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.BranchInstruction;
  import org.apache.bcel.generic.ConstantPoolGen;
  import org.apache.bcel.generic.INVOKESTATIC;
  import org.apache.bcel.generic.InstructionList;
  import org.apache.bcel.generic.PUSH;
  import org.apache.xalan.xsltc.compiler.util.BooleanType;
  import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
  import org.apache.xalan.xsltc.compiler.util.ErrorMsg;
  import org.apache.xalan.xsltc.compiler.util.IntType;
  import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
  import org.apache.xalan.xsltc.compiler.util.MethodType;
  import org.apache.xalan.xsltc.compiler.util.NodeSetType;
  import org.apache.xalan.xsltc.compiler.util.NodeType;
  import org.apache.xalan.xsltc.compiler.util.RealType;
  import org.apache.xalan.xsltc.compiler.util.ReferenceType;
  import org.apache.xalan.xsltc.compiler.util.ResultTreeType;
  import org.apache.xalan.xsltc.compiler.util.Type;
  import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
  import org.apache.xalan.xsltc.runtime.Operators;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   */
  final class RelationalExpr extends Expression {
  
      private int _op;
      private Expression _left, _right;
  
      public RelationalExpr(int op, Expression left, Expression right) {
  	_op = op;
  	(_left = left).setParent(this);
  	(_right = right).setParent(this);
      }
  
      public void setParser(Parser parser) {
  	super.setParser(parser);
  	_left.setParser(parser);
  	_right.setParser(parser);
      }
  
      /**
       * 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() {
  	if (_left.hasPositionCall()) return true;
  	if (_right.hasPositionCall()) return true;
  	return false;
      }
  
      /**
       * Returns true if this expressions contains a call to last()
       */
      public boolean hasLastCall() {
              return (_left.hasLastCall() || _right.hasLastCall());
      }
      
      public boolean hasReferenceArgs() {
  	return _left.getType() instanceof ReferenceType ||
  	    _right.getType() instanceof ReferenceType;
      }
  
      public boolean hasNodeArgs() {
  	return _left.getType() instanceof NodeType ||
  	    _right.getType() instanceof NodeType;
      }
  
      public boolean hasNodeSetArgs() {
  	return _left.getType() instanceof NodeSetType ||
  	    _right.getType() instanceof NodeSetType;
      }
  
      public Type typeCheck(SymbolTable stable) throws TypeCheckError {
  	Type tleft = _left.typeCheck(stable); 
  	Type tright = _right.typeCheck(stable);
  
  	//bug fix # 2838, cast to reals if both are result tree fragments
  	if (tleft instanceof ResultTreeType &&
  	    tright instanceof ResultTreeType ) 
    	{
  	    _right = new CastExpr(_right, Type.Real);
  	    _left = new CastExpr(_left, Type.Real);
  	    return _type = Type.Boolean; 
  	}
  
  	// If one is of reference type, then convert the other too
  	if (hasReferenceArgs()) {
  	    Type type = null;
  	    Type typeL = null;
  	    Type typeR = null;
  	    if (tleft instanceof ReferenceType) {
  		if (_left instanceof VariableRefBase) {
  		    VariableRefBase ref = (VariableRefBase)_left;
  		    VariableBase var = ref.getVariable();
  		    typeL = var.getType();
  		}
  	    }
  	    if (tright instanceof ReferenceType) {
  		if (_right instanceof VariableRefBase) {
  		    VariableRefBase ref = (VariableRefBase)_right;
  		    VariableBase var = ref.getVariable();
  		    typeR = var.getType();
  		}
  	    }
  	    // bug fix # 2838 
  	    if (typeL == null)
  		type = typeR;
  	    else if (typeR == null)
  		type = typeL;
  	    else {
  		type = Type.Real;
  	    }
  	    if (type == null) type = Type.Real;
  
  	    _right = new CastExpr(_right, type);
              _left = new CastExpr(_left, type);
  	    return _type = Type.Boolean;
  	}
  
  	if (hasNodeSetArgs()) {
  	    // Ensure that the node-set is the left argument
  	    if (tright instanceof NodeSetType) {
  		final Expression temp = _right; _right = _left; _left = temp;
          _op = (_op == Operators.GT) ? Operators.LT :
              (_op == Operators.LT) ? Operators.GT :
              (_op == Operators.GE) ? Operators.LE : Operators.GE;
  		tright = _right.getType();
  	    }
  
