content: package act.view;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 ActFramework
   * %%
   * 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.
   * #L%
   */
  
  import act.util.ActContext;
  import org.osgl.inject.BeanSpec;
  import org.osgl.util.E;
  import org.osgl.util.S;
  
  /**
   * Defines an implicit variable
   */
  public abstract class VarDef {
      private String name;
      private String type;
  
      /**
       * Construct an implicit variable by name and type
       *
       * @param name the name of the variable. Could be referenced in
       *             view template to get the variable
       * @param type the type of the variable. Some view solution e.g.
       *             Rythm needs to explicitly declare the template
       *             arguments. And type information is used by those
       *             static template engines
       */
      protected VarDef(String name, Class<?> type) {
          E.illegalArgumentIf(S.blank(name), "VarDef name cannot be empty");
          this.name = name;
          this.type = type.getCanonicalName().replace('$', '.');
      }
  
      /**
       * Construct an implicit variable by name and {@link BeanSpec bean spec}
       *
       * @param name the name of the variable. Could be referenced in
       *             view template to get the variable
       * @param type the {@link BeanSpec} of the variable. Some view solution e.g.
       *             Rythm needs to explicitly declare the template
       *             arguments. And type information is used by those
       *             static template engines
       */
      protected VarDef(String name, BeanSpec type) {
          E.illegalArgumentIf(S.blank(name), "VarDef name cannot be empty");
          this.name = name;
          this.type = toString(type);
      }
  
      public String name() {
          return name;
      }
  
      public String type() {
          return type;
      }
  
      /**
       * A specific variable implementation shall override this method to
       * evaluate the variable value at runtime
       *
       * @param context The application context
       * @return the variable value
       */
      public abstract Object evaluate(ActContext context);
  
      @Override
      public String toString() {
          return S.fmt("%s|%s", name, type);
      }
  
      @Override
      public int hashCode() {
          return name.hashCode();
      }
  
      @Override
      public boolean equals(Object obj) {
          if (obj == this) {
              return true;
          }
          if (obj instanceof VarDef) {
              VarDef that = (VarDef) obj;
              return that.name.equals(name);
          }
          return false;
      }
  
      private static String toString(BeanSpec spec) {
          if (spec.typeParams().isEmpty()) {
              return spec.rawType().getName();
          } else {
              return spec.type().toString();
          }
      }
  
  
  }
  