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# A simple xml parser. It is simple in the respect as that it doesn't address
# any of the complexities of XML. This is ruby 1.9.
$:.unshift File.dirname(__FILE__) + "/../lib"
require 'pp'
require 'parslet'
class XML < Parslet::Parser
root :document
rule(:document) {
tag(close: false).as(:o) >> document.as(:i) >> tag(close: true).as(:c) |
text
}
# Perhaps we could have some syntax sugar to make this more easy?
#
def tag(opts={})
close = opts[:close] || false
parslet = str('<')
parslet = parslet >> str('/') if close
parslet = parslet >> (str('>').absent? >> match("[a-zA-Z]")).repeat(1).as(:name)
parslet = parslet >> str('>')
parslet
end
rule(:text) {
match('[^<>]').repeat(0)
}
end
def check(xml)
r = XML.new.parse(xml)
# We'll validate the tree by reducing valid pairs of tags into simply the
# string "verified". If the transformation ends on a string, then the
# document was 'valid'.
#
t = Parslet::Transform.new do
rule(
o: {name: simple(:tag)},
c: {name: simple(:tag)},
i: simple(:t)
) { 'verified' }
end
t.apply(r)
end
pp check("<a><b>some text in the tags</b></a>")
pp check("<b><b>some text in the tags</b></a>")
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