X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=Robust%2Fsrc%2FIR%2FTree%2FSemanticCheck.java;h=32577cc55e14b7dfd2a6a72db34ff03fcb5e10c2;hb=cdcf09c40af1419fa42932aae249cb79b69b5daf;hp=12538e16e10872d4752c002ae5eeeeebe4f985bd;hpb=24f4e575e7d74134ca6418fd4b06af8500bf812e;p=IRC.git

diff --git a/Robust/src/IR/Tree/SemanticCheck.java b/Robust/src/IR/Tree/SemanticCheck.java
deleted file mode 100644
index 12538e16..00000000
--- a/Robust/src/IR/Tree/SemanticCheck.java
+++ /dev/null
@@ -1,962 +0,0 @@
-package IR.Tree;
-
-import java.util.*;
-import IR.*;
-
-public class SemanticCheck {
-    State state;
-    TypeUtil typeutil;
-
-    public SemanticCheck(State state, TypeUtil tu) {
-	this.state=state;
-	this.typeutil=tu;
-    }
-
-    public void semanticCheck() {
-	SymbolTable classtable=state.getClassSymbolTable();
-	Iterator it=classtable.getDescriptorsIterator();
-	// Do descriptors first
-	while(it.hasNext()) {
-	    ClassDescriptor cd=(ClassDescriptor)it.next();
-	    //System.out.println("Checking class: "+cd);
-	    //Set superclass link up
-	    if (cd.getSuper()!=null) {
-		cd.setSuper(typeutil.getClass(cd.getSuper()));
-		// Link together Field, Method, and Flag tables so classes
-		// inherit these from their superclasses
-		cd.getFieldTable().setParent(cd.getSuperDesc().getFieldTable());
-		cd.getMethodTable().setParent(cd.getSuperDesc().getMethodTable());
-		cd.getFlagTable().setParent(cd.getSuperDesc().getFlagTable());
-	    }
-	    
-	    /* Check to see that fields are well typed */
-	    for(Iterator field_it=cd.getFields();field_it.hasNext();) {
-		FieldDescriptor fd=(FieldDescriptor)field_it.next();
-		//System.out.println("Checking field: "+fd);
-		checkField(cd,fd);
-	    }
-
-	    for(Iterator method_it=cd.getMethods();method_it.hasNext();) {
-		MethodDescriptor md=(MethodDescriptor)method_it.next();
-		checkMethod(cd,md);
-	    }
-	}
-
-	it=classtable.getDescriptorsIterator();
-	// Do descriptors first
-	while(it.hasNext()) {
-	    ClassDescriptor cd=(ClassDescriptor)it.next();
-	    for(Iterator method_it=cd.getMethods();method_it.hasNext();) {
-		MethodDescriptor md=(MethodDescriptor)method_it.next();
-		checkMethodBody(cd,md);
-	    }
-	}
-
-	for(Iterator task_it=state.getTaskSymbolTable().getDescriptorsIterator();task_it.hasNext();) {
-	    TaskDescriptor td=(TaskDescriptor)task_it.next();
-	    checkTask(td);
-	    
-	}
-    }
-
-    public void checkTypeDescriptor(TypeDescriptor td) {
-	if (td.isPrimitive())
-	    return; /* Done */
-	else if (td.isClass()) {
-	    String name=td.toString();
-	    ClassDescriptor field_cd=(ClassDescriptor)state.getClassSymbolTable().get(name);
-	    if (field_cd==null)
-		throw new Error("Undefined class "+name);
-	    td.setClassDescriptor(field_cd);
-	    return;
-	} else if (td.isTag())
-	    return;
-	else
-	    throw new Error();
-    }
-
-    public void checkField(ClassDescriptor cd, FieldDescriptor fd) {
-	checkTypeDescriptor(fd.getType());
-    }
-
-    public void checkConstraintCheck(TaskDescriptor td, SymbolTable nametable, Vector ccs) {
-	if (ccs==null)
-	    return; /* No constraint checks to check */
-	for(int i=0;i<ccs.size();i++) {
-	    ConstraintCheck cc=(ConstraintCheck) ccs.get(i);
-	    
-	    for(int j=0;j<cc.numArgs();j++) {
-		ExpressionNode en=cc.getArg(j);
-		checkExpressionNode(td,nametable,en,null);
-	    }
-	}
-    }
-
-    public void checkFlagEffects(TaskDescriptor td, Vector vfe, SymbolTable nametable) {
-	if (vfe==null)
-	    return; /* No flag effects to check */
-	for(int i=0;i<vfe.size();i++) {
-	    FlagEffects fe=(FlagEffects) vfe.get(i);
-	    String varname=fe.getName();
-	    //Make sure the variable is declared as a parameter to the task
-	    VarDescriptor vd=(VarDescriptor)td.getParameterTable().get(varname);
-	    if (vd==null)
-		throw new Error("Parameter "+varname+" in Flag Effects not declared in "+td);
-	    fe.setVar(vd);
-
-	    //Make sure it correspods to a class
-	    TypeDescriptor type_d=vd.getType();
-	    if (!type_d.isClass())
-		throw new Error("Cannot have non-object argument for flag_effect");
-
-	    ClassDescriptor cd=type_d.getClassDesc();
-	    for(int j=0;j<fe.numEffects();j++) {
-		FlagEffect flag=fe.getEffect(j);
-		String name=flag.getName();
-		FlagDescriptor flag_d=(FlagDescriptor)cd.getFlagTable().get(name);
