From e0615011a342e288d93fce4c37f554d54d160e0b Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Wed, 11 Jan 2017 21:55:59 -0500
Subject: [PATCH] add Buffer::apply_change_{operation,unit}() for undo/redo

---
 src/core/Buffer.cc | 22 ++++++++++++++++++++++
 src/core/Buffer.h  |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/src/core/Buffer.cc b/src/core/Buffer.cc
index ddc9021..64a65d8 100644
--- a/src/core/Buffer.cc
+++ b/src/core/Buffer.cc
@@ -364,3 +364,25 @@ void Buffer::save_current_operation()
         m_current_change_operation_index = new_change_operation_index;
     }
 }
+
+void Buffer::apply_change_operation(const ChangeOperation & change_operation, bool forward)
+{
+    for (auto change_unit : change_operation.changes)
+    {
+        apply_change_unit(change_unit, forward);
+    }
+}
+
+void Buffer::apply_change_unit(const ChangeUnit & change_unit, bool forward)
+{
+    if (forward == change_unit.insert)
+    {
+        insert_data(change_unit.buffer_position,
+                m_change_buffer->address(change_unit.change_buffer_offset),
+                change_unit.length);
+    }
+    else
+    {
+        erase_data(change_unit.buffer_position, change_unit.length);
+    }
+}
diff --git a/src/core/Buffer.h b/src/core/Buffer.h
index b234796..e58bfb0 100644
--- a/src/core/Buffer.h
+++ b/src/core/Buffer.h
@@ -165,6 +165,8 @@ protected:
     void erase_data(size_t offset, size_t length);
     size_t lines_in_data(size_t offset, size_t length);
     void post_warp_cursors();
+    void apply_change_operation(const ChangeOperation & change_operation, bool forward);
+    void apply_change_unit(const ChangeUnit & change_unit, bool forward);
 };
 
 #endif