Add simple benchmarks

test/CMakeLists.txt

@@ -29,7 +29,12 @@ include_directories(SYSTEM ${CMAKE_SOURCE_DIR}/../range-v3/include
 
 find_package(Qt5Core)
 
-add_executable(${PROJECT_NAME} "main.cpp" "FooBar.h" "../src/qrange.h" ${QRANGE_IMPL_INCLUDE})
+set(INCLUDES "FooBar.h" "../src/qrange.h" ${QRANGE_IMPL_INCLUDE})
+if(CMAKE_BUILD_TYPE EQUAL "RELEASE")
+    set(INCLUDES "${INCLUDES} benchmarks.h")
+endif(CMAKE_BUILD_TYPE EQUAL "RELEASE")
+
+add_executable(${PROJECT_NAME} "main.cpp" ${INCLUDES})
 
 if(APPLE AND ${CMAKE_VERSION} VERSION_LESS "3.15.0" AND ${CMAKE_CXX_COMPILER_ID} MATCHES "AppleClang")
   set(CMAKE_CXX20_STANDARD_COMPILE_OPTION "-std=c++2a")

test/benchmarks.h

+#ifndef BENCHMARKS_H
+#define BENCHMARKS_H
+
+#ifdef NDEBUG
+#include <chrono>
+#include <iostream>
+#include <memory>
+#include <stack>
+
+#include "qrange.h"
+
+template <class F, class D>
+void measureTime(const std::string &s, F f, D d, std::size_t times)
+{
+    double time = 0;
+
+    for (std::size_t t = 0; t < times; ++t) {
+        auto data = d();
+
+        auto start = std::chrono::system_clock::now();
+        f(data);
+        auto end = std::chrono::system_clock::now();
+
+        std::chrono::duration<double, std::milli> elapsed = end - start;
+        time += elapsed.count();
+    }
+
+    std::cout << s << ": " << (time / times) << " msec" << " (run " << times << " times)" << std::endl;
+}
+
+std::shared_ptr<QObject> genTree(int depth = 22, std::size_t nodeChildrenCount = 2)
+{
+    auto root = std::make_shared<QObject>();
+
+    std::stack<QObject*> s;
+    s.push(root.get());
+
+    while (depth--) {
+
+        std::stack<QObject*> layer;
+        while (!s.empty()) {
+            auto e = s.top();
+            s.pop();
+
+            for (std::size_t cc = 0; cc < nodeChildrenCount; ++cc) {
+                layer.push(new QObject(e));
+            }
+        }
+
+        s.swap(layer);
+    }
+
+    return root;
+}
+
+void setChildrenNamesOld(const std::shared_ptr<QObject> &obj)
+{
+    for (auto &&c : obj->findChildren<QObject*>()) {
+        c->setObjectName("foo");
+    }
+}
+
+void setChildrenNamesNew(const std::shared_ptr<QObject> &obj)
+{
+    for (auto &&c : obj.get() | qt::find_children(Qt::FindChildrenRecursively)) {
+        c->setObjectName("foo");
+    }
+}
+
+void setChildrenNamesNewWithCopy(const std::shared_ptr<QObject> &obj)
+{
+    const std::vector<QObject*> d = obj.get() | qt::find_children(Qt::FindChildrenRecursively);
+    for (auto &&c : d) {
+        c->setObjectName("foo");
+    }
+}
+
+void runBenchmarks()
+{
+    auto gen = []{ static auto tree = genTree(); return tree; };
+
+    measureTime("Old"     , &setChildrenNamesOld        , gen, 10);
+    measureTime("New"     , &setChildrenNamesNew        , gen, 10);
+    measureTime("New copy", &setChildrenNamesNewWithCopy, gen, 10);
+}
+#endif // NDEBUG
+
+#endif // BENCHMARKS_H

test/main.cpp

@@ -4,6 +4,10 @@
 
 #include "FooBar.h"
 
+#ifdef NDEBUG
+#include "benchmarks.h"
+#endif // NDEBUG
+
 #include "qrange.h"
 
 int main(int argc, char *argv[])
@@ -49,5 +53,9 @@ int main(int argc, char *argv[])
         assert(children.at(0) == l4);
     }
 
+#ifdef NDEBUG
+    runBenchmarks();
+#endif // NDEBUG
+
     return 0;
 }