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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 Saxonica Limited
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.functions;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.lib.ExtensionFunctionCall;
import net.sf.saxon.lib.ExtensionFunctionDefinition;
import net.sf.saxon.lib.NamespaceConstant;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.BooleanValue;
import net.sf.saxon.value.SequenceType;
/**
* This class implements the saxon:is-idref() extension function,
* which is specially-recognized by the system because calls are generated by the optimizer.
* The function signature is saxon:is-idref() as boolean
* The result is true if the context item is a node having the idref property.
*/
public class IsIdRef extends ExtensionFunctionDefinition {
private static final StructuredQName qName =
new StructuredQName("", NamespaceConstant.SAXON, "is-idref");
/**
* Get the function name, as a QName
*
* @return the QName of the function
*/
@Override
public StructuredQName getFunctionQName() {
return qName;
}
/**
* Get the minimum number of arguments required by the function
*
* @return the minimum number of arguments that must be supplied in a call to this function
*/
@Override
public int getMinimumNumberOfArguments() {
return 0;
}
/**
* Get the maximum number of arguments allowed by the function
*
* @return the maximum number of arguments that may be supplied in a call to this function
*/
@Override
public int getMaximumNumberOfArguments() {
return 0;
}
/**
* Get the required types for the arguments of this function, counting from zero
*
* @return the required types of the argument, as defined by the function signature. Normally
* this should be an array of size {@link #getMaximumNumberOfArguments()}; however for functions
* that allow a variable number of arguments, the array can be smaller than this, with the last
* entry in the array providing the required type for all the remaining arguments.
*/
@Override
public SequenceType[] getArgumentTypes() {
return new SequenceType[]{};
}
/**
* Get the type of the result of the function
*
* @param suppliedArgumentTypes the static types of the arguments to the function.
* This is provided so that a more precise result type can be returned in the common
* case where the type of the result depends on the type of the first argument. The value
* will be null if the function call has no arguments.
* @return the return type of the function, as defined by its function signature
*/
@Override
public SequenceType getResultType(SequenceType[] suppliedArgumentTypes) {
return SequenceType.SINGLE_BOOLEAN;
}
/**
* Create a call on this function. This method is called by the compiler when it identifies
* a function call that calls this function.
*/
/*@NotNull*/
@Override
public ExtensionFunctionCall makeCallExpression() {
return new IsIdRefCall();
}
private static class IsIdRefCall extends ExtensionFunctionCall {
/**
* Evaluate this function call at run-time
*
* @param context The XPath dynamic evaluation context
* @param arguments The values of the arguments to the function call. Each argument value (which is in general
* a sequence) is supplied in the form of an iterator over the items in the sequence. If required, the
* supplied sequence can be materialized by calling, for example, new SequenceExtent(arguments[i]).
* If the argument is always a singleton, then the single item may be obtained by calling
* arguments[i].next(). The implementation is not obliged to read all the items in each
* SequenceIterator if they are not required to compute the result; but if any SequenceIterator is not read
* to completion, it is good practice to call its close() method.
* @return an iterator over the results of the function. If the result is a single item, it can be
* returned in the form of a {@link net.sf.saxon.tree.iter.SingletonIterator}. If the result is an empty sequence,
* the method should return EmptyIterator.getInstance()
* @throws net.sf.saxon.trans.XPathException
* if a dynamic error occurs during evaluation of the function. The Saxon run-time
* code will add information about the error location.
*/
@Override
public BooleanValue call(XPathContext context, Sequence[] arguments) throws XPathException {
Item contextItem = context.getContextItem();
return BooleanValue.get(contextItem instanceof NodeInfo && ((NodeInfo)contextItem).isIdref());
}
/**
* Get the effective boolean value of the expression. This returns false if the value
* is the empty sequence, a zero-length string, a number equal to zero, or the boolean
* false. Otherwise it returns true.
*
* @param context The context in which the expression is to be evaluated
* @return the effective boolean value
* @throws net.sf.saxon.trans.XPathException
* if any dynamic error occurs evaluating the
* expression
*/
@Override
public boolean effectiveBooleanValue(XPathContext context, Sequence[] arguments) throws XPathException {
Item contextItem = context.getContextItem();
return contextItem instanceof NodeInfo && ((NodeInfo) contextItem).isIdref();
}
}
}