Introduce OUStringBuffer::insert taking OUStringConcat

Avoids some (re)allocations, and aligns with already existing append

Change-Id: I536ba50f56fc560c0f6e8c0a8b65bd4248896a8e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/148777
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/include/rtl/ustrbuf.hxx b/include/rtl/ustrbuf.hxx
index af7d0d0d9ef6..cdfb28ab556c 100644
--- a/include/rtl/ustrbuf.hxx
+++ b/include/rtl/ustrbuf.hxx
@@ -43,6 +43,7 @@
 #include "sal/types.h"
 
 #ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
+#include "o3tl/safeint.hxx"
 #include "rtl/stringconcat.hxx"
 #endif
 
@@ -1015,6 +1016,38 @@ public:
     }
 #endif
 
+#ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
+    /**
+     @overload
+     @internal
+    */
+    template <typename T1, typename T2>
+    OUStringBuffer& insert(sal_Int32 offset, OUStringConcat<T1, T2>&& c)
+    {
+        const size_t l = c.length();
+        if (l == 0)
+            return *this;
+        if (l > o3tl::make_unsigned(std::numeric_limits<sal_Int32>::max() - pData->length))
+            throw std::bad_alloc();
+
+        rtl_uStringbuffer_insert(&pData, &nCapacity, offset, nullptr, l);
+
+        /* insert the new characters */
+        c.addData(pData->buffer + offset);
+        return *this;
+    }
+
+    /**
+     @overload
+     @internal
+    */
+    template <typename T, std::size_t N>
+    OUStringBuffer& insert(sal_Int32 offset, StringNumberBase<sal_Unicode, T, N>&& c)
+    {
+        return insert(offset, c.buf, c.length);
+    }
+#endif
+
     /**
         Inserts the string representation of the <code>char</code> array
         argument into this string buffer.