com.xmlcalabash.extensions.fileutils.Head Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of com.xmlcalabash Show documentation
An XProc 1.0 processor
The newest version!
package com.xmlcalabash.extensions.fileutils;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URI;

import com.xmlcalabash.core.XMLCalabash;
import net.sf.saxon.s9api.QName;
import net.sf.saxon.s9api.SaxonApiException;

import com.xmlcalabash.core.XProcConstants;
import com.xmlcalabash.core.XProcException;
import com.xmlcalabash.core.XProcRuntime;
import com.xmlcalabash.io.DataStore;
import com.xmlcalabash.io.DataStore.DataReader;
import com.xmlcalabash.io.WritablePipe;
import com.xmlcalabash.library.DefaultStep;
import com.xmlcalabash.model.RuntimeValue;
import com.xmlcalabash.runtime.XAtomicStep;
import com.xmlcalabash.util.TreeWriter;

/**
 * Created by IntelliJ IDEA.
 * User: ndw
 * Date: May 24, 2009
 * Time: 3:17:23 PM
 * To change this template use File | Settings | File Templates.
 */

@XMLCalabash(
        name = "pxf:head",
        type = "{http://exproc.org/proposed/steps/file}head " +
                "{http://xmlcalabash.com/ns/extensions/fileutils}head")

public class Head extends DefaultStep {
    private static final QName _href = new QName("href");
    private static final QName _count = new QName("count");
    private static final QName _fail_on_error = new QName("fail-on-error");
    private static final QName c_line = new QName("c", XProcConstants.NS_XPROC_STEP, "line");

    private WritablePipe result = null;

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

    public void setOutput(String port, WritablePipe pipe) {
        result = pipe;
    }

    public void reset() {
        result.resetWriter();
    }

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

        if (runtime.getSafeMode()) {
            throw XProcException.dynamicError(21);
        }

        boolean failOnError = getOption(_fail_on_error, true);
        final int maxCount = getOption(_count, 10);
        final int negMaxCount = -maxCount;

        RuntimeValue href = getOption(_href);

        final TreeWriter tree = new TreeWriter(runtime);
        tree.startDocument(step.getNode().getBaseURI());
        tree.addStartElement(XProcConstants.c_result);
        tree.startContent();

        try {
            DataStore store = runtime.getDataStore();
            store.readEntry(href.getString(), href.getBaseURI().toASCIIString(), "text/*, */*", null, new DataReader() {
                public void load(URI id, String media, InputStream content, long len)
                        throws IOException {
                    Reader rdr = new InputStreamReader(content);
                    BufferedReader brdr = new BufferedReader(rdr);
                    try {
                        String line = null;
                        int count = 0;

                        if (maxCount >= 0) {
                            line = brdr.readLine();
                            while (line != null && count < maxCount) {
                                tree.addStartElement(c_line);
                                tree.startContent();
                                tree.addText(line);
                                tree.addEndElement();
                                tree.addText("\n");
                                count++;
                                line = brdr.readLine();
                            }
                        } else {
                            line = "not null";
                            while (line != null && count < negMaxCount) {
                                count++;
                                line = brdr.readLine();
                            }

                            line = brdr.readLine();
                            while (line != null) {
                                tree.addStartElement(c_line);
                                tree.startContent();
                                tree.addText(line);
                                tree.addEndElement();
                                tree.addText("\n");
                                line = brdr.readLine();
                            }
                        }
                    } finally {
                        brdr.close();
                        // BufferedReader.close() also closes the underlying 
                        // reader, so this second call is unnecessary.
                        // rdr.close();
                    }
                }
            });
        } catch (FileNotFoundException fnfe) {
            URI uri = href.getBaseURI().resolve(href.getString());
            throw new XProcException(step, "Cannot read: file does not exist: " + uri.toASCIIString());
        } catch (IOException ioe) {
            throw new XProcException(ioe);
        }

        tree.addEndElement();
        tree.endDocument();

        result.write(tree.getResult());
    }
}