package net.sf.saxon.instruct;
import net.sf.saxon.Configuration;
import net.sf.saxon.event.SequenceOutputter;
import net.sf.saxon.event.SequenceReceiver;
import net.sf.saxon.expr.*;
import net.sf.saxon.functions.StringFn;
import net.sf.saxon.om.*;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.BuiltInAtomicType;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.type.TypeHierarchy;
import net.sf.saxon.value.Cardinality;
import java.util.Iterator;
import java.util.Stack;
/**
* Common superclass for XSLT instructions whose content template produces a text
* value: xsl:attribute, xsl:comment, xsl:processing-instruction, xsl:namespace,
* and xsl:text, and their XQuery equivalents
*/
public abstract class SimpleNodeConstructor extends Instruction implements DivisibleInstruction {
protected Expression select = null;
/**
* Default constructor used by subclasses
*/
public SimpleNodeConstructor() {
}
/**
* Set the select expression: the value of this expression determines the string-value of the node
* @param select the expression that computes the string value of the node
* @param config the Saxon configuration (used for example to do early validation of the content
* of an attribute against the schema-defined type)
* @throws XPathException
*/
public void setSelect(Expression select, Configuration config) throws XPathException {
this.select = select;
adoptChildExpression(select);
}
/**
* Get the expression that determines the string value of the constructed node
* @return the select expression
*/
public Expression getSelect() {
return select;
}
/**
* Determine whether this instruction creates new nodes.
* This implementation returns true.
*/
public final boolean createsNewNodes() {
return true;
}
/**
* Get the cardinality of the sequence returned by evaluating this instruction
* @return the static cardinality
*/
public int computeCardinality() {
return StaticProperty.EXACTLY_ONE;
}
public Expression simplify(ExpressionVisitor visitor) throws XPathException {
if (select != null) {
select = visitor.simplify(select);
}
return this;
}
/**
* 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
*/
public int computeSpecialProperties() {
return super.computeSpecialProperties() |
StaticProperty.SINGLE_DOCUMENT_NODESET;
}
/**
* Method to perform type-checking specific to the kind of instruction
* @param visitor an expression visitor
* @param contextItemType the static type of the context item
* @throws XPathException
*/
public abstract void localTypeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException;
/**
* The typeCheck() method is called in XQuery, where node constructors
* are implemented as Expressions. In this case the required type for the
* select expression is a single string.
* @param visitor an expression visitor
* @return the rewritten expression
* @throws XPathException if any static errors are found in this expression
* or any of its children
*/
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException {
localTypeCheck(visitor, contextItemType);
if (select != null) {
final TypeHierarchy th = visitor.getConfiguration().getTypeHierarchy();
select = visitor.typeCheck(select, contextItemType);
if (select instanceof ValueOf) {
Expression valSelect = ((ValueOf)select).getSelect();
if (th.isSubType(valSelect.getItemType(th), BuiltInAtomicType.STRING) &&
!Cardinality.allowsMany(valSelect.getCardinality())) {
select = valSelect;
}
}
if (!select.getItemType(th).isAtomicType()) {
Atomizer atomizer = new Atomizer(select);
ExpressionTool.copyLocationInfo(select, atomizer);
select = visitor.simplify(atomizer);
select = visitor.typeCheck(atomizer, contextItemType);
}
ItemType itemType = select.getItemType(th);
if (!(th.isSubType(itemType, BuiltInAtomicType.STRING) ||
th.isSubType(itemType, BuiltInAtomicType.UNTYPED_ATOMIC))) {
select = new AtomicSequenceConverter(select, BuiltInAtomicType.STRING);
}
// Don't bother converting untypedAtomic to string
if (select instanceof StringFn) {
StringFn fn = (StringFn)select;
Expression arg = fn.getArguments()[0];
if (arg.getItemType(th) == BuiltInAtomicType.UNTYPED_ATOMIC && !Cardinality.allowsMany(arg.getCardinality())) {
select = arg;
}
} else if (select instanceof CastExpression && ((CastExpression)select).getTargetType() == BuiltInAtomicType.STRING) {
Expression arg = ((CastExpression)select).getBaseExpression();
if (arg.getItemType(th) == BuiltInAtomicType.UNTYPED_ATOMIC && !Cardinality.allowsMany(arg.getCardinality())) {
select = arg;
}
}
adoptChildExpression(select);
}
return this;
}
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException {
if (select != null) {
select = visitor.optimize(select, contextItemType);
adoptChildExpression(select);
}
return this;
}
public Iterator<Expression> iterateSubExpressions() {
return new MonoIterator(select);
}
/**
* Replace one subexpression by a replacement subexpression
* @param original the original subexpression
* @param replacement the replacement subexpression
* @return true if the original subexpression is found
*/
