[libcxx-commits] [libcxx] r354801 - First part of P1024: Usability Enhancements for std::span. Remove operator() for indexing, and add 'front' and 'back' calls.
Marshall Clow via libcxx-commits
libcxx-commits at lists.llvm.org
Mon Feb 25 09:54:08 PST 2019
Author: marshall
Date: Mon Feb 25 09:54:08 2019
New Revision: 354801
URL: http://llvm.org/viewvc/llvm-project?rev=354801&view=rev
Log:
First part of P1024: Usability Enhancements for std::span. Remove operator() for indexing, and add 'front' and 'back' calls.
Added:
libcxx/trunk/test/std/containers/views/span.elem/back.pass.cpp
libcxx/trunk/test/std/containers/views/span.elem/front.pass.cpp
Modified:
libcxx/trunk/include/span
libcxx/trunk/test/std/containers/views/span.elem/op_idx.pass.cpp
Modified: libcxx/trunk/include/span
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/span?rev=354801&r1=354800&r2=354801&view=diff
==============================================================================
--- libcxx/trunk/include/span (original)
+++ libcxx/trunk/include/span Mon Feb 25 09:54:08 2019
@@ -88,7 +88,8 @@ public:
// [span.elem], span element access
constexpr reference operator[](index_type idx) const;
- constexpr reference operator()(index_type idx) const;
+ constexpr reference front() const;
+ constexpr reference back() const;
constexpr pointer data() const noexcept;
// [span.iterators], span iterator support
@@ -319,10 +320,16 @@ public:
return __data[__idx];
}
- _LIBCPP_INLINE_VISIBILITY constexpr reference operator()(index_type __idx) const noexcept
+ _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept
{
- _LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T,N>() index out of bounds");
- return __data[__idx];
+ static_assert(_Extent > 0, "span<T,N>[].front() on empty span");
+ return __data[0];
+ }
+
+ _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept
+ {
+ static_assert(_Extent > 0, "span<T,N>[].back() on empty span");
+ return __data[size()-1];
}
_LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; }
@@ -484,12 +491,19 @@ public:
return __data[__idx];
}
- _LIBCPP_INLINE_VISIBILITY constexpr reference operator()(index_type __idx) const noexcept
+ _LIBCPP_INLINE_VISIBILITY constexpr reference front() const noexcept
{
- _LIBCPP_ASSERT(__idx >= 0 && __idx < size(), "span<T>() index out of bounds");
- return __data[__idx];
+ _LIBCPP_ASSERT(!empty(), "span<T>[].front() on empty span");
+ return __data[0];
}
+ _LIBCPP_INLINE_VISIBILITY constexpr reference back() const noexcept
+ {
+ _LIBCPP_ASSERT(!empty(), "span<T>[].back() on empty span");
+ return __data[size()-1];
+ }
+
+
_LIBCPP_INLINE_VISIBILITY constexpr pointer data() const noexcept { return __data; }
// [span.iter], span iterator support
Added: libcxx/trunk/test/std/containers/views/span.elem/back.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/containers/views/span.elem/back.pass.cpp?rev=354801&view=auto
==============================================================================
--- libcxx/trunk/test/std/containers/views/span.elem/back.pass.cpp (added)
+++ libcxx/trunk/test/std/containers/views/span.elem/back.pass.cpp Mon Feb 25 09:54:08 2019
@@ -0,0 +1,75 @@
+// -*- C++ -*-
+//===------------------------------ span ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===---------------------------------------------------------------------===//
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+
+// <span>
+
+// constexpr reference back() const noexcept;
+// Expects: empty() is false.
+// Effects: Equivalent to: return *(data() + (size() - 1));
+//
+
+
+#include <span>
+#include <cassert>
+#include <string>
+
+#include "test_macros.h"
+
+
+template <typename Span>
+constexpr bool testConstexprSpan(Span sp)
+{
+ _LIBCPP_ASSERT(sp.back(), "");
+ return std::addressof(sp.back()) == sp.data() + sp.size() - 1;
+}
+
+
+template <typename Span>
+void testRuntimeSpan(Span sp)
+{
+ _LIBCPP_ASSERT(sp.back(), "");
+ assert(std::addressof(sp.back()) == sp.data() + sp.size() - 1);
+}
+
+
+struct A{};
+constexpr int iArr1[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+ int iArr2[] = {10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
+
+int main(int, char**)
+{
+ static_assert(testConstexprSpan(std::span<const int>(iArr1, 1)), "");
+ static_assert(testConstexprSpan(std::span<const int>(iArr1, 2)), "");
+ static_assert(testConstexprSpan(std::span<const int>(iArr1, 3)), "");
+ static_assert(testConstexprSpan(std::span<const int>(iArr1, 4)), "");
+
+ static_assert(testConstexprSpan(std::span<const int, 1>(iArr1, 1)), "");
+ static_assert(testConstexprSpan(std::span<const int, 2>(iArr1, 2)), "");
+ static_assert(testConstexprSpan(std::span<const int, 3>(iArr1, 3)), "");
+ static_assert(testConstexprSpan(std::span<const int, 4>(iArr1, 4)), "");
+
+
+ testRuntimeSpan(std::span<int>(iArr2, 1));
+ testRuntimeSpan(std::span<int>(iArr2, 2));
+ testRuntimeSpan(std::span<int>(iArr2, 3));
+ testRuntimeSpan(std::span<int>(iArr2, 4));
+
+
+ testRuntimeSpan(std::span<int, 1>(iArr2, 1));
+ testRuntimeSpan(std::span<int, 2>(iArr2, 2));
+ testRuntimeSpan(std::span<int, 3>(iArr2, 3));
+ testRuntimeSpan(std::span<int, 4>(iArr2, 4));
+
+ std::string s;
+ testRuntimeSpan(std::span<std::string> (&s, 1));
+ testRuntimeSpan(std::span<std::string, 1>(&s, 1));
+
+ return 0;
+}
Added: libcxx/trunk/test/std/containers/views/span.elem/front.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/containers/views/span.elem/front.pass.cpp?rev=354801&view=auto
==============================================================================
--- libcxx/trunk/test/std/containers/views/span.elem/front.pass.cpp (added)
+++ libcxx/trunk/test/std/containers/views/span.elem/front.pass.cpp Mon Feb 25 09:54:08 2019
@@ -0,0 +1,75 @@
+// -*- C++ -*-
+//===------------------------------ span ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===---------------------------------------------------------------------===//
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+
+// <span>
+
+// constexpr reference front() const noexcept;
+// Expects: empty() is false.
