gap-buffer: some cleanup.
John Benediktsson
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ad24fa414f
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1cba716637
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@ -4,8 +4,8 @@
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! gap buffer -- largely influenced by Strandh and Villeneuve's Flexichain
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! for a good introduction see:
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! https://common-lisp.net/project/flexichain/download/StrandhVilleneuveMoore.pdf
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USING: accessors arrays circular fry kernel math math.functions
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math.order multiline sequences sequences.private ;
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USING: accessors arrays circular fry kernel locals math
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math.functions math.order multiline sequences sequences.private ;
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IN: gap-buffer
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! gap-start -- the first element of the gap
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@ -24,30 +24,29 @@ TUPLE: gb
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[ expand-factor>> * ceiling >fixnum ]
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[ min-size>> ] bi max ;
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: <gb> ( seq -- gb )
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:: <gb> ( seq -- gb )
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gb new
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5 >>min-size
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1.5 >>expand-factor
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swap
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[ length >>gap-start ] keep
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[ length over required-space >>gap-end ] keep
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over gap-end>> swap { } like resize-array <circular> >>seq ;
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seq length >>gap-start
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seq length over required-space >>gap-end
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dup gap-end>> seq { } like resize-array <circular> >>seq ;
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M: gb like ( seq gb -- seq ) drop <gb> ;
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: gap-length ( gb -- n ) [ gap-end>> ] keep gap-start>> - ;
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: gap-length ( gb -- n )
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[ gap-end>> ] [ gap-start>> ] bi - ;
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: buffer-length ( gb -- n ) seq>> length ;
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M: gb length ( gb -- n ) [ buffer-length ] keep gap-length - ;
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M: gb length ( gb -- n )
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[ buffer-length ] [ gap-length ] bi - ;
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: valid-position? ( pos gb -- ? )
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! one element past the end of the buffer is a valid position when we're inserting
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! one element past the end of the buffer is a valid position
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! when we're inserting
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length -1 swap between? ;
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: valid-index? ( i gb -- ? )
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buffer-length -1 swap between? ;
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ERROR: position-out-of-bounds position gap-buffer ;
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: position>index ( pos gb -- i )
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@ -59,8 +58,10 @@ ERROR: position-out-of-bounds position gap-buffer ;
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position-out-of-bounds
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] if ;
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TUPLE: index-out-of-bounds index gap-buffer ;
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C: <index-out-of-bounds> index-out-of-bounds
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: valid-index? ( i gb -- ? )
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buffer-length -1 swap between? ;
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ERROR: index-out-of-bounds index gap-buffer ;
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: index>position ( i gb -- pos )
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2dup valid-index? [
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@ -68,18 +69,10 @@ C: <index-out-of-bounds> index-out-of-bounds
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gap-length -
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] [ drop ] if
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] [
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<index-out-of-bounds> throw
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index-out-of-bounds
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] if ;
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M: gb virtual@ ( n gb -- n seq ) [ position>index ] keep seq>> ;
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M: gb nth ( n gb -- elt ) bounds-check virtual@ nth-unsafe ;
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M: gb nth-unsafe ( n gb -- elt ) virtual@ nth-unsafe ;
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M: gb set-nth ( elt n seq -- ) bounds-check virtual@ set-nth-unsafe ;
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M: gb set-nth-unsafe ( elt n seq -- ) virtual@ set-nth-unsafe ;
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M: gb virtual-exemplar seq>> ;
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@ -108,13 +101,14 @@ INSTANCE: gb virtual-sequence
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[ over - ] dip swap copy-elements-back
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] if ;
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! the gap can be moved either forward or back. Moving the gap 'inside' means
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! moving elements across the gap. Moving the gap 'around' means changing the
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! start of the circular buffer to avoid moving as many elements.
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! the gap can be moved either forward or back. Moving the gap
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! 'inside' means moving elements across the gap. Moving the gap
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! 'around' means changing the start of the circular buffer to
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! avoid moving as many elements.
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! We decide which method (inside or around) to pick based on the number of
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! elements that will need to be moved. We always try to move as few elements as
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! possible.
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! We decide which method (inside or around) to pick based on the
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! number of elements that will need to be moved. We always try
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! to move as few elements as possible.
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: move-gap? ( i gb -- i gb ? ) 2dup gap-end>> = not ;
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@ -122,17 +116,21 @@ INSTANCE: gb virtual-sequence
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: move-gap-back-inside? ( i gb -- i gb ? )
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! is it cheaper to move the gap inside than around?
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2dup [ gap-start>> swap 2 * - ] keep [ buffer-length ] keep gap-end>> - <= ;
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2dup [ gap-start>> swap 2 * - ] keep
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[ buffer-length ] keep gap-end>> - <= ;
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: move-gap-forward-inside? ( i gb -- i gb ? )
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! is it cheaper to move the gap inside than around?
