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EE4J Compatible Implementation for Jakarta Faces API
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/*
 * Copyright (c) 1997, 2020 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2005-2007 The Apache Software Foundation
 *
 * 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 jakarta.faces.view.facelets;

import jakarta.el.ExpressionFactory;
import jakarta.el.MethodExpression;
import jakarta.el.ValueExpression;
import jakarta.faces.view.Location;

/**
 * 
 * Representation of an XML attribute name=value pair on an XML element in a
 * Facelet file.
 * 
 *
 * @since 2.0
 */
public abstract class TagAttribute {

    /**
     * 
     * If literal,return {@link Boolean#valueOf(java.lang.String) Boolean.valueOf(java.lang.String)} passing our value,
     * otherwise call {@link #getObject(FaceletContext, Class) getObject(FaceletContext, Class)}.
     * 
     *
     * @see Boolean#valueOf(java.lang.String)
     * @see #getObject(FaceletContext, Class)
     * @param ctx FaceletContext to use
     * @return boolean value
     */
    public abstract boolean getBoolean(FaceletContext ctx);

    /**
     * If literal, call {@link Integer#parseInt(java.lang.String) Integer.parseInt(String)}, otherwise call
     * {@link #getObject(FaceletContext, Class) getObject(FaceletContext, Class)}.
     *
     * @see Integer#parseInt(java.lang.String)
     * @see #getObject(FaceletContext, Class)
     * @param ctx FaceletContext to use
     * @return int value
     */
    public abstract int getInt(FaceletContext ctx);

    /**
     * Local name of this attribute
     *
     * @return local name of this attribute
     */
    public abstract String getLocalName();

    /**
     * The location of this attribute in the FaceletContext
     *
     * @return the TagAttribute's location
     */
    public abstract Location getLocation();

    /**
     * Create a MethodExpression, using this attribute's value as the expression String.
     *
     * @see ExpressionFactory#createMethodExpression(jakarta.el.ELContext, java.lang.String, java.lang.Class,
     * java.lang.Class[])
     * @see MethodExpression
     * @param ctx FaceletContext to use
     * @param type expected return type
     * @param paramTypes parameter type
     * @return a MethodExpression instance
     */
    public abstract MethodExpression getMethodExpression(FaceletContext ctx, Class type, Class[] paramTypes);

    /**
     * The resolved Namespace for this attribute
     *
     * @return resolved Namespace
     */
    public abstract String getNamespace();

    /**
     * Delegates to getObject with Object.class as a param
     *
     * @see #getObject(FaceletContext, Class)
     * @param ctx FaceletContext to use
     * @return Object representation of this attribute's value
     */
    public abstract Object getObject(FaceletContext ctx);

    /**
     * The qualified name for this attribute
     *
     * @return the qualified name for this attribute
     */
    public abstract String getQName();

    /**
     * Return the literal value of this attribute
     *
     * @return literal value
     */
    public abstract String getValue();

    /**
     * If literal, then return our value, otherwise delegate to getObject, passing String.class.
     *
     * @see #getObject(FaceletContext, Class)
     * @param ctx FaceletContext to use
     * @return String value of this attribute
     */
    public abstract String getValue(FaceletContext ctx);

    /**
     * If literal, simply coerce our String literal value using an ExpressionFactory, otherwise create a ValueExpression and
     * evaluate it.
     *
     * @see ExpressionFactory#coerceToType(java.lang.Object, java.lang.Class)
     * @see ExpressionFactory#createValueExpression(jakarta.el.ELContext, java.lang.String, java.lang.Class)
     * @see ValueExpression
     * @param ctx FaceletContext to use
     * @param type expected return type
     * @return Object value of this attribute
     */
    public abstract Object getObject(FaceletContext ctx, Class type);

    /**
     * Create a ValueExpression, using this attribute's literal value and the passed expected type.
     *
     * @param ctx FaceletContext to use.
     * @param type expected return type.
     * @return the {@link ValueExpression}.
     * @see ExpressionFactory#createValueExpression(jakarta.el.ELContext, java.lang.String, java.lang.Class)
     * @see ValueExpression
     */
    public abstract ValueExpression getValueExpression(FaceletContext ctx, Class type);

    /**
     * If this TagAttribute is literal (not #{..} or ${..})
     *
     * @return true if this attribute is literal.
     */
    public abstract boolean isLiteral();

    /**
     * 
     * A reference to the Tag for which this class represents the attributes. For compatibility with previous
     * implementations, an implementation is provided that returns {@code null}.
     * 
     *
     * @return the {@link Tag} for which this class represents the attributes.
     * @since 2.2
     */
    public Tag getTag() {
        return null;
    }

    /**
     * 
     * Set a reference to the Tag for which this class represents the attributes. The VDL runtime must ensure that this
     * method is called before any {@link FaceletHandler}s for this element are instantiated. For compatibility with
     * previous implementations, a no-op implementation is provided.
     * 
     *
     * @param tag the tag we represent.
     * @since 2.2
     */
    public void setTag(Tag tag) {

    }
}