com.google.gwt.uibinder.elementparsers.HtmlInterpreter.java Source code

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Here is the source code for com.google.gwt.uibinder.elementparsers.HtmlInterpreter.java

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/*
 * Copyright 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.uibinder.elementparsers;

import com.google.gwt.core.ext.UnableToCompleteException;
import com.google.gwt.safehtml.shared.SafeHtml;
import com.google.gwt.uibinder.rebind.UiBinderWriter;
import com.google.gwt.uibinder.rebind.XMLElement;
import com.google.gwt.uibinder.rebind.XMLElement.Interpreter;

/**
 * This is the most generally useful interpreter, and the most likely to be used
 * by a custom parser when calling {@link XMLElement#consumeInnerHtml}.
 * <ul>
 * <li>Assigns computed values to element attributes (e.g.
 * class="{style.pretty}")
 * <li>Generates fields to hold named dom elements (e.g. &lt;div
 * gwt:field="importantDiv"&gt;)
 * <li>Turns &lt;ui:msg&gt; and &lt;ui:attr&gt; elements into methods on a
 * generated Messages interface
 * <li>Fails if any element encountered is a widget
 * </ul>
 */
public class HtmlInterpreter implements XMLElement.Interpreter<String> {
    /**
     * A convenience factory method for the most common use of this class, to work
     * with HTML that will eventually be rendered under a
     * {@link com.google.gwt.user.client.ui.UIObject} (or really, any object that
     * responds to <code>getElement()</code>). Uses an instance of
     * {@link HtmlMessageInterpreter} to process message elements.
     *
     * @param uiExpression An expression that can be evaluated at runtime to find
     *          an object whose getElement() method can be called to get an
     *          ancestor of all Elements generated from the interpreted HTML.
     */
    public static HtmlInterpreter newInterpreterForUiObject(UiBinderWriter writer, String uiExpression) {
        String ancestorExpression = writer.useLazyWidgetBuilders() ? uiExpression : uiExpression + ".getElement()";
        return new HtmlInterpreter(writer, ancestorExpression,
                new HtmlMessageInterpreter(writer, ancestorExpression));
    }

    private final UiBinderWriter writer;
    private final InterpreterPipe<String> pipe;

    /**
     * Rather than using this constructor, you probably want to use the
     * {@link #newInterpreterForUiObject} factory method.
     *
     * @param ancestorExpression An expression that can be evaluated at runtime to
     *          find an Element that will be an ancestor of all Elements generated
     *          from the interpreted HTML.
     * @param messageInterpreter an interpreter to handle msg and ph elements,
     *          typically an instance of {@link HtmlMessageInterpreter}. This
     *          interpreter gets last crack
     */
    public HtmlInterpreter(UiBinderWriter writer, String ancestorExpression,
            Interpreter<String> messageInterpreter) {
        this.writer = writer;
        this.pipe = new InterpreterPipe<String>();

        pipe.add(new FieldInterpreter(writer, ancestorExpression));
        /* UiTextInterpreter and UiSafeHtmlInterpreter must be invoked before
         * ComputedAttributeInterpreter to function properly
         */
        pipe.add(new UiTextInterpreter(writer));
        pipe.add(new UiSafeHtmlInterpreter(writer));
        pipe.add(new ComputedAttributeInterpreter(writer));
        pipe.add(new AttributeMessageInterpreter(writer));
        pipe.add(messageInterpreter);
    }

    public String interpretElement(XMLElement elem) throws UnableToCompleteException {
        if (writer.useLazyWidgetBuilders() && writer.isElementAssignableTo(elem, SafeHtml.class)) {
            String childFieldName = writer.parseElementToField(elem);
            return writer.tokenForSafeHtmlExpression(childFieldName);
        }
        if (writer.isImportedElement(elem)) {
            writer.die(elem, "Not allowed in an HTML context");
        }
        return pipe.interpretElement(elem);
    }
}