Consistently have the namespace closing comment
[folly.git] / folly / test / ConvTest.cpp
index bf4c68ddf95813e0369d86d4d927b81de17888a0..115a32bfc0edffd144f6fe285ab2d9f6884a39ed 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * limitations under the License.
  */
 
-#include <folly/Benchmark.h>
-#include <folly/Conv.h>
-#include <folly/Foreach.h>
+#ifndef __STDC_FORMAT_MACROS
+#define __STDC_FORMAT_MACROS 1
+#endif
+
 #include <boost/lexical_cast.hpp>
-#include <gtest/gtest.h>
+
+#include <folly/Conv.h>
+#include <folly/container/Foreach.h>
+#include <folly/portability/GTest.h>
+
+#include <algorithm>
+#include <cinttypes>
 #include <limits>
+#include <sstream>
 #include <stdexcept>
+#include <tuple>
 
 using namespace std;
 using namespace folly;
 
-static int8_t s8;
-static uint8_t u8;
-static int16_t s16;
-static uint16_t u16;
-static int32_t s32;
-static uint32_t u32;
-static int64_t s64;
-static uint64_t u64;
-
-TEST(Conv, digits10Minimal) {
-  // Not much of a test (and it's included in the test below anyway).
-  // I just want to inspect the generated assembly for this function.
-  folly::doNotOptimizeAway(digits10(random() * random()));
-}
 
 TEST(Conv, digits10) {
   char buffer[100];
@@ -59,18 +54,18 @@ TEST(Conv, digits10) {
   // try the first X nonnegatives.
   // Covers some more cases of 2^p, 10^p
   for (uint64_t i = 0; i < 100000; i++) {
-    snprintf(buffer, sizeof(buffer), "%lu", i);
+    snprintf(buffer, sizeof(buffer), "%" PRIu64, i);
     EXPECT_EQ(strlen(buffer), digits10(i));
   }
 
   // try powers of 2
   power = 1;
   for (int p = 0; p < 64; p++) {
-    snprintf(buffer, sizeof(buffer), "%lu", power);
+    snprintf(buffer, sizeof(buffer), "%" PRIu64, power);
     EXPECT_EQ(strlen(buffer), digits10(power));
-    snprintf(buffer, sizeof(buffer), "%lu", power - 1);
+    snprintf(buffer, sizeof(buffer), "%" PRIu64, power - 1);
     EXPECT_EQ(strlen(buffer), digits10(power - 1));
-    snprintf(buffer, sizeof(buffer), "%lu", power + 1);
+    snprintf(buffer, sizeof(buffer), "%" PRIu64, power + 1);
     EXPECT_EQ(strlen(buffer), digits10(power + 1));
     power *= 2;
   }
@@ -78,11 +73,11 @@ TEST(Conv, digits10) {
   // try powers of 10
   power = 1;
   for (int p = 0; p < 20; p++) {
-    snprintf(buffer, sizeof(buffer), "%lu", power);
+    snprintf(buffer, sizeof(buffer), "%" PRIu64, power);
     EXPECT_EQ(strlen(buffer), digits10(power));
-    snprintf(buffer, sizeof(buffer), "%lu", power - 1);
+    snprintf(buffer, sizeof(buffer), "%" PRIu64, power - 1);
     EXPECT_EQ(strlen(buffer), digits10(power - 1));
-    snprintf(buffer, sizeof(buffer), "%lu", power + 1);
+    snprintf(buffer, sizeof(buffer), "%" PRIu64, power + 1);
     EXPECT_EQ(strlen(buffer), digits10(power + 1));
     power *= 10;
   }
@@ -90,10 +85,13 @@ TEST(Conv, digits10) {
 
 // Test to<T>(T)
 TEST(Conv, Type2Type) {
+  bool boolV = true;
+  EXPECT_EQ(to<bool>(boolV), true);
+
   int intV = 42;
   EXPECT_EQ(to<int>(intV), 42);
 
-  float floatV = 4.2;
+  float floatV = 4.2f;
   EXPECT_EQ(to<float>(floatV), 4.2f);
 
   double doubleV = 0.42;
@@ -109,6 +107,7 @@ TEST(Conv, Type2Type) {
   EXPECT_EQ(to<folly::StringPiece>(spV), "StringPiece");
 
   // Rvalues
+  EXPECT_EQ(to<bool>(true), true);
   EXPECT_EQ(to<int>(42), 42);
   EXPECT_EQ(to<float>(4.2f), 4.2f);
   EXPECT_EQ(to<double>(.42), .42);
@@ -120,7 +119,7 @@ TEST(Conv, Type2Type) {
 
 TEST(Conv, Integral2Integral) {
   // Same size, different signs
-  s64 = numeric_limits<uint8_t>::max();
+  int64_t s64 = numeric_limits<uint8_t>::max();
   EXPECT_EQ(to<uint8_t>(s64), s64);
 
   s64 = numeric_limits<int8_t>::max();
@@ -128,7 +127,7 @@ TEST(Conv, Integral2Integral) {
 }
 
 TEST(Conv, Floating2Floating) {
-  float f1 = 1e3;
+  float f1 = 1e3f;
   double d1 = to<double>(f1);
   EXPECT_EQ(f1, d1);
 
@@ -148,7 +147,7 @@ TEST(Conv, Floating2Floating) {
     EXPECT_TRUE(shouldWork == std::numeric_limits<float>::min() ||
                 shouldWork == 0.f);
   } catch (...) {
-    EXPECT_TRUE(false);
+    ADD_FAILURE();
   }
 }
 
@@ -208,6 +207,15 @@ void test128Bit2String() {
   svalue = 0;
   EXPECT_EQ(to<String>(svalue), "0");
 
+  value = ~__int128(0);
+  EXPECT_EQ(to<String>(value), "340282366920938463463374607431768211455");
+
+  svalue = -(Uint(1) << 127);
+  EXPECT_EQ(to<String>(svalue), "-170141183460469231731687303715884105728");
+
+  svalue = (Uint(1) << 127) - 1;
+  EXPECT_EQ(to<String>(svalue), "170141183460469231731687303715884105727");
+
   // TODO: the following do not compile to<__int128> ...
 
