Telethon/telethon/parser/markdown_parser.py
2016-11-30 00:29:42 +03:00

147 lines
6.5 KiB
Python

from telethon.tl.types import (MessageEntityBold, MessageEntityCode,
MessageEntityItalic, MessageEntityTextUrl)
def parse_message_entities(msg):
"""Parses a message and returns the parsed message and the entities (bold, italic...).
Note that although markdown-like syntax is used, this does not reflect the complete specification!"""
# Store the entities here
entities = []
# Convert the message to a mutable list
msg = list(msg)
# First, let's handle all the text links in the message, so afterwards it's clean
# for us to get our hands dirty with the other indicators (bold, italic and fixed)
url_indices = [None] * 4 # start/end text index, start/end url index
valid_url_indices = [] # all the valid url_indices found
for i, c in enumerate(msg):
if c is '[':
url_indices[0] = i
# From now on, also ensure that the last item was set
elif c == ']' and url_indices[0]:
url_indices[1] = i
elif c == '(' and url_indices[1]:
# If the previous index (']') is not exactly before the current index ('('),
# then it's not a valid text link, so clear the previous state
if url_indices[1] != i - 1:
url_indices[:2] = [None] * 2
else:
url_indices[2] = i
elif c == ')' and url_indices[2]:
# We have succeeded to find a markdown-like text link!
url_indices[3] = i
valid_url_indices.append(url_indices[:]) # Append a copy
url_indices = [None] * 4
# Iterate in reverse order to clean the text from the urls
# (not to affect previous indices) and append MessageEntityTextUrl's
for i in range(len(valid_url_indices) - 1, -1, -1):
vui = valid_url_indices[i]
# Add 1 when slicing the message not to include the [] nor ()
# There is no need to subtract 1 on the later part because that index is already excluded
link_text = ''.join(msg[vui[0] + 1:vui[1]])
link_url = ''.join(msg[vui[2] + 1:vui[3]])
# After we have retrieved both the link text and url, replace them in the message
# Now we do have to add 1 to include the [] and () when deleting and replacing!
del msg[vui[2]:vui[3] + 1]
msg[vui[0]:vui[1] + 1] = link_text
# Finally, update the current valid index url to reflect that all the previous VUI's will be removed
# This is because, after the previous VUI's get done, their part of the message is removed too,
# hence we need to update the current VUI subtracting that removed part length
for prev_vui in valid_url_indices[:i]:
prev_vui_length = prev_vui[3] - prev_vui[2] - 1
displacement = prev_vui_length + len('[]()')
vui[0] -= displacement
vui[1] -= displacement
# No need to subtract the displacement from the URL part (indices 2 and 3)
# When calculating the length, subtract 1 again not to include the previously called ']'
entities.append(
MessageEntityTextUrl(
offset=vui[0], length=vui[1] - vui[0] - 1, url=link_url))
# After the message is clean from links, handle all the indicator flags
indicator_flags = {'*': None, '_': None, '`': None}
# Iterate over the list to find the indicators of entities
for i, c in enumerate(msg):
# Only perform further check if the current character is an indicator
if c in indicator_flags:
# If it is the first time we find this indicator, update its index
if indicator_flags[c] is None:
indicator_flags[c] = i
# Otherwise, it means that we found it before. Hence, the message entity *is* complete
else:
# Then we have found a new whole valid entity
offset = indicator_flags[c]
length = i - offset - 1 # Subtract -1 not to include the indicator itself
# Add the corresponding entity
if c == '*':
entities.append(
MessageEntityBold(
offset=offset, length=length))
elif c == '_':
entities.append(
MessageEntityItalic(
offset=offset, length=length))
elif c == '`':
entities.append(
MessageEntityCode(
offset=offset, length=length))
# Clear the flag to start over with this indicator
indicator_flags[c] = None
# Sort the entities by their offset first
entities = sorted(entities, key=lambda e: e.offset)
# Now that all the entities have been found and sorted, remove
# their indicators from the message and update the offsets
for entity in entities:
if type(entity) is not MessageEntityTextUrl:
# Clean the message from the current entity's indicators
del msg[entity.offset + entity.length + 1]
del msg[entity.offset]
# Iterate over all the entities but the current
for subentity in [e for e in entities if e is not entity]:
# First case, one in one out: so*me_th_in*g.
# In this case, the current entity length is decreased by two,
# and all the subentities offset decreases 1
if (subentity.offset > entity.offset and
subentity.offset + subentity.length <
entity.offset + entity.length):
entity.length -= 2
subentity.offset -= 1
# Second case, both inside: so*me_th*in_g.
# In this case, the current entity length is decreased by one,
# and all the subentities offset and length decrease 1
elif (entity.offset < subentity.offset < entity.offset +
entity.length < subentity.offset + subentity.length):
entity.length -= 1
subentity.offset -= 1
subentity.length -= 1
# Third case, both outside: so*me*th_in_g.
# In this case, the current entity is left untouched,
# and all the subentities offset decreases 2
elif subentity.offset > entity.offset + entity.length:
subentity.offset -= 2
# Finally, we can join our poor mutilated message back and return
msg = ''.join(msg)
return msg, entities