Package org.apache.xpath.functions
Class Function
- java.lang.Object
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- org.apache.xpath.Expression
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- org.apache.xpath.functions.Function
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,ExpressionNode
,XPathVisitable
- Direct Known Subclasses:
FuncCurrent
,FuncExtFunction
,FuncFalse
,FuncLast
,FuncPosition
,FunctionOneArg
,FuncTrue
public abstract class Function extends Expression
This is a superclass of all XPath functions. This allows two ways for the class to be called. One method is that the super class processes the arguments and hands the results to the derived class, the other method is that the derived class may process it's own arguments, which is faster since the arguments don't have to be added to an array, but causes a larger code footprint.- See Also:
- Serialized Form
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Constructor Summary
Constructors Constructor Description Function()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
callArgVisitors(XPathVisitor visitor)
Call the visitors for the function arguments.void
callVisitors(ExpressionOwner owner, XPathVisitor visitor)
This will traverse the heararchy, calling the visitor for each member.void
checkNumberArgs(int argNum)
Check that the number of arguments passed to this function is correct.boolean
deepEquals(Expression expr)
Compare this object with another object and see if they are equal, include the sub heararchy.XObject
execute(XPathContext xctxt)
Execute an XPath function object.void
postCompileStep(Compiler compiler)
This function is currently only being used by Position() and Last().void
setArg(Expression arg, int argNum)
Set an argument expression for a function.-
Methods inherited from class org.apache.xpath.Expression
asIterator, asIteratorRaw, asNode, assertion, bool, canTraverseOutsideSubtree, error, execute, execute, execute, executeCharsToContentHandler, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, fixupVariables, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isNodesetExpr, isStableNumber, num, warn, xstr
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Method Detail
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setArg
public void setArg(Expression arg, int argNum) throws WrongNumberArgsException
Set an argument expression for a function. This method is called by the XPath compiler.- Parameters:
arg
- non-null expression that represents the argument.argNum
- The argument number index.- Throws:
WrongNumberArgsException
- If the argNum parameter is beyond what is specified for this function.
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checkNumberArgs
public void checkNumberArgs(int argNum) throws WrongNumberArgsException
Check that the number of arguments passed to this function is correct. This method is meant to be overloaded by derived classes, to check for the number of arguments for a specific function type. This method is called by the compiler for static number of arguments checking.- Parameters:
argNum
- The number of arguments that is being passed to the function.- Throws:
WrongNumberArgsException
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execute
public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
Execute an XPath function object. The function must return a valid object.- Specified by:
execute
in classExpression
- Parameters:
xctxt
- The execution current context.- Returns:
- A valid XObject.
- Throws:
javax.xml.transform.TransformerException
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callArgVisitors
public void callArgVisitors(XPathVisitor visitor)
Call the visitors for the function arguments.
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callVisitors
public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
Description copied from interface:XPathVisitable
This will traverse the heararchy, calling the visitor for each member. If the called visitor method returns false, the subtree should not be called.- Parameters:
owner
- The owner of the visitor, where that path may be rewritten if needed.visitor
- The visitor whose appropriate method will be called.- See Also:
XPathVisitable.callVisitors(ExpressionOwner, XPathVisitor)
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deepEquals
public boolean deepEquals(Expression expr)
Description copied from class:Expression
Compare this object with another object and see if they are equal, include the sub heararchy.- Specified by:
deepEquals
in classExpression
- Parameters:
expr
- Another expression object.- Returns:
- true if this objects class and the expr object's class are the same, and the data contained within both objects are considered equal.
- See Also:
Expression.deepEquals(Expression)
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postCompileStep
public void postCompileStep(Compiler compiler)
This function is currently only being used by Position() and Last(). See respective functions for more detail.
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