code: /*
   * The contents of this file are subject to the terms
   * of the Common Development and Distribution License
   * (the "License").  You may not use this file except
   * in compliance with the License.
   * 
   * You can obtain a copy of the license at
   * https://jwsdp.dev.java.net/CDDLv1.0.html
   * See the License for the specific language governing
   * permissions and limitations under the License.
   * 
   * When distributing Covered Code, include this CDDL
   * HEADER in each file and include the License file at
   * https://jwsdp.dev.java.net/CDDLv1.0.html  If applicable,
   * add the following below this CDDL HEADER, with the
   * fields enclosed by brackets "[]" replaced with your
   * own identifying information: Portions Copyright [yyyy]
   * [name of copyright owner]
   */
  package com.sun.xml.xsom.impl;
  
  import com.sun.xml.xsom.XSComplexType;
  import com.sun.xml.xsom.XSType;
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Set;
  
  /**
   * 
   * 
   * @author
   *     Kohsuke Kawaguchi (kohsuke.kawaguchi@sun.com)
   */
  class Util {
      private static XSType[] listDirectSubstitutables( XSType _this ) {
          ArrayList r = new ArrayList();
          
          // TODO: handle @block
          Iterator itr = ((SchemaImpl)_this.getOwnerSchema()).parent.iterateTypes();
          while( itr.hasNext() ) {
              XSType t = (XSType)itr.next();
              if( t.getBaseType()==_this )
                  r.add(t);
          }
          return (XSType[]) r.toArray(new XSType[r.size()]);
      }
  
      public static XSType[] listSubstitutables( XSType _this ) {
          Set substitables = new HashSet();
          buildSubstitutables( _this, substitables );
          return (XSType[]) substitables.toArray(new XSType[substitables.size()]);
      }
      
      public static void buildSubstitutables( XSType _this, Set substitutables ) {
          if( _this.isLocal() )    return;
          buildSubstitutables( _this, _this, substitutables );
      }
      
      private static void buildSubstitutables( XSType head, XSType _this, Set substitutables ) {
          if(!isSubstitutable(head,_this))
              return;    // no derived type of _this can substitute head.
          
          if(substitutables.add(_this)) {
              XSType[] child = listDirectSubstitutables(_this);
              for( int i=0; i<child.length; i++ )
                  buildSubstitutables( head, child[i], substitutables );
          }
      }
      
      /**
       * Implements
       * <code>Validation Rule: Schema-Validity Assessment (Element) 1.2.1.2.4</code> 
       */
      private static boolean isSubstitutable( XSType _base, XSType derived ) {
          // too ugly to the point that it's almost unbearable.
          // I mean, it's not even transitive. Thus we end up calling this method
          // for each candidate
          if( _base.isComplexType() ) {
              XSComplexType base = _base.asComplexType();
              
              for( ; base!=derived; derived=derived.getBaseType() ) {
                  if( base.isSubstitutionProhibited( derived.getDerivationMethod() ) )
                      return false;    // Type Derivation OK (Complex)-1
              }
              return true;
          } else {
              // simple type don't have any @block
              return true;
          }
      }
  
  }
  