_ss->call_function("[]", m_loc, params, t_ss.conversions());
          }
          catch(const exception::dispatch_error &e){
            throw exception::eval_error("Can not find appropriate array lookup operator '[]'.", e.parameters, e.functions, false, *t_ss );
          }
        }
 
 
      private:
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
    template<typename T>
    struct Dot_Access_AST_Node final : AST_Node_Impl<T> {
        Dot_Access_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Dot_Access, std::move(t_loc), std::move(t_children)),
          m_fun_name(
              ((this->children[1]->identifier == AST_Node_Type::Fun_Call) || (this->children[1]->identifier == AST_Node_Type::Array_Call))?
              this->children[1]->children[0]->text:this->children[1]->text) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          chaiscript::eval::detail::Function_Push_Pop fpp(t_ss);
 
 
          Boxed_Value retval = this->children[0]->eval(t_ss);
          std::vector<Boxed_Value> params{retval};
 
          bool has_function_params = false;
          if (this->children[1]->children.size() > 1) {
            has_function_params = true;
            for (const auto &child : this->children[1]->children[1]->children) {
              params.push_back(child->eval(t_ss));
            }
          }
 
          fpp.save_params(params);
 
          try {
            retval = t_ss->call_member(m_fun_name, m_loc, std::move(params), has_function_params, t_ss.conversions());
          }
          catch(const exception::dispatch_error &e){
            if (e.functions.empty())
            {
              throw exception::eval_error("'" + m_fun_name + "' is not a function.");
            } else {
              throw exception::eval_error(std::string(e.what()) + " for function '" + m_fun_name + "'", e.parameters, e.functions, true, *t_ss);
            }
          }
          catch(detail::Return_Value &rv) {
            retval = std::move(rv.retval);
          }
 
          if (this->children[1]->identifier == AST_Node_Type::Array_Call) {
            try {
              retval = t_ss->call_function("[]", m_array_loc, {retval, this->children[1]->children[1]->eval(t_ss)}, t_ss.conversions());
            }
            catch(const exception::dispatch_error &e){
              throw exception::eval_error("Can not find appropriate array lookup operator '[]'.", e.parameters, e.functions, true, *t_ss);
            }
          }
 
          return retval;
        }
 
      private:
        mutable std::atomic_uint_fast32_t m_loc = {0};
        mutable std::atomic_uint_fast32_t m_array_loc = {0};
        const std::string m_fun_name;
    };
 
 
    template<typename T>
    struct Lambda_AST_Node final : AST_Node_Impl<T> {
        Lambda_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(t_ast_node_text, 
              AST_Node_Type::Lambda, 
              std::move(t_loc), 
              std::vector<AST_Node_Impl_Ptr<T>>(std::make_move_iterator(t_children.begin()), 
                                                std::make_move_iterator(std::prev(t_children.end())))
              ),
          m_param_names(Arg_List_AST_Node<T>::get_arg_names(*this->children[1])),
          m_this_capture(has_this_capture(this->children[0]->children)),
          m_lambda_node(std::move(t_children.back()))
        { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
 
          const auto captures = [&]()->std::map<std::string, Boxed_Value>{
            std::map<std::string, Boxed_Value> named_captures;
            for (const auto &capture : this->children[0]->children) {
              named_captures.insert(std::make_pair(capture->children[0]->text, capture->children[0]->eval(t_ss)));
            }
            return named_captures;
          }();
 
          const auto numparams = this->children[1]->children.size();
          const auto param_types = Arg_List_AST_Node<T>::get_arg_types(*this->children[1], t_ss);
 
          std::reference_wrapper<chaiscript::detail::Dispatch_Engine> engine(*t_ss);
 
