wrap: faster (and simpler) wrapping algorithm.
John Benediktsson
parent
6d5775e732
commit
3f8c9e4150
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@ -39,7 +39,7 @@ word wrap."
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[ "hello how are you today?" 3 wrap-string ] unit-test
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{ "aaa\nbb cc\nddddd" } [ "aaa bb cc ddddd" 6 wrap-string ] unit-test
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{ "aaa\nbb ccc\ndddddd" } [ "aaa bb ccc dddddd" 6 wrap-string ] unit-test
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{ "aaa bb\nccc\ndddddd" } [ "aaa bb ccc dddddd" 6 wrap-string ] unit-test
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{ "aaa bb\ncccc\nddddd" } [ "aaa bb cccc ddddd" 6 wrap-string ] unit-test
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{ "aaa bb\nccccccc\nddddddd" } [ "aaa bb ccccccc ddddddd" 6 wrap-string ] unit-test
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@ -9,3 +9,15 @@ ARTICLE: "wrap" "Word wrapping"
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"The " { $vocab-link "wrap" } " vocabulary implements word wrapping. Wrapping can take place based on simple strings, assumed to be monospace, or abstract word objects."
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{ $vocab-subsection "String word wrapping" "wrap.strings" }
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{ $vocab-subsection "Word object wrapping" "wrap.words" } ;
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HELP: element
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{ $class-description "An element to be wrapped. It has the following slots:" }
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{ $table
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{ { $slot "contents" } "The object being wrapped." }
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{ { $slot "black" } "The width of the object (e.g., the text length)." }
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{ { $slot "white" } "The space after the object (e.g., trailing whitespace)." }
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} ;
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HELP: wrap
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{ $values { "elements" { $sequence element } } { "width" real } }
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{ $description "Break the " { $snippet "elements" } " into lines such that the total width of each line tries to be less than " { $snippet "width" } " while attempting to minimize the raggedness represented by the amount of space at the end of each line. Returns an array of lines." } ;
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@ -1,72 +1,46 @@
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! Copyright (C) 2009 Daniel Ehrenberg
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! Copyright (C) 2017 John Benediktsson
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! See http://factorcode.org/license.txt for BSD license.
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USING: accessors arrays combinators combinators.short-circuit
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fry kernel kernel.private lists locals math sequences typed ;
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USING: accessors arrays kernel locals math sequences
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sequences.private ;
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IN: wrap
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! black is the text length, white is the whitespace length
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TUPLE: element contents black white ;
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C: <element> element
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<PRIVATE
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:: wrap ( elements width -- array )
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elements length integer>fixnum-strict :> #elements
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elements [ black>> ] { } map-as :> black
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elements [ white>> ] { } map-as :> white
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: element-length ( element -- n )
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[ black>> ] [ white>> ] bi + ; inline
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#elements 1 + f <array> :> minima
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#elements 1 + 0 <array> :> breaks
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TUPLE: paragraph line-max lines head-width tail-cost ;
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C: <paragraph> paragraph
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0 0 minima set-nth-unsafe
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: if-one-line ( paragraph true false -- )
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[ dup lines>> 1list? ] 2dip if ; inline
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minima [| base i |
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0 i 1 + [ dup #elements <= ] [| j |
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j 1 - black nth-unsafe + dup :> w
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j 1 - white nth-unsafe +
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TYPED: top-fits? ( paragraph: paragraph -- ? )
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[ head-width>> ] [ line-max>> ] bi <= ; inline
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w width > [
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j 1 - i = [
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0 j minima set-nth-unsafe
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i j breaks set-nth-unsafe
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] when #elements
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] [
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base
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j #elements = [ width w - sq + ] unless :> cost
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j minima nth-unsafe [ cost >= ] [ t ] if* [
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cost j minima set-nth-unsafe
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i j breaks set-nth-unsafe
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] when j
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] if 1 +
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] while 2drop
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] each-index
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TYPED: fits? ( paragraph: paragraph -- ? )
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! Make this not count spaces at end
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{ [ lines>> car 1list? ] [ top-fits? ] } 1|| ; inline
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TYPED: paragraph-cost ( paragraph: paragraph -- cost )
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[ drop 0 ] [
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[ head-width>> ] [ line-max>> - sq ] [ tail-cost>> ] tri +
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] if-one-line ; inline
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: min-cost ( paragraphs -- paragraph )
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[ paragraph-cost ] infimum-by ; inline
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TYPED: new-line ( paragraph: paragraph element: element -- paragraph )
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{
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[ drop line-max>> ]
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[ [ lines>> ] [ 1list ] bi* swons ]
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[ nip black>> ]
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[ drop paragraph-cost ]
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} 2cleave <paragraph> ; inline
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TYPED: add-element ( paragraph: paragraph element: element -- )
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[ '[ _ element-length + ] change-head-width ]
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[ '[ unswons _ swons swons ] change-lines ] bi drop ; inline
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TYPED: wrap-step ( paragraphs: array element: element -- paragraphs )
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[ [ min-cost ] dip new-line ]
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[ dupd '[ _ add-element ] each ]
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2bi swap prefix { array } declare
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[ fits? ] filter ; inline
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: 1paragraph ( line-max element -- paragraph )
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[ 1list 1list ] [ black>> ] bi 0 <paragraph> ;
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: post-process ( paragraph -- array )
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lines>> [ [ contents>> ] lmap>array ] lmap>array ;
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: initial-step ( line-max elements -- elements paragraph )
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reverse unclip swapd 1paragraph 1array ;
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PRIVATE>
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: wrap ( elements width -- array )
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swap [ drop { } ] [
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initial-step
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[ wrap-step ] reduce
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min-cost
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post-process
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] if-empty ;
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#elements [ dup 0 > ] [
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[ breaks nth dup ] keep elements <slice>
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[ contents>> ] map
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] produce nip reverse ;
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