-		//Make sure the flag is declared
-		if (flag_d==null)
-		    throw new Error("Flag descriptor "+name+" undefined in class: "+cd.getSymbol());
-		if (flag_d.getExternal())
-		    throw new Error("Attempting to modify external flag: "+name);
-		flag.setFlag(flag_d);
-	    }
-	    for(int j=0;j<fe.numTagEffects();j++) {
-		TagEffect tag=fe.getTagEffect(j);
-		String name=tag.getName();
-		
-		Descriptor d=(Descriptor)nametable.get(name);
-		if (d==null)
-		    throw new Error("Tag descriptor "+name+" undeclared");
-		else if (!(d instanceof TagVarDescriptor))
-		    throw new Error(name+" is not a tag descriptor");
-		tag.setTag((TagVarDescriptor)d);
-	    }
-	}
-    }
-
-    public void checkTask(TaskDescriptor td) {
-	for(int i=0;i<td.numParameters();i++) {
-	    /* Check that parameter is well typed */
-	    TypeDescriptor param_type=td.getParamType(i);
-	    checkTypeDescriptor(param_type);
-
-	    /* Check the parameter's flag expression is well formed */
-	    FlagExpressionNode fen=td.getFlag(td.getParameter(i));
-	    if (!param_type.isClass())
-		throw new Error("Cannot have non-object argument to a task");
-	    ClassDescriptor cd=param_type.getClassDesc();
-	    if (fen!=null)
-		checkFlagExpressionNode(cd, fen);
-	}
-
-	checkFlagEffects(td, td.getFlagEffects(),td.getParameterTable());
-	/* Check that the task code is valid */
-	BlockNode bn=state.getMethodBody(td);
-	checkBlockNode(td, td.getParameterTable(),bn);
-    }
-
-    public void checkFlagExpressionNode(ClassDescriptor cd, FlagExpressionNode fen) {
-	switch(fen.kind()) {
-	case Kind.FlagOpNode: 
-	    {
-		FlagOpNode fon=(FlagOpNode)fen;
-		checkFlagExpressionNode(cd, fon.getLeft());
-		if (fon.getRight()!=null)
-		    checkFlagExpressionNode(cd, fon.getRight());
-		break;
-	    }
-	case Kind.FlagNode:
-	    {
-		FlagNode fn=(FlagNode)fen;
-		String name=fn.getFlagName();
-		FlagDescriptor fd=(FlagDescriptor)cd.getFlagTable().get(name);
-		if (fd==null)
-		    throw new Error("Undeclared flag: "+name);
-		fn.setFlag(fd);
-		break;
-	    }
-	default:
-	    throw new Error("Unrecognized FlagExpressionNode");
-	}
-    }
-
-    public void checkMethod(ClassDescriptor cd, MethodDescriptor md) {
-	/* Check return type */
-	if (!md.isConstructor())
-	    if (!md.getReturnType().isVoid())
-		checkTypeDescriptor(md.getReturnType());
-
-	for(int i=0;i<md.numParameters();i++) {
-	    TypeDescriptor param_type=md.getParamType(i);
-	    checkTypeDescriptor(param_type);
-	}
-	/* Link the naming environments */
-	if (!md.isStatic()) /* Fields aren't accessible directly in a static method, so don't link in this table */
-	    md.getParameterTable().setParent(cd.getFieldTable());
-	md.setClassDesc(cd);
-	if (!md.isStatic()) {
-	    VarDescriptor thisvd=new VarDescriptor(new TypeDescriptor(cd),"this");
-	    md.setThis(thisvd);
-	}
-    }
-
-    public void checkMethodBody(ClassDescriptor cd, MethodDescriptor md) {
-	ClassDescriptor superdesc=cd.getSuperDesc();
-	if (superdesc!=null) {
-	    Set possiblematches=superdesc.getMethodTable().getSet(md.getSymbol());
-	    for(Iterator methodit=possiblematches.iterator();methodit.hasNext();) {
-		MethodDescriptor matchmd=(MethodDescriptor)methodit.next();
-		if (md.matches(matchmd)) {
-		    if (matchmd.getModifiers().isFinal()) {
-			throw new Error("Try to override final method in method:"+md+" declared in  "+cd);
-		    }
-		}
-	    }
-	}
-	BlockNode bn=state.getMethodBody(md);
-	checkBlockNode(md, md.getParameterTable(),bn);
-    }
-    
-    public void checkBlockNode(Descriptor md, SymbolTable nametable, BlockNode bn) {
-	/* Link in the naming environment */
-	bn.getVarTable().setParent(nametable);
-	for(int i=0;i<bn.size();i++) {
-	    BlockStatementNode bsn=bn.get(i);
-	    checkBlockStatementNode(md, bn.getVarTable(),bsn);
-	}
-    }
-    
-    public void checkBlockStatementNode(Descriptor md, SymbolTable nametable, BlockStatementNode bsn) {
-	switch(bsn.kind()) {
-	case Kind.BlockExpressionNode:
-	    checkBlockExpressionNode(md, nametable,(BlockExpressionNode)bsn);
-	    return;
-
-	case Kind.DeclarationNode:
-	    checkDeclarationNode(md, nametable, (DeclarationNode)bsn);
-	    return;
-
-	case Kind.TagDeclarationNode:
-	    checkTagDeclarationNode(md, nametable, (TagDeclarationNode)bsn);
-	    return;
-	    
