Enhance smart_tokenize function to better support nested tags and quotes (Fixes #321)

[SamuelJennings]

Overview

Fixes issue #321 where django-cotton failed to parse component attributes containing Django template tags with nested quotes, particularly in i18n translation strings.

Problem

Users couldn't pass Django template tags to Cotton components when those tags contained nested quotes:

<c-alert
    message="{% trans "We've sent you an email." %}"
/>

was not parsing properly and would result in:

django.template.exceptions.TemplateSyntaxError: Unclosed tag on line 20: 'cotton'. Looking for one of: endcotton.

Solution

Modified the tokenizer in nested_tag_support.py to track Django template syntax depth ({{ }} and {% %} blocks) and ignore quote characters while inside Django syntax. This prevents premature quote termination during tokenization.

Key Changes (lines 119-177):

• Added django_var_depth counter for {{ }} blocks
• Added django_tag_depth counter for {% %} blocks
• Modified quote handling to only process quotes when both depths are 0
• Enhanced %} handling to distinguish nested blocks from Cotton tag endings

What Now Works ✅

• Original issue case: Passing trans strings with apostrophes
• All Django template tags: {% trans %}, {% blocktrans %}, {% if %}, {% for %}, {% url %}, {% comment %}, {% verbatim %}
• Variable filters: E.g. <c-alert message="{{ "test"|add:'123'|add:"abc" }}" with quoted arguments
• Real-world scenarios: Practical use cases now tested

Test Results

• ✅ 141/141 total tests pass (140 passed + 1 skipped)
• ✅ 26/26 regression tests pass for Parser issue with template tag and quotes into attribute value #321

Files Changed

• django_cotton/nested_tag_support.py - Tokenizer enhancement
• django_cotton/tests/regression/test_nested_quotes_issue_321.py - Comprehensive test suite (26 tests)

[SamuelJennings]

Just for some context, I was having a lot of issues recently with the same thing as described in #321. I understand that not everyone has a lot of free time to work on open source code so I thought I would just have a go at fixing the issue myself.

Totally open to feedback/suggestions.

[wrabit]

@SamuelJennings looks good, thank you.