#!/usr/bin/env python
"""
xhtmlmodels.py - XHTML Content Models
Author: Sean B. Palmer, inamidst.com
"""

import os, re

r_element = re.compile('(?<=element )([A-Za-z0-9]+)')

def elements(text): 
   return frozenset(text.split(' | '))

def format(elems): 
   return '(' + ' & '.join(elem + '*' for elem in sorted(elems)) + ')'

# Transcribed from the XHTML 1.0 Strict DTD: 
# http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd
# Cf. http://www.w3.org/TR/xhtml1/dtds.html#a_dtd_XHTML-1.0-Strict

special_pre = elements('br | span | bdo | map')
special = special_pre | elements('object | img')
fontstyle = elements('tt | i | b | big | small')
phrase = elements('em | strong | dfn | code | q | samp | kbd ' + 
                  '| var | cite | abbr | acronym | sub | sup')
inline_forms = elements('input | select | textarea | label | button')
misc_inline = elements('ins | del | script')
misc = elements('noscript') | misc_inline
inline = elements('a') | special | fontstyle | phrase | inline_forms
Inline = elements('text') | inline | misc_inline
heading = elements('h1 | h2 | h3 | h4 | h5 | h6')
lists = elements('ul | ol | dl')
blocktext = elements('pre | hr | blockquote | address')
block = elements('p') | heading | elements('div') | lists | \
        blocktext | elements('fieldset | table')
Block = block | elements('form') | misc
Flow = elements('text') | block | elements('form') | inline | misc
a_content = elements('text') | special | fontstyle | phrase | \
            inline_forms | misc_inline
pre_content = elements('text | a') | fontstyle | phrase | \
              special_pre | misc_inline | inline_forms
form_content = block | misc
button_content = elements('text | p') | heading | elements('div') | \
                 lists | blocktext | elements('table') | special | \
                 fontstyle | phrase | misc

if os.path.exists('xhtml.rnc'): 
   schema = open('xhtml.rnc')
   subset = frozenset(r_element.findall(schema.read()) + ['text'])
   schema.close()
else: subset = frozenset()

def main(): 
   print "Subset: "
   print subset
   print 

   print "Flow - Block: "
   print (Flow - Block) & subset
   print 

   print "Block - Flow: "
   print (Block - Flow) & subset
   print 

   print "Flow - Inline: "
   print (Flow - Inline) & subset
   print 

   print "Inline - Flow: "
   print (Inline - Flow) & subset
   print 

   print "Flow - Block - Inline: "
   print (Flow - Block - Inline) & subset
   print 

   print "Block - form_content: "
   print (Block - form_content) & subset
   print 

   print '* * *'
   print "Inline - pre_content: "
   print (Inline - pre_content) & subset
   print 

   print "pre_content - Inline: "
   print (pre_content - Inline) & subset
   print 

   print '* * *'
   object_content = elements('text | param | form') | block | inline | misc
   print "Flow - object_content: "
   print (Flow - object_content) & subset
   print 

   print "object_content - Flow: "
   print (object_content - Flow) & subset
   print 

   print '* * *'
   print 'Block:', format(Block & subset)
   print 'Inline:', format(Inline & subset)
   print 'Block - form_content:', (Block - form_content) & subset
   print 'Inline - pre_content:', (Inline - pre_content) & subset

if __name__=="__main__": 
   main()