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