Add Buffer::reload for reloading buffers without loosing options and hooks

src/buffer.cc

@@ -70,6 +70,35 @@ Buffer::~Buffer()
     kak_assert(m_change_listeners.empty());
 }
 
+void Buffer::reload(std::vector<String> lines, time_t fs_timestamp)
+{
+    for (auto listener : m_change_listeners)
+        listener->on_erase(*this, {0,0}, end_coord());
+
+	m_history.clear();
+	m_current_undo_group.clear();
+	m_history_cursor = m_history.begin();
+	m_last_save_undo_index = 0;
+	m_lines.clear();
+    ++m_timestamp;
+
+    if (lines.empty())
+        lines.emplace_back("\n");
+
+    ByteCount pos = 0;
+    m_lines.reserve(lines.size());
+    for (auto& line : lines)
+    {
+        kak_assert(not line.empty() and line.back() == '\n');
+        m_lines.emplace_back(Line{ pos, std::move(line) });
+        pos += m_lines.back().length();
+    }
+    m_fs_timestamp = fs_timestamp;
+
+    for (auto listener : m_change_listeners)
+        listener->on_insert(*this, {0,0}, end_coord());
+}
+
 String Buffer::display_name() const
 {
     if (m_flags & Flags::File)

src/buffer.hh

@@ -163,6 +163,8 @@ public:
 
     std::unordered_set<BufferChangeListener*>& change_listeners() const { return m_change_listeners; }
 
+    void reload(std::vector<String> lines, time_t fs_timestamp = InvalidTime);
+
     void check_invariant() const;
 private:
     struct Line

src/file.cc

@@ -135,8 +135,6 @@ Buffer* create_buffer_from_file(String filename)
     const char* data = (const char*)mmap(nullptr, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
     auto cleanup = on_scope_end([&]{ munmap((void*)data, st.st_size); close(fd); });
 
-    BufferManager::instance().delete_buffer_if_exists(filename);
-
     const char* pos = data;
     bool crlf = false;
     bool bom  = false;
@@ -175,8 +173,12 @@ Buffer* create_buffer_from_file(String filename)
         else
             pos = line_end + 1;
     }
-    Buffer* buffer = new Buffer{filename, Buffer::Flags::File,
-                                std::move(lines), st.st_mtime};
+    Buffer* buffer = BufferManager::instance().get_buffer_ifp(filename);
+    if (buffer)
+        buffer->reload(std::move(lines), st.st_mtime);
+    else
+        buffer = new Buffer{filename, Buffer::Flags::File,
+                            std::move(lines), st.st_mtime};
 
     OptionManager& options = buffer->options();
     options.get_local_option("eolformat").set<String>(crlf ? "crlf" : "lf");