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.util;
  
  import org.apache.bcel.generic.PUSH;
  import org.apache.bcel.generic.ALOAD;
  import org.apache.bcel.generic.ASTORE;
  import org.apache.bcel.generic.ConstantPoolGen;
  import org.apache.bcel.generic.IFEQ;
  import org.apache.bcel.generic.ILOAD;
  import org.apache.bcel.generic.INVOKEINTERFACE;
  import org.apache.bcel.generic.INVOKESTATIC;
  import org.apache.bcel.generic.Instruction;
  import org.apache.bcel.generic.InstructionList;
  
  import org.apache.xalan.xsltc.compiler.Constants;
  import org.apache.xalan.xsltc.compiler.FlowList;
  
  import org.apache.xml.dtm.DTM;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   * @author Erwin Bolwidt <ejb@klomp.org>
   */
  public final class ReferenceType extends Type {
      protected ReferenceType() {}
  
      public String toString() {
  	return "reference";
      }
  
      public boolean identicalTo(Type other) {
  	return this == other;
      }
  
      public String toSignature() {
  	return "Ljava/lang/Object;";
      }
  
      public org.apache.bcel.generic.Type toJCType() {
  	return org.apache.bcel.generic.Type.OBJECT;
      }
  
      /**
       * Translates a reference to an object of internal type <code>type</code>.
       * The translation to int is undefined since references
       * are always converted to reals in arithmetic expressions.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
  			    Type type) {
  	if (type == Type.String) {
  	    translateTo(classGen, methodGen, (StringType) type);
  	}
  	else if (type == Type.Real) {
  	    translateTo(classGen, methodGen, (RealType) type);
  	}
  	else if (type == Type.Boolean) {
  	    translateTo(classGen, methodGen, (BooleanType) type);
  	}
  	else if (type == Type.NodeSet) {
  	    translateTo(classGen, methodGen, (NodeSetType) type);
  	}
  	else if (type == Type.Node) {
  	    translateTo(classGen, methodGen, (NodeType) type);
  	}
  	else if (type == Type.ResultTree) {
  	    translateTo(classGen, methodGen, (ResultTreeType) type);
  	}
  	else if (type == Type.Object) {
  	    translateTo(classGen, methodGen, (ObjectType) type);
  	}
  	else if (type == Type.Reference ) {
          }	
  	else {
  	    ErrorMsg err = new ErrorMsg(ErrorMsg.INTERNAL_ERR, type.toString());
  	    classGen.getParser().reportError(Constants.FATAL, err);
  	}
      }
  
      /**
       * Translates reference into object of internal type <code>type</code>.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
  			    StringType type) {
  	final int current = methodGen.getLocalIndex("current");
  	ConstantPoolGen cpg = classGen.getConstantPool();
  	InstructionList il = methodGen.getInstructionList();
  
  	// If no current, conversion is a top-level
  	if (current < 0) {
  	    il.append(new PUSH(cpg, DTM.ROOT_NODE));  // push root node
  	}
  	else {
  	    il.append(new ILOAD(current));
  	}
  	il.append(methodGen.loadDOM());
  	final int stringF = cpg.addMethodref(BASIS_LIBRARY_CLASS,
  					     "stringF",
  					     "("
  					     + OBJECT_SIG
  					     + NODE_SIG
  					     + DOM_INTF_SIG
  					     + ")" + STRING_SIG);
  	il.append(new INVOKESTATIC(stringF));
      }
  
      /**
       * Translates a reference into an object of internal type <code>type</code>.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
  			    RealType type) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  
  	il.append(methodGen.loadDOM());
  	int index = cpg.addMethodref(BASIS_LIBRARY_CLASS, "numberF",
  				     "("
  				     + OBJECT_SIG
  				     + DOM_INTF_SIG
  				     + ")D");
  	il.append(new INVOKESTATIC(index));
      }
  
      /**
       * Translates a reference to an object of internal type <code>type</code>.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
  			    BooleanType type) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  
  	int index = cpg.addMethodref(BASIS_LIBRARY_CLASS, "booleanF",
  				     "("
  				     + OBJECT_SIG
  				     + ")Z");
  	il.append(new INVOKESTATIC(index));
      }
  
      /**
       * Casts a reference into a NodeIterator.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
  			    NodeSetType type) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  	int index = cpg.addMethodref(BASIS_LIBRARY_CLASS, "referenceToNodeSet",
  				     "("
  				     + OBJECT_SIG
  				     + ")"
  				     + NODE_ITERATOR_SIG);
  	il.append(new INVOKESTATIC(index));
  
  	// Reset this iterator
  	index = cpg.addInterfaceMethodref(NODE_ITERATOR, RESET, RESET_SIG);
  	il.append(new INVOKEINTERFACE(index, 1));
      }
  
      /**
       * Casts a reference into a Node.
       *
       * @see org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
  			    NodeType type) {
  	translateTo(classGen, methodGen, Type.NodeSet);
  	Type.NodeSet.translateTo(classGen, methodGen, type);
      }
  
      /**
       * Casts a reference into a ResultTree.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
  			    ResultTreeType type) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  	int index = cpg.addMethodref(BASIS_LIBRARY_CLASS, "referenceToResultTree",
  				     "(" + OBJECT_SIG + ")" + DOM_INTF_SIG);
  	il.append(new INVOKESTATIC(index));
      }
  
      /**
       * Subsume reference into ObjectType.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
  			    ObjectType type) {
  	methodGen.getInstructionList().append(NOP);
      }
  