          return Boxed_Value(
              dispatch::make_dynamic_proxy_function(
                  [engine, lambda_node = this->m_lambda_node, param_names = this->m_param_names, captures, 
                   this_capture = this->m_this_capture] (const std::vector<Boxed_Value> &t_params)
                  {
                    return detail::eval_function(engine, *lambda_node, param_names, t_params, &captures, this_capture);
                  },
                  static_cast<int>(numparams), m_lambda_node, param_types
                )
              );
        }
 
        static bool has_this_capture(const std::vector<AST_Node_Impl_Ptr<T>> &children) {
          return std::any_of(std::begin(children), std::end(children),
                [](const auto &child){
                  return child->children[0]->text == "this";
                }
              );
        }
 
      private:
        const std::vector<std::string> m_param_names;
        const bool m_this_capture = false;
        const std::shared_ptr<AST_Node_Impl<T>> m_lambda_node;
    };
 
    template<typename T>
    struct Scopeless_Block_AST_Node final : AST_Node_Impl<T> {
        Scopeless_Block_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Scopeless_Block, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          const auto num_children = this->children.size();
          for (size_t i = 0; i < num_children-1; ++i) {
            this->children[i]->eval(t_ss);
          }
          return this->children.back()->eval(t_ss);
        }
    };
 
    template<typename T>
    struct Block_AST_Node final : AST_Node_Impl<T> {
        Block_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Block, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
 
          const auto num_children = this->children.size();
          for (size_t i = 0; i < num_children-1; ++i) {
            this->children[i]->eval(t_ss);
          }
          return this->children.back()->eval(t_ss);
        }
    };
 
    template<typename T>
    struct Def_AST_Node final : AST_Node_Impl<T> {
 
        std::shared_ptr<AST_Node_Impl<T>> m_body_node;
        std::shared_ptr<AST_Node_Impl<T>> m_guard_node;
 
        Def_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Def, std::move(t_loc), 
              std::vector<AST_Node_Impl_Ptr<T>>(std::make_move_iterator(t_children.begin()), 
                                                std::make_move_iterator(std::prev(t_children.end(), has_guard(t_children, 1)?2:1)))
              ),
              // This apparent use after move is safe because we are only moving out the specific elements we need
              // on each operation.
              m_body_node(get_body_node(std::move(t_children))),
              m_guard_node(get_guard_node(std::move(t_children), t_children.size()-this->children.size()==2))
 
        { }
 
        static std::shared_ptr<AST_Node_Impl<T>> get_guard_node(std::vector<AST_Node_Impl_Ptr<T>> &&vec, bool has_guard)
        {
          if (has_guard) {
            return std::move(*std::prev(vec.end(), 2));
          } else {
            return {};
          }
        }
 
        static std::shared_ptr<AST_Node_Impl<T>> get_body_node(std::vector<AST_Node_Impl_Ptr<T>> &&vec)
        {
          return std::move(vec.back());
        }
 
        static bool has_guard(const std::vector<AST_Node_Impl_Ptr<T>> &t_children, const std::size_t offset)
        {
          if ((t_children.size() > 2 + offset) && (t_children[1+offset]->identifier == AST_Node_Type::Arg_List)) {
            if (t_children.size() > 3 + offset) {
              return true;
            }
          }
          else {
            if (t_children.size() > 2 + offset) {
              return true;
            }
          }
          return false;
        }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override{
          std::vector<std::string> t_param_names;
          size_t numparams = 0;
 
          dispatch::Param_Types param_types;
 
          if ((this->children.size() > 1) && (this->children[1]->identifier == AST_Node_Type::Arg_List)) {
            numparams = this->children[1]->children.size();
            t_param_names = Arg_List_AST_Node<T>::get_arg_names(*this->children[1]);
            param_types = Arg_List_AST_Node<T>::get_arg_types(*this->children[1], t_ss);
          }
 
          std::reference_wrapper<chaiscript::detail::Dispatch_Engine> engine(*t_ss);
          std::shared_ptr<dispatch::Proxy_Function_Base> guard;
          if (m_guard_node) {
            guard = dispatch::make_dynamic_proxy_function(
                [engine, guardnode = m_guard_node, t_param_names](const std::vector<Boxed_Value> &t_params)
                {
                  return detail::eval_function(engine, *guardnode, t_param_names, t_params);
                },
                static_cast<int>(numparams), m_guard_node);
          }
 