  	    // Promote nodes to node sets
  	    if (tright instanceof NodeType) {
  		_right = new CastExpr(_right, Type.NodeSet);
  	    }
  	    // Promote integer to doubles to have fewer compares
  	    if (tright instanceof IntType) {
  		_right = new CastExpr(_right, Type.Real);
  	    }
  	    // Promote result-trees to strings
  	    if (tright instanceof ResultTreeType) {
  		_right = new CastExpr(_right, Type.String);
  	    }
  	    return _type = Type.Boolean;
  	}
  
  	// In the node-boolean case, convert node to boolean first
  	if (hasNodeArgs()) {
  	    if (tleft instanceof BooleanType) {
  		_right = new CastExpr(_right, Type.Boolean);
  		tright = Type.Boolean;
  	    }
  	    if (tright instanceof BooleanType) {
  		_left = new CastExpr(_left, Type.Boolean);
  		tleft = Type.Boolean;
  	    }
  	}
  
  	// Lookup the table of primops to find the best match
      MethodType ptype = lookupPrimop(stable, Operators.getOpNames(_op),
                  new MethodType(Type.Void, tleft, tright)); 
  
  	if (ptype != null) {
  	    Type arg1 = (Type) ptype.argsType().elementAt(0);
  	    if (!arg1.identicalTo(tleft)) {
  		_left = new CastExpr(_left, arg1);
  	    }
  	    Type arg2 = (Type) ptype.argsType().elementAt(1);
  	    if (!arg2.identicalTo(tright)) {
  		_right = new CastExpr(_right, arg1);				
  	    }
  	    return _type = ptype.resultType();
  	}
  	throw new TypeCheckError(this);
      }
  
      public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
  	if (hasNodeSetArgs() || hasReferenceArgs()) {
  	    final ConstantPoolGen cpg = classGen.getConstantPool();
  	    final InstructionList il = methodGen.getInstructionList();
  
  	    // Call compare() from the BasisLibrary
  	    _left.translate(classGen, methodGen);
  	    _left.startIterator(classGen, methodGen);
  	    _right.translate(classGen, methodGen);
  	    _right.startIterator(classGen, methodGen);
  
  	    il.append(new PUSH(cpg, _op));
  	    il.append(methodGen.loadDOM());
  
  	    int index = cpg.addMethodref(BASIS_LIBRARY_CLASS, "compare",
  					 "("
  					 + _left.getType().toSignature() 
  					 + _right.getType().toSignature()
  					 + "I"
  					 + DOM_INTF_SIG
  					 + ")Z");
  	    il.append(new INVOKESTATIC(index));
  	}
  	else {
  	    translateDesynthesized(classGen, methodGen);
  	    synthesize(classGen, methodGen);
  	}
      }
  
      public void translateDesynthesized(ClassGenerator classGen,
  				       MethodGenerator methodGen) {
  	if (hasNodeSetArgs() || hasReferenceArgs()) {
  	    translate(classGen, methodGen);
  	    desynthesize(classGen, methodGen);
  	}
  	else {
  	    BranchInstruction bi = null;
  	    final InstructionList il = methodGen.getInstructionList();
  
  	    _left.translate(classGen, methodGen);
  	    _right.translate(classGen, methodGen);
  
  	    // TODO: optimize if one of the args is 0
  
  	    boolean tozero = false;
  	    Type tleft = _left.getType(); 
  
  	    if (tleft instanceof RealType) {
          il.append(tleft.CMP(_op == Operators.LT || _op == Operators.LE));
  		tleft = Type.Int;
  		tozero = true;
  	    }
  
  	    switch (_op) {
          case Operators.LT:
  		bi = tleft.GE(tozero);	
  		break;
  		
          case Operators.GT:
  		bi = tleft.LE(tozero);
  		break;
  		
          case Operators.LE:
  		bi = tleft.GT(tozero);
  		break;
  		
          case Operators.GE:
  		bi = tleft.LT(tozero);
  		break;
  		
  	    default:
  		ErrorMsg msg = new ErrorMsg(ErrorMsg.ILLEGAL_RELAT_OP_ERR,this);
  		getParser().reportError(Constants.FATAL, msg);
  	    }
  
  	    _falseList.add(il.append(bi));		// must be backpatched
  	}
      }
  
      public String toString() {
          return Operators.getOpNames(_op) + '(' + _left + ", " + _right + ')';
      }
  }
  