Optimize string literals in refcounted strings

6 files changed, 67 insertions, 110 deletions

diff --git a/src/strings/astring.cpp b/src/strings/astring.cpp
index f1f12c3..e2521df 100644
--- a/src/strings/astring.cpp
+++ b/src/strings/astring.cpp
@@ -47,7 +47,6 @@ namespace strings
         std::copy(src + 0, src + 255, dst);
     }
 
-    // TODO dedup all this code once I drop gcc 4.6 support
     AString::AString()
     : data{}, special()
     {
@@ -100,78 +99,43 @@ namespace strings
     }
 
     AString::AString(const MString& s)
-    : data{}, special()
+    : AString(s.begin(), s.end())
     {
-        if (s.size() > 255 || s.size() == 0)
-        {
-            new(r_ptr()) RString(s);
-            special = 255;
-        }
-        else
-        {
-            *std::copy(s.begin(), s.end(), data) = '\0';
-            special = 255 - s.size();
-        }
     }
 
     AString::AString(XPair p)
-    : data{}, special()
+    : AString(p.begin(), p.end())
     {
-        new(r_ptr()) RString();
-        special = 255;
-        *this = XString(p);
     }
 
     AString::AString(const TString& t)
-    : data{}, special()
+    : AString(XString(t))
     {
-        new(r_ptr()) RString();
-        special = 255;
-        *this = XString(t);
     }
     AString::AString(const SString& s)
-    : data{}, special()
+    : AString(XString(s))
     {
-        new(r_ptr()) RString();
-        special = 255;
-        *this = XString(s);
     }
     AString::AString(ZString z)
-    : data{}, special()
+    : AString(XString(z))
     {
-        new(r_ptr()) RString();
-        special = 255;
-        *this = XString(z);
     }
     AString::AString(XString x)
-    : data{}, special()
+    : AString()
     {
         if (const RString *r = x.base())
         {
             if (&*r->begin() == &*x.begin() && &*r->end() == &*x.end())
             {
-                new(r_ptr()) RString(*r);
-                special = 255;
+                *this = *r;
                 return;
             }
         }
-        if (x.size() > 255 || x.size() == 0)
-        {
-            new(r_ptr()) RString(x);
-            special = 255;
-        }
-        else
-        {
-            *std::copy(x.begin(), x.end(), data) = '\0';
-            special = 255 - x.size();
-        }
+        *this = AString(x.begin(), x.end());
     }
     AString::AString(LString l)
-    : data{}, special()
+    : AString(RString(l))
     {
-        new(r_ptr()) RString();
-        special = 255;
-        *this = XString(l);
     }
 
     AString::iterator AString::begin() const
diff --git a/src/strings/astring.hpp b/src/strings/astring.hpp
index 83399f0..ccf2be6 100644
--- a/src/strings/astring.hpp
+++ b/src/strings/astring.hpp
@@ -35,7 +35,7 @@ namespace strings
 #ifdef __clang__
         __attribute__((unused))
 #endif
-        RString *align[0];
+        RString align[0];
         char data[255];
         unsigned char special;
         RString *r_ptr() { return reinterpret_cast<RString *>(data); }
diff --git a/src/strings/rstring.cpp b/src/strings/rstring.cpp
index 3e5a46d..e74d1d5 100644
--- a/src/strings/rstring.cpp
+++ b/src/strings/rstring.cpp
@@ -36,45 +36,46 @@ namespace tmwa
 {
 namespace strings
 {
-    static_assert(sizeof(RString) == sizeof(const char *), "RString");
-
-    uint8_t RString::empty_string_rep[sizeof(Rep) + 1];
-
     RString::RString()
-    : owned(reinterpret_cast<Rep *>(&empty_string_rep))
+    : u{.begin= ""}, maybe_end(u.begin)
+    {
+    }
+    RString::RString(LString l)
+    : u{.begin= &*l.begin()}, maybe_end(&*l.end())
     {
-        owned->count++;
     }
 
     RString::RString(const RString& r)
-    : owned(r.owned)
+    : u(r.u), maybe_end(r.maybe_end)
     {
-        owned->count++;
+        if (!maybe_end)
+            u.owned->count++;
     }
     RString::RString(RString&& r)
-    : owned(reinterpret_cast<Rep *>(&empty_string_rep))
+    : RString()
     {
-        std::swap(owned, r.owned);
-        r.owned->count++;
+        *this = std::move(r);
     }
     RString& RString::operator = (const RString& r)
     {
         // order important for self-assign
-        r.owned->count++;
-        // owned can be nullptr from ctors
-        // TODO do ctors *properly* (requires gcc 4.7 to stay sane)
-        if (owned && !owned->count--)
-            ::operator delete(owned);
-        owned = r.owned;
+        if (!r.maybe_end)
+            r.u.owned->count++;
+        if (!maybe_end && !u.owned->count--)
+            ::operator delete(u.owned);
+        u = r.u;
+        maybe_end = r.maybe_end;
         return *this;
     }
     RString& RString::operator = (RString&& r)
     {
-        std::swap(owned, r.owned);
+        std::swap(u, r.u);
+        std::swap(maybe_end, r.maybe_end);
         return *this;
     }
+
     RString::RString(AString a)
-    : owned(nullptr)
+    : RString()
     {
         if (RString *r = const_cast<RString *>(a.base()))
         {
@@ -87,41 +88,36 @@ namespace strings
     }
     RString::~RString()
     {
-        if (owned && !owned->count--)
-            ::operator delete(owned);
-        owned = nullptr;
+        if (!maybe_end && !u.owned->count--)
+            ::operator delete(u.owned);
     }
 
