468 lines
18 KiB
C++
468 lines
18 KiB
C++
#pragma once
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/*
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* Copyright (C) 2024 Brett Terpstra
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef BLT_GP_PROGRAM_H
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#define BLT_GP_PROGRAM_H
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#include <cstddef>
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#include <functional>
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#include <type_traits>
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#include <string_view>
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#include <string>
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#include <utility>
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#include <iostream>
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#include <random>
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#include <algorithm>
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#include <memory>
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#include <blt/std/ranges.h>
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#include <blt/std/hashmap.h>
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#include <blt/std/types.h>
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#include <blt/std/utility.h>
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#include <blt/std/memory.h>
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#include <blt/gp/fwdecl.h>
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#include <blt/gp/typesystem.h>
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#include <blt/gp/operations.h>
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#include <blt/gp/transformers.h>
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#include <blt/gp/tree.h>
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#include <blt/gp/stack.h>
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namespace blt::gp
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{
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struct argc_t
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{
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blt::u32 argc = 0;
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blt::u32 argc_context = 0;
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[[nodiscard]] bool is_terminal() const
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{
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return argc == 0;
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}
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};
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struct operator_info
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{
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// types of the arguments
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std::vector<type_id> argument_types;
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// return type of this operator
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type_id return_type;
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// number of arguments for this operator
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argc_t argc;
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// function to call this operator
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detail::callable_t function;
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// function used to transfer values between stacks
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detail::transfer_t transfer;
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};
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struct operator_storage
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{
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// indexed from return TYPE ID, returns index of operator
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blt::expanding_buffer<std::vector<operator_id>> terminals;
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blt::expanding_buffer<std::vector<operator_id>> non_terminals;
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blt::expanding_buffer<std::vector<std::pair<operator_id, blt::size_t>>> operators_ordered_terminals;
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// indexed from OPERATOR ID (operator number)
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blt::hashset_t<operator_id> static_types;
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std::vector<operator_info> operators;
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std::vector<detail::print_func_t> print_funcs;
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std::vector<std::optional<std::string_view>> names;
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};
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template<typename Context = detail::empty_t>
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class operator_builder
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{
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friend class gp_program;
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friend class blt::gp::detail::operator_storage_test;
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public:
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explicit operator_builder(type_provider& system): system(system)
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{}
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template<typename ArgType, typename Return, typename... Args>
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operator_builder& add_operator(const operation_t<ArgType, Return(Args...)>& op, bool is_static = false)
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{
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auto return_type_id = system.get_type<Return>().id();
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auto operator_id = blt::gp::operator_id(storage.operators.size());
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auto& operator_list = op.get_argc() == 0 ? storage.terminals : storage.non_terminals;
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operator_list[return_type_id].push_back(operator_id);
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operator_info info;
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if constexpr (sizeof...(Args) > 0)
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{
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(add_non_context_argument<Args>(info.argument_types), ...);
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}
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info.argc.argc_context = info.argc.argc = sizeof...(Args);
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info.return_type = system.get_type<Return>().id();
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((std::is_same_v<detail::remove_cv_ref<Args>, Context> ? info.argc.argc -= 1 : (blt::size_t) nullptr), ...);
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BLT_ASSERT(info.argc.argc_context - info.argc.argc <= 1 && "Cannot pass multiple context as arguments!");
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info.function = op.template make_callable<Context>();
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info.transfer = [](std::optional<std::reference_wrapper<stack_allocator>> to, stack_allocator& from) {
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#if BLT_DEBUG_LEVEL >= 3
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auto value = from.pop<Return>();
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//BLT_TRACE_STREAM << value << "\n";
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if (to){
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to->get().push(value);
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}
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#else
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if (to)
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{
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to->get().push(from.pop<Return>());
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} else
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{
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from.pop<Return>();
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}
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#endif
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};
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storage.operators.push_back(info);
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storage.print_funcs.push_back([](std::ostream& out, stack_allocator& stack) {
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out << stack.pop<Return>();
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});
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storage.names.push_back(op.get_name());
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if (is_static)
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storage.static_types.insert(operator_id);
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return *this;
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}
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operator_storage&& build()
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{
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blt::hashset_t<type_id> has_terminals;
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for (const auto& v : blt::enumerate(storage.terminals))
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{
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if (!v.second.empty())
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has_terminals.insert(v.first);
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}
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for (const auto& op_r : blt::enumerate(storage.non_terminals))
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{
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if (op_r.second.empty())
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continue;
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auto return_type = op_r.first;
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std::vector<std::pair<operator_id, blt::size_t>> ordered_terminals;
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for (const auto& op : op_r.second)
