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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2015 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.evpull.EmptyEventIterator;
import net.sf.saxon.evpull.EventIterator;
import net.sf.saxon.expr.instruct.Block;
import net.sf.saxon.expr.instruct.UserFunction;
import net.sf.saxon.expr.parser.*;
import net.sf.saxon.om.*;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trace.LocationKind;
import net.sf.saxon.trans.SaxonErrorCode;
import net.sf.saxon.trans.SymbolicName;
import net.sf.saxon.trans.Visibility;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.util.FastStringBuffer;
import net.sf.saxon.type.AnyItemType;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.value.Cardinality;
import net.sf.saxon.value.EmptySequence;
import net.sf.saxon.value.SequenceType;
import net.sf.saxon.value.Whitespace;
import java.util.ArrayList;
import java.util.List;
/**
* This class represents a call to a user-defined function in the stylesheet or query.
*/
public class UserFunctionCall extends FunctionCall implements UserFunctionResolvable, ComponentInvocation, ContextOriginator {
private SequenceType staticType;
private UserFunction function;
private int bindingSlot = -1;
private int tailCall = NOT_TAIL_CALL;
private StructuredQName name;
/*@Nullable*/ private int[] argumentEvaluationModes = null;
public static final int NOT_TAIL_CALL = 0;
public static final int FOREIGN_TAIL_CALL = 1;
public static final int SELF_TAIL_CALL = 2;
/**
* Create a function call to a user-written function in a query or stylesheet
*/
public UserFunctionCall() {
}
/**
* Set the name of the function being called
*
* @param name the name of the function
*/
public final void setFunctionName(StructuredQName name) {
this.name = name;
}
/**
* Set the static type
*
* @param type the static type of the result of the function call
*/
public void setStaticType(SequenceType type) {
staticType = type;
}
/**
* Create the reference to the function to be called
*
* @param compiledFunction the function being called
*/
public void setFunction(UserFunction compiledFunction) {
function = compiledFunction;
}
/**
* Set the binding slot to be used. This is the offset within the binding vector of the containing
* component where the actual target template is to be found. The target function is not held directly
* in the UserFunctionCall expression itself because it can be overridden in a using package.
*
* @param slot the offset in the binding vector of the containing package where the target template
* can be found.
*/
public void setBindingSlot(int slot) {
this.bindingSlot = slot;
}
/**
* Get the binding slot to be used. This is the offset within the binding vector of the containing
* component where the actual target template is to be found.
*
* @return the offset in the binding vector of the containing package where the target template
* can be found.
*/
public int getBindingSlot() {
return bindingSlot;
}
/**
* Get the function that is being called by this function call. This is the provisional
* binding: the actual function might be an override of this one.
*
* @return the function being called
*/
public UserFunction getFunction() {
return function;
}
public Component getFixedTarget() {
Visibility v = function.getDeclaringComponent().getVisibility();
if (v == Visibility.PRIVATE || v == Visibility.FINAL) {
return function.getDeclaringComponent();
} else {
return null;
}
}
/**
* Determine whether this is a tail call (not necessarily a recursive tail call)
*
* @return true if this function call is a tail call
*/
public boolean isTailCall() {
return tailCall != NOT_TAIL_CALL;
}
public boolean isRecursiveTailCall() {
return tailCall == SELF_TAIL_CALL;
}
/**
* Get the qualified of the function being called
*
* @return the qualified name
*/
public final StructuredQName getFunctionName() {
if (name == null) {
return function.getFunctionName();
} else {
return name;
}
}
public SymbolicName getSymbolicName() {
return new SymbolicName(StandardNames.XSL_FUNCTION, getFunctionName(), getArity());
}
public Component getTarget() {
return function.getDeclaringComponent();
}
/**
* Get the evaluation modes that have been determined for each of the arguments
*
* @return an array of integers representing the evaluation modes, one for each argument
*/
public int[] getArgumentEvaluationModes() {
return argumentEvaluationModes;
}
/**
* Set the argument evaluation modes
* @param evalModes the argument evaluation modes to be used
*/
public void setArgumentEvaluationModes(int[] evalModes) {
argumentEvaluationModes = evalModes;
}
/**
* Pre-evaluate a function at compile time. This version of the method suppresses
* early evaluation by doing nothing.
