A more lightweight O[U]StringConcatenation

...compared to a full-blown O[U]String, for temporary objects holding an
O[U]StringConcat result that can then be used as a std::[u16]string_view.

It's instructive to see how some invocations of operator ==, operator !=, and
O[U]StringBuffer::insert with an O[U]StringConcat argument required implicit
materialization of an O[U]String temporary, and how that expensive operation has
now been made explicit with the explicit O[U]StringConcatenation ctor.

(The additional operator == and operator != overloads are necessary because the
overloads taking two std::[u16]string_view parameters wouldn't even be found
here with ADL.  And the OUString-related ones would cause ambiguities in at
least sal/qa/rtl/strings/test_oustring_stringliterals.cxx built with
RTL_STRING_UNITTEST, so have simply been disabled for that special test-code
case.)

Change-Id: Id29799fa8da21a09ff9794cbc7cc9b366e6803b8
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/122890
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/rtl/ustring.hxx b/include/rtl/ustring.hxx
index 96bb504f77a8..5fbf00d64a6d 100644
--- a/include/rtl/ustring.hxx
+++ b/include/rtl/ustring.hxx
@@ -3393,6 +3393,17 @@ void operator !=(OUString const &, std::nullptr_t) = delete;
 void operator !=(std::nullptr_t, OUString const &) = delete;
 #endif
 
+#if defined LIBO_INTERNAL_ONLY && !defined RTL_STRING_UNITTEST
+inline bool operator ==(OUString const & lhs, OUStringConcatenation const & rhs)
+{ return lhs == std::u16string_view(rhs); }
+inline bool operator !=(OUString const & lhs, OUStringConcatenation const & rhs)
+{ return lhs != std::u16string_view(rhs); }
+inline bool operator ==(OUStringConcatenation const & lhs, OUString const & rhs)
+{ return std::u16string_view(lhs) == rhs; }
+inline bool operator !=(OUStringConcatenation const & lhs, OUString const & rhs)
+{ return std::u16string_view(lhs) != rhs; }
+#endif
+
 #if defined LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
 /// @cond INTERNAL
 
@@ -3560,6 +3571,7 @@ using ::rtl::OStringToOUString;
 using ::rtl::OUStringToOString;
 using ::rtl::OUStringLiteral;
 using ::rtl::OUStringChar;
+using ::rtl::OUStringConcatenation;
 #endif
 
 /// @cond INTERNAL