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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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.expr.instruct;
import net.sf.saxon.event.Outputter;
import net.sf.saxon.expr.*;
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.lib.NamespaceConstant;
import net.sf.saxon.om.StandardNames;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.pattern.NodeKindTest;
import net.sf.saxon.style.StyleElement;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.SymbolicName;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.ItemType;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* This instruction corresponds to a single QName appearing within a use-attribute-sets attribute on a
* literal result element, xsl:element, or xsl:copy instruction. Binding to a specific attribute set
* component is done in the same way as function calls or call-template, allowing attribute sets defined
* in one package to be overridden in another.
*/
public class UseAttributeSet extends Instruction implements ComponentInvocation, ContextOriginator {
private final StructuredQName targetName;
private AttributeSet target;
private final boolean declaredStreamable;
private int bindingSlot = -1;
/**
* Create a use-attribute-set expression
*
* @param name the name of the target attribute set
* @param streamable true if the attribute set is streamable
*/
public UseAttributeSet(StructuredQName name, boolean streamable) {
this.targetName = name;
this.declaredStreamable = streamable;
}
@Override
public boolean isInstruction() {
return false;
}
/**
* Make an expression whose effect is to expand the attribute sets named in an [xsl]use-attribute-sets
* attribute, for example on a literal result element
*
* @param targets the QNames contained in the use-attribute-sets attribute
* @param instruction the instruction on which the use-attribute-sets attribute appears
* @return the required expression
* @throws XPathException if an error occurs, for example no attribute set found with the required name
*/
public static Expression makeUseAttributeSets(StructuredQName[] targets, StyleElement instruction) throws XPathException {
List list = makeUseAttributeSetInstructions(targets, instruction);
return makeCompositeExpression(list);
}
/**
* Make a list of expressions whose combined effect is to expand the attribute sets named in an
* [xsl]use-attribute-sets attribute, for example on a literal result element
*
* @param targets the QNames contained in the use-attribute-sets attribute
* @param instruction the instruction on which the use-attribute-sets attribute appears
* @return the required expression
* @throws XPathException if an error occurs, for example no attribute set found with the required name
*/
public static List makeUseAttributeSetInstructions(StructuredQName[] targets, StyleElement instruction) throws XPathException {
List list = new ArrayList<>(targets.length);
for (StructuredQName name : targets) {
UseAttributeSet use = makeUseAttributeSet(name, instruction);
if (use != null) {
list.add(use);
}
}
return list;
}
/**
* Given a list of UseAttributeSet expressions, combine them into a single expression
*
* @param targets the list of expressions
* @return the combined expression
*/
public static Expression makeCompositeExpression(List targets) {
if (targets.size() == 0) {
return Literal.makeEmptySequence();
} else if (targets.size() == 1) {
return targets.get(0);
} else {
return new Block(targets.toArray(new UseAttributeSet[0]));
}
}
/**
* Make a UseAttributeSet expression corresponding to a single attribute-set name
*
* @param name the name of the attribute-set to be expanded
* @param instruction the containing instruction
* @return a UseAttributeSet expression whose effect is to expand this attribute-set
* @throws XPathException if a dynamic error occurs
*/
private static UseAttributeSet makeUseAttributeSet(StructuredQName name, StyleElement instruction) throws XPathException {
AttributeSet target;
if (name.hasURI(NamespaceConstant.XSLT) && name.getLocalPart().equals("original")) {
target = (AttributeSet) instruction.getXslOriginal(StandardNames.XSL_ATTRIBUTE_SET);
} else {
Component invokee = instruction.getContainingPackage().getComponent(new SymbolicName(StandardNames.XSL_ATTRIBUTE_SET, name));
instruction.getPrincipalStylesheetModule().getAttributeSetDeclarations(name);
if (invokee == null) {
instruction.compileError("Unknown attribute set " + name.getEQName(), "XTSE0710");
return null; // to prevent compile warnings
}
target = (AttributeSet) invokee.getActor();
}
UseAttributeSet invocation = new UseAttributeSet(name, target.isDeclaredStreamable());
invocation.setTarget(target);
invocation.setBindingSlot(-1);
invocation.setRetainedStaticContext(instruction.makeRetainedStaticContext());
return invocation;
}
public boolean isDeclaredStreamable() {
return declaredStreamable;
}
/**
* Set the attribute set to be used.
*
* @param target the attribute set to be used
*/
public void setTarget(AttributeSet target) {
this.target = target;
}
/**
* Set the binding slot to be used. This is the offset within the binding vector of the containing
* component where the actual target component is to be found. The target template is not held directly
* in the invocation instruction/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 component
* can be found.
*/
@Override
public void setBindingSlot(int slot) {
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 component is to be found.
*
* @return the offset in the binding vector of the containing package where the target component
* can be found.
*/
@Override
public int getBindingSlot() {
return bindingSlot;
}
/**
* Get the symbolic name of the component that this invocation references
*
* @return the symbolic name of the target component
*/
@Override
public SymbolicName getSymbolicName() {
return new SymbolicName(StandardNames.XSL_ATTRIBUTE_SET, targetName);
}
/**
* Get the target attribute set to which this instruction is provisionally bound
*
* @return the provisional attribute set (which might be overridden in another package)
*/
public AttributeSet getTargetAttributeSet() {
return target;
}
@Override
public Component getFixedTarget() {
if (target != null && bindingSlot < 0) {
return target.getDeclaringComponent();
}
return null;
}
@Override
public Iterable operands() {
return Collections.emptyList();
}
/**
* Perform optimisation of an expression and its subexpressions.
