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 Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   */
  final class AbsoluteLocationPath extends Expression {
      private Expression _path;	// may be null 
  
      public AbsoluteLocationPath() {
  	_path = null;
      }
  
      public AbsoluteLocationPath(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 "AbsoluteLocationPath(" +
  	    (_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 initAI = cpg.addMethodref(ABSOLUTE_ITERATOR,
  						"<init>",
  						"("
  						+ NODE_ITERATOR_SIG
  						+ ")V");
  
  	    // Compile relative path iterator(s)
              //
              // 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
              // this argument to its constructor.  Instead we calculate the
              // value of the argument to the constructor first, store it in
              // a temporary variable, create the object and reload the argument
              // from the temporary to avoid the problem.
  	    _path.translate(classGen, methodGen);
              LocalVariableGen relPathIterator
                      = methodGen.addLocalVariable("abs_location_path_tmp",
                                         Util.getJCRefType(NODE_ITERATOR_SIG),
                                         null, null);
              relPathIterator.setStart(
                      il.append(new ASTORE(relPathIterator.getIndex())));
  
  	    // Create new AbsoluteIterator
  	    il.append(new NEW(cpg.addClass(ABSOLUTE_ITERATOR)));
  	    il.append(DUP);
              relPathIterator.setEnd(
                      il.append(new ALOAD(relPathIterator.getIndex())));
  
  	    // Initialize AbsoluteIterator with iterator from the stack
  	    il.append(new INVOKESPECIAL(initAI));
  	}
  	else {
  	    final int gitr = cpg.addInterfaceMethodref(DOM_INTF,
  						       "getIterator",
  						       "()"+NODE_ITERATOR_SIG);
  	    il.append(methodGen.loadDOM());
  	    il.append(new INVOKEINTERFACE(gitr, 1));
  	}
      }
  }
  