factor/basis/wrap/wrap.factor

87 lines
2.2 KiB
Factor

! Copyright (C) 2009 Daniel Ehrenberg
! See http://factorcode.org/license.txt for BSD license.
USING: kernel sequences math arrays locals fry accessors
lists splitting make combinators.short-circuit namespaces
grouping splitting.monotonic ;
IN: wrap
! black is the text length, white is the whitespace length
TUPLE: element contents black white ;
C: <element> element
: element-length ( element -- n )
[ black>> ] [ white>> ] bi + ;
TUPLE: paragraph lines head-width tail-cost ;
C: <paragraph> paragraph
SYMBOL: line-max
SYMBOL: line-ideal
: deviation ( length -- n )
line-ideal get - sq ;
: top-fits? ( paragraph -- ? )
[ head-width>> ]
[ lines>> 1list? line-ideal line-max ? get ] bi <= ;
: fits? ( paragraph -- ? )
! Make this not count spaces at end
{ [ lines>> car 1list? ] [ top-fits? ] } 1|| ;
:: min-by ( seq quot -- elt )
f 1/0. seq [| key value new |
new quot call :> newvalue
newvalue value < [ new newvalue ] [ key value ] if
] each drop ; inline
: paragraph-cost ( paragraph -- cost )
dup lines>> 1list? [ drop 0 ] [
[ head-width>> deviation ]
[ tail-cost>> ] bi +
] if ;
: min-cost ( paragraphs -- paragraph )
[ paragraph-cost ] min-by ;
: new-line ( paragraph element -- paragraph )
[ [ lines>> ] [ 1list ] bi* swons ]
[ nip black>> ]
[ drop paragraph-cost ] 2tri
<paragraph> ;
: glue ( paragraph element -- paragraph )
[ [ lines>> unswons ] dip swons swons ]
[ [ head-width>> ] [ element-length ] bi* + ]
[ drop tail-cost>> ] 2tri
<paragraph> ;
: wrap-step ( paragraphs element -- paragraphs )
[ '[ _ glue ] map ]
[ [ min-cost ] dip new-line ]
2bi prefix
[ fits? ] filter ;
: 1paragraph ( element -- paragraph )
[ 1list 1list ]
[ black>> ] bi
0 <paragraph> ;
: post-process ( paragraph -- array )
lines>> [ [ contents>> ] lmap>array ] lmap>array ;
: initialize ( elements -- elements paragraph )
<reversed> unclip-slice 1paragraph 1array ;
: wrap ( elements line-max line-ideal -- paragraph )
[
line-ideal set
line-max set
[ { } ] [
initialize
[ wrap-step ] reduce
min-cost
post-process
] if-empty
] with-scope ;