*
* @param visitor an expression visitor
*/
public Expression preEvaluate(ExpressionVisitor visitor) {
return this;
}
/**
* Determine the data type of the expression, if possible
*
* @return Type.ITEM (meaning not known in advance)
*/
/*@NotNull*/
public ItemType getItemType() {
if (staticType == null) {
// the actual type is not known yet, so we return an approximation
return AnyItemType.getInstance();
} else {
return staticType.getPrimaryType();
}
}
public int getIntrinsicDependencies() {
return StaticProperty.DEPENDS_ON_USER_FUNCTIONS;
}
/**
* Determine whether this is an updating expression as defined in the XQuery update specification
*
* @return true if this is an updating expression
*/
public boolean isUpdatingExpression() {
return function.isUpdating();
}
/**
* Compute the special properties of this expression. These properties are denoted by a bit-significant
* integer, possible values are in class {@link net.sf.saxon.expr.StaticProperty}. The "special" properties are properties
* other than cardinality and dependencies, and most of them relate to properties of node sequences, for
* example whether the nodes are in document order.
*
* @return the special properties, as a bit-significant integer
*/
protected int computeSpecialProperties() {
// Inherit the properties of the function being called if possible. But we have to prevent
// looping when the function is recursive. For safety, we only consider the properties of the
// function body if it contains no further function calls.
if (function == null || function.getBody() == null) {
return super.computeSpecialProperties();
} else {
int props;
List calledFunctions = new ArrayList();
ExpressionTool.gatherCalledFunctions(function.getBody(), calledFunctions);
if (calledFunctions.isEmpty()) {
props = function.getBody().computeSpecialProperties();
} else {
props = super.computeSpecialProperties();
}
if (function.getDeterminism() != UserFunction.Determinism.PROACTIVE) {
props |= StaticProperty.NON_CREATIVE;
}
return props;
}
}
/**
* Copy an expression. This makes a deep copy.
*
* @return the copy of the original expression
* @param rebindings
*/
/*@NotNull*/
public Expression copy(RebindingMap rebindings) {
if (function == null) {
// not bound yet, we have no way to register the new copy with the XSLFunction
throw new UnsupportedOperationException("UserFunctionCall.copy()");
}
UserFunctionCall ufc = new UserFunctionCall();
ufc.setFunction(function);
ufc.setStaticType(staticType);
int numArgs = getArity();
Expression[] a2 = new Expression[numArgs];
for (int i = 0; i < numArgs; i++) {
a2[i] = getArg(i).copy(rebindings);
}
ufc.setArguments(a2);
if (argumentEvaluationModes != null) {
int[] am2 = new int[argumentEvaluationModes.length];
System.arraycopy(argumentEvaluationModes, 0, am2, 0, am2.length);
ufc.argumentEvaluationModes = am2;
}
ExpressionTool.copyLocationInfo(this, ufc);
return ufc;
}
/**
* Determine the cardinality of the result
*/
public int computeCardinality() {
if (staticType == null) {
// the actual type is not known yet, so we return an approximation
return StaticProperty.ALLOWS_ZERO_OR_MORE;
} else {
return staticType.getCardinality();
}
}
/*@NotNull*/
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException {
Expression e = super.typeCheck(visitor, contextInfo);
if (e != this) {
return e;
}
if (function != null) {
if (function.getFunctionName() == null) {
// This is an inline function item; add type-checking for the argument types and the result type
checkFunctionCall(function, visitor);
Expression body = function.getBody();
body = body.typeCheck(visitor, ContextItemStaticInfo.ABSENT);
RoleDiagnostic role = new RoleDiagnostic(RoleDiagnostic.FUNCTION_RESULT, "", 0);
body = TypeChecker.staticTypeCheck(body, function.getResultType(), visitor.getStaticContext().isInBackwardsCompatibleMode(), role, visitor);
function.setBody(body);
}
computeArgumentEvaluationModes();
if (staticType == SequenceType.ANY_SEQUENCE) {
// try to get a better type
staticType = function.getResultType();
}
}
return this;
}
/*@NotNull*/
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException {
Expression e = super.optimize(visitor, contextItemType);
if (e == this && function != null) {
computeArgumentEvaluationModes();
Expression e2 = getConfiguration().obtainOptimizer().tryInlineFunctionCall(
this, visitor, contextItemType);
if (e2 != this) {
return e2.optimize(visitor, contextItemType);
}
return e2;
}
return e;
}
/**
* Reset the static properties of the expression to -1, so that they have to be recomputed
* next time they are used.
