tobago-extension/tobago-facelets/src/main/java/org/apache/myfaces/tobago/facelets/PositionRule.java

package org.apache.myfaces.tobago.facelets;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

import com.sun.facelets.FaceletContext;
import com.sun.facelets.el.ELAdaptor;
import com.sun.facelets.tag.MetaRule;
import com.sun.facelets.tag.Metadata;
import com.sun.facelets.tag.MetadataTarget;
import com.sun.facelets.tag.TagAttribute;
import org.apache.myfaces.tobago.component.Attributes;
import org.apache.myfaces.tobago.component.Position;
import org.apache.myfaces.tobago.layout.Measure;

import javax.el.ValueExpression;
import javax.faces.component.UIComponent;

public class PositionRule extends MetaRule {
  
  public static final PositionRule INSTANCE = new PositionRule();

  public Metadata applyRule(String name, TagAttribute attribute, MetadataTarget metadataTarget) {
    if (Attributes.LEFT.equals(name)) {
      return new LeftMapper(attribute);
    }
    if (Attributes.TOP.equals(name)) {
      return new TopMapper(attribute);
    }
    return null;
  }

  static final class LeftMapper extends Metadata {
    private final TagAttribute attribute;

    LeftMapper(TagAttribute attribute) {
      this.attribute = attribute;
    }

    public void applyMetadata(FaceletContext ctx, Object instance) {
      if (attribute.isLiteral()) {
        ((Position) instance).setLeft(Measure.parse(attribute.getValue()));
      } else {
        ValueExpression expression = attribute.getValueExpression(ctx, Object.class);
        ELAdaptor.setExpression((UIComponent) instance, Attributes.LEFT, expression);
      }
    }
  }

  static final class TopMapper extends Metadata {
    private final TagAttribute attribute;

    TopMapper(TagAttribute attribute) {
      this.attribute = attribute;
    }

    public void applyMetadata(FaceletContext ctx, Object instance) {
      if (attribute.isLiteral()) {
         ((Position) instance).setTop(Measure.parse(attribute.getValue()));
      } else {
        ValueExpression expression = attribute.getValueExpression(ctx, Object.class);
        ELAdaptor.setExpression((UIComponent) instance, Attributes.TOP, expression);
      }
    }
  }
}