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

1 files changed, 71 insertions, 0 deletions

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);
+}
+
+}