smart_word_wrap_lazy.sf

#!/usr/bin/ruby

# Author: Daniel "Trizen" Șuteu
# License: GPLv3
# Date: 15th October 2013
# https://trizenx.blogspot.com
# https://trizenx.blogspot.com/2013/11/smart-word-wrap.html

# Smart word wrap algorithm
# See: https://en.wikipedia.org/wiki/Word_wrap#Minimum_raggedness

class SmartWordWrap {

    has width = 80

    # This is the ugliest method! It, recursively,
    # prepares the words for the combine() function.
    method prepare_words(array, depth=0, callback) {

        var root = []
        var len = 0
        var i = -1

        var limit = array.end
        while (++i <= limit) {
            len += (var word_len = array[i].len)

            if (len > width) {
                if (word_len > width) {
                    len -= word_len
                    array.splice(i, 1, array[i].split(width)...)
                    limit = array.end
                    --i; next
                }
                break
            }

            root << [
                array.first(i+1).join(' '),
                self.prepare_words(array.slice(i+1), depth+1, callback)
            ]

            if (depth.is_zero) {
                callback(root[0])
                root = []
            }

            break if (++len >= width)
        }

        root
    }

    # This function combines the
    # the parents with the childrens.
    method combine(root, path, callback) {
        var key = path.shift
        path.each { |value|
            root << key
            if (value.is_empty) {
                callback(root)
            }
            else {
                value.each { |item|
                    self.combine(root, item, callback)
                }
            }
            root.pop
        }
    }

    # This is the main function of the algorithm
    # which calls all the other functions and
    # returns the best possible wrapped string.
    method smart_wrap(text, width) {

        self.width = width
        var words = (text.kind_of(Array) ? text : text.words)

        var best = Hash(
            score => Inf,
            value => [],
        )

        self.prepare_words(words, callback: { |path|
            self.combine([], path, { |combination|
                var score = 0
                combination.slice(0, -1).each { |line|
                    score += (width - line.len -> sqr)
                }

                if (score < best{:score}) {
                    best{:score} = score
                    best{:value} = []+combination
                }
            })
        })

        best{:value}.join("\n")
    }
}

#
## Usage examples
#

var obj = SmartWordWrap();

var text = 'aaa bb cc ddddd';
var t1 = obj.smart_wrap(text, 6);
say t1;

assert_eq(t1, <<'EOT'.chomp)
aaa
bb cc
ddddd
EOT

say '-'*80;

text = 'As shown in the above phases (or steps), the algorithm does many useless transformations';
var t2 = obj.smart_wrap(text, 20);
say t2;

assert_eq(t2, <<'EOT'.chomp)
As shown in the
above phases
(or steps), the
algorithm does
many useless
transformations
EOT

say '-'*80;

text = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.';
var t3 = obj.smart_wrap(text, 20);
say t3;

assert_eq(t3, <<'EOT'.chomp)
Lorem ipsum
dolor sit amet,
consectetur
adipiscing elit.
EOT