com.google.gxp.compiler.parser.ParsedElement.java Source code

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Here is the source code for com.google.gxp.compiler.parser.ParsedElement.java

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/*
 * Copyright (C) 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.gxp.compiler.parser;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.gxp.compiler.alerts.SourcePosition;
import com.google.gxp.compiler.base.AbstractNode;

import java.util.List;

/**
 * Represents an XML element in the parse tree.
 */
public abstract class ParsedElement extends AbstractNode {
    private final ImmutableList<ParsedAttribute> attrs;
    private final ImmutableList<ParsedElement> children;

    protected ParsedElement(SourcePosition sourcePosition, String displayName, List<ParsedAttribute> attrs,
            List<? extends ParsedElement> children) {
        super(sourcePosition, displayName);
        this.attrs = ImmutableList.copyOf(attrs);
        this.children = ImmutableList.copyOf(children);
    }

    public List<ParsedAttribute> getAttributes() {
        return attrs;
    }

    public List<ParsedElement> getChildren() {
        return children;
    }

    /**
     * Indicates if the element is allowed to be the root element of a GXP
     * document.
     */
    public boolean canBeRoot() {
        return false;
    }

    /**
     * Accepts the specified {@code ParsedElementVisitor} and returns the result
     * of the visit.
     */
    public abstract <T> T acceptVisitor(ParsedElementVisitor<T> visitor);

    /**
     * <p>This incomplete implementation checks to see if the chidren are the
     * same as this {@code ParsedElement}'s children, and if so returns this.
     * Otherwise it delegates to the {@code withChildrenImpl} method.
     */
    public final ParsedElement withChildren(List<ParsedElement> newChildren) {
        return ((children == newChildren) || Iterables.elementsEqual(children, newChildren)) ? this
                : withChildrenImpl(newChildren);
    }

    /**
     * Underlying implementation for the slow path of the {@code withChildren}
     * method. Subclasses should override this so that it creates a new {@code
     * ParsedElement} that's identical to themselves except for having the
     * specified children.
     */
    protected abstract ParsedElement withChildrenImpl(List<ParsedElement> children);
}