-	case Kind.IfStatementNode:
-	    checkIfStatementNode(md, nametable, (IfStatementNode)bsn);
-	    return;
-	    
-	case Kind.LoopNode:
-	    checkLoopNode(md, nametable, (LoopNode)bsn);
-	    return;
-	    
-	case Kind.ReturnNode:
-	    checkReturnNode(md, nametable, (ReturnNode)bsn);
-	    return;
-
-	case Kind.TaskExitNode:
-	    checkTaskExitNode(md, nametable, (TaskExitNode)bsn);
-	    return;
-
-	case Kind.SubBlockNode:
-	    checkSubBlockNode(md, nametable, (SubBlockNode)bsn);
-	    return;
-
-	case Kind.AtomicNode:
-	    checkAtomicNode(md, nametable, (AtomicNode)bsn);
-	    return;
-	}
-	throw new Error();
-    }
-
-    void checkBlockExpressionNode(Descriptor md, SymbolTable nametable, BlockExpressionNode ben) {
-	checkExpressionNode(md, nametable, ben.getExpression(), null);
-    }
-
-    void checkDeclarationNode(Descriptor md, SymbolTable nametable,  DeclarationNode dn) {
-	VarDescriptor vd=dn.getVarDescriptor();
-	checkTypeDescriptor(vd.getType());
-	Descriptor d=nametable.get(vd.getSymbol());
-	if ((d==null)||
-	    (d instanceof FieldDescriptor)) {
-	    nametable.add(vd);
-	} else
-	    throw new Error(vd.getSymbol()+" in "+md+" defined a second time");
-	if (dn.getExpression()!=null)
-	    checkExpressionNode(md, nametable, dn.getExpression(), vd.getType());
-    }
-
-    void checkTagDeclarationNode(Descriptor md, SymbolTable nametable,  TagDeclarationNode dn) {
-	TagVarDescriptor vd=dn.getTagVarDescriptor();
-	Descriptor d=nametable.get(vd.getSymbol());
-	if ((d==null)||
-	    (d instanceof FieldDescriptor)) {
-	    nametable.add(vd);
-	} else
-	    throw new Error(vd.getSymbol()+" defined a second time");
-    }
-    
-    void checkSubBlockNode(Descriptor md, SymbolTable nametable, SubBlockNode sbn) {
-	checkBlockNode(md, nametable, sbn.getBlockNode());
-    }
-
-    void checkAtomicNode(Descriptor md, SymbolTable nametable, AtomicNode sbn) {
-	checkBlockNode(md, nametable, sbn.getBlockNode());
-    }
-
-    void checkReturnNode(Descriptor d, SymbolTable nametable, ReturnNode rn) {
-	if (d instanceof TaskDescriptor)
-	    throw new Error("Illegal return appears in Task: "+d.getSymbol());
-	MethodDescriptor md=(MethodDescriptor)d;
-	if (rn.getReturnExpression()!=null)
-	    if (md.getReturnType()==null) 
-		throw new Error("Constructor can't return something.");
-	    else if (md.getReturnType().isVoid())
-		throw new Error(md+" is void");
-	    else
-		checkExpressionNode(md, nametable, rn.getReturnExpression(), md.getReturnType());
-	else
-	    if (md.getReturnType()!=null&&!md.getReturnType().isVoid())
-		throw new Error("Need to return something for "+md);
-    }
-
-    void checkTaskExitNode(Descriptor md, SymbolTable nametable, TaskExitNode ten) {
-	if (md instanceof MethodDescriptor)
-	    throw new Error("Illegal taskexit appears in Method: "+md.getSymbol());
-	checkFlagEffects((TaskDescriptor)md, ten.getFlagEffects(),nametable);
-	checkConstraintCheck((TaskDescriptor) md, nametable, ten.getChecks());
-    }
-
-    void checkIfStatementNode(Descriptor md, SymbolTable nametable, IfStatementNode isn) {
-	checkExpressionNode(md, nametable, isn.getCondition(), new TypeDescriptor(TypeDescriptor.BOOLEAN));
-	checkBlockNode(md, nametable, isn.getTrueBlock());
-	if (isn.getFalseBlock()!=null)
-	    checkBlockNode(md, nametable, isn.getFalseBlock());
-    }
-    
-    void checkExpressionNode(Descriptor md, SymbolTable nametable, ExpressionNode en, TypeDescriptor td) {
-	switch(en.kind()) {
-        case Kind.AssignmentNode:
-            checkAssignmentNode(md,nametable,(AssignmentNode)en,td);
-	    return;
-        case Kind.CastNode:
-	    checkCastNode(md,nametable,(CastNode)en,td);
-	    return;
-        case Kind.CreateObjectNode:
-	    checkCreateObjectNode(md,nametable,(CreateObjectNode)en,td);
-	    return;
-        case Kind.FieldAccessNode:
-	    checkFieldAccessNode(md,nametable,(FieldAccessNode)en,td);
-	    return;
-        case Kind.ArrayAccessNode:
-	    checkArrayAccessNode(md,nametable,(ArrayAccessNode)en,td);
-	    return;
-        case Kind.LiteralNode:
-	    checkLiteralNode(md,nametable,(LiteralNode)en,td);
-	    return;
-        case Kind.MethodInvokeNode:
-	    checkMethodInvokeNode(md,nametable,(MethodInvokeNode)en,td);
-	    return;
-        case Kind.NameNode:
-	    checkNameNode(md,nametable,(NameNode)en,td);
