Splitting into separate files.

undo.h

@@ -0,0 +1,44 @@
+#ifndef KE_UNDO
+#define KE_UNDO
+
+
+typedef enum undo_kind {
+	UNDO_INSERT  = 1 << 0,
+	UNDO_UNKNOWN = 1 << 1,
+} undo_kind;
+
+
+typedef struct undo_node {
+	undo_kind		 op;
+	size_t			 row, col;
+	abuf			 text;
+
+	struct undo_node	*next;
+	struct undo_node	*parent;
+
+} undo_node;
+
+
+typedef struct undo_tree {
+	undo_node	*root;		/* the start of the undo sequence */
+	undo_node	*current;	/* where we are currently at */
+	undo_node	*pending;	/* the current undo operations being built */
+} undo_tree;
+
+
+undo_node	*undo_node_new(undo_kind kind);
+void		 undo_node_free(undo_node *node);
+void		 undo_tree_init(undo_tree *tree);
+void		 undo_tree_free(undo_tree *tree);
+void		 undo_begin(undo_tree *tree, undo_kind kind);
+void		 undo_prepend(abuf *buf);
+void		 undo_append(buf *buf);
+void		 undo_prependch(char c);
+void		 undo_appendch(char c);
+void		 undo_commit(undo_tree *tree);
+void		 undo_apply(undo_node *node);
+void		 editor_undo(void);
+void		 editor_redo(void);
+
+
+#endif