content: /* Alloy Analyzer 4 -- Copyright (c) 2006-2009, Felix Chang
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files
   * (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify,
   * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
   * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
   * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  package edu.mit.csail.sdg.ast;
  
  import static edu.mit.csail.sdg.ast.Type.EMPTY;
  
  import java.util.Collection;
  
  import edu.mit.csail.sdg.alloy4.Err;
  import edu.mit.csail.sdg.alloy4.ErrorWarning;
  import edu.mit.csail.sdg.alloy4.JoinableList;
  import edu.mit.csail.sdg.alloy4.Pos;
  
  /**
   * Immutable; represents a custom node.
   * <p>
   * <b>Invariant:</b> this.type==EMPTY && this.errors.size()==1
   */
  
  public abstract class ExprCustom extends Expr {
  
      /** {@inheritDoc} */
      @Override
      public Pos span() {
          return pos;
      }
  
      /**
       * Constructs an ExprCustom object.
       *
       * @param pos - the Pos for this expression (can be Pos.UNKNOWN if unknown)
       * @param error - the error to display if this node does not get desugared
       */
      public ExprCustom(Pos pos, Err error) {
          super(pos, null, false, EMPTY, 0, 0, new JoinableList<Err>(error));
          if (error == null)
              throw new NullPointerException();
      }
  
      /** {@inheritDoc} */
      @Override
      public Expr resolve(Type t, Collection<ErrorWarning> warns) {
          return this;
      }
  
      /** {@inheritDoc} */
      @Override
      public <T> T accept(VisitReturn<T> visitor) throws Err {
          throw errors.pick();
      }
  }
  