Add `RegisterBenchmark(name, func, args...)` for creating/registering benchmarks. (#259)

* Add RegisterBenchmark

* fix test inputs

* fix UB caused by unitialized value

* Add RegisterBenchmark

* fix test inputs

* fix UB caused by unitialized value

* Work around GCC 4.6/4.7/4.8 bug

README.md

@@ -206,6 +206,34 @@ BENCHMARK_CAPTURE(BM_takes_args, int_string_test, 42, std::string("abc"));
 Note that elements of `...args` may refer to global variables. Users should
 avoid modifying global state inside of a benchmark.
 
+## Using RegisterBenchmark(name, fn, args...)
+
+The `RegisterBenchmark(name, func, args...)` function provides an alternative
+way to create and register benchmarks.
+`RegisterBenchmark(name, func, args...)` creates, registers, and returns a
+pointer to a new benchmark with the specified `name` that invokes
+`func(st, args...)` where `st` is a `benchmark::State` object.
+
+Unlike the `BENCHMARK` registration macros, which can only be used at the global
+scope, the `RegisterBenchmark` can be called anywhere. This allows for
+benchmark tests to be registered programmatically.
+
+Additionally `RegisterBenchmark` allows any callable object to be registered
+as a benchmark. Including capturing lambdas and function objects. This
+allows the creation
+
+For Example:
+```c++
+auto BM_test = [](benchmark::State& st, auto Inputs) { /* ... */ };
+
+int main(int argc, char** argv) {
+  for (auto& test_input : { /* ... */ })
+      benchmark::RegisterBenchmark(test_input.name(), BM_test, test_input);
+  benchmark::Initialize(&argc, argv);
+  benchmark::RunSpecifiedBenchmarks();
+}
+```
+
 ### Multithreaded benchmarks
 In a multithreaded test (benchmark invoked by multiple threads simultaneously),
 it is guaranteed that none of the threads will start until all have called

include/benchmark/benchmark_api.h

@@ -155,6 +155,11 @@ BENCHMARK(BM_test)->Unit(benchmark::kMillisecond);
 
 #include "macros.h"
 
+#if defined(BENCHMARK_HAS_CXX11)
+#include <type_traits>
+#include <utility>
+#endif
+
 namespace benchmark {
 class BenchmarkReporter;
 
@@ -592,6 +597,20 @@ private:
   Benchmark& operator=(Benchmark const&);
 };
 
+} // namespace internal
+
+// Create and register a benchmark with the specified 'name' that invokes
+// the specified functor 'fn'.
+//
+// RETURNS: A pointer to the registered benchmark.
+internal::Benchmark* RegisterBenchmark(const char* name, internal::Function* fn);
+
+#if defined(BENCHMARK_HAS_CXX11)
+template <class Lambda>
+internal::Benchmark* RegisterBenchmark(const char* name, Lambda&& fn);
+#endif
+
+namespace internal {
 // The class used to hold all Benchmarks created from static function.
 // (ie those created using the BENCHMARK(...) macros.
 class FunctionBenchmark : public Benchmark {
@@ -605,8 +624,55 @@ private:
     Function* func_;
 };
 
+#ifdef BENCHMARK_HAS_CXX11
+template <class Lambda>
+class LambdaBenchmark : public Benchmark {
+public:
+    virtual void Run(State& st) { lambda_(st); }
+
+private:
+  template <class OLambda>
+  LambdaBenchmark(const char* name, OLambda&& lam)
+      : Benchmark(name), lambda_(std::forward<OLambda>(lam)) {}
+
+  LambdaBenchmark(LambdaBenchmark const&) = delete;
+
+private:
+  template <class Lam>
+  friend Benchmark* ::benchmark::RegisterBenchmark(const char*, Lam&&);
+
+  Lambda lambda_;
+};
+#endif
+
 }  // end namespace internal
 