-	    return;
-        case Kind.OpNode:
-            checkOpNode(md,nametable,(OpNode)en,td);
-	    return;
-        }
-	throw new Error();
-    }
-
-    void checkCastNode(Descriptor md, SymbolTable nametable, CastNode cn, TypeDescriptor td) {
-	/* Get type descriptor */
-	if (cn.getType()==null) {
-	    NameDescriptor typenamed=cn.getTypeName().getName();
-	    String typename=typenamed.toString();
-	    TypeDescriptor ntd=new TypeDescriptor(typeutil.getClass(typename));
-	    cn.setType(ntd);
-	}
-
-	/* Check the type descriptor */
-	TypeDescriptor cast_type=cn.getType();
-	checkTypeDescriptor(cast_type);
-
-	/* Type check */
-	if (td!=null) {
-	    if (!typeutil.isSuperorType(td,cast_type))
-		throw new Error("Cast node returns "+cast_type+", but need "+td);
-	}
-
-	ExpressionNode en=cn.getExpression();
-	checkExpressionNode(md, nametable, en, null);
-	TypeDescriptor etd=en.getType();
-	if (typeutil.isSuperorType(cast_type,etd)) /* Cast trivially succeeds */
-	    return;
-
-	if (typeutil.isSuperorType(etd,cast_type)) /* Cast may succeed */
-	    return;
-	if (typeutil.isCastable(etd, cast_type))
-	    return;
-	
-	/* Different branches */
-	/* TODO: change if add interfaces */
-	throw new Error("Cast will always fail\n"+cn.printNode(0));
-    }
-
-    void checkFieldAccessNode(Descriptor md, SymbolTable nametable, FieldAccessNode fan, TypeDescriptor td) {
-	ExpressionNode left=fan.getExpression();
-	checkExpressionNode(md,nametable,left,null);
-	TypeDescriptor ltd=left.getType();
-	String fieldname=fan.getFieldName();
-
-	FieldDescriptor fd=null;
-	if (ltd.isArray()&&fieldname.equals("length"))
-	    fd=FieldDescriptor.arrayLength;
-	else
-	    fd=(FieldDescriptor) ltd.getClassDesc().getFieldTable().get(fieldname);
-	if (fd==null)
-	    throw new Error("Unknown field "+fieldname + " in "+fan.printNode(0)+" in "+md);
-	fan.setField(fd);
-	if (td!=null)
-	    if (!typeutil.isSuperorType(td,fan.getType()))
-		throw new Error("Field node returns "+fan.getType()+", but need "+td);
-    }
-
-    void checkArrayAccessNode(Descriptor md, SymbolTable nametable, ArrayAccessNode aan, TypeDescriptor td) {
-	ExpressionNode left=aan.getExpression();
-	checkExpressionNode(md,nametable,left,null);
-
-	checkExpressionNode(md,nametable,aan.getIndex(),new TypeDescriptor(TypeDescriptor.INT));
-	TypeDescriptor ltd=left.getType();
-
-	if (td!=null)
-	    if (!typeutil.isSuperorType(td,aan.getType()))
-		throw new Error("Field node returns "+aan.getType()+", but need "+td);
-    }
-
-    void checkLiteralNode(Descriptor md, SymbolTable nametable, LiteralNode ln, TypeDescriptor td) {
-	/* Resolve the type */
-	Object o=ln.getValue();
-	if (ln.getTypeString().equals("null")) {
-	    ln.setType(new TypeDescriptor(TypeDescriptor.NULL));
-	} else if (o instanceof Integer) {
-	    ln.setType(new TypeDescriptor(TypeDescriptor.INT));
-	} else if (o instanceof Long) {
-	    ln.setType(new TypeDescriptor(TypeDescriptor.LONG));
-      	} else if (o instanceof Float) {
-	    ln.setType(new TypeDescriptor(TypeDescriptor.FLOAT));
-      	} else if (o instanceof Boolean) {
-	    ln.setType(new TypeDescriptor(TypeDescriptor.BOOLEAN));
-      	} else if (o instanceof Double) {
-	    ln.setType(new TypeDescriptor(TypeDescriptor.DOUBLE));
-      	} else if (o instanceof Character) {
-	    ln.setType(new TypeDescriptor(TypeDescriptor.CHAR));
-      	} else if (o instanceof String) {
-	    ln.setType(new TypeDescriptor(typeutil.getClass(TypeUtil.StringClass)));
-      	}
-
-	if (td!=null)
-	    if (!typeutil.isSuperorType(td,ln.getType()))
-		throw new Error("Field node returns "+ln.getType()+", but need "+td);
-    }
-
-    void checkNameNode(Descriptor md, SymbolTable nametable, NameNode nn, TypeDescriptor td) {
-	NameDescriptor nd=nn.getName();
-	if (nd.getBase()!=null) {
-	    /* Big hack */
-	    /* Rewrite NameNode */
-	    ExpressionNode en=translateNameDescriptorintoExpression(nd);
-	    nn.setExpression(en);
-	    checkExpressionNode(md,nametable,en,td);
-	} else {
-	    String varname=nd.toString();
-	    Descriptor d=(Descriptor)nametable.get(varname);
-	    if (d==null) {
-		throw new Error("Name "+varname+" undefined in: "+md);
-	    }
-	    if (d instanceof VarDescriptor) {
-		nn.setVar(d);
-	    } else if (d instanceof FieldDescriptor) {
