Package org.apache.cocoon.woody.transformation

Source Code of org.apache.cocoon.woody.transformation.WidgetReplacingPipe

/*

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package org.apache.cocoon.woody.transformation;

import java.io.IOException;
import java.io.StringReader;
import java.util.Locale;

import org.apache.avalon.excalibur.pool.Recyclable;
import org.apache.cocoon.components.sax.XMLByteStreamCompiler;
import org.apache.cocoon.components.sax.XMLByteStreamInterpreter;
import org.apache.cocoon.woody.Constants;
import org.apache.cocoon.woody.formmodel.Repeater;
import org.apache.cocoon.woody.formmodel.Widget;
import org.apache.cocoon.woody.formmodel.Form;
import org.apache.cocoon.xml.AbstractXMLPipe;
import org.apache.cocoon.i18n.I18nUtils;
import org.apache.commons.jxpath.JXPathException;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;

/**
* The basic operation of this Pipe is that it replaces wi:widget tags (having an id attribute)
* by the XML representation of the corresponding widget instance.
*
* <p>These XML fragments (normally all in the {@link Constants#WI_NS "Woody Instance"} namespace, can
* then be translated to a HTML presentation by an XSL. This XSL will then only have to style
* individual widget, and will not need to do the whole page layout.
*
* <p>For more information about the supported tags and their function, see the user documentation
* for the woody template transformer.</p>
*/
public class WidgetReplacingPipe extends AbstractXMLPipe {
        
    protected static final String FORM_TEMPLATE_EL = "form-template";
    protected static final String STYLING_EL = "styling";
    /** Default key under which the woody form is stored in the JXPath context. */
    public static final String WOODY_FORM = "woody-form";

    protected Widget contextWidget;
    /** Indicates whether we're currently in a widget element. */
    protected boolean inWidgetElement;
    /** Compiler used to record the XML inside wi:widget elements. */
    protected XMLByteStreamCompiler xmlCompiler = new XMLByteStreamCompiler();
    /** Counts the element nesting. */
    protected int elementNestingCounter;
    /**
     * Contains the value of the {@link #elementNestingCounter} on the moment the transformer
     * encountered a wi:widget element. Used to detect the corresponding endElement call
     * for the wi:widget element.
     */
    protected int widgetElementNesting;
    /**
     * If {@link #inWidgetElement} = true, then this contains the widget currenlty being handled.
     */
    protected Widget widget;
    /** Boolean indicating wether the current widget requires special repeater-treatement. */
    protected boolean repeaterWidget;

    protected WoodyTemplateTransformer.InsertStylingContentHandler stylingHandler = new WoodyTemplateTransformer.InsertStylingContentHandler();
    protected WoodyTemplateTransformer pipeContext;

    public void init(Widget contextWidget, WoodyTemplateTransformer pipeContext) {
        this.contextWidget = contextWidget;
        inWidgetElement = false;
        elementNestingCounter = 0;
        this.pipeContext = pipeContext;
    }

    public void startElement(String namespaceURI, String localName, String qName, Attributes attributes)
            throws SAXException {
        elementNestingCounter++;
        if (!inWidgetElement && namespaceURI.equals(Constants.WT_NS)
                && (localName.equals("widget") || localName.equals("repeater-widget"))) {
            checkContextWidgetAvailable(qName);
            inWidgetElement = true;
            widgetElementNesting = elementNestingCounter;
            xmlCompiler.recycle();

