Deduplicate O(U)StringConcatenation

And use an overloaded helper function with a better (?) unified name
to show that the result is not an O(U)String.

Change-Id: I8956338b05d02bf46a6185828130ea8ef145d46b
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/141203
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

3 files changed, 26 insertions, 36 deletions

diff --git a/include/rtl/string.hxx b/include/rtl/string.hxx
index 9ae30586e549..0e0c3c75d5a9 100644
--- a/include/rtl/string.hxx
+++ b/include/rtl/string.hxx
@@ -2169,13 +2169,13 @@ public:
 };
 
 #if defined LIBO_INTERNAL_ONLY
-inline bool operator ==(OString const & lhs, OStringConcatenation const & rhs)
+inline bool operator ==(OString const & lhs, StringConcatenation<char> const & rhs)
 { return lhs == std::string_view(rhs); }
-inline bool operator !=(OString const & lhs, OStringConcatenation const & rhs)
+inline bool operator !=(OString const & lhs, StringConcatenation<char> const & rhs)
 { return lhs != std::string_view(rhs); }
-inline bool operator ==(OStringConcatenation const & lhs, OString const & rhs)
+inline bool operator ==(StringConcatenation<char> const & lhs, OString const & rhs)
 { return std::string_view(lhs) == rhs; }
-inline bool operator !=(OStringConcatenation const & lhs, OString const & rhs)
+inline bool operator !=(StringConcatenation<char> const & lhs, OString const & rhs)
 { return std::string_view(lhs) != rhs; }
 #endif
 
@@ -2282,7 +2282,7 @@ typedef rtlunittest::OString OString;
 #if defined LIBO_INTERNAL_ONLY && !defined RTL_STRING_UNITTEST
 using ::rtl::OString;
 using ::rtl::OStringChar;
-using ::rtl::OStringConcatenation;
+using ::rtl::Concat2View;
 using ::rtl::OStringHash;
 using ::rtl::OStringLiteral;
 #endif
diff --git a/include/rtl/stringconcat.hxx b/include/rtl/stringconcat.hxx
index 51605d0731e9..c2862c5c49ad 100644
--- a/include/rtl/stringconcat.hxx
+++ b/include/rtl/stringconcat.hxx
@@ -355,45 +355,35 @@ int operator+( const StringConcatInvalid&, const T& )
     }
 #endif
 
-// Lightweight alternative to OString when a (temporary) object is needed to hold an OStringConcat
-// result that can then be used as a std::string_view:
-class OStringConcatenation {
+// Lightweight alternative to O(U)String when a (temporary) object is needed to hold
+// an O(U)StringConcat result that can then be used as a std::(u16)string_view:
+template <typename C> class StringConcatenation {
 public:
-    template<typename T1, typename T2>
-    explicit OStringConcatenation(OStringConcat<T1, T2> const & c):
+    template <class Concat>
+    explicit StringConcatenation(Concat const& c):
         length_(c.length()),
-        buffer_(new char[length_])
+        buffer_(new C[length_])
     {
         auto const end = c.addData(buffer_.get());
         assert(end == buffer_.get() + length_); (void)end;
     }
 
-    operator std::string_view() const { return {buffer_.get(), length_}; }
+    operator std::basic_string_view<C>() const { return {buffer_.get(), length_}; }
 
 private:
     std::size_t length_;
-    std::unique_ptr<char[]> buffer_;
+    std::unique_ptr<C[]> buffer_;
 };
 
-// Lightweight alternative to OUString when a (temporary) object is needed to hold an
-// OUStringConcat result that can then be used as a std::u16string_view:
-class OUStringConcatenation {
-public:
-    template<typename T1, typename T2>
-    explicit OUStringConcatenation(OUStringConcat<T1, T2> const & c):
-        length_(c.length()),
-        buffer_(new char16_t[length_])
-    {
-        auto const end = c.addData(buffer_.get());
-        assert(end == buffer_.get() + length_); (void)end;
-    }
-
-    operator std::u16string_view() const { return {buffer_.get(), length_}; }
+template <typename T1, typename T2> auto Concat2View(OStringConcat<T1, T2> const& c)
+{
+    return StringConcatenation<char>(c);
+}
 
-private:
-    std::size_t length_;
-    std::unique_ptr<char16_t[]> buffer_;
-};
+template <typename T1, typename T2> auto Concat2View(OUStringConcat<T1, T2> const& c)
+{
+    return StringConcatenation<char16_t>(c);
+}
 
 /**
  @internal
diff --git a/include/rtl/ustring.hxx b/include/rtl/ustring.hxx
index c9067905a0a0..cddba5dfadd5 100644
--- a/include/rtl/ustring.hxx
+++ b/include/rtl/ustring.hxx
@@ -3347,13 +3347,13 @@ 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)
+inline bool operator ==(OUString const & lhs, StringConcatenation<char16_t> const & rhs)
 { return lhs == std::u16string_view(rhs); }
-inline bool operator !=(OUString const & lhs, OUStringConcatenation const & rhs)
+inline bool operator !=(OUString const & lhs, StringConcatenation<char16_t> const & rhs)
 { return lhs != std::u16string_view(rhs); }
-inline bool operator ==(OUStringConcatenation const & lhs, OUString const & rhs)
+inline bool operator ==(StringConcatenation<char16_t> const & lhs, OUString const & rhs)
 { return std::u16string_view(lhs) == rhs; }
-inline bool operator !=(OUStringConcatenation const & lhs, OUString const & rhs)
+inline bool operator !=(StringConcatenation<char16_t> const & lhs, OUString const & rhs)
 { return std::u16string_view(lhs) != rhs; }
 #endif
 
@@ -3525,7 +3525,7 @@ using ::rtl::OStringToOUString;
 using ::rtl::OUStringToOString;
 using ::rtl::OUStringLiteral;
 using ::rtl::OUStringChar;
-using ::rtl::OUStringConcatenation;
+using ::rtl::Concat2View;
 #endif
 
 /// @cond INTERNAL