[docs]class LocationReplace(object):
""" Applies location based layers to XML nodes. We use XML so that we only
take into account the original text when we're doing a replacement. """
def __init__(self):
self.offset_starter = 0
self.offset_counters = None
self.offsets = None
[docs] @staticmethod
def find_all_offsets(pattern, text, offset=0):
"""Don't use regular expressions as they are a tad slow"""
matches = []
pattern_len = len(pattern)
next_match = text.find(pattern)
while next_match != -1:
matches.append((next_match + offset,
next_match + pattern_len + offset))
next_match = text.find(pattern, next_match + 1)
return matches
[docs] def update_offsets(self, original, text):
""" Offsets change everytime we replace the text, since we add more
characters. Update the offsets. """
list_offsets = []
lt = text.find('<')
gt = -1
while lt != -1:
subtext = text[gt+1: lt]
list_offsets.extend(LocationReplace.find_all_offsets(
original, subtext, gt + 1))
gt = text.find('>', lt)
lt = text.find('<', gt)
list_offsets.extend(LocationReplace.find_all_offsets(
original, text[gt+1:], gt + 1))
self.offset_counters = list(range(self.offset_starter,
self.offset_starter + len(list_offsets)))
self.offsets = dict(zip(self.offset_counters, list_offsets))
[docs] def update_offset_starter(self):
""" As we're navigating the XML node, we need to keep track of how many
offsets we've already seen. """
if len(self.offset_counters) > 0:
self.offset_starter = self.offset_counters[-1] + 1
[docs] def location_replace_text(self, text, original, replacement, locations):
"""Given plain text, do replacements"""
self.update_offsets(original, text)
text_segments = []
relevant_locations = sorted(self.offsets.keys())
relevant_locations = [l for l in relevant_locations if l in locations]
text_begin = 0
for location in relevant_locations:
start, end = self.offsets[location]
# unrelated text
text_segments.append(text[text_begin:start])
# s/original/replacement
text_segments.append(replacement)
text_begin = end
# tail of unrelated text
text_segments.append(text[text_begin:])
# offset_starter is shared between segments of xml nodes (in
# location_replace, below)
if original not in replacement:
self.offset_starter += len(locations)
self.update_offset_starter()
return "".join(text_segments)
[docs] def location_replace(self, xml_node, original, replacement, locations):
""" For the xml_node, replace the locations instances of orginal with
replacement.
@todo: This doesn't appear to be used anymore?"""
if xml_node.text:
xml_node.text = self.location_replace_text(
xml_node.text, original, replacement, locations)
for c in xml_node.getchildren():
self.location_replace(c, original, replacement, locations)
if xml_node.tail:
xml_node.tail = self.location_replace_text(
xml_node.tail, original, replacement, locations)