            // retrieve widget here, but its XML will only be streamed in the endElement call
            widget = getWidget(attributes);
            repeaterWidget = localName.equals("repeater-widget");
            if (repeaterWidget && !(widget instanceof Repeater))
                throw new SAXException("WoodyTemplateTransformer: the element \"repeater-widget\" can only be used for repeater widgets.");
        } else if (inWidgetElement) {
            xmlCompiler.startElement(namespaceURI, localName, qName, attributes);
        } else if (namespaceURI.equals(Constants.WT_NS)) {
            if (localName.equals("widget-label")) {
                checkContextWidgetAvailable(qName);
                Widget widget = getWidget(attributes);
                widget.generateLabel(contentHandler);
            } else if (localName.equals("repeater-widget-label")) {
                checkContextWidgetAvailable(qName);
                Widget widget = getWidget(attributes);
                if (!(widget instanceof Repeater))
                    throw new SAXException("WoodyTemplateTransformer: the element \"repeater-widget-label\" can only be used for repeater widgets.");
                String widgetId = attributes.getValue("widget-id");
                if (widgetId == null || widgetId.equals(""))
                    throw new SAXException("WoodyTemplateTransformer: the element \"repeater-widget-label\" requires a \"widget-id\" attribute.");
                ((Repeater)widget).generateWidgetLabel(widgetId, contentHandler);
            } else if (localName.equals("repeater-size")) {
                checkContextWidgetAvailable(qName);
                Widget widget = getWidget(attributes);
                if (!(widget instanceof Repeater))
                    throw new SAXException("WoodyTemplateTransformer: the element \"repeater-size\" can only be used for repeater widgets.");
                contentHandler.startPrefixMapping(Constants.WI_PREFIX, Constants.WI_NS);
                ((Repeater)widget).generateSize(contentHandler);
                contentHandler.endPrefixMapping(Constants.WI_PREFIX);
            } else if (localName.equals(FORM_TEMPLATE_EL)) {
                if (contextWidget != null)
                    throw new SAXException("Detected nested wt:form-template elements, this is not allowed.");
                contentHandler.startPrefixMapping(Constants.WI_PREFIX, Constants.WI_NS);

                // ====> Retrieve the form

                // first look for the form using the location attribute, if any
                String formJXPath = attributes.getValue("location");
                if (formJXPath != null) {
                    // remove the location attribute
                    AttributesImpl attrsCopy = new AttributesImpl(attributes);
                    attrsCopy.removeAttribute(attributes.getIndex("location"));
                    attributes = attrsCopy;

                    Object form = pipeContext.getJXPathContext().getValue(formJXPath);
                    if (form == null)
                        throw new SAXException("No form found at location \"" + formJXPath + "\".");
                    if (!(form instanceof Form))
                        throw new SAXException("Object returned by expression \"" + formJXPath + "\" is not a Woody Form.");
                    contextWidget = (Form)form;
                } else if (pipeContext.getAttributeName() != null) { // then see if an attribute-name was specified
                    contextWidget = (Form)pipeContext.getRequest().getAttribute(pipeContext.getAttributeName());
                    if (contextWidget == null)
                        throw new SAXException("No form found in request attribute with name \"" + pipeContext.getAttributeName() + "\"");
                } else { // and then see if we got a form from the flow
                    formJXPath = "/" + WoodyTemplateTransformer.WOODY_FORM;
                    Object form = null;
                    try {
                        form = pipeContext.getJXPathContext().getValue(formJXPath);
                    } catch (JXPathException e) {}
                    if (form != null)
                        contextWidget = (Form)form;
                    else
                        throw new SAXException("No Woody form found.");
                }

                // ====> Determine the Locale

                String localeAttr = attributes.getValue("locale");
                if (localeAttr != null) { // first use value of locale attribute if any
                    localeAttr = translateText(localeAttr);
                    pipeContext.setLocale(I18nUtils.parseLocale(localeAttr));
                } else if (pipeContext.getLocaleParameter() != null) { // then use locale specified as transformer parameter, if any
                    pipeContext.setLocale(pipeContext.getLocaleParameter());
                } else { // use locale specified in bizdata supplied for form
                    String localeJXPath = "/locale";
                    Object locale = null;
                    try {
                        locale = pipeContext.getJXPathContext().getValue(localeJXPath);
                    } catch (JXPathException e) {}
                    if (locale != null)
                        pipeContext.setLocale((Locale)locale);
                    else // final solution: use US locale
                        pipeContext.setLocale(Locale.getDefault());
                }