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{
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// count number of terminals
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blt::size_t terminals = 0;
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for (const auto& type : storage.operators[op].argument_types)
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{
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if (has_terminals.contains(type))
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terminals++;
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}
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ordered_terminals.emplace_back(op, terminals);
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}
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bool found_terminal_inputs = false;
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bool matches_argc = false;
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for (const auto& terms : ordered_terminals)
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{
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if (terms.second == storage.operators[terms.first].argc.argc)
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matches_argc = true;
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if (terms.second != 0)
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found_terminal_inputs = true;
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if (matches_argc && found_terminal_inputs)
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break;
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}
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if (!found_terminal_inputs)
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BLT_ABORT(("Failed to find function with terminal arguments for return type " + std::to_string(return_type)).c_str());
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if (!matches_argc)
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{
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BLT_ABORT(("Failed to find a function which purely translates types "
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"(that is all input types are terminals) for return type " + std::to_string(return_type)).c_str());
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}
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std::sort(ordered_terminals.begin(), ordered_terminals.end(), [](const auto& a, const auto& b) {
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return a.second > b.second;
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});
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auto first_size = *ordered_terminals.begin();
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auto iter = ordered_terminals.begin();
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while (++iter != ordered_terminals.end() && iter->second == first_size.second)
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{}
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ordered_terminals.erase(iter, ordered_terminals.end());
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storage.operators_ordered_terminals[return_type] = ordered_terminals;
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}
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return std::move(storage);
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}
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private:
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template<typename T>
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void add_non_context_argument(decltype(operator_info::argument_types)& types)
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{
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if constexpr (!std::is_same_v<Context, detail::remove_cv_ref<T>>)
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{
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types.push_back(system.get_type<T>().id());
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}
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}
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type_provider& system;
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operator_storage storage;
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};
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class gp_program
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{
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public:
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struct config_t
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{
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blt::size_t population_size = 500;
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blt::size_t initial_min_tree_size = 3;
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blt::size_t initial_max_tree_size = 10;
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std::reference_wrapper<mutation_t> mutator;
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std::reference_wrapper<crossover_t> crossover;
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std::reference_wrapper<population_initializer_t> pop_initializer;
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// default config (ramped half-and-half init) or for buildering
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config_t();
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// default config with a user specified initializer
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config_t(const std::reference_wrapper<population_initializer_t>& popInitializer); // NOLINT
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config_t(size_t populationSize, size_t initialMinTreeSize, size_t initialMaxTreeSize);
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config_t(size_t populationSize, size_t initialMinTreeSize, size_t initialMaxTreeSize,
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const std::reference_wrapper<population_initializer_t>& popInitializer);
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config_t(size_t populationSize, size_t initialMinTreeSize, size_t initialMaxTreeSize,
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const std::reference_wrapper<mutation_t>& mutator, const std::reference_wrapper<crossover_t>& crossover,
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const std::reference_wrapper<population_initializer_t>& popInitializer);
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config_t& set_pop_size(blt::size_t pop)
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{
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population_size = pop;
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return *this;
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}
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config_t& set_initial_min_tree_size(blt::size_t size)
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{
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initial_min_tree_size = size;
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return *this;
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}
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config_t& set_initial_max_tree_size(blt::size_t size)
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{
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initial_max_tree_size = size;
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return *this;
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}
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config_t& set_crossover(crossover_t& ref)
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{
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crossover = ref;
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return *this;
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}
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config_t& set_mutation(mutation_t& ref)
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{
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mutator = ref;
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return *this;
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}
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config_t& set_initializer(population_initializer_t& ref)
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{
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pop_initializer = ref;
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return *this;
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}
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};
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/**
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* Note about context size: This is required as context is passed to every operator in the GP tree, this context will be provided by your
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* call to one of the evaluator functions. This was the nicest way to provide this as C++ lacks reflection
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*
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* @param system type system to use in tree generation
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* @param engine random engine to use throughout the program. TODO replace this with something better
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* @param context_size number of arguments which are always present as "context" to the GP system / operators
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*/
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explicit gp_program(type_provider& system, std::mt19937_64 engine):
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system(system), engine(engine)
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{}
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explicit gp_program(type_provider& system, std::mt19937_64 engine, config_t config):
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system(system), engine(engine), config(config)
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{}
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void generate_population(type_id root_type);
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/**
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* takes in a lambda for the fitness evaluation function (must return a value convertable to double)
