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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.instruct;
import net.sf.saxon.Controller;
import net.sf.saxon.event.Outputter;
import net.sf.saxon.expr.*;
import net.sf.saxon.expr.accum.Accumulator;
import net.sf.saxon.expr.elab.Elaborator;
import net.sf.saxon.expr.elab.PushElaborator;
import net.sf.saxon.expr.elab.PushEvaluator;
import net.sf.saxon.expr.elab.StringEvaluator;
import net.sf.saxon.expr.parser.*;
import net.sf.saxon.functions.DocumentFn;
import net.sf.saxon.lib.ParseOptions;
import net.sf.saxon.lib.Validation;
import net.sf.saxon.om.AllElementsSpaceStrippingRule;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.om.SpaceStrippingRule;
import net.sf.saxon.pattern.NodeKindTest;
import net.sf.saxon.style.StylesheetPackage;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.QuitParsingException;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.trans.XsltController;
import net.sf.saxon.tree.iter.ManualIterator;
import net.sf.saxon.type.SchemaType;
import net.sf.saxon.value.SequenceType;
import java.util.Set;
import java.util.function.Supplier;
/**
* Non-streamable implementation of the xsl:source-document instruction
*/
public class SourceDocument extends Instruction {
protected Operand hrefOp;
protected Operand bodyOp;
protected ParseOptions parseOptions;
protected Set accumulators;
public SourceDocument(Expression hrefExp, Expression body, ParseOptions options) {
hrefOp = new Operand(this, hrefExp, OperandRole.SINGLE_ATOMIC);
bodyOp = new Operand(this, body, new OperandRole(OperandRole.HAS_SPECIAL_FOCUS_RULES, OperandUsage.TRANSMISSION));
this.parseOptions = options;
this.accumulators = options.getApplicableAccumulators();
}
/**
* Set the whitespace stripping rule to be used. (This method is used when
* reloading the instruction from a SEF file)
* @param rule the whitespace stripping rule
*/
public void setSpaceStrippingRule(SpaceStrippingRule rule) {
parseOptions = parseOptions.withSpaceStrippingRule(rule);
}
/**
* 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 "xsl:source-document";
}
public String getExportTag() {
return "sourceDoc";
}
public Expression getHref() {
return hrefOp.getChildExpression();
}
public void setHref(Expression href) {
hrefOp.setChildExpression(href);
}
public Expression getBody() {
return bodyOp.getChildExpression();
}
public void setBody(Expression body) {
bodyOp.setChildExpression(body);
}
public void setUsedAccumulators(Set used) {
accumulators = used;
}
@Override
public Iterable operands() {
return operandList(hrefOp, bodyOp);
}
/**
* Ask whether common subexpressions found in the operands of this expression can
* be extracted and evaluated outside the expression itself. The result is irrelevant
* in the case of operands evaluated with a different focus, which will never be
* extracted in this way, even if they have no focus dependency.
*
* @return false for this kind of expression
*/
@Override
public boolean allowExtractingCommonSubexpressions() {
return false;
}
/**
* Perform type checking of an expression and its subexpressions. This is the second phase of
* static optimization.
*/
@Override
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException {
hrefOp.typeCheck(visitor, contextInfo);
Supplier role = () -> new RoleDiagnostic(RoleDiagnostic.INSTRUCTION, "xsl:stream/href", 0);
TypeChecker tc = visitor.getConfiguration().getTypeChecker(false);
hrefOp.setChildExpression(tc.staticTypeCheck(
hrefOp.getChildExpression(), SequenceType.SINGLE_STRING, role, visitor));
ContextItemStaticInfo newType =
getConfiguration().makeContextItemStaticInfo(NodeKindTest.DOCUMENT, false);
newType.setContextPostureStriding();
bodyOp.typeCheck(visitor, newType);
return this;
}
/**
* Perform optimisation of an expression and its subexpressions. This is the third and final
* phase of static optimization.
* 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)
*/
@Override
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException {
ContextItemStaticInfo newType =
getConfiguration().makeContextItemStaticInfo(NodeKindTest.DOCUMENT, false);
newType.setContextPostureStriding();
hrefOp.optimize(visitor, contextItemType);
bodyOp.optimize(visitor, newType);
return this;
}
/**
* Determine whether this instruction creates new nodes.
* This implementation returns a default value of false
*
* @return true if the instruction creates new nodes (or if it can't be proved that it doesn't)
*/
@Override
public boolean mayCreateNewNodes() {
return !getBody().hasSpecialProperty(StaticProperty.NO_NODES_NEWLY_CREATED);
}
/**
* Compute the dependencies of an expression, as the union of the
* dependencies of its subexpressions. (This is overridden for path expressions
* and filter expressions, where the dependencies of a subexpression are not all
* propogated). This method should be called only once, to compute the dependencies;
* after that, getDependencies should be used.
