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#!/usr/bin/env python
# -*- coding: utf-8 -*-
Context-independent xHTML pair matcher
Use method <code>match(html, start_ix)</code> to find matching pair.
If pair was found, this function returns a list of indexes where tag pair
starts and ends. If pair wasn't found, <code>None</code> will be returned.
The last matched (or unmatched) result is saved in <code>last_match</code>
dictionary for later use.
@author: Sergey Chikuyonok (
import re
start_tag = r'<([\w\:\-]+)((?:\s+[\w\-:]+(?:\s*=\s*(?:(?:"[^"]*")|(?:\'[^\']*\')|[^>\s]+))?)*)\s*(\/?)>'
end_tag = r'<\/([\w\:\-]+)[^>]*>'
attr = r'([\w\-:]+)(?:\s*=\s*(?:(?:"((?:\\.|[^"])*)")|(?:\'((?:\\.|[^\'])*)\')|([^>\s]+)))?'
"Last matched HTML pair"
last_match = {
'opening_tag': None, # Tag() or Comment() object
'closing_tag': None, # Tag() or Comment() object
'start_ix': -1,
'end_ix': -1
cur_mode = 'xhtml'
"Current matching mode"
def set_mode(new_mode):
global cur_mode
if new_mode != 'html': new_mode = 'xhtml'
cur_mode = new_mode
def make_map(elems):
Create dictionary of elements for faster searching
@param elems: Elements, separated by comma
@type elems: str
obj = {}
for elem in elems.split(','):
obj[elem] = True
return obj
# Empty Elements - HTML 4.01
empty = make_map("area,base,basefont,br,col,frame,hr,img,input,isindex,link,meta,param,embed");
# Block Elements - HTML 4.01
block = make_map("address,applet,blockquote,button,center,dd,dir,div,dl,dt,fieldset,form,frameset,hr,iframe,isindex,li,map,menu,noframes,noscript,object,ol,p,pre,script,table,tbody,td,tfoot,th,thead,tr,ul");
# Inline Elements - HTML 4.01
inline = make_map("a,abbr,acronym,applet,b,basefont,bdo,big,br,button,cite,code,del,dfn,em,font,i,iframe,img,input,ins,kbd,label,map,object,q,s,samp,select,small,span,strike,strong,sub,sup,textarea,tt,u,var");
# Elements that you can, intentionally, leave open
# (and which close themselves)
close_self = make_map("colgroup,dd,dt,li,options,p,td,tfoot,th,thead,tr");
# Attributes that have their values filled in disabled="disabled"
fill_attrs = make_map("checked,compact,declare,defer,disabled,ismap,multiple,nohref,noresize,noshade,nowrap,readonly,selected");
#Special Elements (can contain anything)
# serge.che: parsing data inside <scipt> elements is a "feature"
special = make_map("style");
class Tag():
"""Matched tag"""
def __init__(self, match, ix):
@type match: MatchObject
@param match: Matched HTML tag
@type ix: int
@param ix: Tag's position
global cur_mode
name = = name
self.full_tag =
self.start = ix
self.end = ix + len(self.full_tag)
self.unary = ( len(match.groups()) > 2 and bool( ) or (name in empty and cur_mode == 'html')
self.type = 'tag'
self.close_self = (name in close_self and cur_mode == 'html')
class Comment():
"Matched comment"
def __init__(self, start, end):
self.start = start
self.end = end
self.type = 'comment'
def make_range(opening_tag=None, closing_tag=None, ix=0):
Makes selection ranges for matched tag pair
@type opening_tag: Tag
@type closing_tag: Tag
@type ix: int
@return list
start_ix, end_ix = -1, -1
if opening_tag and not closing_tag: # unary element
start_ix = opening_tag.start
end_ix = opening_tag.end
elif opening_tag and closing_tag: # complete element
if (opening_tag.start < ix and opening_tag.end > ix) or (closing_tag.start <= ix and closing_tag.end > ix):
start_ix = opening_tag.start
end_ix = closing_tag.end;
start_ix = opening_tag.end
end_ix = closing_tag.start
return start_ix, end_ix
def save_match(opening_tag=None, closing_tag=None, ix=0):
Save matched tag for later use and return found indexes
@type opening_tag: Tag
@type closing_tag: Tag
@type ix: int
@return list
last_match['opening_tag'] = opening_tag;
last_match['closing_tag'] = closing_tag;
last_match['start_ix'], last_match['end_ix'] = make_range(opening_tag, closing_tag, ix)
return last_match['start_ix'] != -1 and (last_match['start_ix'], last_match['end_ix']) or (None, None)
def match(html, start_ix, mode='xhtml'):
Search for matching tags in <code>html</code>, starting from
<code>start_ix</code> position. The result is automatically saved
in <code>last_match</code> property
return _find_pair(html, start_ix, mode, save_match)
def find(html, start_ix, mode='xhtml'):
Search for matching tags in <code>html</code>, starting from
<code>start_ix</code> position.
