External function binding bug (early binding)

Hi Mike,

There is another small bug in the way saxon-8.4 searches and binds  
Java extension functions.
It's triggered if there's a public method in an external function  
class that uses argument types in its signature that are not on the  
class path, even if that method is not used in any way by the query.  
In the spirit of late dynamic binding, I think Saxon should not fail  
here. Rather, it should catch and ignore the relevant exceptions on  
function binding if the function is never used.

The case arises if one has a class with various utility extension  
functions, some of which are typically rarely used, but have  
dependencies on various third-party libs. If those rare functions are  
not used, a user should not need to download and include those third- 
party libs.

Here's an example to reproduce (assuming you have lucene.jar from  
http://lucene.apache.org/java/docs/index.html on the classpath at  
compile time, but not at runtime):

package nux.xom.tests;

import org.apache.lucene.analysis.Analyzer;

public class ExternalFunctionTest {
    public static String foo(String bar) { return bar; }
    public static void unused(String baz, Analyzer anal) {} // this  
method is never used at runtime
}


package nux.xom.tests;

public class ExternalFunctionTestWorkAround {
    public static String foo(String bar) { return  
ExternalFunctionTest.foo(bar); }
}


This works fine:
===========================================
declare namespace util =  
"java:nux.xom.tests.ExternalFunctionTestWorkAround";
util:foo("x")


[hoschek /Users/hoschek/unix/devel/nux] fire-xquery ext-workaround.xq
<atomic-value xsi:type="xs:string" xmlns="http://dsd.lbl.gov/nux";  
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";>x</atomic-value>


This triggers the bug:
===========================================
declare namespace util = "java:nux.xom.tests.ExternalFunctionTest";
util:foo("x")


[hoschek /Users/hoschek/unix/devel/nux] fire-xquery ext.xq
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/ 
lucene/analysis/Analyzer
        at java.lang.Class.getDeclaredMethods0(Native Method)
        at java.lang.Class.privateGetDeclaredMethods(Class.java:1655)
        at java.lang.Class.privateGetPublicMethods(Class.java:1778)
        at java.lang.Class.getMethods(Class.java:832)
        at net.sf.saxon.functions.JavaExtensionLibrary.bind 
(JavaExtensionLibrary.java:307)
        at net.sf.saxon.functions.FunctionLibraryList.bind 
(FunctionLibraryList.java:71)
        at net.sf.saxon.expr.ExpressionParser.parseFunctionCall 
(ExpressionParser.java:1732)
        at net.sf.saxon.expr.ExpressionParser.parseBasicStep 
(ExpressionParser.java:1234)
        at net.sf.saxon.expr.ExpressionParser.parseStepExpression 
(ExpressionParser.java:1149)
        at net.sf.saxon.expr.ExpressionParser.parseRelativePath 
(ExpressionParser.java:1089)
        at net.sf.saxon.expr.ExpressionParser.parsePathExpression 
(ExpressionParser.java:1075)
        at net.sf.saxon.expr.ExpressionParser.parseUnaryExpression 
(ExpressionParser.java:954)
        at net.sf.saxon.expr.ExpressionParser.parseCastExpression 
(ExpressionParser.java:625)
        at net.sf.saxon.expr.ExpressionParser.parseCastableExpression 
(ExpressionParser.java:600)
        at net.sf.saxon.expr.ExpressionParser.parseTreatExpression 
(ExpressionParser.java:581)
        at  
net.sf.saxon.expr.ExpressionParser.parseInstanceOfExpression 
(ExpressionParser.java:563)
        at  
net.sf.saxon.expr.ExpressionParser.parseIntersectExpression 
(ExpressionParser.java:987)
        at net.sf.saxon.expr.ExpressionParser.parseUnionExpression 
(ExpressionParser.java:969)
        at  
net.sf.saxon.expr.ExpressionParser.parseMultiplicativeExpression 
(ExpressionParser.java:906)
        at net.sf.saxon.expr.ExpressionParser.parseAdditiveExpression 
(ExpressionParser.java:886)
        at net.sf.saxon.expr.ExpressionParser.parseRangeExpression 
(ExpressionParser.java:798)
        at  
net.sf.saxon.expr.ExpressionParser.parseComparisonExpression 
(ExpressionParser.java:748)
        at net.sf.saxon.expr.ExpressionParser.parseAndExpression 
(ExpressionParser.java:370)
        at net.sf.saxon.expr.ExpressionParser.parseOrExpression 
(ExpressionParser.java:352)
        at net.sf.saxon.expr.ExpressionParser.parseExprSingle 
(ExpressionParser.java:306)
        at net.sf.saxon.expr.ExpressionParser.parseExpression 
(ExpressionParser.java:269)
        at net.sf.saxon.query.QueryParser.parseQuery 
(QueryParser.java:144)
        at net.sf.saxon.query.QueryParser.makeXQueryExpression 
(QueryParser.java:71)
        at net.sf.saxon.query.StaticQueryContext.compileQuery 
(StaticQueryContext.java:254)
        at nux.xom.xquery.XQuery.<init>(XQuery.java:413)
        at nux.xom.pool.XQueryFactory.createXQuery 
(XQueryFactory.java:139)
        at nux.xom.pool.XQueryFactory.createXQuery 
(XQueryFactory.java:165)
        at nux.xom.pool.XQueryFactory.createXQuery 
(XQueryFactory.java:114)
        at nux.xom.tests.XQueryCommand.main(XQueryCommand.java:132)
[hoschek /Users/hoschek/unix/devel/nux]



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