package net.sf.saxon.functions;
import net.sf.saxon.charcode.UTF16CharacterSet;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.ExpressionVisitor;
import net.sf.saxon.expr.StringLiteral;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.FastStringBuffer;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.NameChecker;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.NumericValue;
import net.sf.saxon.value.StringValue;
/**
* This class supports the function codepoints-to-string
*/
public class CodepointsToString extends SystemFunction {
/**
* Pre-evaluate a function at compile time. Functions that do not allow
* pre-evaluation, or that need access to context information, can override this method.
* @param visitor an expression visitor
*/
public Expression preEvaluate(ExpressionVisitor visitor) throws XPathException {
final XPathContext context = visitor.getStaticContext().makeEarlyEvaluationContext();
return new StringLiteral(
unicodeToString(argument[0].iterate(context), context));
}
/**
* Evaluate
*/
public Item evaluateItem(XPathContext c) throws XPathException {
return StringValue.makeStringValue(unicodeToString(argument[0].iterate(c), c));
}
/**
* Return the Unicode string corresponding to a given sequence of Unicode code values
* @param chars iterator delivering the characters as integer values
* @param context the evaluation context
* @throws net.sf.saxon.trans.XPathException if any of the integers is not the codepoint of a valid XML character
*/
public static CharSequence unicodeToString(SequenceIterator chars, XPathContext context) throws XPathException {
FastStringBuffer sb = new FastStringBuffer(FastStringBuffer.SMALL);
NameChecker checker = context.getConfiguration().getNameChecker();
while (true) {
NumericValue nextInt = (NumericValue)chars.next();
if (nextInt == null) {
return sb.condense();
}
long next = nextInt.longValue();
if (next < 0 || next > Integer.MAX_VALUE || !checker.isValidChar((int)next)) {
XPathException e = new XPathException("Invalid XML character [x " + Integer.toHexString((int)next) + ']');
e.setErrorCode("FOCH0001");
if (context instanceof XPathContext) {
e.setXPathContext((XPathContext)context);
}
throw e;
}
if (next<65536) {
sb.append((char)next);
} else { // output a surrogate pair
sb.append(UTF16CharacterSet.highSurrogate((int)next));
sb.append(UTF16CharacterSet.lowSurrogate((int)next));
}
}
}
}
//
// 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.
//