Add SafeClamp(), which accepts args of different types

webrtc/base/safe_minmax_unittest.cc

 /*
  *  Copyright 2017 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include <algorithm>
 #include <limits>
 
 #include "webrtc/base/safe_minmax.h"
 #include "webrtc/test/gtest.h"
 
 namespace rtc {
 
 namespace {
 
-// Functions that check that SafeMin() and SafeMax() return the specified type.
-// The functions that end in "R" use an explicitly given return type.
+// Functions that check that SafeMin(), SafeMax(), and SafeClamp() return the
+// specified type. The functions that end in "R" use an explicitly given return
+// type.
 
 template <typename T1, typename T2, typename Tmin, typename Tmax>
 constexpr bool TypeCheckMinMax() {
   return std::is_same<decltype(SafeMin(std::declval<T1>(), std::declval<T2>())),
                       Tmin>::value &&
          std::is_same<decltype(SafeMax(std::declval<T1>(), std::declval<T2>())),
                       Tmax>::value;
 }
 
 template <typename T1, typename T2, typename R>
 constexpr bool TypeCheckMinR() {
   return std::is_same<
       decltype(SafeMin<R>(std::declval<T1>(), std::declval<T2>())), R>::value;
 }
 
 template <typename T1, typename T2, typename R>
 constexpr bool TypeCheckMaxR() {
   return std::is_same<
       decltype(SafeMax<R>(std::declval<T1>(), std::declval<T2>())), R>::value;
 }
 
+template <typename L, typename H, typename T, typename R>
+constexpr bool TypeCheckClamp() {
+  return std::is_same<decltype(SafeClamp(std::declval<L>(), std::declval<H>(),
+                                         std::declval<T>())),
+                      R>::value;
+}
+
+template <typename L, typename H, typename T, typename R>
+constexpr bool TypeCheckClampR() {
+  return std::is_same<decltype(SafeClamp<R>(std::declval<L>(),
+                                            std::declval<H>(),
+                                            std::declval<T>())),
+                      R>::value;
+}
+
 // clang-format off
 
 // SafeMin/SafeMax: Check that all combinations of signed/unsigned 8/64 bits
 // give the correct default result type.
 static_assert(TypeCheckMinMax<  int8_t,   int8_t,   int8_t,   int8_t>(), "");
 static_assert(TypeCheckMinMax<  int8_t,  uint8_t,   int8_t,  uint8_t>(), "");
 static_assert(TypeCheckMinMax<  int8_t,  int64_t,  int64_t,  int64_t>(), "");
 static_assert(TypeCheckMinMax<  int8_t, uint64_t,   int8_t, uint64_t>(), "");
 static_assert(TypeCheckMinMax< uint8_t,   int8_t,   int8_t,  uint8_t>(), "");
 static_assert(TypeCheckMinMax< uint8_t,  uint8_t,  uint8_t,  uint8_t>(), "");
 static_assert(TypeCheckMinMax< uint8_t,  int64_t,  int64_t,  int64_t>(), "");
 static_assert(TypeCheckMinMax< uint8_t, uint64_t,  uint8_t, uint64_t>(), "");
 static_assert(TypeCheckMinMax< int64_t,   int8_t,  int64_t,  int64_t>(), "");
 static_assert(TypeCheckMinMax< int64_t,  uint8_t,  int64_t,  int64_t>(), "");
 static_assert(TypeCheckMinMax< int64_t,  int64_t,  int64_t,  int64_t>(), "");
 static_assert(TypeCheckMinMax< int64_t, uint64_t,  int64_t, uint64_t>(), "");
 static_assert(TypeCheckMinMax<uint64_t,   int8_t,   int8_t, uint64_t>(), "");
 static_assert(TypeCheckMinMax<uint64_t,  uint8_t,  uint8_t, uint64_t>(), "");
 static_assert(TypeCheckMinMax<uint64_t,  int64_t,  int64_t, uint64_t>(), "");
 static_assert(TypeCheckMinMax<uint64_t, uint64_t, uint64_t, uint64_t>(), "");
 