*
* @return the depencies, as a bit-mask
*/
@Override
public int computeDependencies() {
// Focus-dependency in the body is not relevant.
int dependencies = 0;
dependencies |= getHref().getDependencies();
dependencies |= getBody().getDependencies() & ~StaticProperty.DEPENDS_ON_FOCUS;
return dependencies;
}
/**
* Get the static properties of this expression (other than its type). The result is
* bit-signficant. These properties are used for optimizations. In general, if
* property bit is set, it is true, but if it is unset, the value is unknown.
*
* @return a set of flags indicating static properties of this expression
*/
@Override
protected int computeSpecialProperties() {
// Not sure of the general rules here but we'll pick up some special cases which are useful for XQuery streaming
// use cases written using saxon:stream() - where the body is always a call on snapshot()
Expression body = getBody();
if ((body.getSpecialProperties() & StaticProperty.ALL_NODES_NEWLY_CREATED) != 0) {
return StaticProperty.ORDERED_NODESET | StaticProperty.PEER_NODESET;
}
return super.computeSpecialProperties();
}
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*
* @param out the expression presenter used to display the structure
*/
@Override
public void export(ExpressionPresenter out) throws XPathException {
ExpressionPresenter.ExportOptions options = out.getOptions();
out.startElement(getExportTag(), this);
int validation = parseOptions.getSchemaValidationMode();
if (validation != Validation.SKIP && validation != Validation.BY_TYPE) {
out.emitAttribute("validation", validation+"");
}
SchemaType schemaType = parseOptions.getTopLevelType();
if (schemaType != null) {
out.emitAttribute("schemaType", schemaType.getStructuredQName());
}
SpaceStrippingRule xsltStripSpace = getPackageData() instanceof StylesheetPackage
? ((StylesheetPackage) getPackageData()).getSpaceStrippingRule()
: null;
String flags = "";
if (parseOptions.getSpaceStrippingRule() == xsltStripSpace) {
flags += "s";
} else if (parseOptions.getSpaceStrippingRule() == AllElementsSpaceStrippingRule.getInstance()) {
flags += "S";
}
if (parseOptions.isLineNumbering()) {
flags += "l";
}
if (parseOptions.isExpandAttributeDefaults()) {
flags += "a";
}
if (parseOptions.getDTDValidationMode() == Validation.STRICT) {
flags += "d";
}
if (parseOptions.isXIncludeAware()) {
flags += "i";
}
out.emitAttribute("flags", flags);
if (accumulators != null && !accumulators.isEmpty()) {
StringBuilder fsb = new StringBuilder(256);
for (Accumulator acc : accumulators) {
if (fsb.length() != 0) {
fsb.append(" ");
}
fsb.append(acc.getAccumulatorName().getEQName());
}
out.emitAttribute("accum", fsb.toString());
}
out.setChildRole("href");
getHref().export(out);
out.setChildRole("body");
getBody().export(out);
out.endElement();
}
/**
* 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) {
SourceDocument exp = new SourceDocument(getHref().copy(rebindings), getBody().copy(rebindings), parseOptions);
exp.setRetainedStaticContext(getRetainedStaticContext());
ExpressionTool.copyLocationInfo(this, exp);
return exp;
}
/**
* Evaluate the instruction in push mode
* @param output the destination for the result
* @param context the evaluation context
* @throws XPathException in the event of a failure
* @throws QuitParsingException if there was an early exit, that is, if the instruction was evaluated
* without reading the input to completion
*/
public void push(Outputter output, XPathContext context) throws XPathException {
String href = hrefOp.getChildExpression().evaluateAsString(context).toString();
NodeInfo doc = DocumentFn.makeDoc(href, getStaticBaseURIString(), getPackageData(),
parseOptions, context, getLocation(), false);
if (doc != null) {
Controller controller = context.getController();
if (accumulators != null && controller instanceof XsltController) {
((XsltController) controller).getAccumulatorManager().setApplicableAccumulators(
doc.getTreeInfo(), accumulators);
}
XPathContext c2 = context.newMinorContext();
c2.setCurrentIterator(new ManualIterator(doc));
bodyOp.getChildExpression().process(output, c2);
}
}
@Override
public Elaborator getElaborator() {
return new SourceDocumentElaborator();
}
private static class SourceDocumentElaborator extends PushElaborator {
@Override
public PushEvaluator elaborateForPush() {
SourceDocument expr = (SourceDocument) getExpression();
StringEvaluator hrefEval = expr.getHref().makeElaborator().elaborateForString(false);
PushEvaluator bodyPush = expr.getBody().makeElaborator().elaborateForPush();
return (output, context) -> {
String href = hrefEval.eval(context);
NodeInfo doc = DocumentFn.makeDoc(href, expr.getStaticBaseURIString(), expr.getPackageData(),
expr.parseOptions, context, expr.getLocation(), false);
if (doc != null) {
Controller controller = context.getController();
if (expr.accumulators != null && controller instanceof XsltController) {
((XsltController) controller).getAccumulatorManager().setApplicableAccumulators(
doc.getTreeInfo(), expr.accumulators);
}
XPathContext c2 = context.newMinorContext();
c2.setCurrentIterator(new ManualIterator(doc));
return bodyPush.processLeavingTail(output, c2);
} else {
return null;
}
};
}
}
}