*/
@Override
public void resetLocalStaticProperties() {
super.resetLocalStaticProperties();
argumentEvaluationModes = null;
}
/**
* Compute the evaluation mode of each argument
*/
public void computeArgumentEvaluationModes() {
int numArgs = getArity();
argumentEvaluationModes = new int[numArgs];
for (int i = 0; i < numArgs; i++) {
if (function.getParameterDefinitions()[i].isIndexedVariable()) {
argumentEvaluationModes[i] = ExpressionTool.MAKE_INDEXED_VARIABLE;
} else {
Expression arg = getArg(i);
if ((arg.getDependencies() & StaticProperty.DEPENDS_ON_USER_FUNCTIONS) != 0) {
// if the argument contains a call to a user-defined function, then it might be a recursive call.
// It's better to evaluate it now, rather than waiting until we are on a new stack frame, as
// that can blow the stack if done repeatedly. (See test func42)
argumentEvaluationModes[i] = ExpressionTool.eagerEvaluationMode(arg);
} else if (!Cardinality.allowsMany(arg.getCardinality()) && arg.getCost() < 20) {
// the argument is cheap to evaluate and doesn't use much memory...
argumentEvaluationModes[i] = ExpressionTool.eagerEvaluationMode(arg);
} else if (arg instanceof Block && ((Block) arg).isCandidateForSharedAppend()) {
// If the expression is a Block, that is, it is appending a value to a sequence,
// then we have the opportunity to use a shared list underpinning the old value and
// the new. This takes precedence over lazy evaluation (it would be possible to do this
// lazily, but more difficult). We currently do this for any Block that has a variable
// reference as one of its subexpressions. The most common case is that the first argument is a reference
// to an argument of recursive function, where the recursive function returns the result of
// appending to the sequence.
argumentEvaluationModes[i] = ExpressionTool.SHARED_APPEND_EXPRESSION;
} else {
argumentEvaluationModes[i] = ExpressionTool.MAKE_MEMO_CLOSURE;
}
}
}
}
/**
* Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited
* by an expression in a source tree.
*
* The default implementation of this method assumes that an expression does no navigation other than
* the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the
* same context as the containing expression. The method must be overridden for any expression
* where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression,
* and RootExpression (because they perform navigation), and for the doc(), document(), and collection()
* functions because they create a new navigation root. Implementations also exist for PathExpression and
* FilterExpression because they have subexpressions that are evaluated in a different context from the
* calling expression.
*
* @param pathMap the PathMap to which the expression should be added
* @param pathMapNodeSet the PathMapNodeSet to which the paths embodied in this expression should be added
* @return the pathMapNode representing the focus established by this expression, in the case where this
* expression is the first operand of a path expression or filter expression. For an expression that does
* navigation, it represents the end of the arc in the path map that describes the navigation route. For other
* expressions, it is the same as the input pathMapNode.
