libstdc++: Add P1206R7 from_range members to std::string [PR111055]

This is the last piece of P1206R7, adding new members to
std::basic_string.

libstdc++-v3/ChangeLog:

	PR libstdc++/111055
	* include/bits/basic_string.h (_S_copy_range): New function.
	(basic_string(from_range_t, R%%, const Alloc&)): New
	constructor.
	(append_range, assign_range, insert_range, replace_with_range):
	New functions.
	* include/bits/cow_string.h: Likewise.
	* testsuite/21_strings/basic_string/cons/from_range.cc: New
	test.
	* testsuite/21_strings/basic_string/modifiers/append/append_range.cc:
	New test.
	* testsuite/21_strings/basic_string/modifiers/assign/assign_range.cc:
	New test.
	* testsuite/21_strings/basic_string/modifiers/insert/insert_range.cc:
	New test.
	* testsuite/21_strings/basic_string/modifiers/replace/replace_with_range.cc:
	New test.

Co-authored-by: Tomasz Kamiński <tkaminsk@redhat.com>

1 files changed, 125 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/append/append_range.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/append/append_range.cc
new file mode 100644
index 00000000000..6c0bc0cab18
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/append/append_range.cc
@@ -0,0 +1,125 @@
+// { dg-do run { target c++23 } }
+
+#include <span>
+#include <string>
+#include <testsuite_allocator.h>
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+template<typename Range, typename Alloc>
+constexpr void
+do_test()
+{
+  // The vector's value_type.
+  using V = typename std::allocator_traits<Alloc>::value_type;
+  using CT = std::char_traits<V>;
+
+  // The range's value_type.
+  using T = std::ranges::range_value_t<Range>;
+  T a[]{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+	'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'};
+
+  auto eq = [](const std::basic_string<V, CT, Alloc>& l, std::span<T> r) {
+    if (l.size() != r.size())
+      return false;
+    for (auto i = 0u; i < l.size(); ++i)
+      if (l[i] != r[i])
+	return false;
+    return true;
+  };
+
+  Range r4(a, a+4);
+  Range r5(a+4, a+9);
+  Range r11(a+9, a+20);
+
+  std::basic_string<V, CT, Alloc> v;
+  v.append_range(r4);
+  VERIFY( eq(v, {a, 4}) );
+  v.append_range(r5);
+  VERIFY( eq(v, {a, 9}) );
+
+  std::basic_string<V, CT, Alloc> const s = v;
+  v.append_range(r11);
+  VERIFY( eq(v, a) );
+  v.append_range(Range(a, a));
+  VERIFY( eq(v, a) );
+  v.clear();
+  v.append_range(Range(a, a));
+  VERIFY( v.empty() );
+}
+
+template<typename Range>
+void
+do_test_a()
+{
+  do_test<Range, std::allocator<char>>();
+  do_test<Range, __gnu_test::SimpleAllocator<char>>();
+  do_test<Range, std::allocator<wchar_t>>();
+  do_test<Range, __gnu_test::SimpleAllocator<wchar_t>>();
+}
+
+bool
+test_ranges()
+{
+  using namespace __gnu_test;
+
+  do_test_a<test_forward_range<char>>();
+  do_test_a<test_forward_sized_range<char>>();
+  do_test_a<test_sized_range_sized_sent<char, forward_iterator_wrapper>>();
+
+  do_test_a<test_input_range<char>>();
+  do_test_a<test_input_sized_range<char>>();
+  do_test_a<test_sized_range_sized_sent<char, input_iterator_wrapper>>();
+
+  do_test_a<test_range<char, input_iterator_wrapper_nocopy>>();
+  do_test_a<test_sized_range<char, input_iterator_wrapper_nocopy>>();
+  do_test_a<test_sized_range_sized_sent<char, input_iterator_wrapper_nocopy>>();
+
+  // Not lvalue-convertible to char
+  struct C {
+    C(char v) : val(v) { }
+    operator char() && { return val; }
+    bool operator==(char b) const { return b == val; }
+    char val;
+  };
+  using rvalue_input_range = test_range<C, input_iterator_wrapper_rval>;
+  do_test<rvalue_input_range, std::allocator<char>>();
+
+  return true;
+}
+
+void
+test_overlapping()
+{
+  std::string const s = "1234abcd";
+
+  std::string c = s;
+  c.append_range(std::string_view(c));
+  VERIFY( c == "1234abcd1234abcd" );
+
+  c = s;
+  c.append_range(std::string_view(c).substr(4, 4));
+  VERIFY( c == "1234abcdabcd" );
+
+  c = s;
+  c.reserve(12);
+  c.append_range(std::string_view(c).substr(0, 4));
+  VERIFY( c == "1234abcd1234" );
+}
+
+constexpr bool
+test_constexpr()
+{
+#if _GLIBCXX_USE_CXX11_ABI
+  // XXX: this doesn't test the non-forward_range code paths are constexpr.
+  do_test<std::string_view, std::allocator<char>>();
+#endif // _GLIBCXX_USE_CXX11_ABI
+  return true;
+}
+
+int main()
+{
+  test_ranges();
+  test_overlapping();
+  static_assert( test_constexpr() );
+}