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.BranchInstruction;
  import org.apache.bcel.generic.Instruction;
  import org.apache.xalan.xsltc.compiler.Constants;
  import org.apache.xalan.xsltc.compiler.FlowList;
  import org.apache.xalan.xsltc.compiler.NodeTest;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   * @author Morten Jorgensen
   */
  public abstract class Type implements Constants {
      public static final Type Int        = new IntType();
      public static final Type Real       = new RealType();
      public static final Type Boolean    = new BooleanType();
      public static final Type NodeSet    = new NodeSetType();
      public static final Type String     = new StringType();
      public static final Type ResultTree = new ResultTreeType();
      public static final Type Reference  = new ReferenceType();
      public static final Type Void       = new VoidType();    
      public static final Type Object     = new ObjectType(java.lang.Object.class);
  
      public static final Type Node       = new NodeType(NodeTest.ANODE);
      public static final Type Root       = new NodeType(NodeTest.ROOT);
      public static final Type Element    = new NodeType(NodeTest.ELEMENT);
      public static final Type Attribute  = new NodeType(NodeTest.ATTRIBUTE);
      public static final Type Text       = new NodeType(NodeTest.TEXT);
      public static final Type Comment    = new NodeType(NodeTest.COMMENT);
      public static final Type Processing_Instruction = new NodeType(NodeTest.PI);
  
      /**
       * Factory method to instantiate object types. Returns a pre-defined
       * instance for "java.lang.Object" and "java.lang.String".
       */
      public static Type newObjectType(String javaClassName) {
          if (javaClassName == "java.lang.Object") {
              return Type.Object;
          }
          else if (javaClassName == "java.lang.String") {
              return Type.String;
          } 
          else {
              return new ObjectType(javaClassName);
          }
      }
      
     /**
       * Factory method to instantiate object types. Returns a pre-defined
       * instance for java.lang.Object.class and java.lang.String.class.
       */
      public static Type newObjectType(Class clazz) {
          if (clazz == java.lang.Object.class) {
              return Type.Object;
          }
          else if (clazz == java.lang.String.class) {
              return Type.String;
          }
          else {
              return new ObjectType(clazz);
          }
      }
      
      /**
       * Returns a string representation of this type.	
       */
      public abstract String toString();
  
      /**
       * Returns true if this and other are identical types.
       */
      public abstract boolean identicalTo(Type other);
  
      /**
       * Returns true if this type is a numeric type. Redefined in NumberType.
       */
      public boolean isNumber() {
  	return false;
      }
  
      /**
       * Returns true if this type has no object representaion. Redefined in
       * ResultTreeType.
       */
      public boolean implementedAsMethod() {
  	return false;
      }
  
      /**
       * Returns true if this type is a simple type. Redefined in NumberType,
       * BooleanType and StringType.
       */
      public boolean isSimple() {
  	return false;
      }
  
      public abstract org.apache.bcel.generic.Type toJCType();
  
      /**
       * Returns the distance between two types. This measure is used to select
       * overloaded functions/operators. This method is typically redefined by
       * the subclasses.
       */
      public int distanceTo(Type type) {
  	return type == this ? 0 : Integer.MAX_VALUE;
      }
  
      /**
       * Returns the signature of an internal type's external representation.
       */
      public abstract String toSignature();
  
      /**
       * Translates an object of this type to an object of type
       * <code>type</code>. 
       * Expects an object of the former type and pushes an object of the latter.
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen, 
  			    Type type) {
  	ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  				    toString(), type.toString());
  	classGen.getParser().reportError(Constants.FATAL, err);
      }
  
      /**
       * Translates object of this type to an object of type <code>type</code>. 
       * Expects an object of the former type and pushes an object of the latter
       * if not boolean. If type <code>type</code> is boolean then a branchhandle
       * list (to be appended to the false list) is returned.
       */
      public FlowList translateToDesynthesized(ClassGenerator classGen, 
  					     MethodGenerator methodGen, 
  					     Type type) {
  	FlowList fl = null;
  	if (type == Type.Boolean) {
  	    fl = translateToDesynthesized(classGen, methodGen,
  					  (BooleanType)type);
  	}
  	else {
  	    translateTo(classGen, methodGen, type);
  	}
  	return fl;
      }
  
      /**
       * Translates an object of this type to an non-synthesized boolean. It
       * does not push a 0 or a 1 but instead returns branchhandle list to be
       * appended to the false list.
       */ 
      public FlowList translateToDesynthesized(ClassGenerator classGen, 
  					     MethodGenerator methodGen, 
  					     BooleanType type) {
  	ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  				    toString(), type.toString());
  	classGen.getParser().reportError(Constants.FATAL, err);
  	return null;
      }
  
      /**
       * Translates an object of this type to the external (Java) type denoted
       * by <code>clazz</code>. This method is used to translate parameters 
       * when external functions are called.
       */ 
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen, 
  			    Class clazz) {
  	ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  				    toString(), clazz.getClass().toString());
  	classGen.getParser().reportError(Constants.FATAL, err);
      }
  
      /**
       * Translates an external (Java) type denoted by <code>clazz</code> to 
       * an object of this type. This method is used to translate return values 
       * when external functions are called.
       */ 
      public void translateFrom(ClassGenerator classGen, MethodGenerator methodGen,
  			      Class clazz) {
  	ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  				    clazz.getClass().toString(), toString());
  	classGen.getParser().reportError(Constants.FATAL, err);
      }
  
      /**
       * Translates an object of this type to its boxed representation.
       */ 
      public void translateBox(ClassGenerator classGen,
  			     MethodGenerator methodGen) {
  	ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  				    toString(), "["+toString()+"]");
  	classGen.getParser().reportError(Constants.FATAL, err);
      }
  
      /**
       * Translates an object of this type to its unboxed representation.
       */ 
      public void translateUnBox(ClassGenerator classGen,
  			       MethodGenerator methodGen) {
  	ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  				    "["+toString()+"]", toString());
  	classGen.getParser().reportError(Constants.FATAL, err);
      }
  
      /**
       * Returns the class name of an internal type's external representation.
       */
      public String getClassName() {
  	return(EMPTYSTRING);
      }
  
      public Instruction ADD() {
  	return null;		// should never be called
      }
  
      public Instruction SUB() {
  	return null;		// should never be called
      }
  
      public Instruction MUL() {
  	return null;		// should never be called
      }
  
      public Instruction DIV() {
  	return null;		// should never be called
      }
  
      public Instruction REM() {
  	return null;		// should never be called
      }
  
      public Instruction NEG() {
  	return null;		// should never be called
      }
  
      public Instruction LOAD(int slot) {
  	return null;		// should never be called
      }
  	
      public Instruction STORE(int slot) {
  	return null;		// should never be called
      }
  
      public Instruction POP() {
  	return POP;
      }
  
      public BranchInstruction GT(boolean tozero) {
  	return null;		// should never be called
      }
  
      public BranchInstruction GE(boolean tozero) {
  	return null;		// should never be called
      }
  
      public BranchInstruction LT(boolean tozero) {
  	return null;		// should never be called
      }
  
      public BranchInstruction LE(boolean tozero) {
  	return null;		// should never be called
      }
  
      public Instruction CMP(boolean less) {
  	return null;		// should never be called
      }
  	
      public Instruction DUP() {
  	return DUP;	// default
      }
  }
  