public boolean replaceSubExpression(Expression original, Expression replacement) {
boolean found = false;
if (select == original) {
select = replacement;
found = true;
}
return found;
}
/**
* Process this instruction
* @param context the dynamic context of the transformation
* @return a TailCall to be executed by the caller, always null for this instruction
*/
public TailCall processLeavingTail(XPathContext context) throws XPathException {
CharSequence value = expandChildren(context);
processValue(value, context);
return null;
}
/**
* In streaming mode, process the first half of the instruction (for example, to start a new document or element)
* @param contextStack
* @param state a stack on which the instruction can save state information during the call on processLeft()
*/
public final void processLeft(Stack<XPathContext> contextStack, Stack state) throws XPathException {
XPathContext context = contextStack.peek();
SequenceReceiver out = context.getReceiver();
state.push(out);
SequenceOutputter out2 = new SequenceOutputter();
out2.setPipelineConfiguration(out.getPipelineConfiguration());
context.setReceiver(out2);
}
/**
* In streaming mode, process the right half of the instruction (for example, to end a new document or element)
* @param contextStack
* @param state a stack on which the instruction can save state information during the call on processLeft()
*/
public final void processRight(Stack<XPathContext> contextStack, Stack state) throws XPathException {
XPathContext context = contextStack.peek();
SequenceOutputter out2 = (SequenceOutputter)context.getReceiver();
SequenceReceiver out = (SequenceReceiver)state.pop();
SequenceIterator iter = out2.iterate();
FastStringBuffer buff = new FastStringBuffer(100);
while (true) {
Item item = iter.next();
if (item == null) {
break;
}
buff.append(item.getStringValueCS());
}
context.setReceiver(out);
processValue(buff, context);
}
/**
* Process the value of the node, to create the new node.
* @param value the string value of the new node
* @param context the dynamic evaluation context
* @throws XPathException
*/
protected abstract void processValue(CharSequence value, XPathContext context) throws XPathException;
/**
* Expand the stylesheet elements subordinate to this one, returning the result
* as a string. The expansion must not generate any element or attribute nodes.
* @param context The dynamic context for the transformation
* @return the value that will be used as the string value of the constructed node
* @throws XPathException if any error occurs
*/
public final CharSequence expandChildren(XPathContext context) throws XPathException {
Item item = select.evaluateItem(context);
if (item==null) {
return "";
} else {
return item.getStringValueCS();
}
}
/**
* Evaluate as an expression. We rely on the fact that when these instructions
* are generated by XQuery, there will always be a valueExpression to evaluate
* the content
*/
public Item evaluateItem(XPathContext context) throws XPathException {
String content = (select==null ?
"" :
select.evaluateAsString(context).toString());
content = checkContent(content, context);
final TypeHierarchy th = context.getConfiguration().getTypeHierarchy();
Orphan o = new Orphan(context.getConfiguration());
o.setNodeKind((short)getItemType(th).getPrimitiveType());
o.setStringValue(content);
o.setNameCode(evaluateNameCode(context));
return o;
}
/**
* Check the content of the node, and adjust it if necessary. The checks depend on the node kind.
* @param data the supplied content
* @param context the dynamic context
* @return the original content, unless adjustments are needed
* @throws XPathException if the content is invalid
*/
protected String checkContent(String data, XPathContext context) throws XPathException {
return data;
}
/**
* Run-time method to compute the name of the node being constructed. This is overridden
* for nodes that have a name. The default implementation returns -1, which is suitable for
* unnamed nodes such as comments
* @param context the XPath dynamic evaluation context
* @return the name pool nameCode identifying the name of the constructed node
* @throws XPathException if any failure occurs
*/
public int evaluateNameCode(XPathContext context) throws XPathException {
return -1;
}
public SequenceIterator iterate(XPathContext context) throws XPathException {
return SingletonIterator.makeIterator(evaluateItem(context));
}
/**
* Offer promotion for subexpressions. 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.
*
* @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
* @exception XPathException if any error is detected
*/
protected void promoteInst(PromotionOffer offer) throws XPathException {
if (select != null) {
select = doPromotion(this, select, offer);
}
super.promoteInst(offer);
}
}
//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
// you may not use this file except in compliance with the License. You may obtain a copy of the
// License at http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//