+inline internal::Benchmark*
+RegisterBenchmark(const char* name, internal::Function* fn) {
+    return internal::RegisterBenchmarkInternal(
+        ::new internal::FunctionBenchmark(name, fn));
+}
+
+#ifdef BENCHMARK_HAS_CXX11
+template <class Lambda>
+internal::Benchmark* RegisterBenchmark(const char* name, Lambda&& fn) {
+    using BenchType = internal::LambdaBenchmark<typename std::decay<Lambda>::type>;
+    return internal::RegisterBenchmarkInternal(
+        ::new BenchType(name, std::forward<Lambda>(fn)));
+}
+
+#if !defined(BENCHMARK_GCC_VERSION) || BENCHMARK_GCC_VERSION >= 409
+template <class Lambda, class ...Args>
+internal::Benchmark* RegisterBenchmark(const char* name, Lambda&& fn,
+                                       Args&&... args) {
+    return benchmark::RegisterBenchmark(name,
+        [=](benchmark::State& st) { fn(st, args...); });
+}
+#else
+#define BENCHMARK_HAS_NO_VARIADIC_REGISTER_BENCHMARK
+#endif
+#endif // BENCHMARK_HAS_CXX11
+
 // The base class for all fixture tests.
 class Fixture: public internal::Benchmark {
 public:

include/benchmark/macros.h

@@ -14,7 +14,11 @@
 #ifndef BENCHMARK_MACROS_H_
 #define BENCHMARK_MACROS_H_
 
-#if __cplusplus < 201103L
+#if __cplusplus >= 201103L
+#define BENCHMARK_HAS_CXX11
+#endif
+
+#ifndef BENCHMARK_HAS_CXX11
 # define BENCHMARK_DISALLOW_COPY_AND_ASSIGN(TypeName)  \
     TypeName(const TypeName&);                         \
     TypeName& operator=(const TypeName&)
@@ -53,4 +57,8 @@
 # define BENCHMARK_BUILTIN_EXPECT(x, y) x
 #endif
 
+#if defined(__GNUC__) && !defined(__clang__)
+#define BENCHMARK_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
+#endif
+
 #endif  // BENCHMARK_MACROS_H_

test/CMakeLists.txt

@@ -45,6 +45,9 @@ add_test(donotoptimize_test donotoptimize_test --benchmark_min_time=0.01)
 compile_benchmark_test(fixture_test)
 add_test(fixture_test fixture_test --benchmark_min_time=0.01)
 
+compile_benchmark_test(register_benchmark_test)
+add_test(register_benchmark_test register_benchmark_test --benchmark_min_time=0.01)
+
 compile_benchmark_test(map_test)
 add_test(map_test map_test --benchmark_min_time=0.01)
 

