matches should still return an Iterator when no match is found

[filipeom]

I'm trying to rewrite a bunch of code, however a few source files will not match the pattern and matches simply explodes on jsn = json.loads(self.call(cmd_s, text=source)) because call returns None. Is this the expected behaviour? To bypass this I'm catching the JSONDecodeError and going to the next file, but it would be nice if we simply had an empty Iterator

[ChrisTimperley]

That's surprising. I wouldn't have expected p.stdout.decode('utf-8') to be able to return None. Thanks for reporting it. I agree that matches should still return an Iterator when a match isn't found.

Just to double check, what version of comby-python are you using? Also, would you mind sharing some text that reproduces the issue?

[ChrisTimperley]

A possible workaround is to add a keyword argument suppress_errors: bool = True to matches that allows JSONDecodeError to be caught (and maybe writes a warning to the logger).

[filipeom]

I'm running python-comby 0.0.2 with comby binary 1.0.0

>>> from comby import Comby
>>> comby = Comby()
>>> source = 'a[i] = a[i] + 1'
>>> match = ':[[var]] ='
>>> replace = ':[var]_:[id()] ='
>>> list(comby.matches(source, match))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/filipe/.local/lib/python3.9/site-packages/comby/binary.py", line 106, in matches
    jsn = json.loads(self.call(cmd_s, text=source))
  File "/usr/lib/python3.9/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.9/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.9/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

I'm also going to update comby to see if the error persists over the updated version. For my use case I think that workaround would also work!

[jrfaller]

I also got this bug, with lib 0.02 and bin 1.6.0 on Mac OS X.

from comby import Comby

comby = Comby()
match = 'foo'
source= 'bar'
match = list(comby.matches(source, match))
print(match)

leads to:

Traceback (most recent call last):
  File "/Users/falleri/work/code/nbshowcase/./test_comby.py", line 8, in <module>
    match = list(comby.matches(source, match))
  File "/usr/local/lib/python3.9/site-packages/comby/binary.py", line 106, in matches
    jsn = json.loads(self.call(cmd_s, text=source))
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

Could you tell me how to apply the workaround advised above?

Cheers!

[jrfaller]

Apparently modifying the end of the matches function in binary.py as such works :

        jsn = json.loads(self.call(cmd_s, text=source) or 'null')
        if jsn is not None:
            jsn = jsn['matches']
            for jsn_match in jsn:
                yield Match.from_dict(jsn_match)

Do you think it make sense? I can supply a pull-request if you want.

[ChrisTimperley]

Apparently modifying the end of the matches function in binary.py as such works :

        jsn = json.loads(self.call(cmd_s, text=source) or 'null')
        if jsn is not None:
            jsn = jsn['matches']
            for jsn_match in jsn:
                yield Match.from_dict(jsn_match)

Do you think it make sense? I can supply a pull-request if you want.

That makes sense. It would be great if you could submit a PR. Thanks!

[jrfaller]

It's done, I have also added a test case to avoid any regression in the future.

Cheers!