content: /*
   * 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.
   */
  
  package org.apache.asterix.lang.sqlpp.clause;
  
  import java.util.Objects;
  
  import org.apache.asterix.common.exceptions.CompilationException;
  import org.apache.asterix.lang.common.base.AbstractClause;
  import org.apache.asterix.lang.common.base.Expression;
  import org.apache.asterix.lang.common.visitor.base.ILangVisitor;
  import org.apache.asterix.lang.sqlpp.visitor.base.ISqlppVisitor;
  
  public class Projection extends AbstractClause {
  
      public enum Kind {
          NAMED_EXPR, // expr AS name
          STAR, // *
          VAR_STAR, // variable.*
          EVERY_VAR_STAR // *.* (currently only used in SQL-compatible mode)
      }
  
      private Kind kind;
      private Expression expr;
      private String name;
  
      public Projection(Kind kind, Expression expr, String name) {
          validateKind(kind, expr, name);
          this.kind = kind;
          this.expr = expr;
          this.name = name;
      }
  
      private static void validateKind(Kind kind, Expression expr, String name) {
          switch (kind) {
              case NAMED_EXPR:
                  if (expr == null) {
                      throw new NullPointerException();
                  }
                  break;
              case STAR:
              case EVERY_VAR_STAR:
                  if (expr != null || name != null) {
                      throw new IllegalArgumentException();
                  }
                  break;
              case VAR_STAR:
                  if (expr == null) {
                      throw new NullPointerException();
                  }
                  if (name != null) {
                      throw new IllegalArgumentException();
                  }
                  break;
              default:
                  throw new IllegalArgumentException();
          }
      }
  
      @Deprecated
      public Projection(Expression expr, String name, boolean star, boolean varStar) {
          this(asKind(star, varStar), expr, name);
      }
  
      @Deprecated
      private static Kind asKind(boolean star, boolean varStar) {
          return star ? Kind.STAR : varStar ? Kind.VAR_STAR : Kind.NAMED_EXPR;
      }
  
      @Override
      public <R, T> R accept(ILangVisitor<R, T> visitor, T arg) throws CompilationException {
          return ((ISqlppVisitor<R, T>) visitor).visit(this, arg);
      }
  
      @Override
      public ClauseType getClauseType() {
          return ClauseType.PROJECTION;
      }
  
      public Expression getExpression() {
          return expr;
      }
  
      public void setExpression(Expression expr) {
          this.expr = expr;
      }
  
      public boolean hasExpression() {
          return expr != null;
      }
  
      public String getName() {
          return name;
      }
  
      public void setName(String name) {
          this.name = name;
      }
  
      public boolean hasName() {
          return name != null;
      }
  
      public Kind getKind() {
          return kind;
      }
  
      public void setKind(Kind kind) {
          this.kind = kind;
      }
  
      @Deprecated
      public boolean star() {
          return kind == Kind.STAR;
      }
  
      @Deprecated
      public boolean varStar() {
          return kind == Kind.VAR_STAR;
      }
  
      @Override
      public String toString() {
          switch (kind) {
              case NAMED_EXPR:
                  return expr + (hasName() ? " as " + getName() : "");
              case STAR:
                  return "*";
              case VAR_STAR:
                  return expr + ".*";
              case EVERY_VAR_STAR:
                  return "*.*";
              default:
                  throw new IllegalStateException();
          }
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(kind, expr, name);
      }
  
      @Override
      public boolean equals(Object object) {
          if (this == object) {
              return true;
          }
          if (!(object instanceof Projection)) {
              return false;
          }
          Projection target = (Projection) object;
          return kind == target.kind && Objects.equals(expr, target.expr) && Objects.equals(name, target.name);
      }
  }
  