test/register_benchmark_test.cc

@@ -0,0 +1,147 @@
+
+#undef NDEBUG
+#include "benchmark/benchmark.h"
+#include "../src/check.h" // NOTE: check.h is for internal use only!
+#include <cassert>
+#include <vector>
+
+namespace {
+
+class TestReporter : public benchmark::ConsoleReporter {
+public:
+  virtual void ReportRuns(const std::vector<Run>& report) {
+    all_runs_.insert(all_runs_.end(), begin(report), end(report));
+    ConsoleReporter::ReportRuns(report);
+  }
+
+  std::vector<Run> all_runs_;
+};
+
+struct TestCase {
+  std::string name;
+  const char* label;
+  TestCase(const char* xname) : name(xname), label(nullptr) {}
+  TestCase(const char* xname, const char* xlabel)
+    : name(xname), label(xlabel) {}
+
+  typedef benchmark::BenchmarkReporter::Run Run;
+
+  void CheckRun(Run const& run) const {
+    CHECK(name == run.benchmark_name) << "expected " << name
+                                      << " got " << run.benchmark_name;
+    if (label) {
+      CHECK(run.report_label == label) << "expected " << label
+                                       << " got " << run.report_label;
+    } else {
+      CHECK(run.report_label == "");
+    }
+  }
+};
+
+std::vector<TestCase> ExpectedResults;
+
+int AddCases(std::initializer_list<TestCase> const& v) {
+  for (auto N : v) {
+    ExpectedResults.push_back(N);
+  }
+  return 0;
+}
+
+#define CONCAT(x, y) CONCAT2(x, y)
+#define CONCAT2(x, y) x##y
+#define ADD_CASES(...) \
+int CONCAT(dummy, __LINE__) = AddCases({__VA_ARGS__})
+
+}  // end namespace
+
+typedef benchmark::internal::Benchmark* ReturnVal;
+
+//----------------------------------------------------------------------------//
+// Test RegisterBenchmark with no additional arguments
+//----------------------------------------------------------------------------//
+void BM_function(benchmark::State& state) { while (state.KeepRunning()) {} }
+BENCHMARK(BM_function);
+ReturnVal dummy = benchmark::RegisterBenchmark(
+    "BM_function_manual_registration",
+     BM_function);
+ADD_CASES({"BM_function"}, {"BM_function_manual_registration"});
+
+//----------------------------------------------------------------------------//
+// Test RegisterBenchmark with additional arguments
+// Note: GCC <= 4.8 do not support this form of RegisterBenchmark because they
+//       reject the variadic pack expansion of lambda captures.
+//----------------------------------------------------------------------------//
+#ifndef BENCHMARK_HAS_NO_VARIADIC_REGISTER_BENCHMARK
+
+void BM_extra_args(benchmark::State& st, const char* label) {
+  while (st.KeepRunning()) {}
+  st.SetLabel(label);
+}
+int RegisterFromFunction() {
+  std::pair<const char*, const char*> cases[] = {
+      {"test1", "One"},
+      {"test2", "Two"},
+      {"test3", "Three"}
+  };
+  for (auto& c : cases)
+    benchmark::RegisterBenchmark(c.first, &BM_extra_args, c.second);
+  return 0;
+}
+int dummy2 = RegisterFromFunction();
+ADD_CASES(
+  {"test1", "One"},
+  {"test2", "Two"},
+  {"test3", "Three"}
+);
+
+#endif // BENCHMARK_HAS_NO_VARIADIC_REGISTER_BENCHMARK
+
+//----------------------------------------------------------------------------//
+// Test RegisterBenchmark with different callable types
+//----------------------------------------------------------------------------//
+
+struct CustomFixture {
+  void operator()(benchmark::State& st) {
+    while (st.KeepRunning()) {}
+  }
+};
+
+void TestRegistrationAtRuntime() {
+  {
+    CustomFixture fx;
+    benchmark::RegisterBenchmark("custom_fixture", fx);
+    AddCases({"custom_fixture"});
+  }
+#ifndef BENCHMARK_HAS_NO_VARIADIC_REGISTER_BENCHMARK
+  {
+    int x = 42;
+    auto capturing_lam = [=](benchmark::State& st) {
+      while (st.KeepRunning()) {}
+      st.SetLabel(std::to_string(x));
+    };
+    benchmark::RegisterBenchmark("lambda_benchmark", capturing_lam);
+    AddCases({{"lambda_benchmark", "42"}});
+  }
+#endif
+}
+
+int main(int argc, char* argv[]) {
+  TestRegistrationAtRuntime();
+
+  benchmark::Initialize(&argc, argv);
+
+  TestReporter test_reporter;
+  benchmark::RunSpecifiedBenchmarks(&test_reporter);
+
+  typedef benchmark::BenchmarkReporter::Run Run;
+  auto EB = ExpectedResults.begin();
+
+  for (Run const& run : test_reporter.all_runs_) {
+    assert(EB != ExpectedResults.end());
+    EB->CheckRun(run);
+    ++EB;
+  }
+  assert(EB == ExpectedResults.end());
+
+  return 0;
+}