net.sf.saxon.functions.CodepointsToString Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of saxon9 Show documentation
Provides a basic XSLT 2.0 and XQuery 1.0 processor (W3C Recommendations, January 2007). Command line interfaces and implementations of several Java APIs (DOM, XPath, s9api) are also included.
The newest version!
package net.sf.saxon.functions;
import net.sf.saxon.charcode.UTF16;
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(256);
        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(UTF16.highSurrogate((int)next));
                sb.append(UTF16.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.
//