[Support] Add FormatVariadic support for chrono types

Summary:
The formatter has three knobs:
- the user can choose which time unit to use for formatting (default: whatever is the unit of the input)
- he can choose whether the unit gets displayed (default: yes)
- he can affect the way the number itself is formatted via standard number formatting options (default:default)

Reviewers: zturner, inglorion

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29481

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294326 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/Chrono.h

@@ -11,6 +11,7 @@
 #define LLVM_SUPPORT_CHRONO_H
 
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/FormatProviders.h"
 
 #include <chrono>
 #include <ctime>
@@ -50,6 +51,106 @@ toTimePoint(std::time_t T) {
 
 raw_ostream &operator<<(raw_ostream &OS, sys::TimePoint<> TP);
 
+/// Implementation of format_provider<T> for duration types.
+///
+/// The options string of a duration  type has the grammar:
+///
+///   duration_options  ::= [unit][show_unit [number_options]]
+///   unit              ::= `h`|`m`|`s`|`ms|`us`|`ns`
+///   show_unit         ::= `+` | `-`
+///   number_options    ::= options string for a integral or floating point type
+///
+///   Examples
+///   =================================
+///   |  options  | Input | Output    |
+///   =================================
+///   | ""        | 1s    | 1 s       |
+///   | "ms"      | 1s    | 1000 ms   |
+///   | "ms-"     | 1s    | 1000      |
+///   | "ms-n"    | 1s    | 1,000     |
+///   | ""        | 1.0s  | 1.00 s    |
+///   =================================
+///
+///  If the unit of the duration type is not one of the units specified above,
+///  it is still possible to format it, provided you explicitly request a
+///  display unit or you request that the unit is not displayed.
+
+namespace detail {
+template <typename Period> struct unit { static constexpr char value[] = ""; };
+template <typename Period> constexpr char unit<Period>::value[];
+
+template <> struct unit<std::ratio<3600>> {
+  static constexpr char value[] = "h";
+};
+
+template <> struct unit<std::ratio<60>> {
+  static constexpr char value[] = "m";
+};
+
+template <> struct unit<std::ratio<1>> { static constexpr char value[] = "s"; };
+template <> struct unit<std::milli> { static constexpr char value[] = "ms"; };
+template <> struct unit<std::micro> { static constexpr char value[] = "us"; };
+template <> struct unit<std::nano> { static constexpr char value[] = "ns"; };
+} // namespace detail
+
+template <typename Rep, typename Period>
+struct format_provider<std::chrono::duration<Rep, Period>> {
+private:
+  typedef std::chrono::duration<Rep, Period> Dur;
+  typedef typename std::conditional<
+      std::chrono::treat_as_floating_point<Rep>::value, double, intmax_t>::type
+      InternalRep;
+
+  template <typename AsPeriod> static InternalRep getAs(const Dur &D) {
+    using namespace std::chrono;
+    return duration_cast<duration<InternalRep, AsPeriod>>(D).count();
+  }
+
+  static std::pair<InternalRep, StringRef> consumeUnit(StringRef &Style,
+                                                        const Dur &D) {
+    using namespace std::chrono;
+    if (Style.consume_front("ns"))
+      return {getAs<std::nano>(D), "ns"};
+    if (Style.consume_front("us"))
+      return {getAs<std::micro>(D), "us"};
+    if (Style.consume_front("ms"))
+      return {getAs<std::milli>(D), "ms"};
+    if (Style.consume_front("s"))
+      return {getAs<std::ratio<1>>(D), "s"};
+    if (Style.consume_front("m"))
+      return {getAs<std::ratio<60>>(D), "m"};
+    if (Style.consume_front("h"))
+      return {getAs<std::ratio<3600>>(D), "h"};
+    return {D.count(), detail::unit<Period>::value};
+  }
+
+  static bool consumeShowUnit(StringRef &Style) {
+    if (Style.empty())
+      return true;
+    if (Style.consume_front("-"))
+      return false;
+    if (Style.consume_front("+"))
+      return true;
+    assert(0 && "Unrecognised duration format");
+    return true;
+  }
+
+public:
+  static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style) {
+    InternalRep count;
+    StringRef unit;
+    std::tie(count, unit) = consumeUnit(Style, D);
+    bool show_unit = consumeShowUnit(Style);
+
+    format_provider<InternalRep>::format(count, Stream, Style);
+
+    if (show_unit) {
+      assert(!unit.empty());
+      Stream << " " << unit;
+    }
+  }
+};
+
 } // namespace llvm
 
 #endif // LLVM_SUPPORT_CHRONO_H

lib/Support/Chrono.cpp

@@ -16,6 +16,13 @@ namespace llvm {
 
 using namespace sys;
 
+constexpr char detail::unit<std::ratio<3600>>::value[];
+constexpr char detail::unit<std::ratio<60>>::value[];
+constexpr char detail::unit<std::ratio<1>>::value[];
+constexpr char detail::unit<std::milli>::value[];
+constexpr char detail::unit<std::micro>::value[];
+constexpr char detail::unit<std::nano>::value[];
+
 static inline struct tm getStructTM(TimePoint<> TP) {
   struct tm Storage;
   std::time_t OurTime = toTimeT(TP);

unittests/Support/Chrono.cpp

@@ -9,6 +9,7 @@
 
 #include "llvm/Support/Chrono.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/FormatVariadic.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
@@ -76,4 +77,34 @@ TEST(Chrono, ImplicitConversions) {
   EXPECT_EQ(TimeT, toTimeT(Nano));
 }
 
+TEST(Chrono, DurationFormat) {
+  EXPECT_EQ("1 h", formatv("{0}", hours(1)).str());
+  EXPECT_EQ("1 m", formatv("{0}", minutes(1)).str());
+  EXPECT_EQ("1 s", formatv("{0}", seconds(1)).str());
+  EXPECT_EQ("1 ms", formatv("{0}", milliseconds(1)).str());
+  EXPECT_EQ("1 us", formatv("{0}", microseconds(1)).str());
+  EXPECT_EQ("1 ns", formatv("{0}", nanoseconds(1)).str());
+
+  EXPECT_EQ("1 s", formatv("{0:+}", seconds(1)).str());
+  EXPECT_EQ("1", formatv("{0:-}", seconds(1)).str());
+
+  EXPECT_EQ("1000 ms", formatv("{0:ms}", seconds(1)).str());
+  EXPECT_EQ("1000000 us", formatv("{0:us}", seconds(1)).str());
+  EXPECT_EQ("1000", formatv("{0:ms-}", seconds(1)).str());
+
+  EXPECT_EQ("1,000 ms", formatv("{0:+n}", milliseconds(1000)).str());
+  EXPECT_EQ("0x3e8", formatv("{0:-x}", milliseconds(1000)).str());
+  EXPECT_EQ("010", formatv("{0:-3}", milliseconds(10)).str());
+  EXPECT_EQ("10,000", formatv("{0:ms-n}", seconds(10)).str());
+
+  EXPECT_EQ("1.00 s", formatv("{0}", duration<float>(1)).str());
+  EXPECT_EQ("0.123 s", formatv("{0:+3}", duration<float>(0.123f)).str());
+  EXPECT_EQ("1.230e-01 s", formatv("{0:+e3}", duration<float>(0.123f)).str());
+
+  typedef duration<float, std::ratio<60 * 60 * 24 * 14, 1000000>>
+      microfortnights;
+  EXPECT_EQ("1.00", formatv("{0:-}", microfortnights(1)).str());
+  EXPECT_EQ("1209.60 ms", formatv("{0:ms}", microfortnights(1)).str());
+}
+
 } // anonymous namespace