Is there a way to pretty print XML with vertical alignment?

Question

I have a config file which has some XML like:

<Presidents>
  <President first="George" last="Washington" number="1" year="1789" />
  <President first="John" last="Adams" number="2" year="1797" />
</Presidents>

I would like to have a pretty printer vertically align my attributes so the file looks like:

<Presidents>
  <President first="George" last="Washington" number="1" year="1789" />
  <President first="John"   last="Adams"      number="2" year="1797" />
</Presidents>

This formatting style depends on having a list of elements with the same attributes, so it probably couldn't be applied generically to any xml document, however, it is a common style for config files. I've read the man pages for xmllint and xmlstarlet and I can't find any reference to a feature like this.

Answer 1

I created the following script to align the columns. I first pass my xml thought xmllint, and then through the following:

#!/usr/bin/env ruby
#
# vertically aligns columns

def print_buf(b)
  max_lengths={}
  max_lengths.default=0

  b.each do |line|
    for i in (0..line.size() - 1)
      d = line[i]
      s = d.size()
      if s > max_lengths[i] then
        max_lengths[i] = s
      end
    end
  end

  b.each do |line|
    for i in (0..line.size() - 1)
      print line[i], ' ' * (max_lengths[i] - line[i].size())
    end
  end

end

cols=0
buf=[]

ARGF.each do |line|
  columns=line.split(/( |\r\n|\n|\r)(?=(?:[^\"]*\"[^\"]*\")*(?![^\"]*\"))/m)
  if columns.size != cols then
    print_buf(buf) if !buf.empty?
    buf=[]
  end
  buf << columns
  cols = columns.size
end

print_buf(buf)