 #if 0
@@ -226,8 +234,8 @@ void test128Bit2String() {
 #endif
 
 TEST(Conv, Integral2String) {
-  testIntegral2String<std::string, char, short, int, long>();
-  testIntegral2String<fbstring, char, short, int, long>();
+  testIntegral2String<std::string, int8_t, int16_t, int32_t, int64_t>();
+  testIntegral2String<fbstring, int8_t, int16_t, int32_t, int64_t>();
 
 #if FOLLY_HAVE_INT128_T
   test128Bit2String<std::string>();
@@ -423,9 +431,9 @@ void testString2Integral() {
 }
 
 TEST(Conv, String2Integral) {
-  testString2Integral<const char*, signed char, short, int, long, long long>();
-  testString2Integral<std::string, signed char, short, int, long, long long>();
-  testString2Integral<fbstring, signed char, short, int, long, long long>();
+  testString2Integral<const char*, int8_t, int16_t, int32_t, int64_t>();
+  testString2Integral<std::string, int8_t, int16_t, int32_t, int64_t>();
+  testString2Integral<fbstring, int8_t, int16_t, int32_t, int64_t>();
 
   // Testing the behavior of the StringPiece* API
   // StringPiece* normally parses as much valid data as it can,
@@ -565,27 +573,62 @@ TEST(Conv, FBStringToString) {
 }
 
 TEST(Conv, StringPieceToDouble) {
-  string s = "2134123.125 zorro";
-  StringPiece pc(s);
-  EXPECT_EQ(to<double>(&pc), 2134123.125);
-  EXPECT_EQ(pc, " zorro");
-
-  EXPECT_THROW(to<double>(StringPiece(s)), std::range_error);
-  EXPECT_EQ(to<double>(StringPiece(s.data(), pc.data())), 2134123.125);
+  vector<tuple<const char*, const char*, double>> strs{
+      make_tuple("2134123.125 zorro", " zorro", 2134123.125),
+      make_tuple("  2134123.125 zorro", " zorro", 2134123.125),
+      make_tuple(" 2134123.125  zorro", "  zorro", 2134123.125),
+      make_tuple(" 2134123.125  zorro ", "  zorro ", 2134123.125),
+      make_tuple("2134123.125zorro", "zorro", 2134123.125),
+      make_tuple("0 zorro", " zorro", 0.0),
+      make_tuple("  0 zorro", " zorro", 0.0),
+      make_tuple(" 0  zorro", "  zorro", 0.0),
+      make_tuple(" 0  zorro ", "  zorro ", 0.0),
+      make_tuple("0zorro", "zorro", 0.0),
+      make_tuple("0.0 zorro", " zorro", 0.0),
+      make_tuple("  0.0 zorro", " zorro", 0.0),
+      make_tuple(" 0.0  zorro", "  zorro", 0.0),
+      make_tuple(" 0.0  zorro ", "  zorro ", 0.0),
+      make_tuple("0.0zorro", "zorro", 0.0),
+  };
+  for (const auto& s : strs) {
+    StringPiece pc(get<0>(s));
+    EXPECT_EQ(get<2>(s), to<double>(&pc)) << "\"" << get<0>(s) << "\"";
+    EXPECT_EQ(get<1>(s), pc);
+    EXPECT_THROW(to<double>(StringPiece(get<0>(s))), std::range_error);
+    EXPECT_EQ(get<2>(s), to<double>(StringPiece(get<0>(s), pc.data())));
+  }
 
-// Test NaN conversion
+  // Test NaN conversion
   try {
     to<double>("not a number");
-    EXPECT_TRUE(false);
+    ADD_FAILURE();
   } catch (const std::range_error &) {
   }
 
+  EXPECT_TRUE(std::isnan(to<double>("nan")));
   EXPECT_TRUE(std::isnan(to<double>("NaN")));
+  EXPECT_TRUE(std::isnan(to<double>("NAN")));
+  EXPECT_TRUE(std::isnan(to<double>("-nan")));
+  EXPECT_TRUE(std::isnan(to<double>("-NaN")));
+  EXPECT_TRUE(std::isnan(to<double>("-NAN")));
+
   EXPECT_EQ(to<double>("inf"), numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("Inf"), numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("INF"), numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("inF"), numeric_limits<double>::infinity());
   EXPECT_EQ(to<double>("infinity"), numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("Infinity"), numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("INFINITY"), numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("iNfInItY"), numeric_limits<double>::infinity());
   EXPECT_THROW(to<double>("infinitX"), std::range_error);
   EXPECT_EQ(to<double>("-inf"), -numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("-Inf"), -numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("-INF"), -numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("-inF"), -numeric_limits<double>::infinity());
   EXPECT_EQ(to<double>("-infinity"), -numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("-Infinity"), -numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("-INFINITY"), -numeric_limits<double>::infinity());
+  EXPECT_EQ(to<double>("-iNfInItY"), -numeric_limits<double>::infinity());
   EXPECT_THROW(to<double>("-infinitX"), std::range_error);
 }
 