+// SafeClamp: Check that all combinations of signed/unsigned 8/64 bits give the
+// correct result type.
+static_assert(TypeCheckClamp<  int8_t,   int8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,   int8_t,  uint8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,   int8_t,  int64_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,   int8_t, uint64_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  uint8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  uint8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  uint8_t,  int64_t,  int16_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  uint8_t, uint64_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  int64_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  int64_t,  uint8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  int64_t, uint64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<  int8_t, uint64_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t, uint64_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t, uint64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<  int8_t, uint64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,   int8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,   int8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,   int8_t,  int64_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,   int8_t, uint64_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  uint8_t,   int8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  uint8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  uint8_t,  int64_t,  int16_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  uint8_t, uint64_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  int64_t,   int8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  int64_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  int64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp< uint8_t, uint64_t,   int8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp< uint8_t, uint64_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t, uint64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< uint8_t, uint64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,   int8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< int64_t,   int8_t,  uint8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< int64_t,   int8_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,   int8_t, uint64_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  uint8_t,   int8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  uint8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  uint8_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  uint8_t, uint64_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  int64_t,   int8_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  int64_t,  uint8_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  int64_t, uint64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t, uint64_t,   int8_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t, uint64_t,  uint8_t, uint64_t>(), "");
+static_assert(TypeCheckClamp< int64_t, uint64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t, uint64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,   int8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,   int8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,   int8_t,  int64_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,   int8_t, uint64_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  uint8_t,   int8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  uint8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  uint8_t,  int64_t,  int16_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  uint8_t, uint64_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  int64_t,   int8_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  int64_t,  uint8_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  int64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t, uint64_t,   int8_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t, uint64_t,  uint8_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t, uint64_t,  int64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t, uint64_t, uint64_t, uint64_t>(), "");
+
 enum DefaultE { kFoo = -17 };
 enum UInt8E : uint8_t { kBar = 17 };
 
 // SafeMin/SafeMax: Check that we can use enum types.
 static_assert(TypeCheckMinMax<unsigned, unsigned, unsigned, unsigned>(), "");
 static_assert(TypeCheckMinMax<unsigned, DefaultE,      int, unsigned>(), "");
 static_assert(TypeCheckMinMax<unsigned,   UInt8E,  uint8_t, unsigned>(), "");
 static_assert(TypeCheckMinMax<DefaultE, unsigned,      int, unsigned>(), "");
 static_assert(TypeCheckMinMax<DefaultE, DefaultE,      int,      int>(), "");
 static_assert(TypeCheckMinMax<DefaultE,   UInt8E,      int,      int>(), "");
 static_assert(TypeCheckMinMax<  UInt8E, unsigned,  uint8_t, unsigned>(), "");
 static_assert(TypeCheckMinMax<  UInt8E, DefaultE,     int,       int>(), "");
 static_assert(TypeCheckMinMax<  UInt8E,   UInt8E,  uint8_t,  uint8_t>(), "");
 
+// SafeClamp: Check that we can use enum types.
+static_assert(TypeCheckClamp<unsigned, unsigned, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned, unsigned, DefaultE, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned, unsigned,   UInt8E, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned, DefaultE, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned, DefaultE, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<unsigned, DefaultE,   UInt8E, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned,   UInt8E, unsigned,  uint8_t>(), "");
+static_assert(TypeCheckClamp<unsigned,   UInt8E, DefaultE,  int16_t>(), "");
+static_assert(TypeCheckClamp<unsigned,   UInt8E,   UInt8E,  uint8_t>(), "");
+static_assert(TypeCheckClamp<DefaultE, unsigned, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<DefaultE, unsigned, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE, unsigned,   UInt8E, unsigned>(), "");
+static_assert(TypeCheckClamp<DefaultE, DefaultE, unsigned,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE, DefaultE, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE, DefaultE,   UInt8E,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE,   UInt8E, unsigned,  uint8_t>(), "");
+static_assert(TypeCheckClamp<DefaultE,   UInt8E, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE,   UInt8E,   UInt8E,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E, unsigned, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<  UInt8E, unsigned, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<  UInt8E, unsigned,   UInt8E,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E, DefaultE, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<  UInt8E, DefaultE, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<  UInt8E, DefaultE,   UInt8E,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E,   UInt8E, unsigned,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E,   UInt8E, DefaultE,  int16_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E,   UInt8E,   UInt8E,  uint8_t>(), "");
+
 using ld = long double;
 