*/
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) {
return addExternalFunctionCallToPathMap(pathMap, pathMapNodeSet);
}
/**
* Mark tail-recursive calls on stylesheet functions. This marks the function call as tailRecursive if
* if is a call to the containing function, and in this case it also returns "true" to the caller to indicate
* that a tail call was found.
*/
public int markTailFunctionCalls(StructuredQName qName, int arity) {
tailCall = getFunctionName().equals(qName) &&
arity == getArity() ? SELF_TAIL_CALL : FOREIGN_TAIL_CALL;
return tailCall;
}
public int getImplementationMethod() {
if (Cardinality.allowsMany(getCardinality())) {
return ITERATE_METHOD | PROCESS_METHOD;
} else {
return EVALUATE_METHOD;
}
}
/**
* Call the function, returning the value as an item. This method will be used
* only when the cardinality is zero or one. If the function is tail recursive,
* it returns an Object representing the arguments to the next (recursive) call
*/
public Item evaluateItem(XPathContext c) throws XPathException {
return callFunction(c).head();
}
/**
* Call the function, returning an iterator over the results. (But if the function is
* tail recursive, it returns an iterator over the arguments of the recursive call)
*/
/*@NotNull*/
public SequenceIterator iterate(XPathContext c) throws XPathException {
return callFunction(c).iterate();
}
/**
* Evaluate an updating expression, adding the results to a Pending Update List.
* The default implementation of this method, which is used for non-updating expressions,
* throws an UnsupportedOperationException
*
* @param context the XPath dynamic evaluation context
* @param pul the pending update list to which the results should be written
*/
public void evaluatePendingUpdates(XPathContext context, PendingUpdateList pul) throws XPathException {
Sequence[] actualArgs = evaluateArguments(context);
XPathContextMajor c2 = context.newCleanContext();
c2.setOrigin(this);
function.callUpdating(actualArgs, c2, pul);
}
/**
* This is the method that actually does the function call (in pull mode)
*
* @param context the dynamic context
* @return the result of the function
* @throws XPathException if dynamic errors occur
*/
private Sequence callFunction(XPathContext context) throws XPathException {
UserFunction targetFunction;
Sequence[] actualArgs = evaluateArguments(context);
XPathContextMajor c2;
if (isTailCall()) {
requestTailCall(context, actualArgs);
return EmptySequence.getInstance();
}
if (bindingSlot >= 0) {
Component target = getTargetComponent(context);
targetFunction = (UserFunction)target.getCode();
Component targetComponent = (Component)target;
if (targetComponent.getVisibility() == Visibility.ABSENT) {
throw new XPathException("Cannot call a function defined with visibility=absent", "XTDE3052");
}
c2 = targetFunction.makeNewContext(context);
c2.setCurrentComponent(targetComponent);
} else {
targetFunction = function;
actualArgs = evaluateArguments(context);
c2 = targetFunction.makeNewContext(context);
}
try {
return targetFunction.call(c2, actualArgs);
} catch (StackOverflowError err) {
throw new XPathException("Too many nested function calls. May be due to infinite recursion",
SaxonErrorCode.SXLM0001, getLocation());
}
}
private void requestTailCall(XPathContext context, Sequence[] actualArgs) throws XPathException {
if (bindingSlot >= 0) {
TailCallLoop.TailCallComponent info = new TailCallLoop.TailCallComponent();
Component target = getTargetComponent(context);
info.component = target;
info.function = (UserFunction) target.getCode();
((XPathContextMajor) context).requestTailCall(info, actualArgs);
} else {
TailCallLoop.TailCallFunction info = new TailCallLoop.TailCallFunction();
info.function = function;
((XPathContextMajor) context).requestTailCall(info, actualArgs);
}
}
/**
* Process the function call in push mode
*
* @param context the XPath dynamic context
* @throws XPathException
*/
