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implement more robust private-person replacer 

The previous method occasionally gave incorrect results because it
performed replacements on an entire line, rather than on individual
instances of the text to replace. This usually worked fine, but in rare
cases could create wrong/ugly output, and with future improvements to
what can be replaced could end up causing leaks.

This was a royal PITA to get working, but I'm fairly sure it's correct
now due to all the doctests. Please add more if you find any regressions
or think of cases that aren't covered.
This commit is contained in:
Soren I. Bjornstad 2022-03-16 09:19:49 -05:00
parent e14709be40
commit f0bd41f65a
1 changed files with 145 additions and 21 deletions
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166
tzk/builders.py
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@ -19,7 +19,7 @@ import re
import shutil
import subprocess
import tempfile
from typing import Callable, Dict, List, Optional, Set, Sequence, Tuple
from typing import Callable, Dict, Generator, List, Optional, Set, Sequence, Tuple
from tzk import git
from tzk import tw
@ -359,6 +359,146 @@ def _private_people_replacement_table(
}
def _privatize_line(line: str, replacement_table: Dict[str, str],
replace_link_text: bool = False) -> Optional[str]:
"""
Given a line and a table of replacements to make, replace all instances
of all private people defined in the replacement table.
Basics:
>>> _privatize_line("MsAlice is a test person.", {'MsAlice': 'A.'})
'<<privateperson "A.">> is a test person.'
>>> _privatize_line("This woman, known as MsAlice, is a test person.", \
{'MsAlice': 'A.'})
'This woman, known as <<privateperson "A.">>, is a test person.'
>>> _privatize_line("[[MsAlice]] is a test person.", {'MsAlice': 'A.'})
'[[A.|PrivatePerson]] is a test person.'
>>> _privatize_line("When we talk about [[MsAlice]] in the middle of a " \
"sentence, that's fine too.", {'MsAlice': 'A.'})
"When we talk about [[A.|PrivatePerson]] in the middle of a sentence, that's fine too."
Links with different text and target:
>>> _privatize_line("We can talk about [[Alice|MsAlice]] " \
"with different text.", {'MsAlice': 'A.'})
'We can talk about [[Alice|PrivatePerson]] with different text.'
Multiple replacements with different people:
>>> _privatize_line("We can have [[MsAlice]] and MrBob talk to each other " \
"in the same line.", {'MsAlice': 'A.', 'MrBob': 'B.'})
'We can have [[A.|PrivatePerson]] and <<privateperson "B.">> talk to each other in the same line.'
Multiple replacements with the same person:
>>> _privatize_line("We can have MsAlice talk to herself (MsAlice) " \
"in the same line.", {'MsAlice': 'A.'})
'We can have <<privateperson "A.">> talk to herself (<<privateperson "A.">>) in the same line.'
>>> _privatize_line("Likewise [[MsAlice]] can do it with brackets " \
"([[MsAlice]]).", {'MsAlice': 'A.'})
'Likewise [[A.|PrivatePerson]] can do it with brackets ([[A.|PrivatePerson]]).'
>>> _privatize_line('We can talk about [[Alice|MsAlice]] lots of ways, ' \
'like MsAlice and [[MsAlice]].', {'MsAlice': 'A.'})
'We can talk about [[Alice|PrivatePerson]] lots of ways, like <<privateperson "A.">> and [[A.|PrivatePerson]].'
We don't want to replace places where a CamelCase match is a substring of another
word. This is expected to yield no output because there's nothing to replace:
>>> _privatize_line("But an EmbeddedCamelWithMsAliceInIt isn't her.", \
{'MsAlice': 'A.'})
"""
def iteroccurrences(needle: str) -> Generator[int, int, None]:
"""
Iterate over the start indices of occurrences of substring
``needle`` in the line /line/ in outer scope.
(We have to use outer scope because it can be changed while we're iterating
and the generator is only bound to arguments once.)
