Implement std::string_view as described in http://wg21.link/P0254R1. Reviewed as https://reviews.llvm.org/D21459

llvm-svn: 276238
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp
new file mode 100644
index 0000000..0a2ed837
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp
@@ -0,0 +1,101 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string_view>
+
+// size_type copy(charT* s, size_type n, size_type pos = 0) const;
+
+// Throws: out_of_range if pos > size().
+// Remarks: Let rlen be the smaller of n and size() - pos.
+// Requires: [s, s+rlen) is a valid range.
+// Effects: Equivalent to std::copy_n(begin() + pos, rlen, s).
+// Returns: rlen.
+
+
+#include <string_view>
+#include <cassert>
+
+#include "test_macros.h"
+
+template<typename CharT>
+void test1 ( std::basic_string_view<CharT> sv, size_t n, size_t pos ) {
+    const size_t rlen = std::min ( n, sv.size() - pos );
+
+    CharT *dest1 = new CharT [rlen + 1];    dest1[rlen] = 0;
+    CharT *dest2 = new CharT [rlen + 1];    dest2[rlen] = 0;
+
+    if (pos > sv.size()) {
+#ifndef TEST_HAS_NO_EXCEPTIONS
+        try {
+            sv.copy(dest1, n, pos);
+            assert(false);
+        } catch (const std::out_of_range&) {
+        } catch (...) {
+            assert(false);
+        }
+#endif
+    } else {
+        sv.copy(dest1, n, pos);
+        std::copy_n(sv.begin() + pos, rlen, dest2);
+        for ( size_t i = 0; i <= rlen; ++i )
+            assert ( dest1[i] == dest2[i] );
+    }
+    delete [] dest1;
+    delete [] dest2;
+}
+
+
+template<typename CharT>
+void test ( const CharT *s ) {
+    typedef std::basic_string_view<CharT> string_view_t;
+
+    string_view_t sv1 ( s );
+
+    test1(sv1,  0, 0);
+    test1(sv1,  1, 0);
+    test1(sv1, 20, 0);
+    test1(sv1, sv1.size(), 0);
+    test1(sv1, 20, string_view_t::npos);
+
+    test1(sv1,   0, 3);
+    test1(sv1,   2, 3);
+    test1(sv1, 100, 3);
+    test1(sv1, 100, string_view_t::npos);
+
+    test1(sv1, sv1.size(), string_view_t::npos);
+
+    test1(sv1, sv1.size() + 1, 0);
+    test1(sv1, sv1.size() + 1, 1);
+    test1(sv1, sv1.size() + 1, string_view_t::npos);
+
+}
+
+int main () {
+    test ( "ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
+    test ( "ABCDE");
+    test ( "a" );
+    test ( "" );
+
+    test ( L"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
+    test ( L"ABCDE" );
+    test ( L"a" );
+    test ( L"" );
+
+#if TEST_STD_VER >= 11
+    test ( u"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
+    test ( u"ABCDE" );
+    test ( u"a" );
+    test ( u"" );
+
+    test ( U"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
+    test ( U"ABCDE" );
+    test ( U"a" );
+    test ( U"" );
+#endif
+}