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* The lambda must accept a tree for evaluation, container for evaluation context, and a index into that container (current tree)
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*
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* Container must be concurrently accessible from multiple threads using operator[]
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*
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* NOTE: 0 is considered the best, in terms of standardized and adjusted fitness
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*/
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template<typename Return, typename Class, typename Container, typename Lambda = Return(Class::*)(tree_t, Container, blt::size_t) const>
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void evaluate_fitness(Lambda&& fitness_function, Container& result_storage)
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{
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for (const auto& ind : blt::enumerate(current_pop.get_individuals()))
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ind.second.raw_fitness = static_cast<double>(fitness_function(ind.second.tree, result_storage, ind.first));
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double min = 0;
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for (auto& ind : current_pop.get_individuals())
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{
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if (ind.raw_fitness < min)
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min = ind.raw_fitness;
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}
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double overall_fitness = 0;
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double best_fitness = 2;
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double worst_fitness = 0;
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individual* best = nullptr;
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individual* worst = nullptr;
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auto diff = -min;
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for (auto& ind : current_pop.get_individuals())
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{
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auto standardized_fitness = ind.raw_fitness + diff;
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ind.adjusted_fitness = 1.0 / (1.0 + standardized_fitness);
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if (ind.adjusted_fitness > worst_fitness)
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{
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worst_fitness = ind.adjusted_fitness;
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worst = &ind;
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}
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if (ind.adjusted_fitness < best_fitness)
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{
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best_fitness = ind.adjusted_fitness;
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best = &ind;
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}
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overall_fitness += ind.adjusted_fitness;
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}
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current_stats = {overall_fitness, overall_fitness / static_cast<double>(config.population_size), best_fitness, worst_fitness, best,
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worst};
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}
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void next_generation()
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{
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current_pop = next_pop;
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current_generation++;
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}
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[[nodiscard]] inline std::mt19937_64& get_random()
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{
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return engine;
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}
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[[nodiscard]] inline bool choice()
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{
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static std::uniform_int_distribution dist(0, 1);
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return dist(engine);
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}
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/**
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* @param cutoff percent in floating point form chance of the event happening.
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* @return
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*/
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[[nodiscard]] inline bool choice(double cutoff)
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{
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static std::uniform_real_distribution dist(0.0, 1.0);
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return dist(engine) < cutoff;
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}
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[[nodiscard]] inline type_provider& get_typesystem()
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{
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return system;
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}
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inline operator_id select_terminal(type_id id)
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{
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// we wanted a terminal, but could not find one, so we will select from a function that has a terminal
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if (storage.terminals[id].empty())
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return select_non_terminal_too_deep(id);
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std::uniform_int_distribution<blt::size_t> dist(0, storage.terminals[id].size() - 1);
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return storage.terminals[id][dist(engine)];
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}
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inline operator_id select_non_terminal(type_id id)
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{
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std::uniform_int_distribution<blt::size_t> dist(0, storage.non_terminals[id].size() - 1);
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return storage.non_terminals[id][dist(engine)];
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}
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inline operator_id select_non_terminal_too_deep(type_id id)
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{
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std::uniform_int_distribution<blt::size_t> dist(0, storage.operators_ordered_terminals[id].size() - 1);
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return storage.operators_ordered_terminals[id][dist(engine)].first;
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}
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inline operator_info& get_operator_info(operator_id id)
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{
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return storage.operators[id];
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}
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inline detail::print_func_t& get_print_func(operator_id id)
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{
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return storage.print_funcs[id];
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}
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inline std::optional<std::string_view> get_name(operator_id id)
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{
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return storage.names[id];
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}
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inline std::vector<operator_id>& get_type_terminals(type_id id)
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{
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return storage.terminals[id];
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}
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inline std::vector<operator_id>& get_type_non_terminals(type_id id)
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{
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return storage.non_terminals[id];
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}
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inline bool is_static(operator_id id)
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{
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return storage.static_types.contains(static_cast<blt::size_t>(id));
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}
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inline void set_operations(operator_storage&& op)
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{
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storage = std::move(op);
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}
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private:
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type_provider& system;
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blt::gp::stack_allocator alloc;
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operator_storage storage;
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population_t current_pop;
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population_stats current_stats;
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population_t next_pop;
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blt::size_t current_generation = 0;
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std::mt19937_64 engine;
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config_t config;
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};
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}
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#endif //BLT_GP_PROGRAM_H
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