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An OSGi bundle for Saxon-HE
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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.functions;
import net.sf.saxon.event.ComplexContentOutputter;
import net.sf.saxon.event.SequenceReceiver;
import net.sf.saxon.expr.Callable;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StaticProperty;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.expr.parser.ExpressionVisitor;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.util.FastStringBuffer;
import net.sf.saxon.value.Cardinality;
import net.sf.saxon.value.EmptySequence;
import net.sf.saxon.value.StringValue;
/**
* xf:string-join(string* $sequence, string $separator)
*/
public class StringJoin extends SystemFunctionCall implements Callable {
private boolean returnEmptyIfEmpty;
/**
* Indicate that when the input sequence (first argument) is empty, the function should return
* an empty sequence rather than an empty string
*
* @param option true if an empty sequence should be returned when the input is an empty sequence.
*/
public void setReturnEmptyIfEmpty(boolean option) {
returnEmptyIfEmpty = option;
}
public boolean isReturnEmptyIfEmpty() {
return returnEmptyIfEmpty;
}
/**
* Determine the cardinality of the function.
*/
@Override
public int computeCardinality() {
if (returnEmptyIfEmpty) {
return StaticProperty.ALLOWS_ZERO_OR_ONE;
} else {
return StaticProperty.EXACTLY_ONE;
}
}
/*@NotNull*/
@Override
public Expression copy() {
StringJoin sj = (StringJoin) super.copy();
sj.returnEmptyIfEmpty = returnEmptyIfEmpty;
return sj;
}
/**
* Determine whether two expressions are equivalent
*/
@Override
public boolean equals(Object o) {
return (o instanceof StringJoin) &&
super.equals(o) &&
returnEmptyIfEmpty == ((StringJoin)o).returnEmptyIfEmpty;
}
public int getImplementationMethod() {
return super.getImplementationMethod() | ITEM_FEED_METHOD;
}
/*@NotNull*/
public Expression optimize(/*@NotNull*/ ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
throws XPathException {
Expression exp = super.optimize(visitor, contextItemType);
if (exp instanceof StringJoin) {
Expression exp2 = ((StringJoin) exp).simplifySingleton();
if (exp != exp2) {
return visitor.optimize(exp2, contextItemType);
}
}
return exp;
}
private Expression simplifySingleton() {
int card = argument[0].getCardinality();
if (!Cardinality.allowsMany(card)) {
if (Cardinality.allowsZero(card)) {
return SystemFunctionCall.makeSystemFunction("string", new Expression[]{argument[0]});
} else {
return argument[0];
}
}
return this;
}
public StringValue evaluateItem(XPathContext c) throws XPathException {
// This rather tortuous code is designed to ensure that we don't evaluate the
// separator argument unless there are at least two items in the sequence.
SequenceIterator iter = argument[0].iterate(c);
Item it = iter.next();
if (it == null) {
return (returnEmptyIfEmpty ? null : StringValue.EMPTY_STRING);
}
CharSequence first = it.getStringValueCS();
it = iter.next();
if (it == null) {
return StringValue.makeStringValue(first);
}
FastStringBuffer sb = new FastStringBuffer(FastStringBuffer.SMALL);
sb.append(first);
// Type checking ensures that the separator is not an empty sequence
if (argument.length == 1) {
sb.append(it.getStringValueCS());
while (true) {
it = iter.next();
if (it == null) {
return StringValue.makeStringValue(sb.condense());
}
sb.append(it.getStringValueCS());
}
} else {
Item sepItem = argument[1].evaluateItem(c);
assert sepItem != null;
CharSequence sep = sepItem.getStringValueCS();
sb.append(sep);
sb.append(it.getStringValueCS());
while (true) {
it = iter.next();
if (it == null) {
return StringValue.makeStringValue(sb.condense());
}
sb.append(sep);
sb.append(it.getStringValueCS());
}
}
}
/**
* Process the instruction in push mode. This avoids constructing the concatenated string
* in memory, instead its parts can be sent straight to the serializer.
*
* @param context The dynamic context, giving access to the current node,
* the current variables, etc.
*/
public void process(XPathContext context) throws XPathException {
// This rather tortuous code is designed to ensure that we don't evaluate the
// separator argument unless there are at least two items in the sequence.
SequenceReceiver out = context.getReceiver();
if (out instanceof ComplexContentOutputter) {
// Optimization is only safe if evaluated as part of a complex content constructor
// Start and end with an empty string to force space separation from any previous or following outputs
out.append(StringValue.EMPTY_STRING, 0, 0);
SequenceIterator iter = argument[0].iterate(context);
Item it = iter.next();
if (it == null) {
return;
}
CharSequence first = it.getStringValueCS();
out.characters(first, 0, 0);
it = iter.next();
if (it == null) {
out.append(StringValue.EMPTY_STRING, 0, 0);
return;
}
// Type checking ensures that the separator is not an empty sequence
if (argument.length == 1) {
out.characters(it.getStringValueCS(), 0, 0);
while (true) {
it = iter.next();
if (it == null) {
break;
}
out.characters(it.getStringValueCS(), 0, 0);
}
} else {
Item sepItem = argument[1].evaluateItem(context);
assert sepItem != null;
CharSequence sep = sepItem.getStringValueCS();
out.characters(sep, 0, 0);
out.characters(it.getStringValueCS(), 0, 0);
while (true) {
it = iter.next();
if (it == null) {
break;
}
out.characters(sep, 0, 0);
out.characters(it.getStringValueCS(), 0, 0);
}
}
out.append(StringValue.EMPTY_STRING, 0, 0);
} else {
out.append(evaluateItem(context), 0, 0);
}
}
/**
* Evaluate the expression
*
* @param context the dynamic evaluation context
* @param arguments the values of the arguments, supplied as Sequences
* @return the result of the evaluation, in the form of a Sequence
* @throws net.sf.saxon.trans.XPathException
* if a dynamic error occurs during the evaluation of the expression
*/
public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException {
SequenceIterator iter = arguments[0].iterate();
Item it = iter.next();
if (it == null) {
return (returnEmptyIfEmpty ? EmptySequence.getInstance() : StringValue.EMPTY_STRING);
}
CharSequence first = it.getStringValueCS();
it = iter.next();
if (it == null) {
return StringValue.makeStringValue(first);
}
FastStringBuffer sb = new FastStringBuffer(FastStringBuffer.SMALL);
sb.append(first);
// Type checking ensures that the separator is not an empty sequence
if (arguments.length == 1) {
sb.append(it.getStringValueCS());
while (true) {
it = iter.next();
if (it == null) {
return StringValue.makeStringValue(sb.condense());
}
sb.append(it.getStringValueCS());
}
} else {
Item sepItem = arguments[1].head();
assert sepItem != null;
CharSequence sep = sepItem.getStringValueCS();
sb.append(sep);
sb.append(it.getStringValueCS());
while (true) {
it = iter.next();
if (it == null) {
return StringValue.makeStringValue(sb.condense());
}
sb.append(sep);
sb.append(it.getStringValueCS());
}
}
}
}