Fix invalid regex in unconstrained arrays for json_schema.py

[lapp0]

Fixes #913

Enables complete version of PR #914 which allows arrays

Problems

• Unconstrained arrays (arrays without any items types specified) would always result in an illegal regex
• Unconstrained arrays couldn't contain objects or arrays

Change

• Fix Unconstrained array pattern so it doesn't produce an illegal pattern
• Allow objects and arrays within arrays, but use "mock" depth key to prevent infinite recursion

[ekagra-ranjan]

@lapp0 - Right now the array will have at least one element. I think there is missing a parentheses to denote that we want the entire array to be optional and not just the elements which start with , i.e.

rf"\[({whitespace_pattern}({'|'.join(regexes)})(,{whitespace_pattern}({'|'.join(regexes)})){num_repeats}){allow_empty}{whitespace_pattern}\]"

Note the starting bracket after rf"\[ and closing bracket before {allow_empty}.
Wdyt?

[lapp0]

I've refactored a lot of this code so we can do constrained yaml. It's a lot more liberal with parenthesis use. Do you think this makes sense to fix the problem?

    def format_object_with_additional_properties(self, value_pattern, min_properties=None, max_properties=None):
        if max_properties == 0:
            return rf"\{{{self.ws}\}}"

        inner = self._regex_repeat_elem(
            elem_pattern=f"{STRING}{self.ws}:{self.ws}{value_pattern}",
            separator_pattern=f"{self.ws},{self.ws}",
            min_elem=min_properties,
            max_elem=max_properties,
            pad=self.ws
        )
        return rf'{{{inner}}}'

    def _regex_repeat_elem(self, elem_pattern, separator_pattern, min_elem=None, max_elem=None, pad=""):
        """Creates a pattern allowing between min_elem and max_elem occurrences of elem_pattern"""
        if max_elem == 0:
            return ""

        base_pattern = f"{elem_pattern}"
        suffix_pattern = f"(?:{separator_pattern}{elem_pattern})"

        min_suffix_repeats = "" if min_elem is None else max(0, int(min_elem) - 1)
        max_suffix_repeats = "" if max_elem is None else max_elem - 1

        if max_suffix_repeats == 0:
            pattern = base_pattern
        else:
            pattern = f"{base_pattern}({suffix_pattern}){{{min_suffix_repeats},{max_suffix_repeats}}}"

        padded_pattern = f"({pad}{pattern}{pad})"

        if not min_elem:
            return f"({padded_pattern}|{pad})"
        else:
            return padded_pattern

[ekagra-ranjan]

Sorry, I didnt get you. I just meant that right now the regex is this:

rf"\[{whitespace_pattern}({'|'.join(regexes)})(,{whitespace_pattern}({'|'.join(regexes)})){num_repeats}{allow_empty}{whitespace_pattern}\]"

and I think it should be this:

rf"\[({whitespace_pattern}({'|'.join(regexes)})(,{whitespace_pattern}({'|'.join(regexes)})){num_repeats}){allow_empty}{whitespace_pattern}\]"

For e.g its this [(true|false)(,(true|false)){0,}?] vs [((true|false)(,(true|false)){0,})?]. The former wont allow [] whereas the latter will allow it

Does this make sense?

[ekagra-ranjan]

@lapp0 are we missing a test case for having arrays inside object?

[lapp0]

Thanks for the comments! It's important that we create patterns that follow json-schema spec expectations. I'll ensure the two conditions you've referenced are tested in the refactor here lapp0#36