public void process(XPathContext context) throws XPathException {
Sequence[] actualArgs = evaluateArguments(context);
if (isTailCall()) {
requestTailCall(context, actualArgs);
return;
}
if (bindingSlot >= 0) {
Component target = getTargetComponent(context);
UserFunction targetFunction = (UserFunction) target.getCode();
if (target.getVisibility() == Visibility.ABSENT) {
throw new XPathException("Cannot call a function defined with visibility=absent", "XTDE3052");
}
XPathContextMajor c2 = targetFunction.makeNewContext(context);
c2.setCurrentComponent(target);
targetFunction.process(actualArgs, c2);
} else {
XPathContextMajor c2 = function.makeNewContext(context);
function.process(actualArgs, c2);
}
}
private Component getTargetComponent(XPathContext context) {
if (bindingSlot == -1) {
// fallback for non-package code
return function.getDeclaringComponent();
} else {
return context.getTargetComponent(bindingSlot);
}
}
public UserFunction getTargetFunction(XPathContext context) {
return (UserFunction)getTargetComponent(context).getCode();
}
/**
* Process the function call in pull mode
*
* @param context the XPath dynamic context
* @throws XPathException
*/
public EventIterator iterateEvents(XPathContext context) throws XPathException {
Sequence[] actualArgs = evaluateArguments(context);
if (isTailCall()) {
requestTailCall(context, actualArgs);
return EmptyEventIterator.getInstance();
}
Component target = getTargetComponent(context);
UserFunction targetFunction = (UserFunction) target.getCode();
Component targetComponent = (Component) target;
if (targetComponent.getVisibility() == Visibility.ABSENT) {
throw new XPathException("Cannot call a function defined with visibility=absent", "XTDE3052");
}
XPathContextMajor c2 = targetFunction.makeNewContext(context);
c2.setCurrentComponent(targetComponent);
return targetFunction.iterateEvents(actualArgs, c2);
}
public Sequence[] evaluateArguments(XPathContext c) throws XPathException {
int numArgs = getArity();
Sequence[] actualArgs = new Sequence[numArgs];
if (argumentEvaluationModes == null) {
// should have been done at compile time
computeArgumentEvaluationModes();
}
for (int i = 0; i < numArgs; i++) {
int refs = 10; // was function.getParameterDefinitions()[i].getReferenceCount();
actualArgs[i] = ExpressionTool.evaluate(getArg(i), argumentEvaluationModes[i], c, refs);
if (actualArgs[i] == null) {
actualArgs[i] = EmptySequence.getInstance();
}
// // If the argument has come in as a (non-memo) closure but there are multiple references to it,
// // then we materialize it in memory now. This shouldn't really happen but it does (tour.xq)
// if (refs > 1 && actualArgs[i] instanceof Closure) {
// actualArgs[i] = ((Closure) actualArgs[i]).reduce();
// }
}
return actualArgs;
}
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*/
public void export(ExpressionPresenter out) throws XPathException {
out.startElement("ufCall", this);
if (getFunctionName() != null) {
out.emitAttribute("name", getFunctionName().getEQName());
out.emitAttribute("tailCall",
tailCall == NOT_TAIL_CALL ? "false" : tailCall == SELF_TAIL_CALL ? "self" : "foreign");
}
out.emitAttribute("bSlot", "" + getBindingSlot());
if (getArgumentEvaluationModes() != null && getArity() > 0) {
FastStringBuffer fsb = new FastStringBuffer(FastStringBuffer.C64);
int[] e = getArgumentEvaluationModes();
for (int i : e) {
fsb.append(i+" ");
}
out.emitAttribute("eval", Whitespace.trim(fsb));
}
for (Operand o : operands()) {
o.getChildExpression().export(out);
}
if (getFunctionName() == null) {
out.setChildRole("inline");
function.getBody().export(out);
out.endElement();
}
out.endElement();
}
public int getConstructType() {
return LocationKind.FUNCTION_CALL;
}
public Object getProperty(String name) {
if (name.equals("target")) {
return function;
}
return super.getProperty(name);
}
public StructuredQName getObjectName() {
return getFunctionName();
}
}
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