From 2ef2ea1728fce0c9a6526b0820b03b7002d234d1 Mon Sep 17 00:00:00 2001
From: wqking <wqking@outlook.com>
Date: Fri, 19 Jul 2024 15:58:29 +0800
Subject: [PATCH] When ranking overloaded callables, break when an exactly
 matched callable is found to improve performance

---
 .../metapp/implement/internal/declareutil_i.h | 13 ++++++-----
 include/metapp/interfaces/metacallable.h      |  8 +++++++
 tests/benchmark/benchmark_misc.cpp            | 22 +++++++++++++++++++
 .../metatypes/test_default_args_function.cpp  |  2 +-
 tests/unittest/test_metacallable.cpp          |  4 ++--
 5 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/include/metapp/implement/internal/declareutil_i.h b/include/metapp/implement/internal/declareutil_i.h
index 0da2c7ae..f3fb9f74 100644
--- a/include/metapp/implement/internal/declareutil_i.h
+++ b/include/metapp/implement/internal/declareutil_i.h
@@ -24,13 +24,10 @@
 #include <type_traits>
 #include <numeric>
 #include <algorithm>
+#include <limits>
 
 namespace metapp {
 
-static constexpr int invokeRankMatch = 1000;
-static constexpr int invokeRankCast = 1;
-static constexpr int invokeRankNone = 0;
-
 namespace internal_ {
 
 template <typename TL, std::size_t N>
@@ -88,7 +85,7 @@ struct MetaCallableInvokeChecker
 	template <int ...Indexes>
 	static int doRankInvoke(const ArgumentSpan & arguments, IntConstantList<Indexes...>) {
 		if(argCount == arguments.size() && arguments.empty()) {
-			return invokeRankMatch;
+			return invokeRankMax;
 		}
 		std::array<int, argCount> rankList {
 			rankArgumentMatching<ArgumentTypeList, Indexes>(arguments)...
@@ -97,13 +94,17 @@ struct MetaCallableInvokeChecker
 		(void)arguments;
 		(void)rankList;
 		int rank = 0;
+		bool allMatchExactly = true;
 		for(auto it = std::begin(rankList); it != std::end(rankList); ++it) {
 			if(*it == invokeRankNone) {
 				return invokeRankNone;
 			}
+			if(*it != invokeRankMatch) {
+				allMatchExactly = false;
+			}
 			rank += *it;
 		}
-		return rank;
+		return allMatchExactly ? invokeRankMax : rank;
 	}
 };
 
diff --git a/include/metapp/interfaces/metacallable.h b/include/metapp/interfaces/metacallable.h
index e02e5f03..b3fbec2a 100644
--- a/include/metapp/interfaces/metacallable.h
+++ b/include/metapp/interfaces/metacallable.h
@@ -115,6 +115,11 @@ class MetaCallable
 	}
 };
 
+static constexpr int invokeRankMatch = 1000;
+static constexpr int invokeRankCast = 1;
+static constexpr int invokeRankNone = 0;
+static constexpr int invokeRankMax = std::numeric_limits<int>::max();
+
 template <typename Iterator>
 Iterator findCallable(
 	Iterator first,
@@ -133,6 +138,9 @@ Iterator findCallable(
 		if(rank > maxRank) {
 			maxRank = rank;
 			result = first;
+			if(rank == invokeRankMax) {
+				break;
+			}
 		}
 	}
 	
diff --git a/tests/benchmark/benchmark_misc.cpp b/tests/benchmark/benchmark_misc.cpp
index c63e5653..4344957d 100644
--- a/tests/benchmark/benchmark_misc.cpp
+++ b/tests/benchmark/benchmark_misc.cpp
@@ -144,5 +144,27 @@ BenchmarkFunc
 	printResult(t2, iterations, "Misc, Fill std::vector<metapp::Variant>, MetaIndexable");
 }
 
+metapp::Variant tempGet(const int n)
+{
+	switch(n) {
+	case 0:
+		return 5LL;
+	case 1:
+		return 6LL;
+	}
+	return "abc";
+}
+
+TEST_CASE("temp")
+{
+	constexpr int iterations = generalIterations;
+	const auto t1 = measureElapsedTime([iterations]() {
+		for(int i = 0; i < iterations; ++i) {
+			metapp::Variant v = tempGet(i % 2);
+			dontOptimizeAway(v);
+		}
+	});
+	printResult(t1, iterations, "Misc, temp");
+}
 
 } //namespace
diff --git a/tests/unittest/metatypes/test_default_args_function.cpp b/tests/unittest/metatypes/test_default_args_function.cpp
index 0ab9374e..1e7b7ea0 100644
--- a/tests/unittest/metatypes/test_default_args_function.cpp
+++ b/tests/unittest/metatypes/test_default_args_function.cpp
@@ -112,7 +112,7 @@ TEST_CASE("metatypes, DefaultArgsFunction, MyClass::myFunc2")
 	REQUIRE(metapp::callableRankInvoke(v, &obj, 5) == metapp::invokeRankNone);
 	// metapp::invokeRankMatch * 3 is each of the three default arguments receives metapp::invokeRankMatch.
 	REQUIRE(metapp::callableRankInvoke(v, &obj, 5, std::string("abc"))
-		== metapp::invokeRankMatch + metapp::invokeRankMatch + metapp::invokeRankMatch * 3);
+		== metapp::invokeRankMax);
 	REQUIRE(metapp::callableRankInvoke(v, &obj, 5, "abc")
 		== metapp::invokeRankMatch + metapp::invokeRankCast + metapp::invokeRankMatch * 3);
 	REQUIRE(metapp::callableRankInvoke(v, &obj, 5, "abc", 6)
diff --git a/tests/unittest/test_metacallable.cpp b/tests/unittest/test_metacallable.cpp
index 5bfdd142..9f1c3df1 100644
--- a/tests/unittest/test_metacallable.cpp
+++ b/tests/unittest/test_metacallable.cpp
@@ -28,10 +28,10 @@ namespace {
 
 TEST_CASE("MetaCallable, rankInvoke")
 {
-	REQUIRE(metapp::callableRankInvoke(std::function<void (int)>(), nullptr, 5) == metapp::invokeRankMatch);
+	REQUIRE(metapp::callableRankInvoke(std::function<void (int)>(), nullptr, 5) == metapp::invokeRankMax);
 	REQUIRE(metapp::callableRankInvoke(std::function<void (int)>(), nullptr, metapp::Variant(5)) == metapp::invokeRankCast);
 
-	REQUIRE(metapp::callableRankInvoke(std::function<void (std::string)>(), nullptr, std::string("abc")) == metapp::invokeRankMatch);
+	REQUIRE(metapp::callableRankInvoke(std::function<void (std::string)>(), nullptr, std::string("abc")) == metapp::invokeRankMax);
 	REQUIRE(metapp::callableRankInvoke(std::function<void (std::string)>(), nullptr, "abc") == metapp::invokeRankCast);
 
 	REQUIRE(metapp::callableRankInvoke(std::function<void (long, std::string)>(), nullptr, 5, "abc") == metapp::invokeRankCast + metapp::invokeRankCast);