return _find_pair(html, start_ix, mode)
def get_tags(html, start_ix, mode='xhtml'):
Search for matching tags in <code>html</code>, starting from
<code>start_ix</code> position. The difference between
<code>match</code> function itself is that <code>get_tags</code>
method doesn't save matched result in <code>last_match</code> property
and returns array of opening and closing tags
This method is generally used for lookups
return _find_pair(html, start_ix, mode, lambda op, cl=None, ix=0: (op, cl) if op and op.type == 'tag' else None)
def _find_pair(html, start_ix, mode='xhtml', action=make_range):
Search for matching tags in <code>html</code>, starting from
<code>start_ix</code> position
@param html: Code to search
@type html: str
@param start_ix: Character index where to start searching pair
(commonly, current caret position)
@type start_ix: int
@param action: Function that creates selection range
@type action: function
@return: list
forward_stack = []
backward_stack = []
opening_tag = None
closing_tag = None
html_len = len(html)
def has_match(substr, start=None):
if start is None:
start = ix
return html.find(substr, start) == start
def find_comment_start(start_pos):
while start_pos:
if html[start_pos] == '<' and has_match('<!--', start_pos):
start_pos -= 1
return start_pos
# find opening tag
ix = start_ix - 1
while ix >= 0:
ch = html[ix]
if ch == '<':
check_str = html[ix:]
m = re.match(end_tag, check_str)
if m: # found closing tag
tmp_tag = Tag(m, ix)
if tmp_tag.start < start_ix and tmp_tag.end > start_ix: # direct hit on searched closing tag
closing_tag = tmp_tag
m = re.match(start_tag, check_str)
if m: # found opening tag
tmp_tag = Tag(m, ix);
if tmp_tag.unary:
if tmp_tag.start < start_ix and tmp_tag.end > start_ix: # exact match
return action(tmp_tag, None, start_ix)
elif backward_stack and backward_stack[-1].name ==
else: # found nearest unclosed tag
opening_tag = tmp_tag
elif check_str.startswith('<!--'): # found comment start
end_ix = check_str.find('-->') + ix + 3;
if ix < start_ix and end_ix >= start_ix:
return action(Comment(ix, end_ix))
elif ch == '-' and has_match('-->'): # found comment end
# search left until comment start is reached
ix = find_comment_start(ix)
ix -= 1
if not opening_tag:
return action(None)
# find closing tag
if not closing_tag:
ix = start_ix
while ix < html_len:
ch = html[ix]
if ch == '<':
check_str = html[ix:]
m = re.match(start_tag, check_str)
if m: # found opening tag
tmp_tag = Tag(m, ix);
if not tmp_tag.unary:
m = re.match(end_tag, check_str)
if m: #found closing tag
tmp_tag = Tag(m, ix);
if forward_stack and forward_stack[-1].name ==
else: # found matched closing tag
closing_tag = tmp_tag;
elif has_match('<!--'): # found comment
ix += check_str.find('-->') + 3
elif ch == '-' and has_match('-->'):
# looks like cursor was inside comment with invalid HTML
if not forward_stack or forward_stack[-1].type != 'comment':
end_ix = ix + 3
return action(Comment( find_comment_start(ix), end_ix ))
ix += 1
return action(opening_tag, closing_tag, start_ix)