@@ -595,7 +638,7 @@ TEST(Conv, EmptyStringToInt) {
 
   try {
     to<int>(pc);
-    EXPECT_TRUE(false);
+    ADD_FAILURE();
   } catch (const std::range_error &) {
   }
 }
@@ -606,7 +649,7 @@ TEST(Conv, CorruptedStringToInt) {
 
   try {
     to<int64_t>(&pc);
-    EXPECT_TRUE(false);
+    ADD_FAILURE();
   } catch (const std::range_error &) {
   }
 }
@@ -617,7 +660,7 @@ TEST(Conv, EmptyStringToDouble) {
 
   try {
     to<double>(pc);
-    EXPECT_TRUE(false);
+    ADD_FAILURE();
   } catch (const std::range_error &) {
   }
 }
@@ -628,7 +671,7 @@ TEST(Conv, IntToDouble) {
   /* This seems not work in ubuntu11.10, gcc 4.6.1
   try {
     auto f = to<float>(957837589847);
-    EXPECT_TRUE(false);
+    ADD_FAILURE();
   } catch (std::range_error& e) {
     //LOG(INFO) << e.what();
   }
@@ -639,9 +682,10 @@ TEST(Conv, DoubleToInt) {
   auto i = to<int>(42.0);
   EXPECT_EQ(i, 42);
   try {
-    auto i = to<int>(42.1);
-    EXPECT_TRUE(false);
-  } catch (std::range_error& e) {
+    auto i2 = to<int>(42.1);
+    LOG(ERROR) << "to<int> returned " << i2 << " instead of throwing";
+    ADD_FAILURE();
+  } catch (std::range_error&) {
     //LOG(INFO) << e.what();
   }
 }
@@ -653,10 +697,12 @@ TEST(Conv, EnumToInt) {
   auto j = to<char>(x);
   EXPECT_EQ(j, 42);
   try {
-    auto i = to<char>(y);
-    LOG(ERROR) << static_cast<unsigned int>(i);
-    EXPECT_TRUE(false);
-  } catch (std::range_error& e) {
+    auto i2 = to<char>(y);
+    LOG(ERROR) << "to<char> returned "
+               << static_cast<unsigned int>(i2)
+               << " instead of throwing";
+    ADD_FAILURE();
+  } catch (std::range_error&) {
     //LOG(INFO) << e.what();
   }
 }
@@ -676,9 +722,12 @@ TEST(Conv, IntToEnum) {
   auto j = to<A>(100);
   EXPECT_EQ(j, 100);
   try {
-    auto i = to<A>(5000000000L);
-    EXPECT_TRUE(false);
-  } catch (std::range_error& e) {
+    auto i2 = to<A>(5000000000L);
+    LOG(ERROR) << "to<A> returned "
+               << static_cast<unsigned int>(i2)
+               << " instead of throwing";
+    ADD_FAILURE();
+  } catch (std::range_error&) {
     //LOG(INFO) << e.what();
   }
 }
@@ -693,30 +742,24 @@ TEST(Conv, UnsignedEnum) {
   EXPECT_EQ(e, x);
   try {
     auto i = to<int32_t>(x);
-    LOG(ERROR) << to<uint32_t>(x);
-    EXPECT_TRUE(false);
-  } catch (std::range_error& e) {
+    LOG(ERROR) << "to<int32_t> returned " << i << " instead of throwing";
+    ADD_FAILURE();
+  } catch (std::range_error&) {
   }
 }
 
-#if defined(__clang__) || __GNUC_PREREQ(4, 7)
-// to<enum class> and to(enum class) only supported in gcc 4.7 onwards
-
 TEST(Conv, UnsignedEnumClass) {
   enum class E : uint32_t { x = 3000000000U };
   auto u = to<uint32_t>(E::x);
   EXPECT_GT(u, 0);
   EXPECT_EQ(u, 3000000000U);
-  auto s = to<string>(E::x);
-  EXPECT_EQ("3000000000", s);
-  auto e = to<E>(3000000000U);
-  EXPECT_EQ(e, E::x);
-  try {
-    auto i = to<int32_t>(E::x);
-    LOG(ERROR) << to<uint32_t>(E::x);
-    EXPECT_TRUE(false);
-  } catch (std::range_error& e) {
-  }
+  EXPECT_EQ("3000000000", to<string>(E::x));
+  EXPECT_EQ(E::x, to<E>(3000000000U));
+  EXPECT_EQ(E::x, to<E>("3000000000"));
+  E e;
+  EXPECT_TRUE(parseTo("3000000000", e).hasValue());
+  EXPECT_EQ(E::x, e);
+  EXPECT_THROW(to<int32_t>(E::x), std::range_error);
 }
 
 // Multi-argument to<string> uses toAppend, a different code path than
@@ -728,9 +771,18 @@ TEST(Conv, EnumClassToString) {
   EXPECT_EQ("foo.65", to<string>("foo.", A::z));
 }
 
-#endif // gcc 4.7 onwards
+TEST(Conv, IntegralToBool) {
+  EXPECT_FALSE(to<bool>(0));
+  EXPECT_FALSE(to<bool>(0ul));
+
+  EXPECT_TRUE(to<bool>(1));
+  EXPECT_TRUE(to<bool>(1ul));
+
+  EXPECT_TRUE(to<bool>(-42));
+  EXPECT_TRUE(to<bool>(42ul));
+}
 
-template<typename Src>
+template <typename Src>
 void testStr2Bool() {
   EXPECT_FALSE(to<bool>(Src("0")));
   EXPECT_FALSE(to<bool>(Src("  000  ")));
@@ -794,6 +846,317 @@ TEST(Conv, StringToBool) {
   EXPECT_EQ(buf5, sp5.begin());
 }
 
