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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.expr.Expression;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.GroundedValue;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.om.SequenceTool;
import net.sf.saxon.trans.UncheckedXPathException;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.Int64Value;
import net.sf.saxon.value.IntegerValue;
/**
* Implementation of the fn:count function
*/
public class Count extends SystemFunction {
/**
* For an expression that returns an integer or a sequence of integers, get
* a lower and upper bound on the values of the integers that may be returned, from
* static analysis. The default implementation returns null, meaning "unknown" or
* "not applicable". Other implementations return an array of two IntegerValue objects,
* representing the lower and upper bounds respectively. The values
* UNBOUNDED_LOWER and UNBOUNDED_UPPER are used by convention to indicate that
* the value may be arbitrarily large. The values MAX_STRING_LENGTH and MAX_SEQUENCE_LENGTH
* are used to indicate values limited by the size of a string or the size of a sequence.
*
* @return the lower and upper bounds of integer values in the result, or null to indicate
* unknown or not applicable.
*/
@Override
public IntegerValue[] getIntegerBounds() {
return new IntegerValue[]{Int64Value.ZERO, Expression.MAX_SEQUENCE_LENGTH};
}
/**
* Get the number of items in a sequence identified by a SequenceIterator
*
* @param iter The SequenceIterator. This method moves the current position
* of the supplied iterator; if this isn't safe, make a copy of the iterator
* first by calling getAnother(). The supplied iterator must be positioned
* before the first item (there must have been no call on next()).
* @return the number of items in the underlying sequence
* @throws net.sf.saxon.trans.XPathException
* if a failure occurs reading the input sequence
*/
public static int count(/*@NotNull*/ SequenceIterator iter) throws XPathException {
if (SequenceTool.supportsGetLength(iter)) {
return SequenceTool.getLength(iter);
} else {
int n = 0;
while (iter.next() != null) {
n++;
}
return n;
}
}
/**
* Get the number of items in a sequence identified by a SequenceIterator
*
* @param iter The SequenceIterator. The supplied iterator must be positioned
* before the first item (there must have been no call on next()). It will
* always be consumed
* @return the number of items in the underlying sequence
* @throws UncheckedXPathException if a failure occurs reading the input sequence
*/
public static int steppingCount(SequenceIterator iter) {
int n = 0;
while (iter.next() != null) {
n++;
}
return n;
}
/**
* 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
*/
@Override
public IntegerValue call(XPathContext context, Sequence[] arguments) throws XPathException {
Sequence arg = arguments[0];
int size = arg instanceof GroundedValue ? ((GroundedValue)arg).getLength() : count(arg.iterate());
return Int64Value.makeIntegerValue(size);
}
@Override
public String getCompilerName() {
return "CountCompiler";
}
@Override
public String getStreamerName() {
return "Count";
}
}