Add support for interned strings

Use interned strings for Modification contents and word database.
Interned strings are guaranteed not to move in memory and are
reference counted.

1 files changed, 50 insertions, 0 deletions

diff --git a/src/interned_string.cc b/src/interned_string.cc
new file mode 100644
index 00000000..b8825f66
--- /dev/null
+++ b/src/interned_string.cc
@@ -0,0 +1,50 @@
+#include "interned_string.hh"
+
+namespace Kakoune
+{
+
+InternedString StringRegistry::acquire(StringView str)
+{
+    auto it = m_slot_map.find(str);
+    if (it == m_slot_map.end())
+    {
+        size_t slot;
+        if (not m_free_slots.empty())
+        {
+            slot = m_free_slots.back();
+            m_free_slots.pop_back();
+            m_storage[slot] = DataAndRefCount({str.begin(), str.end()}, 1);
+        }
+        else
+        {
+            slot = m_storage.size();
+            m_storage.push_back(DataAndRefCount({str.begin(), str.end()}, 1));
+        }
+        // Create a new string view that point to the storage data
+        StringView storage_view{m_storage[slot].first.data(), (int)m_storage[slot].first.size()};
+        m_slot_map[storage_view] = slot;
+
+        return InternedString{storage_view, InternedString::AlreadyAcquired{}};
+    }
+
+    size_t slot = it->second;
+    m_storage[slot].second++;
+    StringView storage_view{m_storage[slot].first.data(), (int)m_storage[slot].first.size()};
+    return InternedString{storage_view, InternedString::AlreadyAcquired{}};
+}
+
+void StringRegistry::release(StringView str)
+{
+    auto it = m_slot_map.find(str);
+    kak_assert(it != m_slot_map.end());
+
+    size_t slot = it->second;
+    if (--m_storage[slot].second == 0)
+    {
+        m_free_slots.push_back(slot);
+        m_slot_map.erase(it);
+        m_storage[slot].first.clear();
+    }
+}
+
+}