Increase SSO from 22 to 23 chars.

1 files changed, 46 insertions, 15 deletions

diff --git a/src/string.cc b/src/string.cc
index fe763165..a6befa13 100644
--- a/src/string.cc
+++ b/src/string.cc
@@ -2,6 +2,8 @@
 
 #include <cstdio>
 #include <cstring>
+#include "assert.hh"
+#include "unit_tests.hh"
 
 namespace Kakoune
 {
@@ -10,13 +12,10 @@ String::Data::Data(const char* data, size_t size, size_t capacity)
 {
     if (capacity > Short::capacity)
     {
-        if (capacity & 1)
-            ++capacity;
-
-        kak_assert(capacity < Long::max_capacity);
+        kak_assert(capacity <= Long::max_capacity);
         u.l.ptr = Alloc{}.allocate(capacity+1);
         u.l.size = size;
-        u.l.capacity = capacity;
+        u.l.set_capacity(capacity);
 
         if (data != nullptr)
             memcpy(u.l.ptr, data, size);
@@ -60,26 +59,27 @@ String::Data& String::Data::operator=(Data&& other) noexcept
 template<bool copy>
 void String::Data::reserve(size_t new_capacity)
 {
-    if (capacity() != 0 and new_capacity <= capacity())
+    auto const current_capacity = capacity();
+    if (current_capacity != 0 and new_capacity <= current_capacity)
         return;
 
-    if (is_long())
-        new_capacity = std::max(u.l.capacity * 2, new_capacity);
+    if (!is_long() and new_capacity <= Short::capacity) 
+        return;
 
-    if (new_capacity & 1)
-        ++new_capacity;
+    kak_assert(new_capacity <= Long::max_capacity);
+    new_capacity = std::max(new_capacity, // Do not upgrade new_capacity to be over limit.
+                            std::min(current_capacity * 2, Long::max_capacity));
 
-    kak_assert(new_capacity < Long::max_capacity);
     char* new_ptr = Alloc{}.allocate(new_capacity+1);
     if (copy)
     {
         memcpy(new_ptr, data(), size()+1);
-        u.l.size = size();
     }
     release();
 
+    u.l.size = size();
     u.l.ptr = new_ptr;
-    u.l.capacity = new_capacity;
+    u.l.set_capacity(new_capacity);
 }
 
 template void String::Data::reserve<true>(size_t);
@@ -89,6 +89,7 @@ void String::Data::force_size(size_t new_size)
 {
     reserve<false>(new_size);
     set_size(new_size);
+    data()[new_size] = 0;
 }
 
 void String::Data::append(const char* str, size_t len)
@@ -131,17 +132,47 @@ void String::Data::set_size(size_t size)
     if (is_long())
         u.l.size = size;
     else
-        u.s.size = (size << 1) | 1;
+        u.s.remaining_size = Short::capacity - size;
 }
 
 void String::Data::set_short(const char* data, size_t size)
 {
-    u.s.size = (size << 1) | 1;
+    kak_assert(size <= Short::capacity);
+    u.s.remaining_size = Short::capacity - size;
     if (data != nullptr)
         memcpy(u.s.string, data, size);
     u.s.string[size] = 0;
 }
 
+UnitTest test_data{[]{
+  using Data = String::Data;
+    { // Basic data usage.
+        Data data;
+        kak_assert(data.size() == 0);
+        kak_assert(not data.is_long());
+        kak_assert(data.capacity() == 23);
+
+        // Should be SSO-ed.
+        data.append("test", 4);
+        kak_assert(data.size() == 4);
+        kak_assert(data.capacity() == 23);
+        kak_assert(not data.is_long());
+        kak_assert(data.data() == StringView("test"));
+    }
+    {
+        char large_buf[2048];
+        memset(large_buf, 'x', 2048);
+        Data data(large_buf, 2048);
+        kak_assert(data.size() == 2048);
+        kak_assert(data.capacity() >= 2048);
+
+        data.clear();
+        kak_assert(data.size() == 0);
+        kak_assert(not data.is_long());
+        kak_assert(data.capacity() == 23);
+    }
+}};
+
 const String String::ms_empty;
 
 }