CE Implement line editing

ce/gapbuffer.h

@@ -0,0 +1,31 @@
+#ifndef _GAPBUFFER_H
+#define _GAPBUFFER_H
+
+#include <stddef.h>
+
+struct gapbuffer {
+  char* buffer;
+  size_t size;
+  size_t gap_start;
+  size_t gap_end;
+};
+
+void gapbuffer_init (struct gapbuffer* gb, size_t capacity);
+
+void gapbuffer_fini (struct gapbuffer* gb);
+
+void gapbuffer_move (struct gapbuffer* gb, size_t pos);
+
+void gapbuffer_insert (struct gapbuffer* gb, char c);
+
+void gapbuffer_backspace (struct gapbuffer* gb);
+
+void gapbuffer_grow (struct gapbuffer* gb);
+
+char* gapbuffer_get_string (struct gapbuffer* gb);
+
+size_t gapbuffer_length (struct gapbuffer* gb);
+
+char* gapbuffer_string_at (struct gapbuffer* gb, size_t pos);
+
+#endif // _GAPBUFFER_H