Fix #151: Allow mixed comma and whitespace separation in transform pa…

[shiinapple]

Modified ParserUtil.java to add a guard if (i - start > 0) before adding tokens to the list. This ensures that consecutive separators (e.g., "-1 , 1") do not produce empty strings, which previously caused parsing failures.

Added two tests in AttributeParserTest.java:

• scale(-1, 1) : Comma separator.
• scale(-1 , 1) : Mixed space and comma separator.
  Both tests now pass correctly.

This is my first pr. Please let me know if anything needs to be adjusted!

[weisJ]

I think this might allow 1,,1 to be parsed as a list of only two strings, while it should really contain the empty string. Can we instead make sure to only avoid splitting while we are seeing whitespace directly after encountering a non whitespace delimiter?

[shiinapple]

Thanks for the review! I’ve reconsidered the splitting rules for transforms and reworked the implementation accordingly.

Changes

1. Cached splitOnWhitespace() in a local variable to avoid repeated calls in the loop.
2. Introduced a lastSplitWasWhiteSpace flag and adjusted the splitting logic so that:
   • Empty entries created by consecutive non‑whitespace separators are preserved (e.g. "1,,1" with SeparatorMode.COMMA_ONLY now produces ["1", "", "1"] ).
   • Only the “whitespace immediately followed by a separator” case avoids creating an extra empty token (e.g. "(-1 , 1)" no longer produces a spurious empty element).
     Verification

• Added two focused test cases in AttributeParserTest and confirmed they pass.