          try {
            const std::string & l_function_name = this->children[0]->text;
            t_ss->add(
                dispatch::make_dynamic_proxy_function(
                  [engine, func_node = m_body_node, t_param_names](const std::vector<Boxed_Value> &t_params)
                  {
                    return detail::eval_function(engine, *func_node, t_param_names, t_params);
                  },
                  static_cast<int>(numparams), m_body_node,
                  param_types, guard), l_function_name);
          } catch (const exception::name_conflict_error &e) {
            throw exception::eval_error("Function redefined '" + e.name() + "'");
          }
          return void_var();
        }
 
    };
 
    template<typename T>
    struct While_AST_Node final : AST_Node_Impl<T> {
        While_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::While, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
 
          try {
            while (this->get_scoped_bool_condition(*this->children[0], t_ss)) {
              try {
                this->children[1]->eval(t_ss);
              } catch (detail::Continue_Loop &) {
                // we got a continue exception, which means all of the remaining 
                // loop implementation is skipped and we just need to continue to
                // the next condition test
              }
            } 
          } catch (detail::Break_Loop &) {
            // loop was broken intentionally
          }
 
          return void_var();
        }
    };
 
    template<typename T>
    struct Class_AST_Node final : AST_Node_Impl<T> {
        Class_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Class, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);

          // put class name in current scope so it can be looked up by the attrs and methods
          t_ss.add_object("_current_class_name", const_var(this->children[0]->text));
 
          this->children[1]->eval(t_ss);
 
          return void_var();
        }
    };
 
 
    template<typename T>
    struct If_AST_Node final : AST_Node_Impl<T> {
        If_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::If, std::move(t_loc), std::move(t_children)) 
        { 
          assert(this->children.size() == 3);
        }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          if (this->get_bool_condition(this->children[0]->eval(t_ss), t_ss)) {
            return this->children[1]->eval(t_ss);
          } else {
            return this->children[2]->eval(t_ss);
          }
        }
    };
 
    template<typename T>
    struct Ranged_For_AST_Node final : AST_Node_Impl<T> {
        Ranged_For_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Ranged_For, std::move(t_loc), std::move(t_children))
          { assert(this->children.size() == 3); }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override{
          const auto get_function = [&t_ss](const std::string &t_name, auto &t_hint){
            uint_fast32_t hint = t_hint;
            auto funs = t_ss->get_function(t_name, hint);
            if (funs.first != hint) { t_hint = uint_fast32_t(funs.first); }
            return std::move(funs.second);
          };
 
          const auto call_function = [&t_ss](const auto &t_funcs, const Boxed_Value &t_param) {
            return dispatch::dispatch(*t_funcs, {t_param}, t_ss.conversions());
          };
 
 
          const std::string &loop_var_name = this->children[0]->text;
          Boxed_Value range_expression_result = this->children[1]->eval(t_ss);
 
 
          const auto do_loop = [&loop_var_name, &t_ss, this](const auto &ranged_thing){
            try {
              for (auto &&loop_var : ranged_thing) {
                // This scope push and pop might not be the best thing for perf
                // but we know it's 100% correct
                chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
                if (!std::is_same<std::decay_t<decltype(loop_var)>, Boxed_Value>::value) {
                  t_ss.add_get_object(loop_var_name, Boxed_Value(std::ref(loop_var)));
                } else {
                  t_ss.add_get_object(loop_var_name, Boxed_Value(loop_var));
                }
                try {
                  this->children[2]->eval(t_ss);
                } catch (detail::Continue_Loop &) {
                }
              }
            } catch (detail::Break_Loop &) {
              // loop broken
            }
            return void_var();
          };
 