"""
idx = -1
while True:
idx = line.find(needle, idx + 1)
if idx == -1:
return
else:
additional_increments = yield idx
if additional_increments is not None:
idx += additional_increments
def anchored_at_one_end(start_index: int, end_index: int) -> bool:
return start_index == 0 or end_index == len(line)
def is_camelcase_link(start_index: int, end_index: int) -> bool:
return (anchored_at_one_end(start_index, end_index)
or (line[start_index-1] != '[' and line[end_index] != ']'))
def is_bare_bracketed_link(start_index: int, end_index: int) -> bool:
return (not anchored_at_one_end(start_index, end_index)
and line[start_index-2:start_index] == '[['
and line[end_index:end_index+2] == ']]')
def is_textual_bracketed_link(start_index: int, end_index: int) -> bool:
return (not anchored_at_one_end(start_index, end_index)
and line[start_index-1] == '|'
and line[end_index:end_index+2] == ']]')
dirty = False
increment_iterator_by = 0
for replace_person, replace_initials in replacement_table.items():
iterator = iteroccurrences(replace_person)
try:
while True:
# NOTE: the "end" index is one after the last index in the string,
# as is needed for slice notation.
if increment_iterator_by:
start_idx = iterator.send(increment_iterator_by)
else:
start_idx = next(iterator)
end_idx = start_idx + len(replace_person)
new_line = None
if is_camelcase_link(start_idx, end_idx):
# camel-case link or unlinked reference in text
def is_spurious_substring():
# If there's not a non-alphanumeric character on both sides of
# the "link", we may be making a clbuttic replacement.
# <https://en.wikipedia.org/wiki/Scunthorpe_problem>
start_ok = start_idx == 0 or not line[start_idx-1].isalnum()
end_ok = end_idx == len(line) or not line[end_idx].isalnum()
return not (start_ok and end_ok)
if not is_spurious_substring():
new_line = (line[0:start_idx]
+ f'<<privateperson "{replace_initials}">>'
+ line[end_idx:])
elif is_bare_bracketed_link(start_idx, end_idx):
# link with the person as the target and text
replacement = replace_initials + '|PrivatePerson'
new_line = line[0:start_idx] + replacement + line[end_idx:]
elif is_textual_bracketed_link(start_idx, end_idx):
# link with the person as the target only;
# beware that you might have put something private in the text
new_line = line[0:start_idx] + 'PrivatePerson' + line[end_idx:]
else:
link = line[start_idx:end_idx]
raise ValueError("Unknown type of link '{link}'.")
if new_line:
line = new_line
dirty = True
# If we changed the length of the string by modifying it,
# we need to update our stored position within the string.
increment_iterator_by = len(new_line) - len(line)
except StopIteration:
pass
if dirty:
return line
else:
return None
@tzk_builder
def replace_private_people(initialer: Callable[[str], str] = None) -> None:
"""
@ -395,26 +535,10 @@ def replace_private_people(initialer: Callable[[str], str] = None) -> None:
with tiddler.open() as f:
lines = f.readlines()
for i in range(len(lines)):
for replace_person, replace_initials in replacement_table.items():
if replace_person in lines[i]:
if '|' + replace_person + ']]' in lines[i]:
# link with the person as the target only;
# beware that you might have put something private in the text
lines[i] = lines[i].replace(replace_person, 'PrivatePerson')
elif '[[' + replace_person + ']]' in lines[i]:
# link with the person as the target and text
lines[i] = lines[i].replace(
replace_person,
replace_initials + '|PrivatePerson')
else:
# camel-case link or unlinked reference in text;
# or spurious substring, so rule that out with the '\b' search
lines[i] = re.sub(
r"\b" + re.escape(replace_person) + r"\b",
f'<<privateperson "{replace_initials}">>',
lines[i]
)
dirty = True
private_line = _privatize_line(lines[i], replacement_table)
if private_line is not None:
lines[i] = private_line
dirty = True
if dirty:
with tiddler.open("w") as f:
f.writelines(lines)