459 lines
18 KiB
C++
459 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 <algorithm>
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#include <memory>
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#include <array>
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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/std/meta.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/selection.h>
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#include <blt/gp/tree.h>
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#include <blt/gp/stack.h>
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#include <blt/gp/config.h>
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#include <blt/gp/random.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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/**
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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, random_t engine):
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system(system), engine(engine)
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{}
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explicit gp_program(type_provider& system, random_t engine, prog_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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current_pop = config.pop_initializer.get().generate(
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{*this, root_type, config.population_size, config.initial_min_tree_size, config.initial_max_tree_size});
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}
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template<typename Crossover, typename Mutation, typename Reproduction, typename Creation_Func = decltype(default_next_pop_creator<Crossover, Mutation, Reproduction>)>
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void create_next_generation(Crossover&& crossover_selection, Mutation&& mutation_selection, Reproduction&& reproduction_selection,
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Creation_Func& func = default_next_pop_creator<Crossover, Mutation, Reproduction>)
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{
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// should already be empty
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next_pop.clear();
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crossover_selection.pre_process(*this, current_pop, current_stats);
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mutation_selection.pre_process(*this, current_pop, current_stats);
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reproduction_selection.pre_process(*this, current_pop, current_stats);
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func(get_selector_args(), std::forward<Crossover>(crossover_selection), std::forward<Mutation>(mutation_selection),
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std::forward<Reproduction>(reproduction_selection));
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}
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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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* tree_t&, Container&, blt::size_t
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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 Container, typename Callable>
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void evaluate_fitness(Callable&& 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 = std::move(next_pop);
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current_generation++;
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}
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template<blt::size_t size>
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std::array<blt::size_t, size> get_best_indexes()
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{
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std::array<blt::size_t, size> arr;
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std::vector<std::pair<blt::size_t, double>> values;
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values.reserve(current_pop.get_individuals().size());
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for (const auto& ind : blt::enumerate(current_pop.get_individuals()))
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values.emplace_back(ind.first, ind.second.adjusted_fitness);
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std::sort(values.begin(), values.end(), [](const auto& a, const auto& b) {
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return a.second < b.second;
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});
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for (blt::size_t i = 0; i < size; i++)
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arr[i] = values[i].first;
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return arr;
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}
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template<blt::size_t size>
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std::array<std::reference_wrapper<tree_t>, size> get_best()
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{
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return convert_array(get_best_indexes<size>(), std::make_integer_sequence<blt::size_t, size>());
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}
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[[nodiscard]] bool should_terminate() const
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{
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return current_generation >= config.max_generations;
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}
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[[nodiscard]] inline random_t& get_random()
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{
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return engine;
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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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return storage.terminals[id][engine.get_size_t(0, storage.terminals[id].size())];
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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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return storage.non_terminals[id][engine.get_size_t(0, storage.non_terminals[id].size())];
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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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return storage.operators_ordered_terminals[id][engine.get_size_t(0, storage.operators_ordered_terminals[id].size())].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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[[nodiscard]] inline auto get_current_generation() const
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{
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return current_generation;
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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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random_t engine;
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prog_config_t config;
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inline selector_args get_selector_args()
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{
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return {*this, next_pop, current_pop, current_stats, config, engine};
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}
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template<blt::size_t size, blt::size_t... indexes>
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inline std::array<std::reference_wrapper<tree_t>, size> convert_array(std::array<blt::size_t, size>&& arr,
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std::integer_sequence<blt::size_t, indexes...>)
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{
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return {current_pop.get_individuals()[arr[indexes]].tree...};
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}
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};
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}
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#endif //BLT_GP_PROGRAM_H
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