          if (range_expression_result.get_type_info().bare_equal_type_info(typeid(std::vector<Boxed_Value>))) {
            return do_loop(boxed_cast<const std::vector<Boxed_Value> &>(range_expression_result));
          } else if (range_expression_result.get_type_info().bare_equal_type_info(typeid(std::map<std::string, Boxed_Value>))) {
            return do_loop(boxed_cast<const std::map<std::string, Boxed_Value> &>(range_expression_result));
          } else {
            const auto range_funcs = get_function("range", m_range_loc);
            const auto empty_funcs = get_function("empty", m_empty_loc);
            const auto front_funcs = get_function("front", m_front_loc);
            const auto pop_front_funcs = get_function("pop_front", m_pop_front_loc);
 
            try {
              const auto range_obj = call_function(range_funcs, range_expression_result);
              while (!boxed_cast<bool>(call_function(empty_funcs, range_obj))) {
                chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
                t_ss.add_get_object(loop_var_name, call_function(front_funcs, range_obj));
                try {
                  this->children[2]->eval(t_ss);
                } catch (detail::Continue_Loop &) {
                }
                call_function(pop_front_funcs, range_obj);
              }
            } catch (detail::Break_Loop &) {
              // loop broken
            }
            return void_var();
          }
 
        }
 
      private:
        mutable std::atomic_uint_fast32_t m_range_loc = {0};
        mutable std::atomic_uint_fast32_t m_empty_loc = {0};
        mutable std::atomic_uint_fast32_t m_front_loc = {0};
        mutable std::atomic_uint_fast32_t m_pop_front_loc = {0};
    };
 
 
    template<typename T>
    struct For_AST_Node final : AST_Node_Impl<T> {
        For_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::For, std::move(t_loc), std::move(t_children)) 
          { assert(this->children.size() == 4); }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override{
          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
 
          try {
            for (
                this->children[0]->eval(t_ss);
                this->get_scoped_bool_condition(*this->children[1], t_ss);
                this->children[2]->eval(t_ss)
                ) {
              try {
                // Body of Loop
                this->children[3]->eval(t_ss);
              } catch (detail::Continue_Loop &) {
                // we got a continue exception, which means all of the remaining 
                // loop implementation is skipped and we just need to continue to
                // the next iteration step
              }
            }
          } catch (detail::Break_Loop &) {
            // loop broken
          }
 
          return void_var();
        }
 
    };
 
    template<typename T>
    struct Switch_AST_Node final : AST_Node_Impl<T> {
        Switch_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Switch, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          bool breaking = false;
          size_t currentCase = 1;
          bool hasMatched = false;
 
          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
 
          Boxed_Value match_value(this->children[0]->eval(t_ss));
 
          while (!breaking && (currentCase < this->children.size())) {
            try {
              if (this->children[currentCase]->identifier == AST_Node_Type::Case) {
                //This is a little odd, but because want to see both the switch and the case simultaneously, I do a downcast here.
                try {
                  if (hasMatched || boxed_cast<bool>(t_ss->call_function("==", m_loc, {match_value, this->children[currentCase]->children[0]->eval(t_ss)}, t_ss.conversions()))) {
                    this->children[currentCase]->eval(t_ss);
                    hasMatched = true;
                  }
                }
                catch (const exception::bad_boxed_cast &) {
                  throw exception::eval_error("Internal error: case guard evaluation not boolean");
                }
              }
              else if (this->children[currentCase]->identifier == AST_Node_Type::Default) {
                this->children[currentCase]->eval(t_ss);
                hasMatched = true;
              }
            }
            catch (detail::Break_Loop &) {
              breaking = true;
            }
            ++currentCase;
          }
          return void_var();
        }
 
