align_ascii_table.rb

#!/usr/bin/env ruby
lines = STDIN.readlines
leading_match = lines.first.match(/^\s+/)
leading = leading_match ? leading_match[0] : ''
lines_without_edges = lines.map { |line| line.strip.sub(/^\|/, '').sub(/\|$/, '') }
lines_without_edges.reject! { |line| line.empty? }
table = lines_without_edges.map { |line| line.split('|').map { |cell| cell.strip } }
cell_count = table.first.size
widths = (0...cell_count).map do |index|
  table.inject(0) do |result, row|
    size = row[index].size
    size > result ? size : result
  end
end
aligned_table = table.map do |row|
  result = []
  row.each_with_index do |cell, index|
    result << cell.ljust(widths[index])
  end
  result
end
aligned_lines = aligned_table.map do |row|
  leading + '| ' + row.join(" | ") + ' |'
end
puts aligned_lines.join("\n")