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.InstructionList;
  import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
  import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
  import org.apache.xalan.xsltc.compiler.util.MethodType;
  import org.apache.xalan.xsltc.compiler.util.Type;
  import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   */
  final class UnaryOpExpr extends Expression {
      private Expression _left;
  	
      public UnaryOpExpr(Expression left) {
  	(_left = left).setParent(this);
      }
  
      /**
       * Returns true if this expressions contains a call to position(). This is
       * needed for context changes in node steps containing multiple predicates.
       */
      public boolean hasPositionCall() {
  	return(_left.hasPositionCall());
      }
  
      /**
       * Returns true if this expressions contains a call to last()
       */
      public boolean hasLastCall() {
              return(_left.hasLastCall());
      }
      
      public void setParser(Parser parser) {
  	super.setParser(parser);
  	_left.setParser(parser);
      }
      
      public Type typeCheck(SymbolTable stable) throws TypeCheckError {
  	final Type tleft = _left.typeCheck(stable); 
  	final MethodType ptype = lookupPrimop(stable, "u-",
  					      new MethodType(Type.Void,
  							     tleft)); 
  	
  	if (ptype != null) {
  	    final Type arg1 = (Type) ptype.argsType().elementAt(0);
  	    if (!arg1.identicalTo(tleft)) {
  		_left = new CastExpr(_left, arg1);
  	    }
  	    return _type = ptype.resultType();
  	}
  
  	throw new TypeCheckError(this);
      }
  
      public String toString() {
  	return "u-" + '(' + _left + ')';
      }
  
      public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
  	InstructionList il = methodGen.getInstructionList();
  	_left.translate(classGen, methodGen);
  	il.append(_type.NEG());
      }
  }
  
  