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
    template<typename T>
    struct Case_AST_Node final : AST_Node_Impl<T> {
        Case_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Case, std::move(t_loc), std::move(t_children)) 
        { assert(this->children.size() == 2); /* how many children does it have? */ }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
 
          this->children[1]->eval(t_ss);
 
          return void_var();
        }
    };
   
    template<typename T>
    struct Default_AST_Node final : AST_Node_Impl<T> {
        Default_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Default, std::move(t_loc), std::move(t_children))
        { assert(this->children.size() == 1); }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
 
          this->children[0]->eval(t_ss);
 
          return void_var();
        }
    };
 
 
    template<typename T>
    struct Inline_Array_AST_Node final : AST_Node_Impl<T> {
        Inline_Array_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Inline_Array, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          try {
            std::vector<Boxed_Value> vec;
            if (!this->children.empty()) {
              vec.reserve(this->children[0]->children.size());
              for (const auto &child : this->children[0]->children) {
                vec.push_back(detail::clone_if_necessary(child->eval(t_ss), m_loc, t_ss));
              }
            }
            return const_var(std::move(vec));
          }
          catch (const exception::dispatch_error &) {
            throw exception::eval_error("Can not find appropriate 'clone' or copy constructor for vector elements");
          }
        }
 
      private:
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
    template<typename T>
    struct Inline_Map_AST_Node final : AST_Node_Impl<T> {
        Inline_Map_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Inline_Map, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override
        {
          try {
            std::map<std::string, Boxed_Value> retval;
 
            for (const auto &child : this->children[0]->children) {
              retval.insert(std::make_pair(t_ss->boxed_cast<std::string>(child->children[0]->eval(t_ss)), 
                            detail::clone_if_necessary(child->children[1]->eval(t_ss), m_loc, t_ss)));
            }
 
            return const_var(std::move(retval));
          }
          catch (const exception::dispatch_error &e) {
            throw exception::eval_error("Can not find appropriate copy constructor or 'clone' while inserting into Map.", e.parameters, e.functions, false, *t_ss);
          }
        }
 
      private:
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
    template<typename T>
    struct Return_AST_Node final : AST_Node_Impl<T> {
        Return_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Return, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override{
          if (!this->children.empty()) {
            throw detail::Return_Value{this->children[0]->eval(t_ss)};
          }
          else {
            throw detail::Return_Value{void_var()};
          }
        }
    };
 
    template<typename T>
    struct File_AST_Node final : AST_Node_Impl<T> {
        File_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::File, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          try {
            const auto num_children = this->children.size();
 
            if (num_children > 0) {
              for (size_t i = 0; i < num_children-1; ++i) {
                this->children[i]->eval(t_ss);
              }
              return this->children.back()->eval(t_ss);
            } else {
              return void_var();
            }
          } catch (const detail::Continue_Loop &) {
            throw exception::eval_error("Unexpected `continue` statement outside of a loop");
          } catch (const detail::Break_Loop &) {
            throw exception::eval_error("Unexpected `break` statement outside of a loop");
          }
        }
    };
 
    template<typename T>
    struct Reference_AST_Node final : AST_Node_Impl<T> {
        Reference_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Reference, std::move(t_loc), std::move(t_children))
        { assert(this->children.size() == 1); }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override{
          Boxed_Value bv;
          t_ss.add_object(this->children[0]->text, bv);
          return bv;
        }
    };
 
    template<typename T>
    struct Prefix_AST_Node final : AST_Node_Impl<T> {
        Prefix_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Prefix, std::move(t_loc), std::move(t_children)),
          m_oper(Operators::to_operator(this->text, true))
        { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override{
          Boxed_Value bv(this->children[0]->eval(t_ss));
 