 // SafeMin/SafeMax: Check that all floating-point combinations give the
 // correct result type.
 static_assert(TypeCheckMinMax< float,  float,  float,  float>(), "");
 static_assert(TypeCheckMinMax< float, double, double, double>(), "");
 static_assert(TypeCheckMinMax< float,     ld,     ld,     ld>(), "");
 static_assert(TypeCheckMinMax<double,  float, double, double>(), "");
 static_assert(TypeCheckMinMax<double, double, double, double>(), "");
 static_assert(TypeCheckMinMax<double,     ld,     ld,     ld>(), "");
 static_assert(TypeCheckMinMax<    ld,  float,     ld,     ld>(), "");
 static_assert(TypeCheckMinMax<    ld, double,     ld,     ld>(), "");
 static_assert(TypeCheckMinMax<    ld,     ld,     ld,     ld>(), "");
 
+// SafeClamp: Check that all floating-point combinations give the correct
+// result type.
+static_assert(TypeCheckClamp< float,  float,  float,  float>(), "");
+static_assert(TypeCheckClamp< float,  float, double, double>(), "");
+static_assert(TypeCheckClamp< float,  float,     ld,     ld>(), "");
+static_assert(TypeCheckClamp< float, double,  float, double>(), "");
+static_assert(TypeCheckClamp< float, double, double, double>(), "");
+static_assert(TypeCheckClamp< float, double,     ld,     ld>(), "");
+static_assert(TypeCheckClamp< float,     ld,  float,     ld>(), "");
+static_assert(TypeCheckClamp< float,     ld, double,     ld>(), "");
+static_assert(TypeCheckClamp< float,     ld,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<double,  float,  float, double>(), "");
+static_assert(TypeCheckClamp<double,  float, double, double>(), "");
+static_assert(TypeCheckClamp<double,  float,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<double, double,  float, double>(), "");
+static_assert(TypeCheckClamp<double, double, double, double>(), "");
+static_assert(TypeCheckClamp<double, double,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<double,     ld,  float,     ld>(), "");
+static_assert(TypeCheckClamp<double,     ld, double,     ld>(), "");
+static_assert(TypeCheckClamp<double,     ld,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,  float,  float,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,  float, double,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,  float,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<    ld, double,  float,     ld>(), "");
+static_assert(TypeCheckClamp<    ld, double, double,     ld>(), "");
+static_assert(TypeCheckClamp<    ld, double,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,     ld,  float,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,     ld, double,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,     ld,     ld,     ld>(), "");
+
 // clang-format on
 
 // SafeMin/SafeMax: Check some cases of explicitly specified return type. The
 // commented-out lines give compilation errors due to the requested return type
 // being too small or requiring an int<->float conversion.
 static_assert(TypeCheckMinR<int8_t, int8_t, int16_t>(), "");
 // static_assert(TypeCheckMinR<int8_t, int8_t, float>(), "");
 static_assert(TypeCheckMinR<uint32_t, uint64_t, uint32_t>(), "");
 // static_assert(TypeCheckMaxR<uint64_t, float, float>(), "");
 // static_assert(TypeCheckMaxR<uint64_t, double, float>(), "");
 static_assert(TypeCheckMaxR<uint32_t, int32_t, uint32_t>(), "");
 // static_assert(TypeCheckMaxR<uint32_t, int32_t, int32_t>(), "");
 
+// SafeClamp: Check some cases of explicitly specified return type. The
+// commented-out lines give compilation errors due to the requested return type
+// being too small.
+static_assert(TypeCheckClampR<int8_t, uint8_t, int16_t, int16_t>(), "");
+static_assert(TypeCheckClampR<int8_t, uint8_t, int16_t, int32_t>(), "");
+// static_assert(TypeCheckClampR<int8_t, uint8_t, int16_t, uint32_t>(), "");
+
 template <typename T1, typename T2, typename Tmin, typename Tmax>
 constexpr bool CheckMinMax(T1 a, T2 b, Tmin min, Tmax max) {
   return TypeCheckMinMax<T1, T2, Tmin, Tmax>() && SafeMin(a, b) == min &&
          SafeMax(a, b) == max;
 }
 
