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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2013 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.pattern;
import net.sf.saxon.Configuration;
import net.sf.saxon.event.LocationProvider;
import net.sf.saxon.expr.*;
import net.sf.saxon.expr.instruct.Executable;
import net.sf.saxon.expr.instruct.SlotManager;
import net.sf.saxon.expr.parser.ExpressionParser;
import net.sf.saxon.expr.parser.ExpressionVisitor;
import net.sf.saxon.expr.parser.PromotionOffer;
import net.sf.saxon.functions.Current;
import net.sf.saxon.om.*;
import net.sf.saxon.sxpath.SimpleContainer;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.iter.AxisIterator;
import net.sf.saxon.tree.iter.EmptyIterator;
import net.sf.saxon.tree.iter.PrependIterator;
import net.sf.saxon.tree.iter.SingletonIterator;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.type.Type;
import java.io.Serializable;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
/**
* A Pattern represents the result of parsing an XSLT pattern string.
* Patterns are created by calling the static method Pattern.make(string).
* The pattern is used to test a particular node by calling match().
*/
public abstract class Pattern implements PatternFinder, Serializable, Container {
private String originalText;
private Executable executable;
private String systemId; // the module where the pattern occurred
private int lineNumber; // the line number where the pattern occurred
/**
* Static factory method to make a Pattern by parsing a String.
*
* @param pattern The pattern text as a String
* @param env An object defining the compile-time context for the expression
* @param exec The executable containing this pattern
* @return The pattern object
* @throws net.sf.saxon.trans.XPathException
* if the pattern is invalid
*/
public static Pattern make(String pattern, StaticContext env, Executable exec) throws XPathException {
PatternParser parser = (PatternParser)env.getConfiguration().newExpressionParser("PATTERN", false, env.getXPathLanguageLevel());
((ExpressionParser)parser).setLanguage(ExpressionParser.XSLT_PATTERN, env.getXPathLanguageLevel());
SimpleContainer container = new SimpleContainer(exec);
container.setLocation(env.getSystemId(), env.getLineNumber());
((ExpressionParser)parser).setDefaultContainer(container);
Pattern pat = parser.parsePattern(pattern, env);
pat.setSystemId(env.getSystemId());
pat.setLineNumber(env.getLineNumber());
// System.err.println("Simplified [" + pattern + "] to " + pat.getClass() + " default prio = " + pat.getDefaultPriority());
// set the pattern text for use in diagnostics
pat.setOriginalText(pattern);
pat.setExecutable(exec);
ExpressionVisitor visitor = ExpressionVisitor.make(env, exec);
pat = pat.simplify(visitor);
return pat;
}
protected static void replaceCurrent(Expression exp, Binding binding) {
Iterator iter = exp.iterateSubExpressions();
while (iter.hasNext()) {
Expression child = iter.next();
if (child instanceof Current) {
LocalVariableReference ref = new LocalVariableReference(binding);
exp.replaceSubExpression(child, ref);
} else {
replaceCurrent(child, binding);
}
}
}
/**
* Replace any calls on current() by a variable reference bound to the supplied binding
*/
public void bindCurrent(Binding binding) {
// default: no action
}
/**
* Get the executable containing this pattern
*
* @return the executable
*/
public Executable getExecutable() {
return executable;
}
/**
* Set the executable containing this pattern
*
* @param executable the executable
*/
public void setExecutable(Executable executable) {
this.executable = executable;
}
/**
* Get the LocationProvider allowing location identifiers to be resolved.
*/
public LocationProvider getLocationProvider() {
return executable.getLocationMap();
}
/**
* Get the granularity of the container.
*
* @return 0 for a temporary container created during parsing; 1 for a container
* that operates at the level of an XPath expression; 2 for a container at the level
* of a global function or template
*/
public int getContainerGranularity() {
return 1;
}
/**
* Set the original text of the pattern for use in diagnostics
*
* @param text the original text of the pattern
*/
public void setOriginalText(String text) {
originalText = text;
}
/**
* Simplify the pattern by applying any context-independent optimisations.
* Default implementation does nothing.
*
* @param visitor the expression visitor
* @return the optimised Pattern
*/
public Pattern simplify(ExpressionVisitor visitor) throws XPathException {
return this;
}
/**
* Type-check the pattern.
*
* @param visitor the expression visitor
* @param contextItemType the type of the context item at the point where the pattern
* is defined. Set to null if it is known that the context item is undefined.