+// Effects: Equivalent to: return *data();
+//
+
+
+#include <span>
+#include <cassert>
+#include <string>
+
+#include "test_macros.h"
+
+
+template <typename Span>
+constexpr bool testConstexprSpan(Span sp)
+{
+ _LIBCPP_ASSERT(sp.front(), "");
+ return std::addressof(sp.front()) == sp.data();
+}
+
+
+template <typename Span>
+void testRuntimeSpan(Span sp)
+{
+ _LIBCPP_ASSERT(sp.front(), "");
+ assert(std::addressof(sp.front()) == sp.data());
+}
+
+
+struct A{};
+constexpr int iArr1[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+ int iArr2[] = {10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
+
+int main(int, char**)
+{
+ static_assert(testConstexprSpan(std::span<const int>(iArr1, 1)), "");
+ static_assert(testConstexprSpan(std::span<const int>(iArr1, 2)), "");
+ static_assert(testConstexprSpan(std::span<const int>(iArr1, 3)), "");
+ static_assert(testConstexprSpan(std::span<const int>(iArr1, 4)), "");
+
+ static_assert(testConstexprSpan(std::span<const int, 1>(iArr1, 1)), "");
+ static_assert(testConstexprSpan(std::span<const int, 2>(iArr1, 2)), "");
+ static_assert(testConstexprSpan(std::span<const int, 3>(iArr1, 3)), "");
+ static_assert(testConstexprSpan(std::span<const int, 4>(iArr1, 4)), "");
+
+
+ testRuntimeSpan(std::span<int>(iArr2, 1));
+ testRuntimeSpan(std::span<int>(iArr2, 2));
+ testRuntimeSpan(std::span<int>(iArr2, 3));
+ testRuntimeSpan(std::span<int>(iArr2, 4));
+
+
+ testRuntimeSpan(std::span<int, 1>(iArr2, 1));
+ testRuntimeSpan(std::span<int, 2>(iArr2, 2));
+ testRuntimeSpan(std::span<int, 3>(iArr2, 3));
+ testRuntimeSpan(std::span<int, 4>(iArr2, 4));
+
+ std::string s;
+ testRuntimeSpan(std::span<std::string> (&s, 1));
+ testRuntimeSpan(std::span<std::string, 1>(&s, 1));
+
+ return 0;
+}
Modified: libcxx/trunk/test/std/containers/views/span.elem/op_idx.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/containers/views/span.elem/op_idx.pass.cpp?rev=354801&r1=354800&r2=354801&view=diff
==============================================================================
--- libcxx/trunk/test/std/containers/views/span.elem/op_idx.pass.cpp (original)
+++ libcxx/trunk/test/std/containers/views/span.elem/op_idx.pass.cpp Mon Feb 25 09:54:08 2019
@@ -26,12 +26,10 @@ template <typename Span>
constexpr bool testConstexprSpan(Span sp, ptrdiff_t idx)
{
_LIBCPP_ASSERT(noexcept(sp[idx]), "");
- _LIBCPP_ASSERT(noexcept(sp(idx)), "");
typename Span::reference r1 = sp[idx];
- typename Span::reference r2 = sp(idx);
- typename Span::reference r3 = *(sp.data() + idx);
- return r1 == r2 && r2 == r3;
+ typename Span::reference r2 = *(sp.data() + idx);
+ return r1 == r2;
}
@@ -39,12 +37,10 @@ template <typename Span>
void testRuntimeSpan(Span sp, ptrdiff_t idx)
{
_LIBCPP_ASSERT(noexcept(sp[idx]), "");
- _LIBCPP_ASSERT(noexcept(sp(idx)), "");
typename Span::reference r1 = sp[idx];
- typename Span::reference r2 = sp(idx);
- typename Span::reference r3 = *(sp.data() + idx);
- assert(r1 == r2 && r2 == r3);
+ typename Span::reference r2 = *(sp.data() + idx);
+ assert(r1 == r2);
}
struct A{};
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