-		nn.setField((FieldDescriptor)d);
-		nn.setVar((VarDescriptor)nametable.get("this")); /* Need a pointer to this */
-	    } else if (d instanceof TagVarDescriptor) {
-		nn.setVar(d);
-	    } else throw new Error("Wrong type of descriptor");
-	    if (td!=null)
-		if (!typeutil.isSuperorType(td,nn.getType()))
-		    throw new Error("Field node returns "+nn.getType()+", but need "+td);
-	}
-    }
-
-    void checkAssignmentNode(Descriptor md, SymbolTable nametable, AssignmentNode an, TypeDescriptor td) {
-	boolean postinc=true;
-	if (an.getOperation().getBaseOp()==null||
-	    (an.getOperation().getBaseOp().getOp()!=Operation.POSTINC&&
-	     an.getOperation().getBaseOp().getOp()!=Operation.POSTDEC))
-	    postinc=false;
-
-	if (!postinc)
-	    checkExpressionNode(md, nametable, an.getSrc() ,td);
-	//TODO: Need check on validity of operation here
-	if (!((an.getDest() instanceof FieldAccessNode)||
-	      (an.getDest() instanceof ArrayAccessNode)||
-	      (an.getDest() instanceof NameNode)))
-	    throw new Error("Bad lside in "+an.printNode(0));
-	checkExpressionNode(md, nametable, an.getDest(), null);
-
-
-	/* We want parameter variables to tasks to be immutable */
-	if (md instanceof TaskDescriptor) {
-	    if (an.getDest() instanceof NameNode) {
-		NameNode nn=(NameNode)an.getDest();
-		if (nn.getVar()!=null) {
-		    if (((TaskDescriptor)md).getParameterTable().contains(nn.getVar().getSymbol()))
-			throw new Error("Can't modify parameter "+nn.getVar()+ " to task "+td.getSymbol());
-		}
-	    }
-	}
-	
-	if (an.getDest().getType().isString()&&an.getOperation().getOp()==AssignOperation.PLUSEQ) {
-	    //String add
-	    ClassDescriptor stringcl=typeutil.getClass(TypeUtil.StringClass);
-	    TypeDescriptor stringtd=new TypeDescriptor(stringcl);
-	    NameDescriptor nd=new NameDescriptor("String");
-	    NameDescriptor valuend=new NameDescriptor(nd, "valueOf");
-	    
-	    if (!(an.getSrc().getType().isString()&&(an.getSrc() instanceof OpNode))) {
-		MethodInvokeNode rightmin=new MethodInvokeNode(valuend);
-		rightmin.addArgument(an.getSrc());
-		an.right=rightmin;
-		checkExpressionNode(md, nametable, an.getSrc(), null);
-	    }
-	}
-
-	
-	if (!postinc&&!typeutil.isSuperorType(an.getDest().getType(),an.getSrc().getType())) {
-	    throw new Error("Type of rside ("+an.getSrc().getType()+") not compatible with type of lside ("+an.getDest().getType()+")"+an.printNode(0));
-	}
-    }
-
-    void checkLoopNode(Descriptor md, SymbolTable nametable, LoopNode ln) {
-	if (ln.getType()==LoopNode.WHILELOOP||ln.getType()==LoopNode.DOWHILELOOP) {
-	    checkExpressionNode(md, nametable, ln.getCondition(), new TypeDescriptor(TypeDescriptor.BOOLEAN));
-	    checkBlockNode(md, nametable, ln.getBody());
-	} else {
-	    //For loop case
-	    /* Link in the initializer naming environment */
-	    BlockNode bn=ln.getInitializer();
-	    bn.getVarTable().setParent(nametable);
-	    for(int i=0;i<bn.size();i++) {
-		BlockStatementNode bsn=bn.get(i);
-		checkBlockStatementNode(md, bn.getVarTable(),bsn);
-	    }
-	    //check the condition
-	    checkExpressionNode(md, bn.getVarTable(), ln.getCondition(), new TypeDescriptor(TypeDescriptor.BOOLEAN));
-	    checkBlockNode(md, bn.getVarTable(), ln.getBody());
-	    checkBlockNode(md, bn.getVarTable(), ln.getUpdate());
-	}
-    }
-
-
-    void checkCreateObjectNode(Descriptor md, SymbolTable nametable, CreateObjectNode con, TypeDescriptor td) {
-	TypeDescriptor[] tdarray=new TypeDescriptor[con.numArgs()];
-	for(int i=0;i<con.numArgs();i++) {
-	    ExpressionNode en=con.getArg(i);
-	    checkExpressionNode(md,nametable,en,null);
-	    tdarray[i]=en.getType();
-	}
-
-	TypeDescriptor typetolookin=con.getType();
-	checkTypeDescriptor(typetolookin);
-
-	if (td!=null&&!typeutil.isSuperorType(td, typetolookin))
-	    throw new Error(typetolookin + " isn't a "+td);
-
-	/* Check flag effects */
-	if (con.getFlagEffects()!=null) {
-	    FlagEffects fe=con.getFlagEffects();
-	    ClassDescriptor cd=typetolookin.getClassDesc();
-	    
-	    for(int j=0;j<fe.numEffects();j++) {
-		FlagEffect flag=fe.getEffect(j);
-		String name=flag.getName();
-		FlagDescriptor flag_d=(FlagDescriptor)cd.getFlagTable().get(name);
-		//Make sure the flag is declared
-		if (flag_d==null)
-		    throw new Error("Flag descriptor "+name+" undefined in class: "+cd.getSymbol());