* This method is called after all references to functions and variables have been resolved
* to the declaration of the function or variable, and after all type checking has been done.
*
* @param visitor an expression visitor
* @param contextItemType the static type of "." at the point where this expression is invoked.
* The parameter is set to null if it is known statically that the context item will be undefined.
* If the type of the context item is not known statically, the argument is set to
* {@link net.sf.saxon.type.Type#ITEM_TYPE}
* @return the original expression, rewritten if appropriate to optimize execution
* @throws XPathException if an error is discovered during this phase
* (typically a type error)
*/
/*@NotNull*/
@Override
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException {
return this;
}
/**
* Copy an expression. This makes a deep copy.
*
* @param rebindings a mutable list of (old binding, new binding) pairs
* that is used to update the bindings held in any
* local variable references that are copied.
* @return the copy of the original expression
*/
/*@NotNull*/
@Override
public Expression copy(RebindingMap rebindings) {
UseAttributeSet ua = new UseAttributeSet(targetName, declaredStreamable);
ua.setTarget(target);
ua.setBindingSlot(bindingSlot);
return ua;
}
/**
* Perform type checking of an expression and its subexpressions.
* This checks statically that the operands of the expression have
* the correct type; if necessary it generates code to do run-time type checking or type
* conversion. A static type error is reported only if execution cannot possibly succeed, that
* is, if a run-time type error is inevitable. The call may return a modified form of the expression.
* This method is called after all references to functions and variables have been resolved
* to the declaration of the function or variable. However, the types of such functions and
* variables may not be accurately known if they have not been explicitly declared.
*
* @param visitor an expression visitor
* @param contextInfo information about the static type of the context item
* @return the original expression, rewritten to perform necessary
* run-time type checks, and to perform other type-related
* optimizations
* @throws XPathException if an error is discovered during this phase
* (typically a type error)
*/
/*@NotNull*/
@Override
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException {
return this;
}
/**
* Get the item type of the items returned by evaluating this instruction
*
* @return the static item type of the instruction
*/
/*@NotNull*/
@Override
public ItemType getItemType() {
return NodeKindTest.ATTRIBUTE;
}
/**
* Determine the intrinsic dependencies of an expression, that is, those which are not derived
* from the dependencies of its subexpressions. For example, position() has an intrinsic dependency
* on the context position, while (position()+1) does not. The default implementation
* of the method returns 0, indicating "no dependencies".
*
* @return a set of bit-significant flags identifying the "intrinsic"
* dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
*/
@Override
public int getIntrinsicDependencies() {
// we have to assume the worst; the target attribute set could be overridden by one that has focus dependencies
return StaticProperty.DEPENDS_ON_XSLT_CONTEXT | StaticProperty.DEPENDS_ON_FOCUS;
}
/**
* Get the target attribute sets of this instruction. Called from generated bytecode.
*
* @return the target attribute sets, as an array
*/
public StructuredQName getTargetAttributeSetName() {
return targetName;
}
/**
* ProcessLeavingTail: called to do the real work of this instruction. This method
* must be implemented in each subclass. The results of the instruction are written
* to the current Receiver, which can be obtained via the Controller.
*
*
* @param output the destination for the result
* @param context The dynamic context of the transformation, giving access to the current node,
* the current variables, etc.
* @return null if the instruction has completed execution; or a TailCall indicating
* a function call or template call that is delegated to the caller, to be made after the stack has
* been unwound so as to save stack space.
*/
/*@Nullable*/
@Override
public TailCall processLeavingTail(Outputter output, XPathContext context) throws XPathException {
Component target;
if (bindingSlot < 0) {
target = getFixedTarget();
} else {
target = context.getTargetComponent(bindingSlot);
if (target.isHiddenAbstractComponent()) {
XPathException err = new XPathException("Cannot expand an abstract attribute set ("
+ targetName.getDisplayName()
+ ") with no implementation", "XTDE3052");
err.setLocation(getLocation());
throw err;
}
}
if (target == null) {
throw new AssertionError("Failed to locate attribute set " + getTargetAttributeSetName().getEQName());
}
AttributeSet as = (AttributeSet) target.getActor();
XPathContextMajor c2 = context.newContext();
c2.setCurrentComponent(target);
c2.setOrigin(this);
SlotManager sm = as.getStackFrameMap();
if (sm == null) {
sm = SlotManager.EMPTY;
}
c2.openStackFrame(sm);
as.expand(output, c2);
return null;
}
/**
* 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 "useAS";
}
/**
* Export of expression structure. The abstract expression tree
* is written to the supplied output destination.
*/
@Override
public void export(ExpressionPresenter out) throws XPathException {
out.startElement("useAS", this);
out.emitAttribute("name", targetName);
out.emitAttribute("bSlot", "" + getBindingSlot());
if (isDeclaredStreamable()) {
out.emitAttribute("flags", "s");
}
out.endElement();
}
/**
* Test whether this UseAttributeSets expression is equal to another
*
* @param obj the other expression
*/
public boolean equals(Object obj) {
if (!(obj instanceof UseAttributeSet)) {
return false;
}
return targetName.equals(((UseAttributeSet) obj).targetName);
}
/**
* Compute a hashcode
*/
@Override
protected int computeHashCode() {
return 0x56423719 ^ targetName.hashCode();
}
/**
* Get the (partial) name of a class that supports streaming of this kind of expression
*
* @return the partial name of a class that can be instantiated to provide streaming support in Saxon-EE,
* or null if there is no such class
*/
@Override
public String getStreamerName() {
return "UseAttributeSet";
}
}