Introduce "..."_tstr as a companion to "..."_ostr/u"..."_ustr in template code

...like

>         *path = "/";

in

> template<typename T> oslFileError getSystemPathFromFileUrl(
>     OUString const & url, T * path, bool resolveHome)

in sal/osl/unx/file_url.cxx, where T is either OString or OUString.  That can
now be replaced with

>         *path = "/"_tstr;

and for OString it will be a no-cost constexpr operation, while for OUString it
will still construct the OUString instance at runtime (as did the original code
for both OString and OUString).

(This change required moving the definition of rtl::detail::OStringHolder
around in include/rtl/string.hxx.  For consistency, I similarly moved around the
definition of rtl::detail::OUStringHolder in include/rtl/ustring.hxx, too.)

Change-Id: I7fb3a81b438f98c609684f7e70b7a60068d32fdb
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/154748
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 64 insertions, 24 deletions

diff --git a/include/rtl/string.hxx b/include/rtl/string.hxx
index aae291f46053..eae18bc30d0d 100644
--- a/include/rtl/string.hxx
+++ b/include/rtl/string.hxx
@@ -186,6 +186,18 @@ private:
     rtl_String* pData;
 };
 
+#if __cplusplus >= 202002L
+
+namespace detail {
+
+template<OStringLiteral L> struct OStringHolder {
+    static constexpr auto & literal = L;
+};
+
+}
+
+#endif
+
 #endif
 
 /* ======================================================================= */
@@ -384,6 +396,12 @@ public:
     /// @endcond
 #endif
 
+#if defined LIBO_INTERNAL_ONLY && __cplusplus >= 202002L
+    // For operator ""_tstr:
+    template<OStringLiteral L> constexpr OString(detail::OStringHolder<L> const & holder):
+        pData(const_cast<rtl_String *>(&holder.literal.str)) {}
+#endif
+
 #if defined LIBO_INTERNAL_ONLY
     explicit OString(std::string_view sv) {
         if (sv.size() > sal_uInt32(std::numeric_limits<sal_Int32>::max())) {
@@ -2275,18 +2293,6 @@ inline bool operator !=(StringConcatenation<char> const & lhs, OString const & r
 
 #ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
 
-#if __cplusplus >= 202002L
-
-namespace detail {
-
-template<OStringLiteral L> struct OStringHolder {
-    static constexpr auto & literal = L;
-};
-
-}
-
-#endif
-
 /**
  @internal
 */
@@ -2409,6 +2415,27 @@ operator ""_ostr() {
         ::detail::OStringHolder<L>::literal;
 }
 
+template<
+#if defined RTL_STRING_UNITTEST
+    rtlunittest::
+#endif
+    OStringLiteral L>
+constexpr
+#if defined RTL_STRING_UNITTEST
+rtlunittest
+#else
+rtl
+#endif
+::detail::OStringHolder<L> operator ""_tstr() {
+    return
+#if defined RTL_STRING_UNITTEST
+        rtlunittest
+#else
+        rtl
+#endif
+        ::detail::OStringHolder<L>();
+}
+
 #endif
 
 /// @cond INTERNAL
diff --git a/include/rtl/ustring.hxx b/include/rtl/ustring.hxx
index 90b195754a17..c273c76ace6a 100644
--- a/include/rtl/ustring.hxx
+++ b/include/rtl/ustring.hxx
@@ -175,6 +175,18 @@ private:
     rtl_uString* pData;
 };
 
+#if __cplusplus >= 202002L
+
+namespace detail {
+
+template<OUStringLiteral L> struct OUStringHolder {
+    static constexpr auto & literal = L;
+};
+
+}
+
+#endif
+
 /// @endcond
 #endif
 
@@ -440,6 +452,19 @@ public:
     /// @endcond
 #endif
 
+#if defined LIBO_INTERNAL_ONLY && __cplusplus >= 202002L
+    // For operator ""_tstr:
+    template<OStringLiteral L> OUString(detail::OStringHolder<L> const & holder) {
+        pData = nullptr;
+        if (holder.literal.getLength() == 0) {
+            rtl_uString_new(&pData);
+        } else {
+            rtl_uString_newFromLiteral(
+                &pData, holder.literal.getStr(), holder.literal.getLength(), 0);
+        }
+    }
+#endif
+
     /**
       New string from an 8-Bit character buffer array.
 
@@ -3414,18 +3439,6 @@ inline bool operator !=(StringConcatenation<char16_t> const & lhs, OUString cons
 #if defined LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
 /// @cond INTERNAL
 
-#if __cplusplus >= 202002L
-
-namespace detail {
-
-template<OUStringLiteral L> struct OUStringHolder {
-    static constexpr auto & literal = L;
-};
-
-}
-
-#endif
-
 /**
  @internal
 */