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129 lines
2.1 KiB
129 lines
2.1 KiB
#pragma once
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#include <gp/utils/iterators/iterator_properties.hpp>
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#include <cstddef>
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#include <cstdint>
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namespace gp {
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struct index_to_1 {
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size_t value;
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index_to_1(size_t v) : value{v + 1}
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{}
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void left() {
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value <<= 1;
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}
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void right() {
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value = (value << 1) + 1;
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}
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void up() {
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value >>= 1;
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}
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bool is_right() const {
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return value & 1;
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}
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bool is_left() const {
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return !(value & 1);
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}
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bool is_root() const {
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return value == 1;
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}
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operator size_t() {
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return value - 1;
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}
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};
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template<typename reflect, typename T, int sign = 1>
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struct flat_tree_iterator {
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reflect& tree;
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size_t index;
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bool has_right(index_to_1 v) const {
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v.right();
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return (v < tree.data().size()) && (tree.data()[v].has_value());
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}
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bool has_left(index_to_1 v) const {
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v.left();
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return (v < tree.data().size()) && (tree.data()[v].has_value());
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}
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flat_tree_iterator& operator++() {
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index = next();
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return *this;
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}
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flat_tree_iterator operator++(int) {
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auto cpy = *this;
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index = next();
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return cpy;
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}
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size_t next() const {
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index_to_1 it{index};
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enum class cases {
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right_climber,
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left_climber,
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descender,
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starter
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};
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const cases current_case = [&](){
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if(index == (size_t)-1) {
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return cases::starter;
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} else if(has_right(it)) {
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return cases::descender;
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} else if(it.is_left()) {
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return cases::left_climber;
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} else {
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return cases::right_climber;
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}
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}();
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switch(current_case) {
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case cases::starter: {
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it = index_to_1{0};
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while(has_left(it)) {
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it.left();
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}
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} break;
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case cases::descender: {
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it.right();
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while(has_left(it)) {
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it.left();
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}
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} break;
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case cases::left_climber: {
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it.up();
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} break;
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case cases::right_climber: {
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while(it.is_right()) {
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it.up();
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}
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if(it.is_root()) {
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it.value = -1;
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}
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} break;
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}
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return it;
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}
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bool operator!=(flat_tree_iterator rhs) {
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return index != rhs.index;
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}
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T& operator*() {
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return tree.data_[index].value();
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}
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};
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}
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