+TEST(Conv, Transform) {
+  const std::vector<int64_t> in{1, 2, 3};
+  std::vector<std::string> out(in.size());
+  std::transform(in.begin(), in.end(), out.begin(), to<std::string, int64_t>);
+  const std::vector<std::string> ref{"1", "2", "3"};
+  EXPECT_EQ(ref, out);
+}
+
+TEST(Conv, FloatToInt) {
+  EXPECT_EQ(to<int>(42.0f), 42);
+  EXPECT_EQ(to<int8_t>(-128.0f), int8_t(-128));
+  EXPECT_THROW(to<int8_t>(-129.0), std::range_error);
+  EXPECT_THROW(to<int8_t>(127.001), std::range_error);
+  EXPECT_THROW(to<uint8_t>(-0.0001), std::range_error);
+  EXPECT_THROW(
+      to<uint64_t>(static_cast<float>(std::numeric_limits<uint64_t>::max())),
+      std::range_error);
+}
+
+TEST(Conv, IntToFloat) {
+  EXPECT_EQ(to<float>(42ULL), 42.0);
+  EXPECT_EQ(to<float>(int8_t(-128)), -128.0);
+  EXPECT_THROW(
+      to<float>(std::numeric_limits<uint64_t>::max()), std::range_error);
+  EXPECT_THROW(
+      to<float>(std::numeric_limits<int64_t>::max()), std::range_error);
+  EXPECT_THROW(
+      to<float>(std::numeric_limits<int64_t>::min() + 1), std::range_error);
+#if FOLLY_HAVE_INT128_T
+  EXPECT_THROW(
+      to<double>(std::numeric_limits<unsigned __int128>::max()),
+      std::range_error);
+  EXPECT_THROW(
+      to<double>(std::numeric_limits<__int128>::max()), std::range_error);
+  EXPECT_THROW(
+      to<double>(std::numeric_limits<__int128>::min() + 1), std::range_error);
+#endif
+}
+
+TEST(Conv, BoolToFloat) {
+  EXPECT_EQ(to<double>(true), 1.0);
+  EXPECT_EQ(to<double>(false), 0.0);
+}
+
+TEST(Conv, FloatToBool) {
+  EXPECT_EQ(to<bool>(1.0), true);
+  EXPECT_EQ(to<bool>(0.0), false);
+  EXPECT_EQ(to<bool>(2.7), true);
+  EXPECT_EQ(to<bool>(std::numeric_limits<double>::max()), true);
+  EXPECT_EQ(to<bool>(std::numeric_limits<double>::min()), true);
+  EXPECT_EQ(to<bool>(std::numeric_limits<double>::lowest()), true);
+  EXPECT_EQ(to<bool>(std::numeric_limits<double>::quiet_NaN()), true);
+  EXPECT_EQ(to<bool>(std::numeric_limits<double>::infinity()), true);
+  EXPECT_EQ(to<bool>(-std::numeric_limits<double>::infinity()), true);
+}
+
+namespace {
+
+template <typename F>
+void testConvError(
+    F&& expr,
+    const char* exprStr,
+    ConversionCode code,
+    const char* value,
+    bool quotedValue,
+    int line) {
+  std::string where = to<std::string>(__FILE__, "(", line, "): ");
+  try {
+    auto res = expr();
+    ADD_FAILURE() << where << exprStr << " -> " << res;
+  } catch (const ConversionError& e) {
+    EXPECT_EQ(code, e.errorCode()) << where << exprStr;
+    std::string str(e.what());
+    EXPECT_FALSE(str.empty()) << where << exprStr << " -> " << str;
+    auto pos = str.find(':');
+    if (value) {
+      std::ostringstream exp;
+      exp << str.substr(0, pos) + ": ";
+      if (quotedValue) {
+        exp << "\"" << value << "\"";
+      } else {
+        exp << value;
+      }
+      EXPECT_EQ(exp.str(), str) << where << exprStr << " -> " << str;
+    } else {
+      EXPECT_EQ(pos, std::string::npos) << where << exprStr << " -> " << str;
+    }
+  }
+}
+} // namespace
+
+#define EXPECT_CONV_ERROR_QUOTE(expr, code, value, quoted) \
+  testConvError(                                           \
+      [&] { return expr; },                                \
+      #expr,                                               \
+      ConversionCode::code,                                \
+      value,                                               \
+      quoted,                                              \
+      __LINE__)
+
+#define EXPECT_CONV_ERROR(expr, code, value) \
+  EXPECT_CONV_ERROR_QUOTE(expr, code, value, true)
+
+#define EXPECT_CONV_ERROR_STR(type, str, code) \
+  EXPECT_CONV_ERROR(to<type>(str), code, str)
+
+#define EXPECT_CONV_ERROR_STR_NOVAL(type, str, code) \
+  EXPECT_CONV_ERROR(to<type>(str), code, nullptr)
+
+TEST(Conv, ConversionErrorStrToBool) {
+  EXPECT_CONV_ERROR_STR_NOVAL(bool, StringPiece(), EMPTY_INPUT_STRING);
+  EXPECT_CONV_ERROR_STR_NOVAL(bool, "", EMPTY_INPUT_STRING);
+  EXPECT_CONV_ERROR_STR(bool, "  ", EMPTY_INPUT_STRING);
+  EXPECT_CONV_ERROR_STR(bool, " 11 ", BOOL_OVERFLOW);
+  EXPECT_CONV_ERROR_STR(bool, "other ", BOOL_INVALID_VALUE);
+  EXPECT_CONV_ERROR_STR(bool, " bla", BOOL_INVALID_VALUE);
+  EXPECT_CONV_ERROR(to<bool>("  offbla"), NON_WHITESPACE_AFTER_END, "bla");
+}
+
+TEST(Conv, ConversionErrorStrToFloat) {
+  EXPECT_CONV_ERROR_STR_NOVAL(float, StringPiece(), EMPTY_INPUT_STRING);
+  EXPECT_CONV_ERROR_STR_NOVAL(float, "", EMPTY_INPUT_STRING);
+  EXPECT_CONV_ERROR_STR(float, "  ", EMPTY_INPUT_STRING);
+  EXPECT_CONV_ERROR_STR(float, "  junk", STRING_TO_FLOAT_ERROR);
+  EXPECT_CONV_ERROR(to<float>("  1bla"), NON_WHITESPACE_AFTER_END, "bla");
+}
+
+TEST(Conv, ConversionErrorStrToInt) {
+  // empty string handling
+  EXPECT_CONV_ERROR_STR_NOVAL(int, StringPiece(), EMPTY_INPUT_STRING);
+  EXPECT_CONV_ERROR_STR_NOVAL(int, "", EMPTY_INPUT_STRING);
+  EXPECT_CONV_ERROR_STR(int, "  ", EMPTY_INPUT_STRING);
+
+  // signed integers
+  EXPECT_CONV_ERROR_STR(int, "  *", INVALID_LEADING_CHAR);
+  EXPECT_CONV_ERROR_STR(int, "  +", NO_DIGITS);
+  EXPECT_CONV_ERROR_STR(int, "  +*", NON_DIGIT_CHAR);
+  EXPECT_CONV_ERROR_STR(int8_t, "  128", POSITIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_STR(int8_t, " -129", NEGATIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_STR(int8_t, " 1000", POSITIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_STR(int8_t, "-1000", NEGATIVE_OVERFLOW);
+  EXPECT_CONV_ERROR(to<int>(" -13bla"), NON_WHITESPACE_AFTER_END, "bla");
+
+  // unsigned integers
+  EXPECT_CONV_ERROR_STR(unsigned, "  -", NON_DIGIT_CHAR);
+  EXPECT_CONV_ERROR_STR(uint8_t, " 256", POSITIVE_OVERFLOW);