          try {
            // short circuit arithmetic operations
            if (m_oper != Operators::Opers::invalid && m_oper != Operators::Opers::bitwise_and && bv.get_type_info().is_arithmetic())
            {
              if ((m_oper == Operators::Opers::pre_increment || m_oper == Operators::Opers::pre_decrement) && bv.is_const())
              {
                throw exception::eval_error("Error with prefix operator evaluation: cannot modify constant value.");
              }
              return Boxed_Number::do_oper(m_oper, bv);
            } else {
              chaiscript::eval::detail::Function_Push_Pop fpp(t_ss);
              fpp.save_params({bv});
              return t_ss->call_function(this->text, m_loc, {std::move(bv)}, t_ss.conversions());
            }
          } catch (const exception::dispatch_error &e) {
            throw exception::eval_error("Error with prefix operator evaluation: '" + this->text + "'", e.parameters, e.functions, false, *t_ss);
          }
        }
 
      private:
        Operators::Opers m_oper = Operators::Opers::invalid;
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
    template<typename T>
    struct Break_AST_Node final : AST_Node_Impl<T> {
        Break_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Break, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &) const override{
          throw detail::Break_Loop();
        }
    };
 
    template<typename T>
    struct Continue_AST_Node final : AST_Node_Impl<T> {
        Continue_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Continue, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &) const override{
          throw detail::Continue_Loop();
        }
    };
 
    template<typename T>
    struct Noop_AST_Node final : AST_Node_Impl<T> {
        Noop_AST_Node() :
          AST_Node_Impl<T>("", AST_Node_Type::Noop, Parse_Location())
        { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &) const override{
          // It's a no-op, that evaluates to "void"
          return val;
        }
 
        Boxed_Value val = void_var();
    };
 
    template<typename T>
    struct Map_Pair_AST_Node final : AST_Node_Impl<T> {
        Map_Pair_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Map_Pair, std::move(t_loc), std::move(t_children)) { }
    };
 
    template<typename T>
    struct Value_Range_AST_Node final : AST_Node_Impl<T> {
        Value_Range_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Value_Range, std::move(t_loc), std::move(t_children)) { }
    };
 
    template<typename T>
    struct Inline_Range_AST_Node final : AST_Node_Impl<T> {
        Inline_Range_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Inline_Range, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override{
          try {
            auto oper1 = this->children[0]->children[0]->children[0]->eval(t_ss);
            auto oper2 = this->children[0]->children[0]->children[1]->eval(t_ss);
            return t_ss->call_function("generate_range", m_loc, {oper1, oper2}, t_ss.conversions());
          }
          catch (const exception::dispatch_error &e) {
            throw exception::eval_error("Unable to generate range vector, while calling 'generate_range'", e.parameters, e.functions, false, *t_ss);
          }
        }
 
      private:
        mutable std::atomic_uint_fast32_t m_loc = {0};
    };
 
    template<typename T>
    struct Try_AST_Node final : AST_Node_Impl<T> {
        Try_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Try, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value handle_exception(const chaiscript::detail::Dispatch_State &t_ss, const Boxed_Value &t_except) const
        {
          Boxed_Value retval;
 
          size_t end_point = this->children.size();
          if (this->children.back()->identifier == AST_Node_Type::Finally) {
            assert(end_point > 0);
            end_point = this->children.size() - 1;
          }
          for (size_t i = 1; i < end_point; ++i) {
            chaiscript::eval::detail::Scope_Push_Pop catch_scope(t_ss);
            auto &catch_block = *this->children[i];
 
            if (catch_block.children.size() == 1) {
              //No variable capture, no guards
              retval = catch_block.children[0]->eval(t_ss);
              break;
            } else if (catch_block.children.size() == 2 || catch_block.children.size() == 3) {
              const auto name = Arg_List_AST_Node<T>::get_arg_name(*catch_block.children[0]);
 
              if (dispatch::Param_Types(
                    std::vector<std::pair<std::string, Type_Info>>{Arg_List_AST_Node<T>::get_arg_type(*catch_block.children[0], t_ss)}
                    ).match(std::vector<Boxed_Value>{t_except}, t_ss.conversions()).first)
              {
                t_ss.add_object(name, t_except);
 
                if (catch_block.children.size() == 2) {
                  //Variable capture, no guards
                  retval = catch_block.children[1]->eval(t_ss);
                  break;
                }
                else if (catch_block.children.size() == 3) {
                  //Variable capture, guards
 
