Skip to content

Instantly share code, notes, and snippets.

@jayvdb
Forked from lordmauve/check_dubious_concat.py
Created July 25, 2016 16:12
Show Gist options
  • Save jayvdb/5499e63acaf46ec44d716a74d341706e to your computer and use it in GitHub Desktop.
Save jayvdb/5499e63acaf46ec44d716a74d341706e to your computer and use it in GitHub Desktop.
Linter for implicit string literal concatentation in list-like context
def check_dubious_concat(src):
"""Check for suspicious string literal concatenation.
We will warn about instances of string literal concatenation in list-like
contexts - that is, where concatenated string literals are adjacent to
commas or inside square brackets.
Such a heuristic will catch instances like this::
foo = [
"item1"
"item2"
]
or::
foo = (
"item1",
"item2"
"item3",
)
but will not warn about instances like this::
msg = (
"This is a long message "
"that has been broken across lines."
)
"""
BEFORE_BAD = ',', '['
AFTER_BAD = ',', ']'
lines = src.splitlines(True)
d = []
prev = None
for type, tok, start, end, line in tokenize.generate_tokens(iter(lines).next):
if type in (tokenize.NL, tokenize.COMMENT):
continue
if type == tokenize.STRING:
d.append((start, end))
else:
if (prev in BEFORE_BAD or tok in AFTER_BAD) and len(d) > 1:
startl, startoff = d[0][0]
endl, endoff = d[-1][1]
if startl == endl:
size = endoff - startoff
else:
size = len(lines[startl - 1]) - startoff
for l in lines[startl:endl - 1]:
size += len(l)
size += endoff
print((
"[line {startl}, col {startoff}, {size} chars] "
"Suspicious string literal concatenation - did you miss a comma?"
).format(**locals()))
else:
prev = tok
del d[:]
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment