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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2023 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.expr;
import net.sf.saxon.expr.elab.Elaborator;
import net.sf.saxon.expr.elab.ItemEvaluator;
import net.sf.saxon.expr.elab.PullEvaluator;
import net.sf.saxon.expr.instruct.OriginalFunction;
import net.sf.saxon.expr.parser.ContextItemStaticInfo;
import net.sf.saxon.expr.parser.ExpressionVisitor;
import net.sf.saxon.expr.parser.RebindingMap;
import net.sf.saxon.functions.SystemFunction;
import net.sf.saxon.om.FunctionItem;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.*;
/**
* A call to a function that is known statically. This is a stricter definition than "static function
* call" in the XPath grammar, because it excludes calls that might be re-bound to a different function
* as a result of XSLT overrides in a different package, calls to functions that hold dynamic context
* information in their closure, and so on.
*/
public class StaticFunctionCall extends FunctionCall implements Callable {
private final FunctionItem target;
public StaticFunctionCall(FunctionItem target, Expression[] arguments) {
if (target.getArity() != arguments.length) {
throw new IllegalArgumentException("Function call to " + target.getFunctionName() + " with wrong number of arguments (" + arguments.length + ")");
}
this.target = target;
setOperanda(arguments, target.getOperandRoles());
}
/**
* Get the target function to be called
*
* @return the target function
*/
public FunctionItem getTargetFunction() {
return target;
}
/**
* Get the target function to be called
*
* @param context the dynamic evaluation context (not used in this implementation)
* @return the target function
*/
@Override
public FunctionItem getTargetFunction(XPathContext context) {
return getTargetFunction();
}
/**
* Get the qualified of the function being called
*
* @return the qualified name
*/
@Override
public StructuredQName getFunctionName() {
return target.getFunctionName();
}
/**
* Ask whether this expression is a call on a particular function
*
* @param function the implementation class of the function in question
* @return true if the expression is a call on the function
*/
@Override
public boolean isCallOn(Class function) {
return function.isAssignableFrom(target.getClass());
}
/**
* Type-check the expression. This also calls preEvaluate() to evaluate the function
* if all the arguments are constant; functions that do not require this behavior
* can override the preEvaluate method.
*
* @param visitor the expression visitor
* @param contextInfo information about the type of the context item
*/
@Override
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException {
checkFunctionCall(target, visitor);
return super.typeCheck(visitor, contextInfo);
}
/**
* Copy an expression. This makes a deep copy.
*
* @return the copy of the original expression
* @param rebindings variables that need to be re-bound
*/
@Override
public Expression copy(RebindingMap rebindings) {
Expression[] args = new Expression[getArity()];
for (int i=0; iThis method should always return a result, though it may be the best approximation
* that is available at the time.
*
* @return a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER,
* Type.NODE, or Type.ITEM (meaning not known at compile time)
*/
@Override
public ItemType getItemType() {
return target.getFunctionItemType().getResultType().getPrimaryType();
}
/**
* Get the static type of the expression as a UType, following precisely the type
* inference rules defined in the XSLT 3.0 specification.
*
* @param contextItemType the static type of the context item
* @return the static item type of the expression according to the XSLT 3.0 defined rules
*/
@Override
public UType getStaticUType(UType contextItemType) {
UType result = getItemType().getUType();
for (Operand o : operands()) {
if (o.getUsage() == OperandUsage.TRANSMISSION) {
result = result.intersection(o.getChildExpression().getStaticUType(contextItemType));
}
}
return result;
}
/**
* Call the Callable.
*
* @param context the dynamic evaluation context
* @param arguments the values of the arguments, supplied as Sequences.
* Generally it is advisable, if calling iterate() to process a supplied sequence, to
* call it only once; if the value is required more than once, it should first be converted
* to a {@link net.sf.saxon.om.GroundedValue} by calling the utility methd
* SequenceTool.toGroundedValue().
* If the expected value is a single item, the item should be obtained by calling
* Sequence.head(): it cannot be assumed that the item will be passed as an instance of
* {@link net.sf.saxon.om.Item} or {@link net.sf.saxon.value.AtomicValue}.
* It is the caller's responsibility to perform any type conversions required
* to convert arguments to the type expected by the callee. An exception is where
* this Callable is explicitly an argument-converting wrapper around the original
* Callable.
* @return the result of the evaluation, in the form of a Sequence. It is the responsibility
* of the callee to ensure that the type of result conforms to the expected result type.
* @throws net.sf.saxon.trans.XPathException if a dynamic error occurs during the evaluation of the expression
*/
@Override
public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException {
return target.call(context, arguments);
}
/**
* Get a name identifying the kind of expression, in terms meaningful to a user.
*
* @return a name identifying the kind of expression, in terms meaningful to a user.
* The name will always be in the form of a lexical XML QName, and should match the name used
* in explain() output displaying the expression.
*/
@Override
public String getExpressionName() {
return "staticFunctionCall";
}
/**
* Serialized output of expression structure. The abstract expression tree
* is written to the supplied output destination.
*
* @param out destination of the SEF output
*/
@Override
public void export(ExpressionPresenter out) throws XPathException {
if (target instanceof OriginalFunction) {
ExpressionPresenter.ExportOptions options = out.getOptions();
OriginalFunction pf = (OriginalFunction) target;
out.startElement("origFC", this);
out.emitAttribute("name", pf.getFunctionName());
out.emitAttribute("pack", options.packageMap.get(pf.getComponent().getContainingPackage()) + "");
for (Operand o : operands()) {
o.getChildExpression().export(out);
}
out.endElement();
} else {
if (target instanceof UnionCastableFunction) {
// Bug 2611. Bug 3822.
final UnionType targetType = ((UnionConstructorFunction) target).getTargetType();
out.startElement("castable", this);
if (targetType instanceof LocalUnionType) {
out.emitAttribute("to", AlphaCode.fromItemType(targetType));
} else {
out.emitAttribute("as", targetType.toExportString());
}
out.emitAttribute("flags", "u" + (((UnionConstructorFunction) target).isAllowEmpty() ? "e" : ""));
for (Operand o : operands()) {
o.getChildExpression().export(out);
}
out.endElement();
} else if (target instanceof ListCastableFunction) {
// Bug 2611. Bug 3822.
out.startElement("castable", this);
out.emitAttribute("as", ((ListConstructorFunction) target).getTargetType().getStructuredQName());
out.emitAttribute("flags", "l" + (((ListConstructorFunction) target).isAllowEmpty() ? "e" : ""));
for (Operand o : operands()) {
o.getChildExpression().export(out);
}
out.endElement();
} else if (target instanceof UnionConstructorFunction) {
// Bug 2611.
final UnionType targetType = ((UnionConstructorFunction) target).getTargetType();
out.startElement("cast", this);
if (targetType instanceof LocalUnionType) {
out.emitAttribute("to", AlphaCode.fromItemType(targetType));
} else{
out.emitAttribute("as", targetType.toExportString());
}
out.emitAttribute("flags", "u" + (((UnionConstructorFunction) target).isAllowEmpty() ? "e" : ""));
for (Operand o : operands()) {
o.getChildExpression().export(out);
}
out.endElement();
} else if (target instanceof ListConstructorFunction) {
// Bug 2611.
out.startElement("cast", this);
out.emitAttribute("as", ((ListConstructorFunction) target).getTargetType().getStructuredQName());
out.emitAttribute("flags", "l" + (((ListConstructorFunction) target).isAllowEmpty() ? "e" : ""));
for (Operand o : operands()) {
o.getChildExpression().export(out);
}
out.endElement();
} else {
super.export(out);
}
}
}
@Override
public Elaborator getElaborator() {
return new StaticFunctionCallElaborator();
}
private static class StaticFunctionCallElaborator extends FunctionCallElaborator {
@Override
public PullEvaluator elaborateForPull() {
StaticFunctionCall expr = (StaticFunctionCall) getExpression();
return context -> expr.call(context, evaluateArguments(context)).iterate();
}
@Override
public ItemEvaluator elaborateForItem() {
StaticFunctionCall expr = (StaticFunctionCall) getExpression();
return context -> expr.call(context, evaluateArguments(context)).head();
}
}
}