                  bool guard = false;
                  try {
                    guard = boxed_cast<bool>(catch_block.children[1]->eval(t_ss));
                  } catch (const exception::bad_boxed_cast &) {
                    if (this->children.back()->identifier == AST_Node_Type::Finally) {
                      this->children.back()->children[0]->eval(t_ss);
                    }
                    throw exception::eval_error("Guard condition not boolean");
                  }
                  if (guard) {
                    retval = catch_block.children[2]->eval(t_ss);
                    break;
                  }
                }
              }
            }
            else {
              if (this->children.back()->identifier == AST_Node_Type::Finally) {
                this->children.back()->children[0]->eval(t_ss);
              }
              throw exception::eval_error("Internal error: catch block size unrecognized");
            }
          }
 
          return retval;
        }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
          Boxed_Value retval;
 
          chaiscript::eval::detail::Scope_Push_Pop spp(t_ss);
 
 
          try {
            retval = this->children[0]->eval(t_ss);
          }
          catch (const exception::eval_error &e) {
            retval = handle_exception(t_ss, Boxed_Value(std::ref(e)));
          }
          catch (const std::runtime_error &e) {
            retval = handle_exception(t_ss, Boxed_Value(std::ref(e)));
          }
          catch (const std::out_of_range &e) {
            retval = handle_exception(t_ss, Boxed_Value(std::ref(e)));
          }
          catch (const std::exception &e) {
            retval = handle_exception(t_ss, Boxed_Value(std::ref(e)));
          }
          catch (Boxed_Value &e) {
            retval = handle_exception(t_ss, e);
          }
          catch (...) {
            if (this->children.back()->identifier == AST_Node_Type::Finally) {
              this->children.back()->children[0]->eval(t_ss);
            }
            throw;
          }
 
 
          if (this->children.back()->identifier == AST_Node_Type::Finally) {
            retval = this->children.back()->children[0]->eval(t_ss);
          }
 
          return retval;
        }
 
    };
 
    template<typename T>
    struct Catch_AST_Node final : AST_Node_Impl<T> {
        Catch_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Catch, std::move(t_loc), std::move(t_children)) { }
    };
 
    template<typename T>
    struct Finally_AST_Node final : AST_Node_Impl<T> {
        Finally_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Finally, std::move(t_loc), std::move(t_children)) { }
    };
 
    template<typename T>
    struct Method_AST_Node final : AST_Node_Impl<T> {
        std::shared_ptr<AST_Node_Impl<T>> m_body_node;
        std::shared_ptr<AST_Node_Impl<T>> m_guard_node;
 
        Method_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Method, std::move(t_loc),
              std::vector<AST_Node_Impl_Ptr<T>>(std::make_move_iterator(t_children.begin()),
                                                std::make_move_iterator(std::prev(t_children.end(), Def_AST_Node<T>::has_guard(t_children, 1)?2:1)))
              ),
            m_body_node(Def_AST_Node<T>::get_body_node(std::move(t_children))),
            m_guard_node(Def_AST_Node<T>::get_guard_node(std::move(t_children), t_children.size()-this->children.size()==2))
          {
          }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override{
 
          AST_Node_Impl_Ptr<T> guardnode;
 
          const std::string & class_name = this->children[0]->text;
 
