Collect the errors for a node recursively. public void ASTNode.collectErrors(Collection c) { for(int i = 0; i < getNumChild(); i++) getChild(i).collectErrors(c); } public void AssignStmt.collectErrors(Collection c) { super.collectErrors(c); if(!getValue().type().isSubtypeOf(getVariable().type())) error(c, "Can not assign a variable of type " + getVariable().type().getName() + " to a value of type " + getValue().type().getName()); } public void ClassDecl.collectErrors(Collection c) { super.collectErrors(c); if(hasCycleOnSuperclassChain()) error(c, "Cyclic inheritance chain for class " + getName()); } public void WhileStmt.collectErrors(Collection c) { super.collectErrors(c); if(!getCondition().type().isSubtypeOf(booleanType())) error(c, "Condition must be a boolean expression"); if(!getCondition().isValue()) error(c, "Condition must be a value"); } public void IdUse.collectErrors(Collection c) { super.collectErrors(c); if(decl().isUnknown() && (!isQualified() || !qualifier().type().isUnknown())) error(c, "Unknown identifier " + getName()); }

All of the error messages for a program. public Collection Program.errors() { Collection c = new ArrayList(); collectErrors(c); return c; }

Is this entity qualified? eq Program.getBlock().isQualified() = false; eq Program.getPredefinedType(int i).isQualified() = false; eq Dot.getIdUse().isQualified() = true; inh boolean IdUse.isQualified(); inh boolean TypeDecl.isQualified();

What is the qualifier? eq Program.getBlock().qualifier() { throw new Error("Can not compute qualifier for non qualified names"); } eq Program.getPredefinedType(int i).qualifier() { throw new Error("Can not compute qualifier for non qualified names"); } eq Dot.getIdUse().qualifier() = getObjectReference(); inh Access IdUse.qualifier(); inh Access TypeDecl.qualifier();

Record a new error in the collection. protected void ASTNode.error(Collection c, String s) { //c.add(getLine(getStart()) + ": " + s); c.add(s); }