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.INVOKEVIRTUAL;
  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.NodeSetType;
  import org.apache.xalan.xsltc.compiler.util.NodeType;
  import org.apache.xalan.xsltc.compiler.util.ReferenceType;
  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 FilterParentPath extends Expression {
  
      private Expression _filterExpr;
      private Expression _path;
      private boolean _hasDescendantAxis = false;
  
      public FilterParentPath(Expression filterExpr, Expression path) {
  	(_path = path).setParent(this);
  	(_filterExpr = filterExpr).setParent(this);
      }
  		
      public void setParser(Parser parser) {
  	super.setParser(parser);
  	_filterExpr.setParser(parser);
  	_path.setParser(parser);
      }
      
      public String toString() {
  	return "FilterParentPath(" + _filterExpr + ", " + _path + ')';
      }
  
      public void setDescendantAxis() {
  	_hasDescendantAxis = true;
      }
  
      /**
       * Type check a FilterParentPath. If the filter is not a node-set add a 
       * cast to node-set only if it is of reference type. This type coercion is
       * needed for expressions like $x/LINE where $x is a parameter reference.
       */
      public Type typeCheck(SymbolTable stable) throws TypeCheckError {
  	final Type ftype = _filterExpr.typeCheck(stable);
  	if (ftype instanceof NodeSetType == false) {
  	    if (ftype instanceof ReferenceType)  {
  		_filterExpr = new CastExpr(_filterExpr, Type.NodeSet);
  	    }
  	    /*
  	    else if (ftype instanceof ResultTreeType)  {
  		_filterExpr = new CastExpr(_filterExpr, Type.NodeSet);
  	    }
  	    */
  	    else if (ftype instanceof NodeType)  {
  		_filterExpr = new CastExpr(_filterExpr, Type.NodeSet);
  	    }
  	    else {
  		throw new TypeCheckError(this);
  	    }
  	}
  
  	// Wrap single node path in a node set
  	final Type ptype = _path.typeCheck(stable);
  	if (!(ptype instanceof NodeSetType)) {
  	    _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();
  	// Create new StepIterator
  	final int initSI = cpg.addMethodref(STEP_ITERATOR_CLASS,
  					    "<init>",
  					    "("
  					    +NODE_ITERATOR_SIG
  					    +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.
  
  	// Recursively compile 2 iterators
  	_filterExpr.translate(classGen, methodGen);
          LocalVariableGen filterTemp =
                  methodGen.addLocalVariable("filter_parent_path_tmp1",
                                             Util.getJCRefType(NODE_ITERATOR_SIG),
                                             null, null);
          filterTemp.setStart(il.append(new ASTORE(filterTemp.getIndex())));
  
  	_path.translate(classGen, methodGen);
          LocalVariableGen pathTemp =
                  methodGen.addLocalVariable("filter_parent_path_tmp2",
                                             Util.getJCRefType(NODE_ITERATOR_SIG),
                                             null, null);
          pathTemp.setStart(il.append(new ASTORE(pathTemp.getIndex())));
  
  	il.append(new NEW(cpg.addClass(STEP_ITERATOR_CLASS)));
  	il.append(DUP);
          filterTemp.setEnd(il.append(new ALOAD(filterTemp.getIndex())));
          pathTemp.setEnd(il.append(new ALOAD(pathTemp.getIndex())));
  
  	// Initialize StepIterator with iterators from the stack
  	il.append(new INVOKESPECIAL(initSI));
  
  	// This is a special case for the //* path with or without predicates
          if (_hasDescendantAxis) {
  	    final int incl = cpg.addMethodref(NODE_ITERATOR_BASE,
  					      "includeSelf",
  					      "()" + NODE_ITERATOR_SIG);
  	    il.append(new INVOKEVIRTUAL(incl));
  	}
  
          SyntaxTreeNode parent = getParent();
  
          boolean parentAlreadyOrdered = 
              (parent instanceof RelativeLocationPath)
                  || (parent instanceof FilterParentPath)
                  || (parent instanceof KeyCall)
                  || (parent instanceof CurrentCall)
                  || (parent instanceof DocumentCall);
  
  	if (!parentAlreadyOrdered) {
  	    final int order = cpg.addInterfaceMethodref(DOM_INTF,
  							ORDER_ITERATOR,
  							ORDER_ITERATOR_SIG);
  	    il.append(methodGen.loadDOM());
  	    il.append(SWAP);
  	    il.append(methodGen.loadContextNode());
  	    il.append(new INVOKEINTERFACE(order, 3));
  	}
      }
  }
  