spine

#!/usr/bin/env ruby

# Align a two-column table along its "spine".

require 'colorize'


# Given an array of lines and a regex representing the spine,
# split each line into an array of pieces, left and right.
# Return the array of arrays of pieces, along with the maximum
# left-piece length.

def split(lines, split_ex)
  pieces = []
  offset = 0
  lines.each do |line|
    matches = split_ex.match(line)
    pieces << [matches[:left], matches[:right]]
    offset = [offset, matches[:left].length].max
  end
  [pieces, offset]
end


# Take the pieces, the offset, and the splitter.
# Output the pieces with left column colorized and right-aligned.

def present(pieces, offset, splitter)
  pieces.each do |piece|
    print(' ' * (offset - piece.first.length),
          piece.first.colorize(:blue),
          splitter, piece.last, "\n")
  end
end


# If we were given a command-line argument, use it as the "splitter";
# otherwise, default to ':'.
splitter = (ARGV.count.nonzero? ? ARGV.shift : ':')
split_ex = /(?<left>.*?)#{splitter}(?<right>.*)/

lines = ARGF.readlines.map(&:chomp)
pieces, offset = split(lines, split_ex)
present(pieces, offset, splitter)