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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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.functions;
import net.sf.saxon.event.Outputter;
import net.sf.saxon.expr.CastExpression;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StaticProperty;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.expr.parser.ContextItemStaticInfo;
import net.sf.saxon.expr.parser.ExpressionVisitor;
import net.sf.saxon.expr.parser.Loc;
import net.sf.saxon.om.GroundedValue;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.str.*;
import net.sf.saxon.trans.UncheckedXPathException;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.BuiltInAtomicType;
import net.sf.saxon.value.Cardinality;
import net.sf.saxon.value.EmptySequence;
import net.sf.saxon.value.StringValue;
/**
* fn:string-join(string* $sequence, string $separator)
*/
public class StringJoin extends FoldingFunction implements PushableFunction {
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 getCardinality(Expression[] arguments) {
if (returnEmptyIfEmpty) {
return StaticProperty.ALLOWS_ZERO_OR_ONE;
} else {
return StaticProperty.EXACTLY_ONE;
}
}
/**
* Determine whether two expressions are equivalent
*/
@Override
public boolean equals(Object o) {
return (o instanceof StringJoin) &&
super.equals(o) &&
returnEmptyIfEmpty == ((StringJoin) o).returnEmptyIfEmpty;
}
@Override
public int hashCode() {
return super.hashCode() | (returnEmptyIfEmpty ? 0x05000000 : 0);
}
/**
* Allow the function to create an optimized call based on the values of the actual arguments
*
* @param visitor the expression visitor
* @param contextInfo information about the context item
* @param arguments the supplied arguments to the function call
* @return either a function call on this function, or an expression that delivers
* the same result, or null indicating that no optimization has taken place
* @throws net.sf.saxon.trans.XPathException if an error is detected
*/
@Override
public Expression makeOptimizedFunctionCall(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo, Expression... arguments) throws XPathException {
Expression e2 = super.makeOptimizedFunctionCall(visitor, contextInfo, arguments);
if (e2 != null) {
return e2;
}
int card = arguments[0].getCardinality();
if (!Cardinality.allowsMany(card)) {
if (Cardinality.allowsZero(card) || arguments[0].getItemType().getPrimitiveItemType() != BuiltInAtomicType.STRING) {
if (returnEmptyIfEmpty) {
return new CastExpression(arguments[0], BuiltInAtomicType.STRING, true);
} else {
return SystemFunction.makeCall("string", getRetainedStaticContext(), arguments[0]);
}
} else {
return arguments[0];
}
}
return null;
}
@Override
public Fold getFold(XPathContext context, Sequence... additionalArguments) throws XPathException {
UnicodeString separator = EmptyUnicodeString.getInstance();
if (additionalArguments.length > 0) {
separator = ((GroundedValue) additionalArguments[0].head()).getUnicodeStringValue();
}
return new StringJoinFold(separator, returnEmptyIfEmpty);
}
@Override
public void process(Outputter destination, XPathContext context, Sequence[] arguments) throws XPathException {
UnicodeString separator = arguments.length > 1 ? ((GroundedValue) arguments[1].head()).getUnicodeStringValue() : EmptyUnicodeString.getInstance();
UniStringConsumer output = destination.getStringReceiver(false, Loc.NONE);
output.open();
boolean first = true;
SequenceIterator iter = arguments[0].iterate();
Item it;
try {
while ((it = iter.next()) != null) {
if (first) {
first = false;
} else {
output.accept(separator);
}
output.accept(it.getUnicodeStringValue());
}
} catch (UncheckedXPathException e) {
throw e.getXPathException();
}
output.close();
}
private static class StringJoinFold implements Fold {
private int position = 0;
private final UnicodeString separator;
private final UnicodeBuilder data;
private final boolean returnEmptyIfEmpty;
public StringJoinFold(UnicodeString separator, boolean returnEmptyIfEmpty) {
this.separator = separator;
this.data = new UnicodeBuilder();
this.returnEmptyIfEmpty = returnEmptyIfEmpty;
}
/**
* Process one item in the input sequence, returning a new copy of the working data
*
* @param item the item to be processed from the input sequence
*/
@Override
public void processItem(Item item) {
if (position == 0) {
data.append(item.getUnicodeStringValue());
position = 1;
} else {
data.accept(separator).accept(item.getUnicodeStringValue());
}
}
/**
* Ask whether the computation has completed. A function that can deliver its final
* result without reading the whole input should return true; this will be followed
* by a call on result() to deliver the final result.
*/
@Override
public boolean isFinished() {
return false;
}
/**
* Compute the final result of the function, when all the input has been processed
* @return the result of the function
*/
@Override
public Sequence result() {
if (position == 0 && returnEmptyIfEmpty) {
return EmptySequence.getInstance();
} else {
return new StringValue(data.toUnicodeString());
}
}
}
@Override
public String getCompilerName() {
return "StringJoinCompiler";
}
}