From: Yedidya Feldblum <yfeldblum@fb.com>
Date: Tue, 12 Dec 2017 04:19:06 +0000 (-0800)
Subject: Assorted tweaks to folly/String.h
X-Git-Tag: v2017.12.18.00~28
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c01c18b26eded07d11079a77d3df36a57fd4bf16;p=folly.git
Assorted tweaks to folly/String.h
Summary:
[Folly] Assorted tweaks to `folly/String.h`.
* Use `void_t` in the definition of `IsConvertible`.
* Remove `AllConvertible`. Callers can use `StrictConjunction` instead.
* Move the `static_assert`s from the header to the source file.
Reviewed By: andrewjcg, ot
Differential Revision: D6501515
fbshipit-source-id: 472ecf23bf7f06be211480b0aceea95f7e60dc21
---
diff --git a/folly/String-inl.h b/folly/String-inl.h
index f6b5ba99..597897db 100644
--- a/folly/String-inl.h
+++ b/folly/String-inl.h
@@ -401,7 +401,8 @@ void splitTo(const Delim& delimiter,
template <bool exact, class Delim, class... OutputTypes>
typename std::enable_if<
- AllConvertible<OutputTypes...>::value && sizeof...(OutputTypes) >= 1,
+ StrictConjunction<IsConvertible<OutputTypes>...>::value &&
+ sizeof...(OutputTypes) >= 1,
bool>::type
split(const Delim& delimiter, StringPiece input, OutputTypes&... outputs) {
return detail::splitFixed<exact>(
diff --git a/folly/String.cpp b/folly/String.cpp
index 097e5bbf..f4a92396 100644
--- a/folly/String.cpp
+++ b/folly/String.cpp
@@ -29,6 +29,12 @@
namespace folly {
+static_assert(IsConvertible<float>::value, "");
+static_assert(IsConvertible<int>::value, "");
+static_assert(IsConvertible<bool>::value, "");
+static_assert(IsConvertible<int>::value, "");
+static_assert(!IsConvertible<std::vector<int>>::value, "");
+
static inline bool is_oddspace(char c) {
return c == '\n' || c == '\t' || c == '\r';
}
diff --git a/folly/String.h b/folly/String.h
index 750863b9..0251b987 100644
--- a/folly/String.h
+++ b/folly/String.h
@@ -34,6 +34,7 @@
#include <folly/Portability.h>
#include <folly/Range.h>
#include <folly/ScopeGuard.h>
+#include <folly/Traits.h>
// Compatibility function, to make sure toStdString(s) can be called
// to convert a std::string or fbstring variable s into type std::string
@@ -468,41 +469,22 @@ void splitTo(const Delim& delimiter,
* Note that this will likely not work if the last field's target is of numeric
* type, in which case folly::to<> will throw an exception.
*/
-template <class T, class Enable = void>
-struct IsConvertible {
- enum { value = false };
-};
+namespace detail {
+template <typename Void, typename OutputType>
+struct IsConvertible : std::false_type {};
-template <class T>
+template <typename OutputType>
struct IsConvertible<
- T,
- decltype(static_cast<void>(
- parseTo(std::declval<folly::StringPiece>(), std::declval<T&>())))> {
- enum { value = true };
-};
-
-template <class... Types>
-struct AllConvertible;
-
-template <class Head, class... Tail>
-struct AllConvertible<Head, Tail...> {
- enum { value = IsConvertible<Head>::value && AllConvertible<Tail...>::value };
-};
-
-template <>
-struct AllConvertible<> {
- enum { value = true };
-};
-
-static_assert(AllConvertible<float>::value, "");
-static_assert(AllConvertible<int>::value, "");
-static_assert(AllConvertible<bool>::value, "");
-static_assert(AllConvertible<int>::value, "");
-static_assert(!AllConvertible<std::vector<int>>::value, "");
+ void_t<decltype(parseTo(StringPiece{}, std::declval<OutputType&>()))>,
+ OutputType> : std::true_type {};
+} // namespace detail
+template <typename OutputType>
+struct IsConvertible : detail::IsConvertible<void, OutputType> {};
template <bool exact = true, class Delim, class... OutputTypes>
typename std::enable_if<
- AllConvertible<OutputTypes...>::value && sizeof...(OutputTypes) >= 1,
+ StrictConjunction<IsConvertible<OutputTypes>...>::value &&
+ sizeof...(OutputTypes) >= 1,
bool>::type
split(const Delim& delimiter, StringPiece input, OutputTypes&... outputs);