                String[] namesToTranslate = {"action"};
                Attributes transAtts = translateAttributes(attributes, namesToTranslate);
                contentHandler.startElement(Constants.WI_NS , FORM_TEMPLATE_EL, Constants.WI_PREFIX_COLON + FORM_TEMPLATE_EL, transAtts);
            } else {
                throw new SAXException("Unsupported WoodyTemplateTransformer element: " + localName);
            }
        } else {
            super.startElement(namespaceURI, localName, qName, attributes);
        }
    }

    private void checkContextWidgetAvailable(String widgetElementName) throws SAXException {
        if (contextWidget == null)
            throw new SAXException(widgetElementName + " cannot be used outside a wt:form-template element");
    }

    private Attributes translateAttributes(Attributes attributes, String[] names) {
        AttributesImpl newAtts = new AttributesImpl(attributes);
        if (names!= null) {
            for (int i = 0; i < names.length; i++) {
                String name = names[i];
                int position = newAtts.getIndex(name);
                String newValue = translateText(newAtts.getValue(position));
                newAtts.setValue(position, newValue);               
            }
        }
        return newAtts;
    }

    /**
     * Replaces JXPath expressions embedded inside #{ and } by their value.
     */
    private String translateText(String original) {
        StringBuffer expression;
        StringBuffer translated = new StringBuffer();
        StringReader in = new StringReader(original);
        int chr;
        try {
            while ((chr = in.read()) != -1) {
                char c = (char) chr;
                if (c == '#') {
                    chr = in.read();
                    if (chr != -1) {
                        c = (char) chr;
                        if (c == '{') {
                            expression = new StringBuffer();
                            boolean more = true;
                            while ( more ) {
                                more = false;
                                if ((chr = in.read()) != -1) {
                                    c = (char)chr;
                                    if (c != '}') {
                                        expression.append(c);
                                        more = true;
                                    } else {
                                        translated.append(evaluateExpression(expression.toString()));
                                    }
                                } else {
                                    translated.append('#').append('{').append(expression);
                                }
                            }
                        }
                    } else {
                        translated.append((char) chr);
                    }
                } else {
                    translated.append(c);
                }
            }
        } catch (IOException ignored) {
            ignored.printStackTrace();
        }

        return translated.toString();
    }

    private String evaluateExpression(String expression) {
        return pipeContext.getJXPathContext().getValue(expression).toString();
    }

    protected Widget getWidget(Attributes attributes) throws SAXException {
        String widgetId = attributes.getValue("id");
        if (widgetId == null || widgetId.equals(""))
            throw new SAXException("WoodyTemplateTransformer: missing id attribute on a woody element.");
        Widget widget = contextWidget.getWidget(widgetId);
        if (widget == null)
            throw new SAXException("WoodyTemplateTransformer: widget with id \"" + widgetId + "\" does not exist in the container " + contextWidget.getFullyQualifiedId());
        return widget;
    }

    public void endElement(String namespaceURI, String localName, String qName)
            throws SAXException {
        if (inWidgetElement && elementNestingCounter == widgetElementNesting &&
                namespaceURI.equals(Constants.WT_NS)
                && (localName.equals("widget") || localName.equals("repeater-widget"))) {

            if (repeaterWidget) {
                Repeater repeater = (Repeater)widget;
                WidgetReplacingPipe rowPipe = new WidgetReplacingPipe();
                XMLByteStreamInterpreter interpreter = new XMLByteStreamInterpreter();
                int rowCount = repeater.getSize();
                Object saxFragment = xmlCompiler.getSAXFragment();
                for (int i = 0; i < rowCount; i++) {
                    Repeater.RepeaterRow row = repeater.getRow(i);
                    rowPipe.init(row, pipeContext);
                    rowPipe.setContentHandler(contentHandler);
                    rowPipe.setLexicalHandler(lexicalHandler);
                    interpreter.setConsumer(rowPipe);
                    interpreter.deserialize(saxFragment);
                    interpreter.recycle();
                    rowPipe.recycle();
                }
            } else {
                stylingHandler.recycle();
                stylingHandler.setSaxFragment(xmlCompiler.getSAXFragment());
                stylingHandler.setContentHandler(contentHandler);
                stylingHandler.setLexicalHandler(lexicalHandler);
                contentHandler.startPrefixMapping(Constants.WI_PREFIX, Constants.WI_NS);
                widget.generateSaxFragment(stylingHandler, pipeContext.getLocale());
                contentHandler.endPrefixMapping(Constants.WI_PREFIX);
            }

