chaiscript_eval.hpp

// This file is distributed under the BSD License.
// See "license.txt" for details.
// Copyright 2009-2012, Jonathan Turner (jonathan@emptycrate.com)
// Copyright 2009-2018, 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::exception {
  class bad_boxed_cast;
} // namespace chaiscript::exception

namespace chaiscript {
  /// \brief Classes and functions that are part of the runtime eval system
  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 {
      /// Helper function that will set up the scope around a function call, including handling the named function parameters
      template<typename T>
      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 Function_Params &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 * {
          if (auto &stack = t_ss.get_stack_data(state.stack_holder()).back(); !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 &[name, value] : *t_locals) {
            state.add_object(name, value);
          }
        }

        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 if (incoming.get_type_info().bare_equal_type_info(typeid(std::string))) {
            return Boxed_Value(*static_cast<const std::string *>(incoming.get_const_ptr()));
          } else {
            std::array<Boxed_Value, 1> params{std::move(incoming)};
            return t_ss->call_function("clone", t_loc, Function_Params{params}, t_ss.conversions());
          }
        } else {
          incoming.reset_return_value();
          return incoming;
        }
      }
    } // namespace detail

    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);
            std::array<Boxed_Value, 2> params{t_lhs, m_rhs};
            fpp.save_params(Function_Params{params});
            return t_ss->call_function(t_oper_string, m_loc, Function_Params{params}, 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);
            std::array<Boxed_Value, 2> params{t_lhs, t_rhs};
            fpp.save_params(Function_Params(params));
            return t_ss->call_function(t_oper_string, m_loc, Function_Params(params), 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(Function_Params{params});
        }

        Boxed_Value fn(this->children[0]->eval(t_ss));

        try {
          return (*t_ss->boxed_cast<const dispatch::Proxy_Function_Base *>(fn))(Function_Params{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, make_vector(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);

        auto params = [&]() {
          // The RHS *must* be evaluated before the LHS
          // consider `var range = range(x)`
          // if we declare the variable in scope first, then the name lookup fails
          // for the RHS
          auto rhs = this->children[1]->eval(t_ss);
          auto lhs = this->children[0]->eval(t_ss);
          std::array<Boxed_Value, 2> p{std::move(lhs), std::move(rhs)};
          return p;
        }();

        if (params[0].is_return_value()) {
          throw exception::eval_error("Error, cannot assign to temporary value.");
        } else if (params[0].is_const()) {
          throw exception::eval_error("Error, cannot assign to constant value.");
        }

        if (m_oper != Operators::Opers::invalid && params[0].get_type_info().is_arithmetic() && params[1].get_type_info().is_arithmetic()) {
          try {
            return Boxed_Number::do_oper(m_oper, params[0], params[1]);
          } catch (const std::exception &) {
            throw exception::eval_error("Error with unsupported arithmetic assignment operation.");
          }
        } else if (m_oper == Operators::Opers::assign) {
          try {
            if (params[0].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)))

              {
                /// \todo This does not handle the case of an unassigned reference variable
                ///       being assigned outside of its declaration
                params[0].assign(params[1]);
                params[0].reset_return_value();
                return params[1];
              } else {
                params[1] = detail::clone_if_necessary(std::move(params[1]), m_clone_loc, t_ss);
              }
            }

            try {
              return t_ss->call_function(this->text, m_loc, Function_Params{params}, 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 (params[0].is_undef() || Boxed_Value::type_match(params[0], params[1])) {
            params[0].assign(params[1]);
            params[0].reset_return_value();
          } else {
            throw exception::eval_error("Mismatched types in equation");
          }
        } else {
          try {
            return t_ss->call_function(this->text, m_loc, Function_Params{params}, 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 params[1];
      }

    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);

        std::array<Boxed_Value, 2> params{this->children[0]->eval(t_ss), this->children[1]->eval(t_ss)};

        try {
          fpp.save_params(Function_Params{params});
          return t_ss->call_function("[]", m_loc, Function_Params{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);
        auto params = make_vector(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(Function_Params{params});

        try {
          retval = t_ss->call_member(m_fun_name, m_loc, Function_Params{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 {
            std::array<Boxed_Value, 2> p{retval, this->children[1]->children[1]->eval(t_ss)};
            retval = t_ss->call_function("[]", m_array_loc, Function_Params{p}, 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 Function_Params &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>> &t_children) noexcept {
        return std::any_of(std::begin(t_children), std::end(t_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) noexcept {
        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 Function_Params &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 Function_Params &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);

        /// \todo do this better
        // 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_loc, funs] = t_ss->get_function(t_name, hint);
          if (funs_loc != hint) {
            t_hint = uint_fast32_t(funs_loc);
          }
          return std::move(funs);
        };

        const auto call_function = [&t_ss](const auto &t_funcs, const Boxed_Value &t_param) {
          return dispatch::dispatch(*t_funcs, Function_Params{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);
              /// to-do make this if-constexpr with C++17 branch
              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 &) {
                // continue statement hit
              }
              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 {
                std::array<Boxed_Value, 2> p{match_value, this->children[currentCase]->children[0]->eval(t_ss)};
                if (hasMatched || boxed_cast<bool>(t_ss->call_function("==", m_loc, Function_Params{p}, 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(Function_Params{bv});
            return t_ss->call_function(this->text, m_loc, Function_Params{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 {
          std::array<Boxed_Value, 2> params{this->children[0]->children[0]->children[0]->eval(t_ss),
                                            this->children[0]->children[0]->children[1]->eval(t_ss)};

          return t_ss->call_function("generate_range", m_loc, Function_Params{params}, 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
            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(Function_Params{t_except}, t_ss.conversions())
                    .first) {
              t_ss.add_object(name, t_except);

              if (catch_block.children.size() == 2) {
                // Variable capture
                retval = catch_block.children[1]->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 Function_Params &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 Function_Params &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 Function_Params &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));
      }
    };
  } // namespace eval

} // namespace chaiscript
#endif /* CHAISCRIPT_EVAL_HPP_ */