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An XProc 1.0 processor
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/*
 * SplitSequence.java
 *
 * Copyright 2008 Mark Logic Corporation.
 * Portions Copyright 2007 Sun Microsystems, Inc.
 * All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common
 * Development and Distribution License("CDDL") (collectively, the
 * "License"). You may not use this file except in compliance with the
 * License. You can obtain a copy of the License at
 * https://xproc.dev.java.net/public/CDDL+GPL.html or
 * docs/CDDL+GPL.txt in the distribution. See the License for the
 * specific language governing permissions and limitations under the
 * License. When distributing the software, include this License Header
 * Notice in each file and include the License file at docs/CDDL+GPL.txt.
 */

package com.xmlcalabash.library;

import com.xmlcalabash.core.XMLCalabash;
import com.xmlcalabash.core.XProcException;
import com.xmlcalabash.core.XProcRuntime;
import com.xmlcalabash.io.ReadablePipe;
import com.xmlcalabash.io.WritablePipe;
import com.xmlcalabash.model.RuntimeValue;
import net.sf.saxon.s9api.QName;
import net.sf.saxon.s9api.SaxonApiException;
import net.sf.saxon.s9api.XdmNode;
import net.sf.saxon.s9api.XPathCompiler;
import net.sf.saxon.s9api.XPathExecutable;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.sxpath.XPathExpression;
import net.sf.saxon.sxpath.XPathDynamicContext;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.value.BooleanValue;

import com.xmlcalabash.runtime.XAtomicStep;
import com.xmlcalabash.util.DocumentSequenceIterator;

/**
 *
 * @author ndw
 */

@XMLCalabash(
        name = "p:split-sequence",
        type = "{http://www.w3.org/ns/xproc}split-sequence")

public class SplitSequence extends DefaultStep {
    private static final QName _test = new QName("", "test");
    private static final QName _initial_only = new QName("", "initial-only");
    private ReadablePipe source = null;
    private WritablePipe matched = null;
    private WritablePipe notMatched = null;
    private boolean initialOnly = false;

    /* Creates a new instance of SplitSequence */
    public SplitSequence(XProcRuntime runtime, XAtomicStep step) {
        super(runtime,step);
    }

    public void setInput(String port, ReadablePipe pipe) {
        source = pipe;
    }

    public void setOutput(String port, WritablePipe pipe) {
        if ("matched".equals(port)) {
            matched = pipe;
        } else {
            notMatched = pipe;
        }
    }

    public void reset() {
        source.resetReader();
        matched.resetWriter();
        notMatched.resetWriter();
    }

    public void run() throws SaxonApiException {
        super.run();

        RuntimeValue test = getOption(_test);
        initialOnly = getOption(_initial_only, false);
        boolean stillOk = true;

        int count = 0;
        while (source.moreDocuments()) {
            count++;
            source.read();
        }
        source.resetReader();

        DocumentSequenceIterator xsi = new DocumentSequenceIterator(); // See below
        xsi.setLast(count);

        XPathCompiler xcomp = runtime.getProcessor().newXPathCompiler();
        xcomp.setBaseURI(step.getNode().getBaseURI());

        for (String prefix : test.getNamespaceBindings().keySet()) {
            xcomp.declareNamespace(prefix, test.getNamespaceBindings().get(prefix));
        }

        XPathExecutable xexec = xcomp.compile(test.getString());

        // From Michael Kay: http://markmail.org/message/vkb2vaq2miylgndu
        //
        // Underneath the s9api XPathExecutable is a net.sf.saxon.sxpath.XPathExpression.

        XPathExpression xexpr = xexec.getUnderlyingExpression();

        int pos = 0;
        while (source.moreDocuments()) {
            XdmNode doc = source.read();
            pos++;

            Item item = null;

            try {
                // Call createDynamicContext() on this to get an XPathDynamicContext object;

                XPathDynamicContext xdc = xexpr.createDynamicContext(doc.getUnderlyingNode());

                // call getXPathContextObject() on that to get the underlying XPathContext.

                XPathContext xc = xdc.getXPathContextObject();

                // Then call XPathContext.setCurrentIterator()
                // to supply a SequenceIterator whose current() and position() methods return
                // the context item and position respectively. If there's any risk that the
                // expression will call the last() method, then it's simplest to make your
                // iterator's getProperties() return LAST_POSITION_FINDER, and implement the
                // LastPositionFinder interface, in which case last() will be implemented by
                // calling the iterator's getLastPosition() method. (Otherwise last() is
                // implemented by calling getAnother() to clone the iterator and calling next()
                // on the clone until the end of the sequence is reached).

                xsi.setPosition(pos);
                xsi.setItem(doc.getUnderlyingNode());
                xc.setCurrentIterator(xsi);

                // Then evaluate the expression by calling iterate() on the
                // net.sf.saxon.sxpath.XPathExpression object.

                SequenceIterator results = xexpr.iterate(xdc);
                // FIXME: What if the expression returns a sequence?
                item = results.next();
            } catch (XPathException xe) {
                throw new XProcException(xe);
            }

            //
            //  Good luck!
            //

            // FIXME: Compute effective boolean value in a more robust way
            boolean pass = false;
            if (item instanceof BooleanValue) {
                pass = ((BooleanValue) item).getBooleanValue();
            } else {
                pass = (item != null);
            }

            stillOk = stillOk && pass;

            if (pass && (!initialOnly || stillOk)) {
                matched.write(doc);
            } else {
                notMatched.write(doc);
            }
        }
    }
}