DynamicBufferIterator: add and use in Selections

DynamicBufferIterator are a new type of BufferIterators that
automatically update themselves when their buffer is modified.

Selections now uses this type of iterators instead of plain ones

7 files changed, 120 insertions, 13 deletions

diff --git a/src/buffer.cc b/src/buffer.cc
index f9aac0b8..d5ec4349 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -254,14 +254,14 @@ void Buffer::notify_saved()
     m_last_save_undo_group = m_history_cursor;
 }
 
-void Buffer::register_modification_listener(BufferModificationListener* listener)
+void Buffer::register_modification_listener(BufferModificationListener* listener) const
 {
     assert(listener);
     assert(not contains(m_modification_listeners, listener));
     m_modification_listeners.push_back(listener);
 }
 
-void Buffer::unregister_modification_listener(BufferModificationListener* listener)
+void Buffer::unregister_modification_listener(BufferModificationListener* listener) const
 {
     assert(listener);
     auto it = std::find(m_modification_listeners.begin(),
diff --git a/src/buffer.hh b/src/buffer.hh
index aee9fba2..ac3f0d60 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -63,6 +63,7 @@ public:
 
     bool is_begin() const;
     bool is_end() const;
+    bool is_valid() const;
 
     const Buffer& buffer() const;
 
@@ -145,8 +146,8 @@ public:
     Type type() const { return m_type; }
     void notify_saved();
 
-    void register_modification_listener(BufferModificationListener* listener);
-    void unregister_modification_listener(BufferModificationListener* listener);
+    void register_modification_listener(BufferModificationListener* listener) const;
+    void unregister_modification_listener(BufferModificationListener* listener) const;
 
 private:
     BufferChar at(BufferPos position) const;
@@ -185,7 +186,7 @@ private:
 
     std::vector<UndoGroup>::iterator m_last_save_undo_group;
 
-    std::vector<BufferModificationListener*> m_modification_listeners;
+    mutable std::vector<BufferModificationListener*> m_modification_listeners;
 };
 
 }
diff --git a/src/buffer_iterator.inl.h b/src/buffer_iterator.inl.h
index db59a8b4..feae368d 100644
--- a/src/buffer_iterator.inl.h
+++ b/src/buffer_iterator.inl.h
@@ -18,6 +18,11 @@ inline const Buffer& BufferIterator::buffer() const
     return *m_buffer;
 }
 
+inline bool BufferIterator::is_valid() const
+{
+    return m_buffer;
+}
+
 inline BufferIterator& BufferIterator::operator=(const BufferIterator& iterator)
 {
     m_buffer = iterator.m_buffer;
diff --git a/src/dynamic_buffer_iterator.cc b/src/dynamic_buffer_iterator.cc
new file mode 100644
index 00000000..42c9d39c
--- /dev/null
+++ b/src/dynamic_buffer_iterator.cc
@@ -0,0 +1,71 @@
+#include "dynamic_buffer_iterator.hh"
+
+namespace Kakoune
+{
+
+DynamicBufferIterator::DynamicBufferIterator(const Buffer& buffer,
+                                             BufferPos position)
+    : BufferIterator(buffer, position)
+{
+    register_ifp();
+}
+
+DynamicBufferIterator::DynamicBufferIterator(DynamicBufferIterator&& other)
+    : BufferIterator(other)
+{
+    register_ifp();
+}
+
+DynamicBufferIterator::DynamicBufferIterator(const BufferIterator& other)
+    : BufferIterator(other)
+{
+    register_ifp();
+}
+
+DynamicBufferIterator& DynamicBufferIterator::operator=(const BufferIterator& other)
+{
+    unregister_ifn();
+    BufferIterator::operator=(other);
+    register_ifp();
+
+    return *this;
+}
+
+DynamicBufferIterator::~DynamicBufferIterator()
+{
+    unregister_ifn();
+}
+
+void DynamicBufferIterator::on_modification(const BufferModification& modification)
+{
+    if (*this < modification.position)
+        return;
+
+    size_t length = modification.content.length();
+    if (modification.type == BufferModification::Erase)
+    {
+        if (*this <= modification.position + length)
+            BufferIterator::operator=(modification.position);
+        else
+            *this -= length;
+    }
+    else
+    {
+        assert(modification.type == BufferModification::Insert);
+        *this += length;
+    }
+}
+
+void DynamicBufferIterator::register_ifp()
+{
+    if (is_valid())
+        buffer().register_modification_listener(this);
+}
+
+void DynamicBufferIterator::unregister_ifn()
+{
+    if (is_valid())
+        buffer().unregister_modification_listener(this);
+}
+
+}
diff --git a/src/dynamic_buffer_iterator.hh b/src/dynamic_buffer_iterator.hh
new file mode 100644
index 00000000..17e74485
--- /dev/null
+++ b/src/dynamic_buffer_iterator.hh
@@ -0,0 +1,35 @@
+#ifndef dynamic_buffer_iterator_hh_INCLUDED
+#define dynamic_buffer_iterator_hh_INCLUDED
+
+#include "buffer.hh"
+
+namespace Kakoune
+{
+
+class DynamicBufferIterator : public BufferIterator,
+                              public BufferModificationListener
+{
+public:
+    DynamicBufferIterator() : BufferIterator() {}
+    DynamicBufferIterator(const Buffer& buffer, BufferPos position);
+    DynamicBufferIterator(const BufferIterator& other);
+    DynamicBufferIterator(const DynamicBufferIterator& other)
+        : BufferIterator(other) { register_ifp(); }
+
+    DynamicBufferIterator(DynamicBufferIterator&& other);
+    DynamicBufferIterator& operator=(const BufferIterator& other);
+    DynamicBufferIterator& operator=(const DynamicBufferIterator& other)
+    { return this->operator= (static_cast<const BufferIterator&>(other)); }
+    ~DynamicBufferIterator();
+
+   void on_modification(const BufferModification& modification);
+
+private:
+   void register_ifp();
+   void unregister_ifn();
+};
+
+
+}
+
+#endif // dynamic_buffer_iterator_hh_INCLUDED
diff --git a/src/window.cc b/src/window.cc
index 0c7991c7..5f10618c 100644
--- a/src/window.cc
+++ b/src/window.cc
@@ -144,10 +144,7 @@ void Window::erase_noundo()
 {
     check_invariant();
     for (auto& sel : m_selections)
-    {
         m_buffer.erase(sel.begin(), sel.end());
-        sel = Selection(sel.begin(), sel.begin());
-    }
     scroll_to_keep_cursor_visible_ifn();
 }
 
@@ -183,10 +180,7 @@ void Window::insert(const String& string)
 void Window::insert_noundo(const String& string)
 {
     for (auto& sel : m_selections)
-    {
         m_buffer.insert(sel.begin(), string);
-        sel.offset(string.length());
-    }
     scroll_to_keep_cursor_visible_ifn();
 }
 
diff --git a/src/window.hh b/src/window.hh
index 9ae7862c..2b62794b 100644
--- a/src/window.hh
+++ b/src/window.hh
@@ -4,6 +4,7 @@
 #include <functional>
 
 #include "buffer.hh"
+#include "dynamic_buffer_iterator.hh"
 #include "display_buffer.hh"
 
 namespace Kakoune
@@ -23,8 +24,8 @@ struct Selection
     void offset(int offset);
 
 private:
-    BufferIterator m_first;
-    BufferIterator m_last;
+    DynamicBufferIterator m_first;
+    DynamicBufferIterator m_last;
 };
 
 typedef std::vector<Selection> SelectionList;