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   *  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
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   *
   *    https://www.apache.org/licenses/LICENSE-2.0
   *
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  package org.apache.cayenne.exp.parser;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.Objects;
  
  import org.apache.cayenne.CayenneRuntimeException;
  import org.apache.cayenne.exp.Expression;
  import org.apache.cayenne.util.Util;
  
  /**
   * Scalar node that represents constant enumeration value.
   * It resolves actual value at a late stage to be parsable in environment where
   * final Enum class is not known, i.e. in Modeler.
   *
   * @since 4.1
   */
  public class ASTEnum extends ASTScalar {
  
      ASTEnum(int id) {
          super(id);
      }
  
      public ASTEnum() {
          super(ExpressionParserTreeConstants.JJTENUM);
      }
  
      public ASTEnum(Object value) {
          super(ExpressionParserTreeConstants.JJTENUM);
          setValue(value);
      }
  
      @Override
      protected Object evaluateNode(Object o) {
          return getValueAsEnum().resolve();
      }
  
      @Override
      public Expression shallowCopy() {
          ASTScalar copy = new ASTEnum(id);
          copy.value = value;
          return copy;
      }
  
      @Override
      public void appendAsEJBQL(List<Object> parameterAccumulator, Appendable out, String rootId) throws IOException {
          Object scalar = getValueAsEnum().resolve();
          SimpleNode.encodeScalarAsEJBQL(parameterAccumulator, out, scalar);
      }
  
      @Override
      public Object getValue() {
          return getValueAsEnum().resolve();
      }
  
      public void setEnumValue(String enumPath) throws ParseException{
          if (enumPath == null) {
              throw new ParseException("Null 'enumPath'");
          }
  
          int dot = enumPath.lastIndexOf('.');
          if (dot <= 0 || dot == enumPath.length() - 1) {
              throw new ParseException("Invalid enum path: " + enumPath);
          }
  
          String className = enumPath.substring(0, dot);
          String enumName = enumPath.substring(dot + 1);
  
          setValue(new ASTEnum.EnumValue(className, enumName));
      }
  
      EnumValue getValueAsEnum() {
          return (EnumValue)value;
      }
  
      static final class EnumValue {
          String className;
          String enumName;
  
          EnumValue(String className, String enumName) {
              this.className = Objects.requireNonNull(className);
              this.enumName = Objects.requireNonNull(enumName);
          }
  
          Enum<?> resolve() {
              Class enumClass;
              try {
                  enumClass = Util.getJavaClass(className);
              } catch (ClassNotFoundException e) {
                  throw new CayenneRuntimeException("Enum class not found: " + className);
              }
              if (!enumClass.isEnum()) {
                  throw new CayenneRuntimeException("Specified class is not an enum: " + className);
              }
              try {
                  return Enum.valueOf(enumClass, enumName);
              } catch (IllegalArgumentException e) {
                  throw new CayenneRuntimeException("Invalid enum path: " + className + "." + enumName);
              }
          }
  
          @Override
          public boolean equals(Object o) {
              if (this == o) return true;
              if (o == null || EnumValue.class != o.getClass()) return false;
  
              EnumValue enumValue = (EnumValue) o;
              return className.equals(enumValue.className) && enumName.equals(enumValue.enumName);
          }
  
          @Override
          public int hashCode() {
              int result = className.hashCode();
              result = 31 * result + enumName.hashCode();
              return result;
          }
  
          @Override
          public String toString() {
              return "enum:" + className + "." + enumName;
          }
      }
  }
  