-		if (flag_d.getExternal())
-		    throw new Error("Attempting to modify external flag: "+name);
-		flag.setFlag(flag_d);
-	    }
-	    for(int j=0;j<fe.numTagEffects();j++) {
-		TagEffect tag=fe.getTagEffect(j);
-		String name=tag.getName();
-		
-		Descriptor d=(Descriptor)nametable.get(name);
-		if (d==null)
-		    throw new Error("Tag descriptor "+name+" undeclared");
-		else if (!(d instanceof TagVarDescriptor))
-		    throw new Error(name+" is not a tag descriptor");
-		tag.setTag((TagVarDescriptor)d);
-	    }
-	}
-
-	if ((!typetolookin.isClass())&&(!typetolookin.isArray())) 
-	    throw new Error("Can't allocate primitive type:"+con.printNode(0));
-
-	if (!typetolookin.isArray()) {
-	    //Array's don't need constructor calls
-	    ClassDescriptor classtolookin=typetolookin.getClassDesc();
-
-	    Set methoddescriptorset=classtolookin.getMethodTable().getSet(typetolookin.getSymbol());
-	    MethodDescriptor bestmd=null;
-	NextMethod:
-	    for(Iterator methodit=methoddescriptorset.iterator();methodit.hasNext();) {
-		MethodDescriptor currmd=(MethodDescriptor)methodit.next();
-		/* Need correct number of parameters */
-		if (con.numArgs()!=currmd.numParameters())
-		    continue;
-		for(int i=0;i<con.numArgs();i++) {
-		    if (!typeutil.isSuperorType(currmd.getParamType(i),tdarray[i]))
-			continue NextMethod;
-		}
-		/* Local allocations can't call global allocator */
-		if (!con.isGlobal()&&currmd.isGlobal())
-		    continue;
-
-		/* Method okay so far */
-		if (bestmd==null)
-		    bestmd=currmd;
-		else {
-		    if (typeutil.isMoreSpecific(currmd,bestmd)) {
-			bestmd=currmd;
-		    } else if (con.isGlobal()&&match(currmd, bestmd)) {
-			if (currmd.isGlobal()&&!bestmd.isGlobal())
-			    bestmd=currmd;
-			else if (currmd.isGlobal()&&bestmd.isGlobal())
-			    throw new Error();
-		    } else if (!typeutil.isMoreSpecific(bestmd, currmd)) {
-			throw new Error("No method is most specific");
-		    }
-		    
-		    /* Is this more specific than bestmd */
-		}
-	    }
-	    if (bestmd==null)
-		throw new Error("No method found for "+con.printNode(0)+" in "+md);
-	    con.setConstructor(bestmd);
-	}
-    }
-
-
-    /** Check to see if md1 is the same specificity as md2.*/
-
-    boolean match(MethodDescriptor md1, MethodDescriptor md2) {
-	/* Checks if md1 is more specific than md2 */
-	if (md1.numParameters()!=md2.numParameters())
-	    throw new Error();
-	for(int i=0;i<md1.numParameters();i++) {
-	    if (!md2.getParamType(i).equals(md1.getParamType(i)))
-		return false;
-	}
-	if (!md2.getReturnType().equals(md1.getReturnType()))
-		return false;
-
-	if (!md2.getClassDesc().equals(md1.getClassDesc()))
-		return false;
-
-	return true;
-    }
-
-
-
-    ExpressionNode translateNameDescriptorintoExpression(NameDescriptor nd) {
-	String id=nd.getIdentifier();
-	NameDescriptor base=nd.getBase();
-	if (base==null) 
-	    return new NameNode(nd);
-	else 
-	    return new FieldAccessNode(translateNameDescriptorintoExpression(base),id);
-    }
-
-
-    void checkMethodInvokeNode(Descriptor md, SymbolTable nametable, MethodInvokeNode min, TypeDescriptor td) {
-	/*Typecheck subexpressions
-	  and get types for expressions*/
-
-	TypeDescriptor[] tdarray=new TypeDescriptor[min.numArgs()];
-	for(int i=0;i<min.numArgs();i++) {
-	    ExpressionNode en=min.getArg(i);
-	    checkExpressionNode(md,nametable,en,null);
-	    tdarray[i]=en.getType();
-	}
-	TypeDescriptor typetolookin=null;
-	if (min.getExpression()!=null) {
-	    checkExpressionNode(md,nametable,min.getExpression(),null);
-	    typetolookin=min.getExpression().getType();
-	} else if (min.getBaseName()!=null) {
-	    String rootname=min.getBaseName().getRoot();
-	    if (rootname.equals("super")) {
-		ClassDescriptor supercd=((MethodDescriptor)md).getClassDesc().getSuperDesc();
-		typetolookin=new TypeDescriptor(supercd);
-	    } else if (nametable.get(rootname)!=null) {
-		//we have an expression
-		min.setExpression(translateNameDescriptorintoExpression(min.getBaseName()));
-		checkExpressionNode(md, nametable, min.getExpression(), null);
-		typetolookin=min.getExpression().getType();
-	    } else {
-		//we have a type
-		ClassDescriptor cd=typeutil.getClass(min.getBaseName().getSymbol());
-		if (cd==null)
-		    throw new Error(min.getBaseName()+" undefined");
