[LUCENE-9567] JapanesePartOfSpeechStopFilterFactory should load built-in stop tags by default

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 8.6
• Component/s: modules/analysis
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Michael Froh
• Created: 07/Oct/20 00:28
• Updated: 28/Aug/22 16:09

Description

If JapanesePartOfSpeechStopFilterFactory is given empty args, it does nothing. It doesn't load any stop tags, and just passes along the TokenStream passed to create().

As a default behavior, this is trappy, since a user may add the filter without explicitly adding any arguments and assume that it would load a "default" stop set. Or they may assume that if an explicit argument is required then an exception will be thrown. Regardless, "doing nothing" is almost certainly not what the user intended.

I'm going to attach a patch to load the default stop tags (using JapaneseAnalyzer.getDefaultStopTags()) if no args are specified, which probably makes sense in 9.0 (as it's consistent with e.g. KoreanPartOfSpeechStopFilterFactory). If we want to apply a fix to 8.x, maybe throw an exception to let the use know that the FilterFactory probably isn't doing what they think it's doing?

Issue Links

• links to: GitHub Pull Request #1961