wrap ( elements width -- array )

Vocabulary

wrap

Inputs

elements	a sequence of elements
width	a real

Outputs

array

an array

Word description

Break the elements into lines such that the total width of each line tries to be less than width while attempting to minimize the raggedness represented by the amount of space at the end of each line. Returns an array of lines.

Definition

USING: accessors arrays kernel math sequences sequences.private
;

IN: wrap

:: wrap ( elements width -- array )
    elements length integer>fixnum-strict :> #elements elements
    [ black>> ] { } map-as :> black elements
    [ white>> ] { } map-as :> white #elements 1 + f <array>
    :> minima #elements 1 + 0 <array>
    :> breaks 0 0 minima set-nth-unsafe minima [| base i |
        0 i 1 +
        [ dup #elements <= ] [| j |
            j 1 - black nth-unsafe + dup :> w j 1 -
            white nth-unsafe + w width > [
                j 1 - i = [
                    0 j minima set-nth-unsafe
                    i j breaks set-nth-unsafe
                ] when #elements
            ] [
                base j #elements = [ width w - sq + ] unless
                :> cost j minima nth-unsafe
                [ cost >= ] [ t ] if* [
                    cost j minima set-nth-unsafe
                    i j breaks set-nth-unsafe
                ] when j
            ] if 1 +
        ] while 2drop
    ] each-index #elements
    [ dup 0 > ] [
        [ breaks nth dup ] keep elements <slice>
        [ contents>> ] map
    ] produce nip reverse ;