-		typetolookin=new TypeDescriptor(cd);
-	    }
-	} else if ((md instanceof MethodDescriptor)&&min.getMethodName().equals("super")) {
-	    ClassDescriptor supercd=((MethodDescriptor)md).getClassDesc().getSuperDesc();
-	    min.methodid=supercd.getSymbol();
-	    typetolookin=new TypeDescriptor(supercd);
-	} else if (md instanceof MethodDescriptor) {
-	    typetolookin=new TypeDescriptor(((MethodDescriptor)md).getClassDesc());
-	} else {
-	    /* If this a task descriptor we throw an error at this point */
-	    throw new Error("Unknown method call to "+min.getMethodName()+"in task"+md.getSymbol());
-	}
-	if (!typetolookin.isClass()) 
-	    throw new Error("Error with method call to "+min.getMethodName());
-	ClassDescriptor classtolookin=typetolookin.getClassDesc();
-	//System.out.println("Method name="+min.getMethodName());
-
-	Set methoddescriptorset=classtolookin.getMethodTable().getSet(min.getMethodName());
-	MethodDescriptor bestmd=null;
-	NextMethod:
-	for(Iterator methodit=methoddescriptorset.iterator();methodit.hasNext();) {
-	    MethodDescriptor currmd=(MethodDescriptor)methodit.next();
-	    /* Need correct number of parameters */
-	    if (min.numArgs()!=currmd.numParameters())
-		continue;
-	    for(int i=0;i<min.numArgs();i++) {
-		if (!typeutil.isSuperorType(currmd.getParamType(i),tdarray[i]))
-		    continue NextMethod;
-	    }
-	    /* Method okay so far */
-	    if (bestmd==null)
-		bestmd=currmd;
-	    else {
-		if (typeutil.isMoreSpecific(currmd,bestmd)) {
-		    bestmd=currmd;
-		} else if (!typeutil.isMoreSpecific(bestmd, currmd))
-		    throw new Error("No method is most specific");
-		
-		/* Is this more specific than bestmd */
-	    }
-	}
-	if (bestmd==null)
-	    throw new Error("No method found for :"+min.printNode(0)+" in class: " + classtolookin+" in "+md);
-	min.setMethod(bestmd);
-
-	if ((td!=null)&&(min.getType()!=null)&&!typeutil.isSuperorType(td,  min.getType()))
-	    throw new Error(min.getType()+ " is not equal to or a subclass of "+td);
-	/* Check whether we need to set this parameter to implied this */
-	if (!bestmd.isStatic()) {
-	    if (min.getExpression()==null) {
-		ExpressionNode en=new NameNode(new NameDescriptor("this"));
-		min.setExpression(en);
-		checkExpressionNode(md, nametable, min.getExpression(), null);
-	    }
-	}
-    }
-
-
-    void checkOpNode(Descriptor md, SymbolTable nametable, OpNode on, TypeDescriptor td) {
-	checkExpressionNode(md, nametable, on.getLeft(), null);
-	if (on.getRight()!=null)
-	    checkExpressionNode(md, nametable, on.getRight(), null);
-	TypeDescriptor ltd=on.getLeft().getType();
-	TypeDescriptor rtd=on.getRight()!=null?on.getRight().getType():null;
-	TypeDescriptor lefttype=null;
-	TypeDescriptor righttype=null;
-	Operation op=on.getOp();
-
-	switch(op.getOp()) {
-	case Operation.LOGIC_OR:
-	case Operation.LOGIC_AND:
-	    if (!(rtd.isBoolean()))
-		throw new Error();
-	    on.setRightType(rtd);
-	case Operation.LOGIC_NOT:
-	    if (!(ltd.isBoolean()))
-		throw new Error();
-	    //no promotion
-	    on.setLeftType(ltd);
-
-	    on.setType(new TypeDescriptor(TypeDescriptor.BOOLEAN));
-   	    break;
-
-	case Operation.BIT_OR:
-	case Operation.BIT_XOR:
-	case Operation.BIT_AND:
-	    // 5.6.2 Binary Numeric Promotion
-	    //TODO unboxing of reference objects
-	    if (ltd.isDouble()||rtd.isDouble())
-		throw new Error();
-	    else if (ltd.isFloat()||rtd.isFloat())
-		throw new Error();
-	    else if (ltd.isLong()||rtd.isLong())
-		lefttype=new TypeDescriptor(TypeDescriptor.LONG);
-	    else 
-		lefttype=new TypeDescriptor(TypeDescriptor.INT);
-	    righttype=lefttype;
-
-	    on.setLeftType(lefttype);
-	    on.setRightType(righttype);
-	    on.setType(lefttype);
-	    break;
-
-	case Operation.ISAVAILABLE:
-	    if (!(ltd.isPtr())) {
-		throw new Error("Can't use isavailable on non-pointers/non-parameters.");
-	    }
-	    lefttype=ltd;
-	    on.setLeftType(lefttype);
-	    on.setType(new TypeDescriptor(TypeDescriptor.BOOLEAN));
-	    break;
-	case Operation.EQUAL:
-	case Operation.NOTEQUAL:
-	    // 5.6.2 Binary Numeric Promotion
-	    //TODO unboxing of reference objects
-	    if (ltd.isBoolean()||rtd.isBoolean()) {
-		if (!(ltd.isBoolean()&&rtd.isBoolean()))
-		    throw new Error();
-		righttype=lefttype=new TypeDescriptor(TypeDescriptor.BOOLEAN);