+  EXPECT_CONV_ERROR(to<unsigned>("42bla"), NON_WHITESPACE_AFTER_END, "bla");
+}
+
+#define EXPECT_CONV_ERROR_PP_VAL(type, str, code, val)                  \
+  do {                                                                  \
+    StringPiece input(str);                                             \
+    EXPECT_CONV_ERROR(to<type>(input.begin(), input.end()), code, val); \
+  } while (0)
+
+#define EXPECT_CONV_ERROR_PP(type, str, code) \
+  EXPECT_CONV_ERROR_PP_VAL(type, str, code, str)
+
+TEST(Conv, ConversionErrorPtrPairToInt) {
+  // signed integers
+  EXPECT_CONV_ERROR_PP(int, "", INVALID_LEADING_CHAR);
+  EXPECT_CONV_ERROR_PP(int, " ", INVALID_LEADING_CHAR);
+  EXPECT_CONV_ERROR_PP(int, "*", INVALID_LEADING_CHAR);
+  EXPECT_CONV_ERROR_PP(int, "+", NO_DIGITS);
+  EXPECT_CONV_ERROR_PP(int8_t, "128", POSITIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_PP(int8_t, "-129", NEGATIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_PP(int8_t, "1000", POSITIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_PP(int8_t, "-1000", NEGATIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_PP(int, "-junk", NON_DIGIT_CHAR);
+
+  // unsigned integers
+  EXPECT_CONV_ERROR_PP(unsigned, "", NO_DIGITS);
+  EXPECT_CONV_ERROR_PP(uint8_t, "256", POSITIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_PP(unsigned, "junk", NON_DIGIT_CHAR);
+}
+
+namespace {
+
+template <typename T, typename V>
+std::string prefixWithType(V value) {
+  std::ostringstream oss;
+#ifdef FOLLY_HAS_RTTI
+  oss << "(" << demangle(typeid(T)) << ") ";
+#endif
+  oss << to<std::string>(value);
+  return oss.str();
+}
+} // namespace
+
+#define EXPECT_CONV_ERROR_ARITH(type, val, code) \
+  EXPECT_CONV_ERROR_QUOTE(                       \
+      to<type>(val), code, prefixWithType<type>(val).c_str(), false)
+
+TEST(Conv, ConversionErrorIntToInt) {
+  EXPECT_CONV_ERROR_ARITH(signed char, 128, ARITH_POSITIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_ARITH(unsigned char, -1, ARITH_NEGATIVE_OVERFLOW);
+}
+
+TEST(Conv, ConversionErrorFloatToFloat) {
+  EXPECT_CONV_ERROR_ARITH(
+      float, std::numeric_limits<double>::max(), ARITH_POSITIVE_OVERFLOW);
+  EXPECT_CONV_ERROR_ARITH(
+      float, std::numeric_limits<double>::lowest(), ARITH_NEGATIVE_OVERFLOW);
+}
+
+TEST(Conv, ConversionErrorIntToFloat) {
+  EXPECT_CONV_ERROR_ARITH(
+      float, std::numeric_limits<long long>::max(), ARITH_LOSS_OF_PRECISION);
+}
+
+TEST(Conv, ConversionErrorFloatToInt) {
+  EXPECT_CONV_ERROR_ARITH(int8_t, 65.5, ARITH_LOSS_OF_PRECISION);
+}
+
+TEST(Conv, TryStringToBool) {
+  auto rv1 = folly::tryTo<bool>("xxxx");
+  EXPECT_FALSE(rv1.hasValue());
+  auto rv2 = folly::tryTo<bool>("false");
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_FALSE(rv2.value());
+  auto rv3 = folly::tryTo<bool>("yes");
+  EXPECT_TRUE(rv3.hasValue());
+  EXPECT_TRUE(rv3.value());
+}
+
+TEST(Conv, TryStringToInt) {
+  auto rv1 = folly::tryTo<int>("1000000000000000000000000000000");
+  EXPECT_FALSE(rv1.hasValue());
+  auto rv2 = folly::tryTo<int>("4711");
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_EQ(rv2.value(), 4711);
+}
+
+TEST(Conv, TryStringToEnum) {
+  enum class A { x = 42, y = 420, z = 65 };
+  auto rv1 = folly::tryTo<A>("1000000000000000000000000000000");
+  EXPECT_FALSE(rv1.hasValue());
+  auto rv2 = folly::tryTo<A>("42");
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_EQ(A::x, rv2.value());
+  auto rv3 = folly::tryTo<A>("50");
+  EXPECT_TRUE(rv3.hasValue());
+  EXPECT_EQ(static_cast<A>(50), rv3.value());
+}
+
+TEST(Conv, TryStringToFloat) {
+  auto rv1 = folly::tryTo<float>("");
+  EXPECT_FALSE(rv1.hasValue());
+  auto rv2 = folly::tryTo<float>("3.14");
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_NEAR(rv2.value(), 3.14, 1e-5);
+}
+
+TEST(Conv, TryStringToDouble) {
+  auto rv1 = folly::tryTo<double>("");
+  EXPECT_FALSE(rv1.hasValue());
+  auto rv2 = folly::tryTo<double>("3.14");
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_NEAR(rv2.value(), 3.14, 1e-10);
+}
+
+TEST(Conv, TryIntToInt) {
+  auto rv1 = folly::tryTo<uint8_t>(256);
+  EXPECT_FALSE(rv1.hasValue());
+  auto rv2 = folly::tryTo<uint8_t>(255);
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_EQ(rv2.value(), 255);
+}
+
+TEST(Conv, TryFloatToFloat) {
+  auto rv1 = folly::tryTo<float>(1e100);
+  EXPECT_FALSE(rv1.hasValue());
+  auto rv2 = folly::tryTo<double>(25.5f);
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_NEAR(rv2.value(), 25.5, 1e-10);
+}
+
+TEST(Conv, TryFloatToInt) {
+  auto rv1 = folly::tryTo<int>(100.001);
+  EXPECT_FALSE(rv1.hasValue());
+  auto rv2 = folly::tryTo<int>(100.0);
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_EQ(rv2.value(), 100);
+}
+
+TEST(Conv, TryIntToFloat) {
+  auto rv1 = folly::tryTo<float>(std::numeric_limits<uint64_t>::max());
+  EXPECT_FALSE(rv1.hasValue());
+  auto rv2 = folly::tryTo<float>(1000ULL);
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_EQ(rv2.value(), 1000.0f);
+}
+
+TEST(Conv, TryPtrPairToInt) {
+  StringPiece sp1("1000000000000000000000000000000");
+  auto rv1 = folly::tryTo<int>(sp1.begin(), sp1.end());
+  EXPECT_FALSE(rv1.hasValue());
+  StringPiece sp2("4711");
+  auto rv2 = folly::tryTo<int>(sp2.begin(), sp2.end());
+  EXPECT_TRUE(rv2.hasValue());
+  EXPECT_EQ(rv2.value(), 4711);
+  StringPiece sp3("-4711");
+  auto rv3 = folly::tryTo<int>(sp3.begin(), sp3.end());
+  EXPECT_TRUE(rv3.hasValue());
+  EXPECT_EQ(rv3.value(), -4711);
+  StringPiece sp4("4711");
+  auto rv4 = folly::tryTo<uint16_t>(sp4.begin(), sp4.end());
+  EXPECT_TRUE(rv4.hasValue());
+  EXPECT_EQ(rv4.value(), 4711);
+}
+
 TEST(Conv, NewUint64ToString) {
   char buf[21];
 