     RString::RString(const MString& s)
-    : owned(nullptr)
+    : RString(s.begin(), s.end())
     {
-        _assign(s.begin(), s.end());
     }
 
     RString::RString(XPair p)
-    : owned(nullptr)
+    : RString(p.begin(), p.end())
     {
-        _assign(p.begin(), p.end());
     }
 
     RString::RString(const TString& t)
-    : owned(nullptr)
+    : RString(XString(t))
     {
-        *this = XString(t);
     }
     RString::RString(const SString& s)
-    : owned(nullptr)
+    : RString(XString(s))
     {
-        *this = XString(s);
     }
     RString::RString(ZString z)
-    : owned(nullptr)
+    : RString(XString(z))
     {
-        *this = XString(z);
     }
     RString::RString(XString x)
-    : owned(nullptr)
+    : RString()
     {
+        // long term this stuff will change again
         const RString *f = x.base();
         const char *xb = &*x.begin();
         const char *xe = &*x.end();
@@ -130,21 +126,20 @@ namespace strings
         if (f && xb == fb && xe == fe)
             *this = *f;
         else
-            _assign(x.begin(), x.end());
-    }
-    RString::RString(LString l)
-    : owned(nullptr)
-    {
-        *this = XString(l);
+            *this = RString(x.begin(), x.end());
     }
 
     RString::iterator RString::begin() const
     {
-        return owned->body;
+        if (maybe_end)
+            return u.begin;
+        return u.owned->body;
     }
     RString::iterator RString::end() const
     {
-        return owned->body + owned->size;
+        if (maybe_end)
+            return maybe_end;
+        return u.owned->body + u.owned->size;
     }
     const RString *RString::base() const
     {
diff --git a/src/strings/rstring.hpp b/src/strings/rstring.hpp
index fd3ee65..ad44beb 100644
--- a/src/strings/rstring.hpp
+++ b/src/strings/rstring.hpp
@@ -39,15 +39,17 @@ namespace strings
             size_t size;
             char body[];
         };
-        static
-        uint8_t empty_string_rep[sizeof(Rep) + 1];
 
-        Rep *owned;
+        union
+        {
+            Rep *owned;
+            const char *begin;
+        } u;
+        const char *maybe_end;
 
-        template<class It>
-        void _assign(It b, It e);
     public:
         RString();
+        RString(LString s);
         RString(const RString&);
         RString(RString&&);
         RString& operator = (const RString&);
@@ -68,7 +70,6 @@ namespace strings
         RString(XString);
         template<uint8_t n>
         RString(const VString<n>& v);
-        RString(LString s);
 
         iterator begin() const;
         iterator end() const;
diff --git a/src/strings/rstring.tcc b/src/strings/rstring.tcc
index c247b8f..8a85b1d 100644
--- a/src/strings/rstring.tcc
+++ b/src/strings/rstring.tcc
@@ -1,6 +1,6 @@
 //    strings/rstring.tcc - Inline functions for rstring.hpp
 //
-//    Copyright © 2013 Ben Longbons <b.r.longbons@gmail.com>
+//    Copyright © 2013-2014 Ben Longbons <b.r.longbons@gmail.com>
 //
 //    This file is part of The Mana World (Athena server)
 //
@@ -25,12 +25,11 @@ namespace tmwa
 namespace strings
 {
     template<class It>
-    void RString::_assign(It b, It e)
+    RString::RString(It b, It e)
+    : RString()
     {
-        owned = nullptr;
         if (b == e)
         {
-            *this = RString();
             return;
         }
         if (!std::is_base_of<std::forward_iterator_tag, typename std::iterator_traits<It>::iterator_category>::value)
@@ -43,23 +42,19 @@ namespace strings
             return;
         }
         size_t diff = std::distance(b, e);
-        owned = static_cast<Rep *>(::operator new(sizeof(Rep) + diff + 1));
-        owned->count = 0;
-        owned->size = diff;
-        std::copy(b, e, owned->body);
-        owned->body[diff] = '\0';
-    }
+        u.owned = static_cast<Rep *>(::operator new(sizeof(Rep) + diff + 1));
+        maybe_end = nullptr;
 
-    template<class It>
-    RString::RString(It b, It e)
-    {
-        _assign(b, e);
+        u.owned->count = 0;
+        u.owned->size = diff;
+        std::copy(b, e, u.owned->body);
+        u.owned->body[diff] = '\0';
     }
 
     template<uint8_t n>
     RString::RString(const VString<n>& v)
+    : RString(v.begin(), v.end())
     {
-        _assign(v.begin(), v.end());
     }
 } // namespace strings
 } // namespace tmwa
diff --git a/src/strings/strings2_test.cpp b/src/strings/strings2_test.cpp
index 18c7db4..8ac8482 100644
--- a/src/strings/strings2_test.cpp
+++ b/src/strings/strings2_test.cpp
@@ -170,9 +170,11 @@ TEST(StringTests, rempty)
 TEST(StringTests, rshort)
 {
     LString short_text = "0123456789"_s;
-    RString r = short_text;
+    EXPECT_EQ(&*short_text.begin(), &*RString(short_text).begin());
+    EXPECT_EQ(&*short_text.begin(), &*AString(short_text).begin());
+    RString r = VString<255>(short_text);
     EXPECT_EQ(r.size(), 10);
-    AString a = short_text;
+    AString a = VString<255>(short_text);
     EXPECT_EQ(r, a);
     AString r2 = r, r3;
     RString a2 = a, a3;