strReplace -> j.u.regex.PatternSyntaxException should throw a ExprEvalException instead

[Jerven Tjalling Bolleman]

Dear Jena Developers,

I am doing some strange stuff with building regexes from data inside a 
sparql store. Sometimes that leads to invalid regexes which ends up 
throwing PatternSyntaxExceptions.

For my use case it is fine that these would not evaluate properly. I 
believe however that the specific exception about pattern syntax should 
be caught and turned into a ExprEvalException so that evaluation of 
queries can continue.

i.e. the following stacktrace (against jena 3.4.0) should be caught and 
not propegated.

java.util.regex.PatternSyntaxException: Illegal repetition near index 10
^(?:-*[^-]){-9}
          ^
        at java.util.regex.Pattern.error(Pattern.java:1955)
        at java.util.regex.Pattern.closure(Pattern.java:3157)
        at java.util.regex.Pattern.group0(Pattern.java:2912)
        at java.util.regex.Pattern.sequence(Pattern.java:2051)
        at java.util.regex.Pattern.expr(Pattern.java:1996)
        at java.util.regex.Pattern.compile(Pattern.java:1696)
        at java.util.regex.Pattern.<init>(Pattern.java:1351)
        at java.util.regex.Pattern.compile(Pattern.java:1054)
        at 
org.apache.jena.sparql.expr.nodevalue.XSDFuncOp.strReplace(XSDFuncOp.java:474)
        at 
org.apache.jena.sparql.expr.nodevalue.XSDFuncOp.strReplace(XSDFuncOp.java:518)


I suggest modifying the function

public static NodeValue strReplace(NodeValue nvStr, NodeValue nvPattern, 
NodeValue nvReplacement, NodeValue nvFlags) {
        String pat = checkAndGetStringLiteral("replace", 
nvPattern).getLiteralLexicalForm() ;
        int flags = 0 ;
        if ( nvFlags != null ) {
            String flagsStr = checkAndGetStringLiteral("replace", 
nvFlags).getLiteralLexicalForm() ;
            flags = RegexJava.makeMask(flagsStr) ;
        }
        return strReplace(nvStr, Pattern.compile(pat, flags), 
nvReplacement) ;
}

to be something like

public static NodeValue strReplace(NodeValue nvStr, NodeValue nvPattern, 
NodeValue nvReplacement, NodeValue nvFlags) {
        String pat = checkAndGetStringLiteral("replace", 
nvPattern).getLiteralLexicalForm() ;
        int flags = 0 ;
        if ( nvFlags != null ) {
            String flagsStr = checkAndGetStringLiteral("replace", 
nvFlags).getLiteralLexicalForm() ;
            flags = RegexJava.makeMask(flagsStr) ;
        }
        try {
            return strReplace(nvStr, Pattern.compile(pat, flags), 
nvReplacement) ;
        } catch (PatternSyntaxException ex){
            throw new ExprEvalException("PatternSyntaxException", ex) ;
        }
}

Does that seem sensible?

Regards,
Jerven
--
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Jerven Bolleman                        Jerven.Bolleman@sib.swiss
SIB Swiss Institute of Bioinformatics  Tel: +41 (0)22 379 58 85
CMU, rue Michel Servet 1               Fax: +41 (0)22 379 58 58
1211 Geneve 4,
Switzerland     www.sib.swiss - www.uniprot.org
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