From a77c1282d047a1c0f64ca09c62596f0868fe5b1f Mon Sep 17 00:00:00 2001
From: Nadav Har'El <nyh@cloudius-systems.com>
Date: Wed, 15 Jan 2014 09:49:04 +0200
Subject: [PATCH] osv/clock.hh: Add std::chrono::duration literals
In <drivers/clock.hh> we had support for time literals looking like 100_ns,
100_us, 100_ms, 100_s. These simply translated to an integer number of
nanoseconds.
Added to <osv/clock.hh> similar literals, but using strongly-typed
std::chrono::duration, so that 100_ms translates to
std::chrono::milliseconds(100), and this is, as usual, automatically
scaled by the compiler to other units when other units (e.g., nanoseconds)
are required.
Because the literals of <drivers/clock.hh> and <osv/clock.hh> have the
same name, to use the latter you need to explicitly enable them in a scope
using the statement
using namespace osv::clock::literals;
One the entire codebase is converted to use <osv/clock.hh> and std::chrono,
the old literals from <drivers/clock.hh> should be removed.
Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
---
include/osv/clock.hh | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/include/osv/clock.hh b/include/osv/clock.hh
index 6defff6cd..c5390f6c2 100644
--- a/include/osv/clock.hh
+++ b/include/osv/clock.hh
@@ -42,8 +42,43 @@ public:
return time_point(duration(::clock::get()->uptime()));
}
};
+
+/**
+ * Convenient literals for specifying std::chrono::duration's.
+ *
+ * C++14 will support std::chrono::duration literals, used as in the following
+ * example:
+ * @code
+ * using namespace std::literals::chrono_literals;
+ * auto d = 100ns;
+ * @endcode
+ * Because these are not yet available to us, we implement a similar feature
+ * but using different names:
+ * @code
+ * using namespace osv::clock::literals;
+ * auto d = 100_ns;
+ * @endcode
+ */
+namespace literals {
+/** Nanoseconds */
+constexpr std::chrono::nanoseconds operator "" _ns(unsigned long long c) {
+ return std::chrono::nanoseconds(c);
+}
+/** Microseconds */
+constexpr std::chrono::microseconds operator "" _us(unsigned long long c) {
+ return std::chrono::microseconds(c);
+}
+/** Milliseconds */
+constexpr std::chrono::milliseconds operator "" _ms(unsigned long long c) {
+ return std::chrono::milliseconds(c);
+}
+/** Seconds */
+constexpr std::chrono::seconds operator "" _s(unsigned long long c) {
+ return std::chrono::seconds(c);
}
}
+}
+}
#endif /* OSV_CLOCK_HH_ */
--
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