* @return the optimised Pattern
*/
public Pattern analyze(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException {
return this;
}
/**
* Get the dependencies of the pattern. The only possible dependency for a pattern is
* on local variables. This is analyzed in those patterns where local variables may appear.
*
* @return the dependencies, as a bit-significant mask
*/
public int getDependencies() {
return 0;
}
/**
* Iterate over the subexpressions within this pattern
*
* @return an iterator over the subexpressions. Default implementation returns an empty sequence
*/
/*@NotNull*/
public Iterator iterateSubExpressions() {
List list = Collections.emptyList();
return list.iterator();
}
/**
* Allocate slots to any variables used within the pattern
*
* @param slotManager the slot manager representing the stack frame for local variables
* @param nextFree the next slot that is free to be allocated
* @return the next slot that is free to be allocated
*/
public int allocateSlots(SlotManager slotManager, int nextFree) {
return nextFree;
}
/**
* Offer promotion for subexpressions within this pattern. The offer will be accepted if the subexpression
* is not dependent on the factors (e.g. the context item) identified in the PromotionOffer.
* By default the offer is not accepted - this is appropriate in the case of simple expressions
* such as constant values and variable references where promotion would give no performance
* advantage. This method is always called at compile time.
*
* Unlike the corresponding method on {@link Expression}, this method does not return anything:
* it can make internal changes to the pattern, but cannot return a different pattern. Only certain
* kinds of promotion are applicable within a pattern: specifically, promotions affecting local
* variable references within the pattern.
*
* @param offer details of the offer, for example the offer to move
* expressions that don't depend on the context to an outer level in
* the containing expression
* @param parent
* @throws net.sf.saxon.trans.XPathException
* if any error is detected
*/
public void promote(PromotionOffer offer, Expression parent) throws XPathException {
// default implementation does nothing
}
/**
* Set the system ID where the pattern occurred
*
* @param systemId the URI of the module containing the pattern
*/
public void setSystemId(String systemId) {
this.systemId = systemId;
}
/**
* Set the line number where the pattern occurred
*
* @param lineNumber the line number of the pattern in the source module
*/
public void setLineNumber(int lineNumber) {
this.lineNumber = lineNumber;
}
/**
* Test whether a pattern is motionless, that is, whether it can be evaluated against a node
* without repositioning the input stream. This is a necessary condition for patterns used
* as the match pattern of a streamed template rule.
*
* @param allowExtensions if false, the result is determined strictly according to the W3C
* "guaranteed streamability rules. If true, Saxon extensions are permitted: that is, constructs
* may be recognized as motionless by Saxon even if they are not recognized as motionless by
* the W3C rules.
* @return true if the pattern is motionless, that is, if it can be evaluated against a streamed
* node without changing the position in the streamed input file
*/
public boolean isMotionless(boolean allowExtensions) {
// default implementation for subclasses
return true;
}
/**
* Determine whether this Pattern matches the given item. This is the main external interface
* for matching patterns: it sets current() to the node being tested
*
* @param item The item to be tested against the Pattern
* @param context The dynamic context. Only relevant if the pattern
* uses variables, or contains calls on functions such as document() or key().
* @return true if the node matches the Pattern, false otherwise
* @throws XPathException if an error occurs while matching the pattern (the caller will usually
* treat this the same as a false result)
*/
public abstract boolean matches(Item item, XPathContext context) throws XPathException;
/**
* Determine whether this pattern matches a given Node within the subtree rooted at a given
* anchor node. This method is used when the pattern is used for streaming.
*
* @param node The NodeInfo representing the Element or other node to be tested against the Pattern
* @param anchor The anchor node, which must match any AnchorPattern subpattern
* @param context The dynamic context. Only relevant if the pattern
* uses variables, or contains calls on functions such as document() or key().
* @return true if the node matches the Pattern, false otherwise
* @throws XPathException if an error occurs while matching the pattern (the caller will usually
* treat this the same as a false result)
*/
public boolean matchesBeneathAnchor(NodeInfo node, NodeInfo anchor, XPathContext context) throws XPathException {
return matches(node, context);
}
/**
* Select nodes in a document using this PatternFinder.
*
* @param doc the document node at the root of a tree
* @param context the dynamic evaluation context
* @return an iterator over the selected nodes in the document.
