public override Expression VisitBasicExpression(BasicExpressionNode node)
{
// First, try to encode inline loop
Expression result = this.EncodeInlinedLoop(node);
if (result != null)
{
return(result);
}
// X3J20 definition: basic_expression ::= primary [messages cascaded_messages].
PrimaryVisitor visitor = new PrimaryVisitor(this);
result = node.Primary.Accept(visitor);
this.IsConstant = visitor.IsConstant;
if (node.Messages != null)
{
MessageVisitor messageVisitor = new MessageVisitor(this, result, visitor.IsSuperSend, this.IsConstant, (node.CascadeMessages != null));
result = node.Messages.Accept(messageVisitor);
this.IsConstant = false; // After first message send, we are no longer a constant
// Cascade messages ... this is handled by telling the message-visitor above that we have cascade messages
// and need the receiver for cascade messages. The message-visitor has created a temporary variable for us
// that contains the result of the next-last message (i.e. the receiver for cascade messages). It has
// also noted if the send for that receiver was a super-send and if it is constant (for optimization).
CascadeMessageSequenceNode cascade = node.CascadeMessages;
if (cascade != null)
{
List <Expression> cascadeExpressions = new List <Expression>();
cascadeExpressions.Add(result);
while (cascade != null)
{
// Loop and process each cascade in the cascade chain. There is nothing special here.
// The receiver, self/super send etc. is determined from the visitor of the original message send.
// We create new message-visitor for each cascade iteration, which has fresh receiver
// and other parameters. The result of the cascade messages is added to an expression list,
// which is converted to expression block. The block fulfills the semantics that the last
// expression in the list caries the result of the evaluation (same as required for sacsades).
MessageVisitor cascadeVisitor = new MessageVisitor(this,
messageVisitor.CascadeReceiver, messageVisitor.CascadeSuperSend, messageVisitor.CascadeConstantReceiver, false);
cascadeExpressions.Add(cascade.Messages.Accept(cascadeVisitor));
cascade = cascade.NextCascade;
}
result = Expression.Block(typeof(object), new ParameterExpression[] { messageVisitor.CascadeReceiver }, cascadeExpressions);
}
}
else if (visitor.IsSuperSend)
{
throw (new SemanticCodeGenerationException(CodeGenerationErrors.SuperNotFollowedByMessage)).SetErrorLocation(node);
}
return(result);
}
public override Expression VisitKeywordArgument(Compiler.SemanticNodes.KeywordArgumentNode node)
{
PrimaryVisitor visitor = new PrimaryVisitor(this);
Expression result = node.Primary.Accept(visitor);
if (node.Messages != null)
{
result = node.Messages.Accept(new MessageVisitor(this, result, visitor.IsSuperSend, visitor.IsConstant, false));
}
else if (visitor.IsSuperSend)
{
throw (new SemanticCodeGenerationException(CodeGenerationErrors.SuperNotFollowedByMessage)).SetErrorLocation(node);
}
return(result);
}
