package net.sf.saxon.expr;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.SequenceExtent;
import net.sf.saxon.value.Value;
/**
* A NumericPromoter performs numeric promotion on each item in a supplied sequence.
* There are two subclasses, to handle promotion to double and promotion to float
*/
public abstract class NumericPromoter extends UnaryExpression {
public NumericPromoter(Expression exp) {
super(exp);
}
/**
* Simplify an expression
* @param visitor an expression visitor
*/
public Expression simplify(ExpressionVisitor visitor) throws XPathException {
operand = visitor.simplify(operand);
if (operand instanceof Literal) {
if (((Literal)operand).getValue() instanceof AtomicValue) {
return Literal.makeLiteral(
promote(((AtomicValue)((Literal)operand).getValue()), null));
} else {
return Literal.makeLiteral(
((Value)SequenceExtent.makeSequenceExtent(
iterate(visitor.getStaticContext().makeEarlyEvaluationContext()))).reduce());
}
}
return this;
}
/**
* Type-check the expression
*/
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException {
operand = visitor.typeCheck(operand, contextItemType);
return this;
}
/**
* Optimize the expression
*/
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException {
operand = visitor.optimize(operand, contextItemType);
return this;
}
/**
* Iterate over the sequence of values
*/
public SequenceIterator iterate(final XPathContext context) throws XPathException {
SequenceIterator base = operand.iterate(context);
ItemMappingFunction promoter = new ItemMappingFunction() {
public Item map(Item item) throws XPathException {
return promote(((AtomicValue)item), context);
}
};
return new ItemMappingIterator(base, promoter, true);
}
/**
* Evaluate as an Item. This should only be called if the expression has cardinality zero-or-one
*/
public Item evaluateItem(XPathContext context) throws XPathException {
Item item = operand.evaluateItem(context);
if (item==null) return null;
return promote(((AtomicValue)item), context);
}
/**
* Perform the promotion
* @param value the numeric or untyped atomic value to be promoted
* @param context the XPath dynamic evaluation context
* @return the value that results from the promotion
*/
protected abstract AtomicValue promote(AtomicValue value, XPathContext context) throws XPathException;
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*/
public void explain(ExpressionPresenter out) {
out.startElement("promoteNumeric");
out.emitAttribute("to", getItemType(out.getTypeHierarchy()).toString(out.getConfiguration().getNamePool()));
operand.explain(out);
out.endElement();
}
}
//
// 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.
//