@@ -848,328 +1211,49 @@ TEST(Conv, allocate_size) {
   EXPECT_EQ(res3, str1 + "," + str2);
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// Benchmarks for ASCII to int conversion
-////////////////////////////////////////////////////////////////////////////////
-// @author: Rajat Goel (rajat)
-
-static int64_t handwrittenAtoi(const char* start, const char* end) {
-
-  bool positive = true;
-  int64_t retVal = 0;
-
-  if (start == end) {
-    throw std::runtime_error("empty string");
+namespace my {
+struct Dimensions {
+  int w, h;
+  std::tuple<const int&, const int&> tuple_view() const {
+    return tie(w, h);
   }
-
-  while (start < end && isspace(*start)) {
-    ++start;
-  }
-
-  switch (*start) {
-    case '-':
-      positive = false;
-    case '+':
-      ++start;
-    default:;
-  }
-
-  while (start < end && *start >= '0' && *start <= '9') {
-    auto const newRetVal = retVal * 10 + (*start++ - '0');
-    if (newRetVal < retVal) {
-      throw std::runtime_error("overflow");
-    }
-    retVal = newRetVal;
-  }
-
-  if (start != end) {
-    throw std::runtime_error("extra chars at the end");
-  }
-
-  return positive ? retVal : -retVal;
-}
-
-static StringPiece pc1 = "1234567890123456789";
-
-void handwrittenAtoiMeasure(unsigned int n, unsigned int digits) {
-  auto p = pc1.subpiece(pc1.size() - digits, digits);
-  FOR_EACH_RANGE (i, 0, n) {
-    doNotOptimizeAway(handwrittenAtoi(p.begin(), p.end()));
-  }
-}
-
-void follyAtoiMeasure(unsigned int n, unsigned int digits) {
-  auto p = pc1.subpiece(pc1.size() - digits, digits);
-  FOR_EACH_RANGE (i, 0, n) {
-    doNotOptimizeAway(folly::to<int64_t>(p.begin(), p.end()));
-  }
-}
-
-void clibAtoiMeasure(unsigned int n, unsigned int digits) {
-  auto p = pc1.subpiece(pc1.size() - digits, digits);
-  assert(*p.end() == 0);
-  static_assert(sizeof(long) == 8, "64-bit long assumed");
-  FOR_EACH_RANGE (i, 0, n) {
-    doNotOptimizeAway(atol(p.begin()));
-  }
-}
-
-void clibStrtoulMeasure(unsigned int n, unsigned int digits) {
-  auto p = pc1.subpiece(pc1.size() - digits, digits);
-  assert(*p.end() == 0);
-  char * endptr;
-  FOR_EACH_RANGE (i, 0, n) {
-    doNotOptimizeAway(strtoul(p.begin(), &endptr, 10));
+  bool operator==(const Dimensions& other) const {
+    return this->tuple_view() == other.tuple_view();
   }
-}
-
-void lexicalCastMeasure(unsigned int n, unsigned int digits) {
-  auto p = pc1.subpiece(pc1.size() - digits, digits);
-  assert(*p.end() == 0);
-  FOR_EACH_RANGE (i, 0, n) {
-    doNotOptimizeAway(boost::lexical_cast<uint64_t>(p.begin()));
-  }
-}
-
-// Benchmarks for unsigned to string conversion, raw
-
-unsigned u64ToAsciiTable(uint64_t value, char* dst) {
-  static const char digits[201] =
-    "00010203040506070809"
-    "10111213141516171819"
-    "20212223242526272829"
-    "30313233343536373839"
-    "40414243444546474849"
-    "50515253545556575859"
-    "60616263646566676869"
-    "70717273747576777879"
-    "80818283848586878889"
-    "90919293949596979899";
-
-  uint32_t const length = digits10(value);
-  uint32_t next = length - 1;
-  while (value >= 100) {
-    auto const i = (value % 100) * 2;
-    value /= 100;
-    dst[next] = digits[i + 1];
-    dst[next - 1] = digits[i];
-    next -= 2;
-  }
-  // Handle last 1-2 digits
-  if (value < 10) {
-    dst[next] = '0' + uint32_t(value);
-  } else {
-    auto i = uint32_t(value) * 2;
-    dst[next] = digits[i + 1];
-    dst[next - 1] = digits[i];
-  }
-  return length;
-}
-
-void u64ToAsciiTableBM(unsigned int n, uint64_t value) {
-  // This is too fast, need to do 10 times per iteration
-  char buf[20];
-  FOR_EACH_RANGE (i, 0, n) {
-    doNotOptimizeAway(u64ToAsciiTable(value + n, buf));
-  }
-}
-
-unsigned u64ToAsciiClassic(uint64_t value, char* dst) {
-  // Write backwards.
-  char* next = (char*)dst;
-  char* start = next;
-  do {
-    *next++ = '0' + (value % 10);
-    value /= 10;
-  } while (value != 0);
-  unsigned length = next - start;
-
-  // Reverse in-place.
-  next--;
-  while (next > start) {
-    char swap = *next;
-    *next = *start;
-    *start = swap;
-    next--;
-    start++;
-  }
-  return length;
-}
-
-void u64ToAsciiClassicBM(unsigned int n, uint64_t value) {
-  // This is too fast, need to do 10 times per iteration
-  char buf[20];
-  FOR_EACH_RANGE (i, 0, n) {
-    doNotOptimizeAway(u64ToAsciiClassic(value + n, buf));
-  }
-}
+};
 