      /**
       * Translates a reference into the Java type denoted by <code>clazz</code>.
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
  			    Class clazz) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  
          int referenceToLong = cpg.addMethodref(BASIS_LIBRARY_CLASS, 
                                                 "referenceToLong", 
                                                 "(" + OBJECT_SIG + ")J");
          int referenceToDouble = cpg.addMethodref(BASIS_LIBRARY_CLASS, 
                                                   "referenceToDouble", 
                                                  "(" + OBJECT_SIG + ")D");      
          int referenceToBoolean = cpg.addMethodref(BASIS_LIBRARY_CLASS, 
                                                    "referenceToBoolean", 
                                                   "(" + OBJECT_SIG + ")Z");
          
  	if (clazz.getName().equals("java.lang.Object")) {
  	    il.append(NOP);
  	}
  	else if (clazz == Double.TYPE) {
  	    il.append(new INVOKESTATIC(referenceToDouble));
  	}
  	else if (clazz.getName().equals("java.lang.Double")) {
  	    il.append(new INVOKESTATIC(referenceToDouble));
              Type.Real.translateTo(classGen, methodGen, Type.Reference);
  	}
  	else if (clazz == Float.TYPE) {
  	    il.append(new INVOKESTATIC(referenceToDouble));
              il.append(D2F);
  	}
  	else if (clazz.getName().equals("java.lang.String")) {
  	    int index = cpg.addMethodref(BASIS_LIBRARY_CLASS, "referenceToString",
  				         "("
  				         + OBJECT_SIG
  				         + DOM_INTF_SIG
  				         + ")"
  				         + "Ljava/lang/String;");
  	    il.append(methodGen.loadDOM());
  	    il.append(new INVOKESTATIC(index));
  	}
  	else if (clazz.getName().equals("org.w3c.dom.Node")) {
  	    int index = cpg.addMethodref(BASIS_LIBRARY_CLASS, "referenceToNode",
  				         "("
  				         + OBJECT_SIG
  				         + DOM_INTF_SIG
  				         + ")"
  				         + "Lorg/w3c/dom/Node;");
  	    il.append(methodGen.loadDOM());
  	    il.append(new INVOKESTATIC(index));
  	}
  	else if (clazz.getName().equals("org.w3c.dom.NodeList")) {
  	    int index = cpg.addMethodref(BASIS_LIBRARY_CLASS, "referenceToNodeList",
  				         "("
  				         + OBJECT_SIG
  				         + DOM_INTF_SIG
  				         + ")"
  				         + "Lorg/w3c/dom/NodeList;");
  	    il.append(methodGen.loadDOM());
  	    il.append(new INVOKESTATIC(index));
  	}
  	else if (clazz.getName().equals("org.apache.xalan.xsltc.DOM")) {
  	    translateTo(classGen, methodGen, Type.ResultTree);
  	}
  	else if (clazz == Long.TYPE) {
  	    il.append(new INVOKESTATIC(referenceToLong));
          }
  	else if (clazz == Integer.TYPE) {
  	    il.append(new INVOKESTATIC(referenceToLong));
              il.append(L2I);
  	}
          else if (clazz == Short.TYPE) {
  	    il.append(new INVOKESTATIC(referenceToLong));
              il.append(L2I);
              il.append(I2S);
          }
          else if (clazz == Byte.TYPE) {
  	    il.append(new INVOKESTATIC(referenceToLong));
              il.append(L2I);
              il.append(I2B);
          }
          else if (clazz == Character.TYPE) {
  	    il.append(new INVOKESTATIC(referenceToLong));
              il.append(L2I);
              il.append(I2C);
          }
  	else if (clazz == java.lang.Boolean.TYPE) {
  	    il.append(new INVOKESTATIC(referenceToBoolean));
  	}
  	else if (clazz.getName().equals("java.lang.Boolean")) {
  	    il.append(new INVOKESTATIC(referenceToBoolean));
              Type.Boolean.translateTo(classGen, methodGen, Type.Reference);
  	}
  	else {
  	    ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  					toString(), clazz.getName());
  	    classGen.getParser().reportError(Constants.FATAL, err);
  	}
      }
  
      /**
       * Translates an external Java type into a reference. Only conversion
       * allowed is from java.lang.Object.
       */
      public void translateFrom(ClassGenerator classGen, MethodGenerator methodGen,
  			      Class clazz) {
  	if (clazz.getName().equals("java.lang.Object")) {
  	    methodGen.getInstructionList().append(NOP);
  	}
  	else {
  	    ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  				toString(), clazz.getName());
  	    classGen.getParser().reportError(Constants.FATAL, err);
          }
      }
  
      /**
       * Expects a reference on the stack and translates it to a non-synthesized
       * boolean. It does not push a 0 or a 1 but instead returns branchhandle
       * list to be appended to the false list.
       *
       * @see org.apache.xalan.xsltc.compiler.util.Type#translateToDesynthesized
       */
      public FlowList translateToDesynthesized(ClassGenerator classGen,
  					     MethodGenerator methodGen,
  					     BooleanType type) {
  	InstructionList il = methodGen.getInstructionList();
  	translateTo(classGen, methodGen, type);
  	return new FlowList(il.append(new IFEQ(null)));
      }
  
      /**
       * Translates an object of this type to its boxed representation.
       */
      public void translateBox(ClassGenerator classGen,
  			     MethodGenerator methodGen) {
      }
  
      /**
       * Translates an object of this type to its unboxed representation.
       */
      public void translateUnBox(ClassGenerator classGen,
  			       MethodGenerator methodGen) {
      }
  
  
      public Instruction LOAD(int slot) {
  	return new ALOAD(slot);
      }
  
      public Instruction STORE(int slot) {
  	return new ASTORE(slot);
      }
  }
  
  