From 3d5a0c672e6f3cf87944b33712e17531aa42c607 Mon Sep 17 00:00:00 2001
From: Maxime Coste <mawww@kakoune.org>
Date: Wed, 28 Feb 2024 19:00:51 +1100
Subject: Templatize StringData::create

This improves performance by letting the compiler optimize most use
cases where string count and length are known are compile time.
---
 src/shared_string.hh | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

(limited to 'src/shared_string.hh')

diff --git a/src/shared_string.hh b/src/shared_string.hh
index 17bb72d8..bb06c7fc 100644
--- a/src/shared_string.hh
+++ b/src/shared_string.hh
@@ -7,6 +7,7 @@
 #include "hash_map.hh"
 
 #include <numeric>
+#include <cstring>
 
 namespace Kakoune
 {
@@ -32,12 +33,11 @@ private:
         static void inc_ref(StringData* r, void*) noexcept { ++r->refcount; }
         static void dec_ref(StringData* r, void*) noexcept
         {
-            if ((--r->refcount & refcount_mask) == 0)
-            {
-                if (r->refcount & interned_flag)
-                    Registry::instance().remove(r->strview());
-                StringData::operator delete(r, sizeof(StringData) + r->length + 1);
-            }
+            if ((--r->refcount & refcount_mask) > 0)
+                return;
+            if (r->refcount & interned_flag)
+                Registry::instance().remove(r->strview());
+            StringData::operator delete(r, sizeof(StringData) + r->length + 1);
         }
         static void ptr_moved(StringData*, void*, void*) noexcept {}
     };
@@ -57,7 +57,23 @@ public:
         HashMap<StringView, StringData*, MemoryDomain::SharedString> m_strings;
     };
 
-    static Ptr create(ArrayView<const StringView> strs);
+    static Ptr create(ConvertibleTo<StringView> auto&&... strs)
+    {
+        const int len = ((int)StringView{strs}.length() + ...);
+        void* ptr = StringData::operator new(sizeof(StringData) + len + 1);
+        auto* res = new (ptr) StringData(len);
+        auto* data = reinterpret_cast<char*>(res + 1);
+        auto append = [&](StringView str) {
+            if (str.empty()) // memccpy(..., nullptr, 0) is UB
+                return;
+            memcpy(data, str.begin(), (size_t)str.length());
+            data += (int)str.length();
+        };
+        (append(strs), ...);
+        *data = 0;
+        return RefPtr<StringData, PtrPolicy>{res};
+    }
+
 };
 
 using StringDataPtr = StringData::Ptr;
-- 
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