--- /dev/null
+/* Copyright (c) 2017, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#ifndef OPENSSL_HEADER_SSL_SPAN_H
+#define OPENSSL_HEADER_SSL_SPAN_H
+
+#include <openssl/base.h>
+
+#if !defined(BORINGSSL_NO_CXX)
+
+extern "C++" {
+
+#include <algorithm>
+#include <cassert>
+#include <cstdlib>
+#include <type_traits>
+
+namespace bssl {
+
+template <typename T>
+class Span;
+
+namespace internal {
+template <typename T>
+class SpanBase {
+ // Put comparison operator implementations into a base class with const T, so
+ // they can be used with any type that implicitly converts into a Span.
+ static_assert(std::is_const<T>::value,
+ "Span<T> must be derived from SpanBase<const T>");
+
+ friend bool operator==(Span<T> lhs, Span<T> rhs) {
+ // MSVC issues warning C4996 because std::equal is unsafe. The pragma to
+ // suppress the warning mysteriously has no effect, hence this
+ // implementation. See
+ // https://msdn.microsoft.com/en-us/library/aa985974.aspx.
+ if (lhs.size() != rhs.size()) {
+ return false;
+ }
+ for (T *l = lhs.begin(), *r = rhs.begin(); l != lhs.end() && r != rhs.end();
+ ++l, ++r) {
+ if (*l != *r) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ friend bool operator!=(Span<T> lhs, Span<T> rhs) { return !(lhs == rhs); }
+};
+} // namespace internal
+
+// A Span<T> is a non-owning reference to a contiguous array of objects of type
+// |T|. Conceptually, a Span is a simple a pointer to |T| and a count of
+// elements accessible via that pointer. The elements referenced by the Span can
+// be mutated if |T| is mutable.
+//
+// A Span can be constructed from container types implementing |data()| and
+// |size()| methods. If |T| is constant, construction from a container type is
+// implicit. This allows writing methods that accept data from some unspecified
+// container type:
+//
+// // Foo views data referenced by v.
+// void Foo(bssl::Span<const uint8_t> v) { ... }
+//
+// std::vector<uint8_t> vec;
+// Foo(vec);
+//
+// For mutable Spans, conversion is explicit:
+//
+// // FooMutate mutates data referenced by v.
+// void FooMutate(bssl::Span<uint8_t> v) { ... }
+//
+// FooMutate(bssl::Span<uint8_t>(vec));
+//
+// You can also use the |MakeSpan| and |MakeConstSpan| factory methods to
+// construct Spans in order to deduce the type of the Span automatically.
+//
+// FooMutate(bssl::MakeSpan(vec));
+//
+// Note that Spans have value type sematics. They are cheap to construct and
+// copy, and should be passed by value whenever a method would otherwise accept
+// a reference or pointer to a container or array.
+template <typename T>
+class Span : private internal::SpanBase<const T> {
+ private:
+ // Heuristically test whether C is a container type that can be converted into
+ // a Span by checking for data() and size() member functions.
+ //
+ // TODO(davidben): Switch everything to std::enable_if_t when we remove
+ // support for MSVC 2015. Although we could write our own enable_if_t and MSVC
+ // 2015 has std::enable_if_t anyway, MSVC 2015's SFINAE implementation is
+ // problematic and does not work below unless we write the ::type at use.
+ template <typename C>
+ using EnableIfContainer = std::enable_if<
+ std::is_convertible<decltype(std::declval<C>().data()), T *>::value &&
+ std::is_integral<decltype(std::declval<C>().size())>::value>;
+
+ static const size_t npos = static_cast<size_t>(-1);
+
+ public:
+ constexpr Span() : Span(nullptr, 0) {}
+ constexpr Span(T *ptr, size_t len) : data_(ptr), size_(len) {}
+
+ template <size_t N>
+ constexpr Span(T (&array)[N]) : Span(array, N) {}
+
+ template <
+ typename C, typename = typename EnableIfContainer<C>::type,
+ typename = typename std::enable_if<std::is_const<T>::value, C>::type>
+ Span(const C &container) : data_(container.data()), size_(container.size()) {}
+
+ template <
+ typename C, typename = typename EnableIfContainer<C>::type,
+ typename = typename std::enable_if<!std::is_const<T>::value, C>::type>
+ explicit Span(C &container)
+ : data_(container.data()), size_(container.size()) {}
+
+ T *data() const { return data_; }
+ size_t size() const { return size_; }
+ bool empty() const { return size_ == 0; }
+
+ T *begin() const { return data_; }
+ const T *cbegin() const { return data_; }
+ T *end() const { return data_ + size_; };
+ const T *cend() const { return end(); };
+
+ T &front() const {
+ assert(size_ != 0);
+ return data_[0];
+ }
+ T &back() const {
+ assert(size_ != 0);
+ return data_[size_ - 1];
+ }
+
+ T &operator[](size_t i) const { return data_[i]; }
+ T &at(size_t i) const { return data_[i]; }
+
+ Span subspan(size_t pos = 0, size_t len = npos) const {
+ if (pos > size_) {
+ abort(); // absl::Span throws an exception here.
+ }
+ return Span(data_ + pos, std::min(size_ - pos, len));
+ }
+
+ private:
+ T *data_;
+ size_t size_;
+};
+
+template <typename T>
+const size_t Span<T>::npos;
+
+template <typename T>
+Span<T> MakeSpan(T *ptr, size_t size) {
+ return Span<T>(ptr, size);
+}
+
+template <typename C>
+auto MakeSpan(C &c) -> decltype(MakeSpan(c.data(), c.size())) {
+ return MakeSpan(c.data(), c.size());
+}
+
+template <typename T>
+Span<const T> MakeConstSpan(T *ptr, size_t size) {
+ return Span<const T>(ptr, size);
+}
+
+template <typename C>
+auto MakeConstSpan(const C &c) -> decltype(MakeConstSpan(c.data(), c.size())) {
+ return MakeConstSpan(c.data(), c.size());
+}
+
+} // namespace bssl
+
+} // extern C++
+
+#endif // !defined(BORINGSSL_NO_CXX)
+
+#endif // OPENSSL_HEADER_SSL_SPAN_H
git://repos.xcallymotion.com / motion2.git / blobdiff