examples

commit c292b86242b6da2bdc3398268d9f3477356e8a01
parent 319adf93a20711ce74b1b868952c5919e8f60f4a
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Sat,  6 Jul 2024 20:55:07 +0000

filter-bubble: Add coroutine generator example which filters expired weak_ptr and keeps them sorted

Diffstat:
A
src/filter-bubble.cpp
 | 
62
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 62 insertions(+), 0 deletions(-)
diff --git a/src/filter-bubble.cpp b/src/filter-bubble.cpp
@@ -0,0 +1,62 @@
+#include <vector>
+#include <string>
+#include <memory>
+#include <print>
+#include <generator>
+#include <algorithm>
+
+template <typename T>
+std::generator<T&> filter_bubble(std::vector<std::weak_ptr<T>>& vec)
+{
+	auto removed = vec.end();
+	auto it = vec.begin();
+
+	while (removed != it && it->expired())
+		std::iter_swap(it, --removed);
+
+	if (it != removed)
+	{
+		auto next = std::next(it);
+
+		while (next != removed)
+		{
+			if (next->expired())
+			{
+				std::iter_swap(next, --removed);
+				continue;
+			}
+			if (next->owner_before(*it))
+				std::iter_swap(it, next);
+			co_yield *it->lock();
+			it = next++;
+		}
+
+		co_yield *it->lock();
+	}
+
+	vec.erase(removed, vec.end());
+	co_return;
+}
+
+int main(int argv, char* argc[])
+{
+	std::vector<std::shared_ptr<std::string>> strings;
+	for (int i = 0; i < argv; ++i)
+		strings.push_back(std::make_shared<std::string>(argc[i]));
+
+	std::vector<std::weak_ptr<std::string>> string_refs;
+	std::ranges::copy(strings, std::back_inserter(string_refs));
+
+	std::random_shuffle(string_refs.begin(), string_refs.end());
+
+	for(unsigned i = 1;;++i)
+	{
+		std::print("round {} (", i);
+		for (auto& x : filter_bubble(string_refs))
+			std::print(" {}", x);
+		std::println(" ) {}", std::ranges::is_sorted(string_refs, std::owner_less<decltype(string_refs)::value_type>{}));
+		if (strings.empty())
+			break;
+		strings.erase(strings.begin() + std::rand() % strings.size());
+	}
+}