elisp: Buffer Gap
26.13 The Buffer Gap
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Emacs buffers are implemented using an invisible “gap” to make insertion
and deletion faster. Insertion works by filling in part of the gap, and
deletion adds to the gap. Of course, this means that the gap must first
be moved to the locus of the insertion or deletion. Emacs moves the gap
only when you try to insert or delete. This is why your first editing
command in one part of a large buffer, after previously editing in
another far-away part, sometimes involves a noticeable delay.
This mechanism works invisibly, and Lisp code should never be
affected by the gap’s current location, but these functions are
available for getting information about the gap status.
-- Function: gap-position
This function returns the current gap position in the current
buffer.
-- Function: gap-size
This function returns the current gap size of the current buffer.
Info Catalog
elisp: Swapping Text
elisp: Buffers