1 files changed, 99 insertions, 0 deletions
diff --git a/undo.h b/undo.h
new file mode 100644
index 0000000..3307205
--- /dev/null
+++ b/undo.h
@@ -0,0 +1,99 @@
+// Copyright (C) 2003 Mooffie <mooffie@typo.co.il>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
+
+#ifndef BDE_UNDO_H
+#define BDE_UNDO_H
+
+#include <vector>
+
+#include "types.h"
+#include "point.h"
+
+// Class UndoStack records the operations (ops) made to EditBox's buffer.
+//
+// Strictly speaking, the UndoStack is not really a stack: you move the
+// "top" pointer up and down within this stack when you undo and redo
+// operations.
+// 
+// UndoStack stores the operations in a vector of UndoOp's. UndoOp contains
+// all the information needed to restore one operation.
+
+enum OpType { opInsert, opDelete, opReplace };
+
+struct UndoOp {
+
+    OpType type;
+    Point point; // the point in the buffer where the operation was made
+    unistring inserted_text;
+    unistring deleted_text;
+
+    size_t calc_size() const {
+	return
+		sizeof(UndoOp)
+		+ inserted_text.len() * sizeof(unichar)
+		+ deleted_text.len()  * sizeof(unichar);
+    }
+    bool merge(const UndoOp &op);
+};
+
+class UndoStack {
+
+private:
+
+    std::vector<UndoOp> stack;
+    unsigned top;
+    
+    size_t bytes_size;		// size of current stack
+
+    size_t bytes_size_limit;	// max size
+
+    bool merge_small_ops;	// merge small ops?
+
+    bool truncated;		// was the stack already truncated
+				// to fit bytes_size_limit?
+
+private:
+
+    void erase_redo_ops();
+
+    void truncate_undo();
+    bool undo_size_too_big() const { return bytes_size >= bytes_size_limit; }
+    void update_size_up(int chars_count);
+    void update_size_up(const UndoOp &op);
+    void update_size_down(const UndoOp &op);
+
+public:
+
+    UndoStack();
+    void clear();
+
+    bool was_truncated() { return truncated; }
+    bool disabled() const { return bytes_size_limit == 0; }
+
+    bool is_undo_available() const { return (top != 0); }
+    bool is_redo_available() const { return (top != stack.size()); }
+
+    void record_op(const UndoOp &op);
+    UndoOp *get_prev_op();
+    UndoOp *get_next_op();
+
+    void set_size_limit(size_t limit);
+    void set_merge(bool value) { merge_small_ops = value; }
+    bool is_merge() const { return merge_small_ops; }
+};
+
+#endif
+