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2dup [ gap-end>> [ 2 * ] dip - ] keep [ gap-start>> ] keep buffer-length + <= ;
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2dup [ gap-end>> [ 2 * ] dip - ] keep
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[ gap-start>> ] keep buffer-length + <= ;
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: move-gap-forward-inside ( i gb -- )
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[ dup gap-length neg swap gap-end>> rot ] keep seq>> copy-elements ;
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[ dup gap-length neg swap gap-end>> rot ] keep
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seq>> copy-elements ;
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: move-gap-back-inside ( i gb -- )
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[ dup gap-length swap gap-start>> 1 - rot 1 - ] keep seq>> copy-elements ;
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[ dup gap-length swap gap-start>> 1 - rot 1 - ] keep
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seq>> copy-elements ;
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: move-gap-forward-around ( i gb -- )
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0 over move-gap-back-inside [
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@ -176,10 +174,10 @@ INSTANCE: gb virtual-sequence
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: fix-gap ( n gb -- )
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2dup [ gap-length + ] keep gap-end<< gap-start<< ;
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! moving the gap to position 5 means that the element in position 5 will be immediately after the gap
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GENERIC: move-gap ( n gb -- )
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M: gb move-gap ( n gb -- ) 2dup [ position>index ] keep (move-gap) fix-gap ;
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! moving the gap to position 5 means that the element in
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! position 5 will be immediately after the gap
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: move-gap ( n gb -- )
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2dup [ position>index ] keep (move-gap) fix-gap ;
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! ------------ resizing -------------------------------------
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@ -198,12 +196,14 @@ M: gb move-gap ( n gb -- ) 2dup [ position>index ] keep (move-gap) fix-gap ;
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dup gap-start>> head ;
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: copy-after-gap ( array gb -- )
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! copy everything after the gap in 'gb' into the end of 'array',
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! and change 'gb's gap-end to reflect the gap-end in 'array'
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! copy everything after the gap in 'gb' into the end of
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! 'array', and change 'gb's gap-end to reflect the gap-end
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! in 'array'
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dup after-gap [ 2dup set-new-gap-end gap-end>> swap ] dip -rot copy ;
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: copy-before-gap ( array gb -- )
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! copy everything before the gap in 'gb' into the start of 'array'
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! copy everything before the gap in 'gb' into the start of
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! 'array'
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before-gap 0 rot copy ; ! gap start doesn't change
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: resize-buffer ( gb new-size -- )
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@ -224,21 +224,17 @@ M: gb move-gap ( n gb -- ) 2dup [ position>index ] keep (move-gap) fix-gap ;
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] [ drop f ] if ;
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: ?decrease ( gb -- )
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dup gb-too-big? [
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decrease-buffer-size
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] [ drop ] if ;
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dup gb-too-big? [ decrease-buffer-size ] [ drop ] if ;
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: ensure-room ( n gb -- )
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! ensure that ther will be enough room for 'n' more elements
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2dup enough-room? [ 2drop ] [
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increase-buffer-size
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] if ;
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2dup enough-room? [ 2drop ] [ increase-buffer-size ] if ;
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! ------- editing operations ---------------
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GENERIC#: insert* 2 ( seq position gb -- )
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GENERIC#: insert* 2 ( seq pos gb -- )
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: prepare-insert ( seq position gb -- seq gb )
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: prepare-insert ( seq pos gb -- seq gb )
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tuck move-gap over length over ensure-room ;
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: insert-elements ( seq gb -- )
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@ -247,20 +243,14 @@ GENERIC#: insert* 2 ( seq position gb -- )
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: increment-gap-start ( gb n -- )
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over gap-start>> + swap gap-start<< ;
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! generic dispatch identifies numbers as sequences before numbers...
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M: number insert* ( elem position gb -- ) [ 1array ] 2dip insert* ;
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! : number-insert ( num position gb -- ) [ 1array ] 2dip insert* ;
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M: number insert*
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[ 1array ] 2dip insert* ;
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M: sequence insert* ( seq position gb -- )
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M: sequence insert*
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prepare-insert [ insert-elements ] 2keep swap length increment-gap-start ;
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: (delete*) ( gb -- )
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dup gap-end>> 1 + over gap-end<< ?decrease ;
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GENERIC: delete* ( pos gb -- )
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M: gb delete* ( position gb -- )
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tuck move-gap (delete*) ;
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: delete* ( pos gb -- )
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tuck move-gap dup gap-end>> 1 + over gap-end<< ?decrease ;
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! -------- stack/queue operations -----------
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@ -268,7 +258,7 @@ M: gb delete* ( position gb -- )
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: push-end ( obj gb -- ) [ length ] keep insert* ;
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: pop-elem ( position gb -- elem ) [ nth ] 2keep delete* ;
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: pop-elem ( pos gb -- elem ) [ nth ] 2keep delete* ;
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: pop-start ( gb -- elem ) 0 swap pop-elem ;
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