Iter stuff

libswan/CMakeLists.txt

@@ -22,7 +22,8 @@ target_link_libraries(libswan ${libraries})
 install(TARGETS libswan DESTINATION swan/libswan)
 
 add_executable(test_libswan EXCLUDE_FROM_ALL
-	test/lib/test.cc)
+	test/lib/test.cc
+	test/util.t.cc)
 target_link_libraries(test_libswan libswan)
 target_include_directories(test_libswan
 	PRIVATE "include/swan")

libswan/include/swan/util.h

@@ -4,6 +4,7 @@
 #include <functional>
 #include <memory>
 #include <chrono>
+#include <type_traits>
 
 namespace Swan {
 
@@ -56,11 +57,11 @@ public:
 	public:
 		It(std::optional<Ret> next, Func &func): next_(std::move(next)), func_(func) {}
 
-		bool operator==(It &other) {
+		bool operator==(const It &other) {
 			return next_ == std::nullopt && other.next_ == std::nullopt;
 		}
 
-		bool operator!=(It &other) {
+		bool operator!=(const It &other) {
 			return !(*this == other);
 		}
 
@@ -104,7 +105,51 @@ auto map(InputIterator first, InputIterator last, Func func) {
 			return std::nullopt;
 
 		RetT r = func(*first);
-		first++;
+		++first;
+		return r;
+	};
+
+	return Iter<RetT, decltype(l)>(l);
+}
+
+template<typename InputIterator, typename Func>
+auto filter(InputIterator first, InputIterator last, Func pred) {
+	using RetT = std::remove_reference_t<decltype(*first)>;
+
+	auto l = [=]() mutable -> std::optional<RetT> {
+		if (first == last)
+			return std::nullopt;
+
+		while (!pred(*first)) {
+			++first;
+			if (first == last)
+				return std::nullopt;
+		}
+
+		RetT r = *first;
+		++first;
+		return r;
+	};
+
+	return Iter<RetT, decltype(l)>(l);
+}
+
+template<typename InputIterator, typename Func>
+auto mapFilter(InputIterator first, InputIterator last, Func func) {
+	using RetT = std::remove_reference_t<decltype(*func(*first))>;
+
+	auto l = [=]() mutable -> std::optional<RetT> {
+		if (first == last)
+			return std::nullopt;
+
+		std::optional<RetT> r;
+		while ((r = func(*first)) == std::nullopt) {
+			++first;
+			if (first == last)
+				return std::nullopt;
+		}
+
+		++first;
 		return r;
 	};
 

libswan/test/util.t.cc

@@ -0,0 +1,41 @@
+#include "util.h"
+
+#include <iostream>
+
+#include "lib/test.h"
+
+test("map") {
+	int ints[] = { 100, 200, 300, 400 };
+	auto mapping = Swan::map(std::begin(ints), std::end(ints), [](int i) { return i / 10; });
+	auto iter = mapping.begin();
+
+	expecteq(*iter, 10); ++iter;
+	expecteq(*iter, 20); ++iter;
+	expecteq(*iter, 30); ++iter;
+	expecteq(*iter, 40); ++iter;
+	expecteq(iter, mapping.end());
+}
+
+test("filter") {
+	int ints[] = { 100, 200, 300, 400 };
+	auto filter = Swan::filter(std::begin(ints), std::end(ints), [](int i) { return i == 200 || i == 400; });
+	auto iter = filter.begin();
+
+	expecteq(*iter, 200); ++iter;
+	expecteq(*iter, 400); ++iter;
+	expecteq(iter, filter.end());
+}
+
+test("mapFilter") {
+	float floats[] = { 10.1, 20.2, 30.3 };
+	auto mapfilt = Swan::mapFilter(std::begin(floats), std::end(floats), [](float f) -> std::optional<int> {
+		if ((int)f == 20)
+			return std::nullopt;
+		return (int)f;
+	});
+	auto iter = mapfilt.begin();
+
+	expecteq(*iter, 10); ++iter;
+	expecteq(*iter, 30); ++iter;
+	expecteq(iter, mapfilt.end());
+}