Chris Koenig created LUCENE-7916:
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Summary: CompositeBreakIterator is brittle under ICU4J upgrade.
Key: LUCENE-7916
URL: https://issues.apache.org/jira/browse/LUCENE-7916
Project: Lucene - Core
Issue Type: Bug
Components: modules/analysis
Affects Versions: 6.6
Reporter: Chris Koenig
We use lucene-analyzers-icu version 6.6.0 in our project. Lucene 6.6.0 is built
against ICU4J version 56.1, but our use case requires us to use the latest
version of ICU4J, 59.1.
The problem that we have encountered is that
CompositeBreakIterator.getBreakIterator(int scriptCode) throws an
ArrayIndexOutOfBoundsException for script codes higher than 167. In ICU4J 56.1
the highest possible script code is 166, but in ICU4j 59.1 it is 174.
Internally, CompositeBreakIterator is creating an array of size
UScript.CODE_LIMIT, but the value of CODE_LIMIT from ICU4J 56.1 is being baked
into the bytecode by the compiler. So even after overriding the version of the
ICU4J dependency to 59.1 in our project, this array will still be size 167,
which is too small.
final class CompositeBreakIterator {
private final ICUTokenizerConfig config;
private final BreakIteratorWrapper wordBreakers[] = new
BreakIteratorWrapper[UScript.CODE_LIMIT];
Output of javap run on CompositeBreakIterator.class from
lucene-analyzers-icu-6.6.0.jar
Compiled from "CompositeBreakIterator.java"
final class org.apache.lucene.analysis.icu.segmentation.CompositeBreakIterator {
org.apache.lucene.analysis.icu.segmentation.CompositeBreakIterator(org.apache.lucene.analysis.icu.segmentation.ICUTokenizerConfig);
descriptor:
(Lorg/apache/lucene/analysis/icu/segmentation/ICUTokenizerConfig;)V
Code:
0: aload_0
1: invokespecial #1 // Method
java/lang/Object."<init>":()V
4: aload_0
5: sipush 167
8: anewarray #3 // class
org/apache/lucene/analysis/icu/segmentation/BreakIteratorWrapper
In our case, the ArrayIndexOutOfBoundsException was triggered when we
encountered a stray character of the Bhaiksuki script (script code 168) in a
chunk of text that we processed.
CompositeBreakIterator can be made more resilient by changing the type of
wordBreakers from an array to a Map and no longer relying on the value of
UScript.CODE_LIMIT.
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