code: /*
   * 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.
   */
  /*
   * $Id$
   */
  
  package org.apache.xalan.xsltc.compiler;
  
  import org.apache.bcel.generic.ALOAD;
  import org.apache.bcel.generic.ASTORE;
  import org.apache.bcel.generic.ConstantPoolGen;
  import org.apache.bcel.generic.INVOKEINTERFACE;
  import org.apache.bcel.generic.INVOKESPECIAL;
  import org.apache.bcel.generic.InstructionList;
  import org.apache.bcel.generic.LocalVariableGen;
  import org.apache.bcel.generic.NEW;
  import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
  import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
  import org.apache.xalan.xsltc.compiler.util.NodeType;
  import org.apache.xalan.xsltc.compiler.util.Type;
  import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
  import org.apache.xalan.xsltc.compiler.util.Util;
  
  /**
   * @author G. Todd Miller 
   */
  final class FilteredAbsoluteLocationPath extends Expression {
      private Expression _path;	// may be null 
  
      public FilteredAbsoluteLocationPath() {
  	_path = null;
      }
  
      public FilteredAbsoluteLocationPath(Expression path) {
  	_path = path;
  	if (path != null) {
  	    _path.setParent(this);
  	}
      }
  
      public void setParser(Parser parser) {
  	super.setParser(parser);
  	if (_path != null) {
  	    _path.setParser(parser);
  	}
      }
  
      public Expression getPath() {
  	return(_path);
      }
      
      public String toString() {
  	return "FilteredAbsoluteLocationPath(" +
  	    (_path != null ? _path.toString() : "null") + ')';
      }
  	
      public Type typeCheck(SymbolTable stable) throws TypeCheckError {
  	if (_path != null) {
  	    final Type ptype = _path.typeCheck(stable);
  	    if (ptype instanceof NodeType) {		// promote to node-set
  		_path = new CastExpr(_path, Type.NodeSet);
  	    }
  	}
  	return _type = Type.NodeSet;	
      }
  	
      public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  	if (_path != null) {
  	    final int initDFI = cpg.addMethodref(DUP_FILTERED_ITERATOR,
  						"<init>",
  						"("
  						+ NODE_ITERATOR_SIG
  						+ ")V");
  
              // Backwards branches are prohibited if an uninitialized object is
              // on the stack by section 4.9.4 of the JVM Specification, 2nd Ed.
              // We don't know whether this code might contain backwards branches,
              // so we mustn't create the new object until after we've created
              // the suspect arguments to its constructor.  Instead we calculate
              // the values of the arguments to the constructor first, store them
              // in temporary variables, create the object and reload the
              // arguments from the temporaries to avoid the problem.
  
  	    // Compile relative path iterator(s)
              LocalVariableGen pathTemp =
                 methodGen.addLocalVariable("filtered_absolute_location_path_tmp",
                                            Util.getJCRefType(NODE_ITERATOR_SIG),
                                            null, null);
  	    _path.translate(classGen, methodGen);
              pathTemp.setStart(il.append(new ASTORE(pathTemp.getIndex())));
  
  	    // Create new Dup Filter Iterator
  	    il.append(new NEW(cpg.addClass(DUP_FILTERED_ITERATOR)));
  	    il.append(DUP);
              pathTemp.setEnd(il.append(new ALOAD(pathTemp.getIndex())));
  
  	    // Initialize Dup Filter Iterator with iterator from the stack
  	    il.append(new INVOKESPECIAL(initDFI));
  	}
  	else {
  	    final int git = cpg.addInterfaceMethodref(DOM_INTF,
  						      "getIterator",
  						      "()"+NODE_ITERATOR_SIG);
  	    il.append(methodGen.loadDOM());
  	    il.append(new INVOKEINTERFACE(git, 1));
  	}
      }
  }
  