*/
public SequenceIterator selectNodes(DocumentInfo doc, final XPathContext context) throws XPathException {
final int kind = getNodeKind();
switch (kind) {
case Type.DOCUMENT:
if (matches(doc, context)) {
return SingletonIterator.makeIterator(doc);
} else {
return EmptyIterator.getInstance();
}
case Type.ATTRIBUTE: {
AxisIterator allElements = doc.iterateAxis(AxisInfo.DESCENDANT, NodeKindTest.ELEMENT);
MappingFunction atts = new MappingFunction() {
public SequenceIterator map(NodeInfo item) {
return item.iterateAxis(AxisInfo.ATTRIBUTE);
}
};
SequenceIterator allAttributes =
new MappingIterator(allElements, atts);
ItemMappingFunction test = new ItemMappingFunction() {
public NodeInfo mapItem(NodeInfo item) throws XPathException {
if ((matches(item, context))) {
return item;
} else {
return null;
}
}
};
return new ItemMappingIterator(allAttributes, test);
}
case Type.ELEMENT:
case Type.COMMENT:
case Type.TEXT:
case Type.PROCESSING_INSTRUCTION: {
AxisIterator allChildren = doc.iterateAxis(AxisInfo.DESCENDANT, NodeKindTest.makeNodeKindTest(kind));
ItemMappingFunction test = new ItemMappingFunction() {
public Item mapItem(Item item) throws XPathException {
if ((matches(item, context))) {
return item;
} else {
return null;
}
}
};
return new ItemMappingIterator(allChildren, test);
}
case Type.NODE: {
AxisIterator allChildren = doc.iterateAxis(AxisInfo.DESCENDANT);
MappingFunction attsOrSelf = new MappingFunction() {
public SequenceIterator map(NodeInfo item) {
return new PrependIterator(item, item.iterateAxis(AxisInfo.ATTRIBUTE));
}
};
SequenceIterator attributesOrSelf =
new MappingIterator(allChildren, attsOrSelf);
ItemMappingFunction test = new ItemMappingFunction() {
public Item mapItem(Item item) throws XPathException {
if ((matches(item, context))) {
return item;
} else {
return null;
}
}
};
return new ItemMappingIterator(attributesOrSelf, test);
}
case Type.NAMESPACE:
throw new UnsupportedOperationException("Patterns can't match namespace nodes");
default:
throw new UnsupportedOperationException("Unknown node kind");
}
}
/**
* Determine the types of nodes to which this pattern applies. Used for optimisation.
* For patterns that match nodes of several types, return Type.NODE. For patterns that
* do not match nodes, return -1.
*
* @return the type of node matched by this pattern. e.g. Type.ELEMENT or Type.TEXT
*/
public int getNodeKind() {
return Type.NODE;
}
/**
* Determine the name fingerprint of nodes to which this pattern applies. Used for
* optimisation.
*
* @return A fingerprint that the nodes must match, or -1 if it can match multiple fingerprints,
* or it if matches atomic values
*/
public int getFingerprint() {
return -1;
}
/**
* Get an ItemType that all the items matching this pattern must satisfy
*
* @return an ItemType, as specific as possible, which all the matching items satisfy
*/
public abstract ItemType getItemType();
/**
* Determine the default priority to use if this pattern appears as a match pattern
* for a template with no explicit priority attribute.
*
* @return the default priority for the pattern
*/
public double getDefaultPriority() {
return 0.5;
}
/**
* Get the system id of the entity in which the pattern occurred
*/
public String getSystemId() {
return systemId;
}
/**
* Get the line number on which the pattern was defined
*/
public int getLineNumber() {
return lineNumber;
}
/**
* Get the column number (always -1)
*/
public int getColumnNumber() {
return -1;
}
/**
* Get the public ID (always null)
*/
public String getPublicId() {
return null;
}
/**
* Get the original pattern text
*/
public String toString() {
if (originalText != null) {
return originalText;
} else {
return "pattern matching " + getItemType().toString();
}
}
/**
* Get the host language (XSLT, XQuery, XPath) used to implement the code in this container
*
* @return typically {@link net.sf.saxon.Configuration#XSLT} or {@link net.sf.saxon.Configuration#XQUERY}
*/
public int getHostLanguage() {
return Configuration.XSLT;
}
/**
* Replace a subexpression by a replacement subexpression
*
* @param original the expression to be replaced
* @param replacement the new expression to be inserted in its place
* @return true if the replacement was carried out
*/
public boolean replaceSubExpression(Expression original, Expression replacement) {
throw new IllegalArgumentException("Invalid replacement");
}
}