/// <summary>
/// Does not print LHS
/// </summary>
void PrintUpdateRHS(ConcreteUpdateStatement s) {
Contract.Requires(s != null);
if (s is UpdateStmt) {
var update = (UpdateStmt)s;
if (update.Lhss.Count != 0) {
wr.Write(" := ");
}
var sep = "";
foreach (var rhs in update.Rhss) {
wr.Write(sep);
PrintRhs(rhs);
sep = ", ";
}
} else if (s is AssignSuchThatStmt) {
var update = (AssignSuchThatStmt)s;
wr.Write(" :| ");
if (update.AssumeToken != null) {
wr.Write("assume ");
}
PrintExpression(update.Expr, true);
} else {
Contract.Assert(s == null); // otherwise, unknown type
}
}
// Checks that statement stmt, defined in the constructed module m, is a refinement of skip in the parent module
void CheckIsOkayUpdateStmt(ConcreteUpdateStatement stmt, ModuleDefinition m)
{
foreach (var lhs in stmt.Lhss) {
var l = lhs.Resolved;
if (l is IdentifierExpr) {
var ident = (IdentifierExpr)l;
Contract.Assert(ident.Var is LocalVariable || ident.Var is Formal); // LHS identifier expressions must be locals or out parameters (ie. formals)
if ((ident.Var is LocalVariable && RefinementToken.IsInherited(((LocalVariable)ident.Var).Tok, m)) || ident.Var is Formal) {
// for some reason, formals are not considered to be inherited.
reporter.Error(MessageSource.RefinementTransformer, l.tok, "refinement method cannot assign to variable defined in parent module ('{0}')", ident.Var.Name);
}
} else if (l is MemberSelectExpr) {
var member = ((MemberSelectExpr)l).Member;
if (RefinementToken.IsInherited(member.tok, m)) {
reporter.Error(MessageSource.RefinementTransformer, l.tok, "refinement method cannot assign to a field defined in parent module ('{0}')", member.Name);
}
} else {
// must be an array element
reporter.Error(MessageSource.RefinementTransformer, l.tok, "new assignments in a refinement method can only assign to state that the module defines (which never includes array elements)");
}
}
if (stmt is UpdateStmt) {
var s = (UpdateStmt)stmt;
foreach (var rhs in s.Rhss) {
if (rhs.CanAffectPreviouslyKnownExpressions) {
reporter.Error(MessageSource.RefinementTransformer, rhs.Tok, "assignment RHS in refinement method is not allowed to affect previously defined state");
}
}
}
}