-void u64ToAsciiFollyBM(unsigned int n, uint64_t value) {
-  // This is too fast, need to do 10 times per iteration
-  char buf[20];
-  FOR_EACH_RANGE (i, 0, n) {
-    doNotOptimizeAway(uint64ToBufferUnsafe(value + n, buf));
-  }
+Expected<StringPiece, ConversionCode> parseTo(
+    folly::StringPiece in,
+    Dimensions& out) {
+  return parseTo(in, out.w)
+      .then([](StringPiece sp) { return sp.removePrefix("x"), sp; })
+      .then([&](StringPiece sp) { return parseTo(sp, out.h); });
 }
 
-// Benchmark uitoa with string append
-
-void u2aAppendClassicBM(unsigned int n, uint64_t value) {
-  string s;
-  FOR_EACH_RANGE (i, 0, n) {
-    // auto buf = &s.back() + 1;
-    char buffer[20];
-    s.append(buffer, u64ToAsciiClassic(value, buffer));
-    doNotOptimizeAway(s.size());
-  }
+template <class String>
+void toAppend(const Dimensions& in, String* result) {
+  folly::toAppend(in.w, 'x', in.h, result);
 }
 
-void u2aAppendFollyBM(unsigned int n, uint64_t value) {
-  string s;
-  FOR_EACH_RANGE (i, 0, n) {
-    // auto buf = &s.back() + 1;
-    char buffer[20];
-    s.append(buffer, uint64ToBufferUnsafe(value, buffer));
-    doNotOptimizeAway(s.size());
-  }
+size_t estimateSpaceNeeded(const Dimensions&in) {
+  return 2000 + folly::estimateSpaceNeeded(in.w) +
+      folly::estimateSpaceNeeded(in.h);
 }
-
-template <class String>
-struct StringIdenticalToBM {
-  StringIdenticalToBM() {}
-  void operator()(unsigned int n, size_t len) const {
-    String s;
-    BENCHMARK_SUSPEND { s.append(len, '0'); }
-    FOR_EACH_RANGE (i, 0, n) {
-      String result = to<String>(s);
-      doNotOptimizeAway(result.size());
-    }
-  }
-};
-
-template <class String>
-struct StringVariadicToBM {
-  StringVariadicToBM() {}
-  void operator()(unsigned int n, size_t len) const {
-    String s;
-    BENCHMARK_SUSPEND { s.append(len, '0'); }
-    FOR_EACH_RANGE (i, 0, n) {
-      String result = to<String>(s, nullptr);
-      doNotOptimizeAway(result.size());
-    }
-  }
-};
-
-static size_t bigInt = 11424545345345;
-static size_t smallInt = 104;
-static char someString[] = "this is some nice string";
-static char otherString[] = "this is a long string, so it's not so nice";
-static char reallyShort[] = "meh";
-static std::string stdString = "std::strings are very nice";
-static float fValue = 1.2355;
-static double dValue = 345345345.435;
-
-BENCHMARK(preallocateTestNoFloat, n) {
-  for (size_t i = 0; i < n; ++i) {
-    auto val1 = to<std::string>(bigInt, someString, stdString, otherString);
-    auto val3 = to<std::string>(reallyShort, smallInt);
-    auto val2 = to<std::string>(bigInt, stdString);
-    auto val4 = to<std::string>(bigInt, stdString, dValue, otherString);
-    auto val5 = to<std::string>(bigInt, someString, reallyShort);
-  }
+} // namespace my
+
+TEST(Conv, custom_kkproviders) {
+  my::Dimensions expected{7, 8};
+  EXPECT_EQ(expected, folly::to<my::Dimensions>("7x8"));
+  auto str = folly::to<std::string>(expected);
+  EXPECT_EQ("7x8", str);
+  // make sure above implementation of estimateSpaceNeeded() is used.
+  EXPECT_GT(str.capacity(), 2000);
+  EXPECT_LT(str.capacity(), 2500);
 }
 