-	    } else if (ltd.isPtr()||rtd.isPtr()) {
-		if (!(ltd.isPtr()&&rtd.isPtr()))
-		    throw new Error();
-		righttype=rtd;
-		lefttype=ltd;
-	    } else if (ltd.isDouble()||rtd.isDouble())
-		righttype=lefttype=new TypeDescriptor(TypeDescriptor.DOUBLE);
-	    else if (ltd.isFloat()||rtd.isFloat())
-		righttype=lefttype=new TypeDescriptor(TypeDescriptor.FLOAT);
-	    else if (ltd.isLong()||rtd.isLong())
-		righttype=lefttype=new TypeDescriptor(TypeDescriptor.LONG);
-	    else 
-		righttype=lefttype=new TypeDescriptor(TypeDescriptor.INT);
-
-	    on.setLeftType(lefttype);
-	    on.setRightType(righttype);
-	    on.setType(new TypeDescriptor(TypeDescriptor.BOOLEAN));
-	    break;
-
-
-
-	case Operation.LT:
-	case Operation.GT:
-	case Operation.LTE:
-	case Operation.GTE:
-	    // 5.6.2 Binary Numeric Promotion
-	    //TODO unboxing of reference objects
-	    if (!ltd.isNumber()||!rtd.isNumber())
-		throw new Error();
-
-	    if (ltd.isDouble()||rtd.isDouble())
-		lefttype=new TypeDescriptor(TypeDescriptor.DOUBLE);
-	    else if (ltd.isFloat()||rtd.isFloat())
-		lefttype=new TypeDescriptor(TypeDescriptor.FLOAT);
-	    else if (ltd.isLong()||rtd.isLong())
-		lefttype=new TypeDescriptor(TypeDescriptor.LONG);
-	    else 
-		lefttype=new TypeDescriptor(TypeDescriptor.INT);
-	    righttype=lefttype;
-	    on.setLeftType(lefttype);
-	    on.setRightType(righttype);
-	    on.setType(new TypeDescriptor(TypeDescriptor.BOOLEAN));
-	    break;
-
-	case Operation.ADD:
-	    if (ltd.isString()||rtd.isString()) {
-		ClassDescriptor stringcl=typeutil.getClass(TypeUtil.StringClass);
-		TypeDescriptor stringtd=new TypeDescriptor(stringcl);
-		NameDescriptor nd=new NameDescriptor("String");
-		NameDescriptor valuend=new NameDescriptor(nd, "valueOf");
-		if (!(ltd.isString()&&(on.getLeft() instanceof OpNode))) {
-		    MethodInvokeNode leftmin=new MethodInvokeNode(valuend);
-		    leftmin.addArgument(on.getLeft());
-		    on.left=leftmin;
-		    checkExpressionNode(md, nametable, on.getLeft(), null);
-		}
-
-		if (!(rtd.isString()&&(on.getRight() instanceof OpNode))) {
-		    MethodInvokeNode rightmin=new MethodInvokeNode(valuend);
-		    rightmin.addArgument(on.getRight());
-		    on.right=rightmin;
-		    checkExpressionNode(md, nametable, on.getRight(), null);
-		}
-
-		on.setLeftType(stringtd);
-		on.setRightType(stringtd);
-		on.setType(stringtd);
-		break;
-	    }
-	    
-	case Operation.SUB:
-	case Operation.MULT:
-	case Operation.DIV:
-	case Operation.MOD:
-	    // 5.6.2 Binary Numeric Promotion
-	    //TODO unboxing of reference objects
-	    if (ltd.isArray()||rtd.isArray()||!ltd.isNumber()||!rtd.isNumber())
-		throw new Error("Error in "+on.printNode(0));
-
-	    if (ltd.isDouble()||rtd.isDouble())
-		lefttype=new TypeDescriptor(TypeDescriptor.DOUBLE);
-	    else if (ltd.isFloat()||rtd.isFloat())
-		lefttype=new TypeDescriptor(TypeDescriptor.FLOAT);
-	    else if (ltd.isLong()||rtd.isLong())
-		lefttype=new TypeDescriptor(TypeDescriptor.LONG);
-	    else 
-		lefttype=new TypeDescriptor(TypeDescriptor.INT);
-	    righttype=lefttype;
-	    on.setLeftType(lefttype);
-	    on.setRightType(righttype);
-	    on.setType(lefttype);
-	    break;
-
-	case Operation.LEFTSHIFT:
-	case Operation.RIGHTSHIFT:
-	    if (!rtd.isIntegerType())
-		throw new Error();
-	    //5.6.1 Unary Numeric Promotion
-	    if (rtd.isByte()||rtd.isShort()||rtd.isInt())
-		righttype=new TypeDescriptor(TypeDescriptor.INT);
-	    else
-		righttype=rtd;
-
-	    on.setRightType(righttype);
-	    if (!ltd.isIntegerType())
-		throw new Error();
-	case Operation.UNARYPLUS:
-	case Operation.UNARYMINUS:
-	    /*	case Operation.POSTINC:
-		case Operation.POSTDEC:
-		case Operation.PREINC:
-		case Operation.PREDEC:*/
-	    if (!ltd.isNumber())
-		throw new Error();
-	    //5.6.1 Unary Numeric Promotion
-	    if (ltd.isByte()||ltd.isShort()||ltd.isInt())
-		lefttype=new TypeDescriptor(TypeDescriptor.INT);
-	    else
-		lefttype=ltd;
-	    on.setLeftType(lefttype);
-	    on.setType(lefttype);
-	    break;
-	default:
-	    throw new Error(op.toString());
-	}
-   
-	if (td!=null)
-	    if (!typeutil.isSuperorType(td, on.getType())) {
-		System.out.println(td);
-		System.out.println(on.getType());
-		throw new Error("Type of rside not compatible with type of lside"+on.printNode(0));	
-	    }
-    }
-}