+template <typename L, typename H, typename T, typename R>
+bool CheckClamp(L min, H max, T x, R clamped) {
+  return TypeCheckClamp<L, H, T, R>() && SafeClamp(min, max, x) == clamped;
+}
+
 // SafeMin/SafeMax: Check a few values.
 static_assert(CheckMinMax(int8_t{1}, int8_t{-1}, int8_t{-1}, int8_t{1}), "");
 static_assert(CheckMinMax(uint8_t{1}, int8_t{-1}, int8_t{-1}, uint8_t{1}), "");
 static_assert(CheckMinMax(uint8_t{5}, uint64_t{2}, uint8_t{2}, uint64_t{5}),
               "");
 static_assert(CheckMinMax(std::numeric_limits<int32_t>::min(),
                           std::numeric_limits<uint32_t>::max(),
                           std::numeric_limits<int32_t>::min(),
                           std::numeric_limits<uint32_t>::max()),
               "");
 static_assert(CheckMinMax(std::numeric_limits<int32_t>::min(),
                           std::numeric_limits<uint16_t>::max(),
                           std::numeric_limits<int32_t>::min(),
                           int32_t{std::numeric_limits<uint16_t>::max()}),
               "");
 // static_assert(CheckMinMax(1.f, 2, 1.f, 2.f), "");
 static_assert(CheckMinMax(1.f, 0.0, 0.0, 1.0), "");
 
+// SafeClamp: Check a few values.
+TEST(SafeMinmaxTest, Clamp) {
+  EXPECT_TRUE(CheckClamp(std::numeric_limits<int16_t>::min(),
+                         std::numeric_limits<int16_t>::max(), int32_t{-1000000},
+                         std::numeric_limits<int16_t>::min()));
+  EXPECT_TRUE(CheckClamp(std::numeric_limits<int16_t>::min(),
+                         std::numeric_limits<int16_t>::max(), uint32_t{1000000},
+                         std::numeric_limits<int16_t>::max()));
+  EXPECT_TRUE(CheckClamp(-1.0, 1.f, 3.f, 1.0));
+  EXPECT_TRUE(CheckClamp(-1.f, 1.f, 3.0, 1.0));
+}
+
 }  // namespace
 
 // clang-format off
 
 // These functions aren't used in the tests, but it's useful to look at the
 // compiler output for them, and verify that (1) the same-signedness *Safe
 // functions result in exactly the same code as their *Ref counterparts, and
 // that (2) the mixed-signedness *Safe functions have just a few extra
 // arithmetic and logic instructions (but no extra control flow instructions).
 int32_t  TestMinRef(  int32_t a,  int32_t b) { return std::min(a, b); }
 uint32_t TestMinRef( uint32_t a, uint32_t b) { return std::min(a, b); }
 int32_t  TestMinSafe( int32_t a,  int32_t b) { return SafeMin(a, b); }
 int32_t  TestMinSafe( int32_t a, uint32_t b) { return SafeMin(a, b); }
 int32_t  TestMinSafe(uint32_t a,  int32_t b) { return SafeMin(a, b); }
 uint32_t TestMinSafe(uint32_t a, uint32_t b) { return SafeMin(a, b); }
 
 // clang-format on
 
+int32_t TestClampRef(int32_t a, int32_t b, int32_t x) {
+  return std::max(a, std::min(x, b));
+}
+uint32_t TestClampRef(uint32_t a, uint32_t b, uint32_t x) {
+  return std::max(a, std::min(x, b));
+}
+int32_t TestClampSafe(int32_t a, int32_t b, int32_t x) {
+  return SafeClamp(a, b, x);
+}
+int32_t TestClampSafe(int32_t a, int32_t b, uint32_t x) {
+  return SafeClamp(a, b, x);
+}
+int32_t TestClampSafe(int32_t a, uint32_t b, int32_t x) {
+  return SafeClamp(a, b, x);
+}
+uint32_t TestClampSafe(int32_t a, uint32_t b, uint32_t x) {
+  return SafeClamp(a, b, x);
+}
+int32_t TestClampSafe(uint32_t a, int32_t b, int32_t x) {
+  return SafeClamp(a, b, x);
+}
+uint32_t TestClampSafe(uint32_t a, int32_t b, uint32_t x) {
+  return SafeClamp(a, b, x);
+}
+int32_t TestClampSafe(uint32_t a, uint32_t b, int32_t x) {
+  return SafeClamp(a, b, x);
+}
+uint32_t TestClampSafe(uint32_t a, uint32_t b, uint32_t x) {
+  return SafeClamp(a, b, x);
+}
+
 }  // namespace rtc