          //The first param of a method is always the implied this ptr.
          std::vector<std::string> t_param_names{"this"};
          dispatch::Param_Types param_types;
 
          if ((this->children.size() > 2) 
               && (this->children[2]->identifier == AST_Node_Type::Arg_List)) {
            auto args = Arg_List_AST_Node<T>::get_arg_names(*this->children[2]);
            t_param_names.insert(t_param_names.end(), args.begin(), args.end());
            param_types = Arg_List_AST_Node<T>::get_arg_types(*this->children[2], t_ss);
          }
 
          const size_t numparams = t_param_names.size();
 
          std::shared_ptr<dispatch::Proxy_Function_Base> guard;
          std::reference_wrapper<chaiscript::detail::Dispatch_Engine> engine(*t_ss);
          if (m_guard_node) {
            guard = dispatch::make_dynamic_proxy_function(
                [engine, t_param_names, guardnode = m_guard_node](const std::vector<Boxed_Value> &t_params) {
                  return chaiscript::eval::detail::eval_function(engine, *guardnode, t_param_names, t_params);
                }, 
                static_cast<int>(numparams), m_guard_node);
          }
 
          try {
            const std::string & function_name = this->children[1]->text;
 
            if (function_name == class_name) {
              param_types.push_front(class_name, Type_Info());
 
              t_ss->add(
                  std::make_shared<dispatch::detail::Dynamic_Object_Constructor>(class_name,
                    dispatch::make_dynamic_proxy_function(
                        [engine, t_param_names, node = m_body_node](const std::vector<Boxed_Value> &t_params) {
                          return chaiscript::eval::detail::eval_function(engine, *node, t_param_names, t_params);
                        },
                        static_cast<int>(numparams), m_body_node, param_types, guard
                      )
                    ),
                  function_name);
 
            } else {
              // if the type is unknown, then this generates a function that looks up the type
              // at runtime. Defining the type first before this is called is better
              auto type = t_ss->get_type(class_name, false);
              param_types.push_front(class_name, type);
 
              t_ss->add(
                  std::make_shared<dispatch::detail::Dynamic_Object_Function>(class_name,
                    dispatch::make_dynamic_proxy_function(
                      [engine, t_param_names, node = m_body_node](const std::vector<Boxed_Value> &t_params) {
                        return chaiscript::eval::detail::eval_function(engine, *node, t_param_names, t_params);
                      },
                      static_cast<int>(numparams), m_body_node, param_types, guard), type), 
                  function_name);
            }
          } catch (const exception::name_conflict_error &e) {
            throw exception::eval_error("Method redefined '" + e.name() + "'");
          }
          return void_var();
        }
 
    };
 
    template<typename T>
    struct Attr_Decl_AST_Node final : AST_Node_Impl<T> {
        Attr_Decl_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Attr_Decl, std::move(t_loc), std::move(t_children)) { }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override 
        {
          std::string class_name = this->children[0]->text;
 
          try {
            std::string attr_name = this->children[1]->text;
 
            t_ss->add(
                std::make_shared<dispatch::detail::Dynamic_Object_Function>(
                     std::move(class_name),
                     fun([attr_name](dispatch::Dynamic_Object &t_obj) {
                           return t_obj.get_attr(attr_name);
                         }),
                     true
 
                ), this->children[1]->text);
          } catch (const exception::name_conflict_error &e) {
            throw exception::eval_error("Attribute redefined '" + e.name() + "'");
          }
          return void_var();
        }
 
    };
 
 
    template<typename T>
    struct Logical_And_AST_Node final : AST_Node_Impl<T> {
        Logical_And_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Logical_And, std::move(t_loc), std::move(t_children)) 
        { assert(this->children.size() == 2); }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override
        {
          return const_var(this->get_bool_condition(this->children[0]->eval(t_ss), t_ss)
              && this->get_bool_condition(this->children[1]->eval(t_ss), t_ss));
        }
 
    };
 
    template<typename T>
    struct Logical_Or_AST_Node final : AST_Node_Impl<T> {
        Logical_Or_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children) :
          AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Logical_Or, std::move(t_loc), std::move(t_children)) 
        { assert(this->children.size() == 2); }
 
        Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override
        {
          return const_var(this->get_bool_condition(this->children[0]->eval(t_ss), t_ss)
              || this->get_bool_condition(this->children[1]->eval(t_ss), t_ss));
        }
    };
  }
 
 
}
#endif /* CHAISCRIPT_EVAL_HPP_ */