-BENCHMARK(preallocateTestFloat, n) {
-  for (size_t i = 0; i < n; ++i) {
-    auto val1 = to<std::string>(stdString, ',', fValue, dValue);
-    auto val2 = to<std::string>(stdString, ',', dValue);
-  }
-}
-BENCHMARK_DRAW_LINE();
-
-static const StringIdenticalToBM<std::string> stringIdenticalToBM;
-static const StringVariadicToBM<std::string> stringVariadicToBM;
-static const StringIdenticalToBM<fbstring> fbstringIdenticalToBM;
-static const StringVariadicToBM<fbstring> fbstringVariadicToBM;
-
-#define DEFINE_BENCHMARK_GROUP(n)                       \
-  BENCHMARK_PARAM(u64ToAsciiClassicBM, n);              \
-  BENCHMARK_RELATIVE_PARAM(u64ToAsciiTableBM, n);       \
-  BENCHMARK_RELATIVE_PARAM(u64ToAsciiFollyBM, n);       \
-  BENCHMARK_DRAW_LINE();
-
-DEFINE_BENCHMARK_GROUP(1);
-DEFINE_BENCHMARK_GROUP(12);
-DEFINE_BENCHMARK_GROUP(123);
-DEFINE_BENCHMARK_GROUP(1234);
-DEFINE_BENCHMARK_GROUP(12345);
-DEFINE_BENCHMARK_GROUP(123456);
-DEFINE_BENCHMARK_GROUP(1234567);
-DEFINE_BENCHMARK_GROUP(12345678);
-DEFINE_BENCHMARK_GROUP(123456789);
-DEFINE_BENCHMARK_GROUP(1234567890);
-DEFINE_BENCHMARK_GROUP(12345678901);
-DEFINE_BENCHMARK_GROUP(123456789012);
-DEFINE_BENCHMARK_GROUP(1234567890123);
-DEFINE_BENCHMARK_GROUP(12345678901234);
-DEFINE_BENCHMARK_GROUP(123456789012345);
-DEFINE_BENCHMARK_GROUP(1234567890123456);
-DEFINE_BENCHMARK_GROUP(12345678901234567);
-DEFINE_BENCHMARK_GROUP(123456789012345678);
-DEFINE_BENCHMARK_GROUP(1234567890123456789);
-DEFINE_BENCHMARK_GROUP(12345678901234567890U);
-
-#undef DEFINE_BENCHMARK_GROUP
-
-#define DEFINE_BENCHMARK_GROUP(n)                       \
-  BENCHMARK_PARAM(clibAtoiMeasure, n);                  \
-  BENCHMARK_RELATIVE_PARAM(lexicalCastMeasure, n);      \
-  BENCHMARK_RELATIVE_PARAM(handwrittenAtoiMeasure, n);  \
-  BENCHMARK_RELATIVE_PARAM(follyAtoiMeasure, n);        \
-  BENCHMARK_DRAW_LINE();
-
-DEFINE_BENCHMARK_GROUP(1);
-DEFINE_BENCHMARK_GROUP(2);
-DEFINE_BENCHMARK_GROUP(3);
-DEFINE_BENCHMARK_GROUP(4);
-DEFINE_BENCHMARK_GROUP(5);
-DEFINE_BENCHMARK_GROUP(6);
-DEFINE_BENCHMARK_GROUP(7);
-DEFINE_BENCHMARK_GROUP(8);
-DEFINE_BENCHMARK_GROUP(9);
-DEFINE_BENCHMARK_GROUP(10);
-DEFINE_BENCHMARK_GROUP(11);
-DEFINE_BENCHMARK_GROUP(12);
-DEFINE_BENCHMARK_GROUP(13);
-DEFINE_BENCHMARK_GROUP(14);
-DEFINE_BENCHMARK_GROUP(15);
-DEFINE_BENCHMARK_GROUP(16);
-DEFINE_BENCHMARK_GROUP(17);
-DEFINE_BENCHMARK_GROUP(18);
-DEFINE_BENCHMARK_GROUP(19);
-
-#undef DEFINE_BENCHMARK_GROUP
-
-#define DEFINE_BENCHMARK_GROUP(T, n)                    \
-  BENCHMARK_PARAM(T ## VariadicToBM, n);                \
-  BENCHMARK_RELATIVE_PARAM(T ## IdenticalToBM, n);      \
-  BENCHMARK_DRAW_LINE();
-
-DEFINE_BENCHMARK_GROUP(string, 32);
-DEFINE_BENCHMARK_GROUP(string, 1024);
-DEFINE_BENCHMARK_GROUP(string, 32768);
-DEFINE_BENCHMARK_GROUP(fbstring, 32);
-DEFINE_BENCHMARK_GROUP(fbstring, 1024);
-DEFINE_BENCHMARK_GROUP(fbstring, 32768);
-
-#undef DEFINE_BENCHMARK_GROUP
-
-int main(int argc, char** argv) {
-  testing::InitGoogleTest(&argc, argv);
-  gflags::ParseCommandLineFlags(&argc, &argv, true);
-  auto ret = RUN_ALL_TESTS();
-  if (!ret && FLAGS_benchmark) {
-    folly::runBenchmarks();
-  }
-  return ret;
+TEST(Conv, TryToThenWithVoid) {
+  auto x = tryTo<int>("42").then([](int) {});
+  EXPECT_TRUE(x.hasValue());
+  Unit u = x.value();
+  (void)u;
 }