            inWidgetElement = false;
            widget = null;
        } else if (inWidgetElement) {
            xmlCompiler.endElement(namespaceURI, localName, qName);
        } else if (namespaceURI.equals(Constants.WT_NS) &&
                (localName.equals("widget-label") || localName.equals("repeater-widget-label")
                || localName.equals("repeater-size"))) {
            // do nothing
        } else if (namespaceURI.equals(Constants.WT_NS) && localName.equals(FORM_TEMPLATE_EL)) {
            contextWidget = null;
            contentHandler.endElement(Constants.WI_NS, FORM_TEMPLATE_EL, Constants.WI_PREFIX_COLON + FORM_TEMPLATE_EL);
            contentHandler.endPrefixMapping(Constants.WI_PREFIX);
        } else {
            super.endElement(namespaceURI, localName, qName);
        }
        elementNestingCounter--;
    }

    public void startPrefixMapping(String prefix, String uri)
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.startPrefixMapping(prefix, uri);
        else
            super.startPrefixMapping(prefix, uri);
    }

    public void endPrefixMapping(String prefix)
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.endPrefixMapping(prefix);
        else
            super.endPrefixMapping(prefix);
    }

    public void characters(char c[], int start, int len)
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.characters(c, start, len);
        else
            super.characters(c, start, len);
    }

    public void ignorableWhitespace(char c[], int start, int len)
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.ignorableWhitespace(c, start, len);
        else
            super.ignorableWhitespace(c, start, len);
    }

    public void processingInstruction(String target, String data)
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.processingInstruction(target, data);
        else
            super.processingInstruction(target, data);
    }

    public void skippedEntity(String name)
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.skippedEntity(name);
        else
            super.skippedEntity(name);
    }

    public void startEntity(String name)
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.startEntity(name);
        else
            super.startEntity(name);
    }

    public void endEntity(String name)
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.endEntity(name);
        else
            super.endEntity(name);
    }

    public void startCDATA()
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.startCDATA();
        else
            super.startCDATA();
    }

    public void endCDATA()
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.endCDATA();
        else
            super.endCDATA();
    }

    public void comment(char ch[], int start, int len)
            throws SAXException {
        if (inWidgetElement)
            xmlCompiler.comment(ch, start, len);
        else
            super.comment(ch, start, len);
    }

    /**
     * This ContentHandler helps in inserting SAX events before the closing tag of the root
     * element.
     */
    public class InsertStylingContentHandler extends AbstractXMLPipe implements Recyclable {
        private int elementNesting = 0;
        private XMLByteStreamInterpreter interpreter = new XMLByteStreamInterpreter();
        private Object saxFragment;

        public void setSaxFragment(Object saxFragment) {
            this.saxFragment = saxFragment;
        }

        public void recycle() {
            super.recycle();
            elementNesting = 0;
            interpreter.recycle();
            saxFragment = null;
        }

        public void startElement(String uri, String loc, String raw, Attributes a)
                throws SAXException {
            elementNesting++;
            super.startElement(uri, loc, raw, a);
        }

        public void endElement(String uri, String loc, String raw)
                throws SAXException {
            elementNesting--;
            if (elementNesting == 0 && saxFragment != null) {
                interpreter.setContentHandler(contentHandler);
                interpreter.setLexicalHandler(lexicalHandler);
                contentHandler.startElement(Constants.WI_NS, STYLING_EL, Constants.WI_PREFIX_COLON + STYLING_EL, Constants.EMPTY_ATTRS);
                interpreter.deserialize(saxFragment);
                contentHandler.endElement(Constants.WI_NS, STYLING_EL, Constants.WI_PREFIX_COLON + STYLING_EL);
            }
            super.endElement(uri, loc, raw);
        }
    }

    public void recycle() {
        super.recycle();
        this.contextWidget = null;
        this.widget = null;
    }

}
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