bool?If_SymbolExists(ConditionalDirective directive)
{
if (directive.condition.IsNullOrEmpty)
{
return(null);
}
return(Values.NameExists(directive.condition.ToString()));
}
bool?If_EvalCondition(ConditionalDirective directive, out Error error)
{
error = Error.None;
if (directive.condition.IsNullOrEmpty)
{
return(null);
}
var condition = directive.condition;
var result = Assembler.Evaluator.EvaluateExpression(ref condition, directive.SourceLine, out error);
if (error.IsError)
{
error = new Error(error, directive.SourceLine);
}
return((int)result.Value != 0);
}
internal void ProcessIfBlockDirective(ConditionalDirective directive, out Error error)
{
error = Error.None;
bool?ifCondition;
switch (directive.part)
{
case ConditionalDirective.ConditionalPart.IF:
// We must note IFs in excluded code to respect nesting (avoid misinterpreting inner ENDIF)
if (InExcludedCode)
{
If_EnterExcludedIf();
}
else
{
ifCondition = If_EvalCondition(directive, out error);
if (error.IsError)
{
return;
}
if (ifCondition == null)
{
error = new Error(ErrorCode.If_Missing_Condition, Error.Msg_MissingCondition, directive.SourceLine);
return;
}
If_EnterIf((bool)ifCondition);
}
break;
case ConditionalDirective.ConditionalPart.ELSEIF:
// We can treat else/else if like it is not in excluded code (if it IS in excluded code, it will look as if
// we already had a block executed, so the else/elseif won't be processed.)
if (!inIfStack)
{
error = new Error(ErrorCode.Missing_Preceeding_If, Error.Msg_NoPreceedingIf, directive.SourceLine);
return;
}
bool considerElseIf = !ifStack.Peek().foundCase; // Has a previous block been executed? (We only process an else if it hasn't)
if (considerElseIf)
{
ifCondition = If_EvalCondition(directive, out error);
if (error.IsError)
{
return;
}
if (ifCondition == null)
{
error = new Error(ErrorCode.If_Missing_Condition, Error.Msg_MissingCondition, directive.SourceLine);
return;
}
If_EnterElse((bool)ifCondition);
}
break;
case ConditionalDirective.ConditionalPart.ELSE:
// We can treat else/else if like it is not in excluded code (if it IS in excluded code, it will look as if
// we already had a block executed, so the else/elseif won't be processed.)
if (!inIfStack)
{
error = new Error(ErrorCode.Missing_Preceeding_If, Error.Msg_NoPreceedingIf, directive.SourceLine);
return;
}
bool runElse = !ifStack.Peek().foundCase; // Has a previous block been executed? (We only process an else if it hasn't)
if (!directive.condition.IsNullOrEmpty)
{
error = new Error(ErrorCode.Unexpected_Text, Error.Msg_NoTextExpected, directive.SourceLine);
return;
}
If_EnterElse(runElse);
break;
case ConditionalDirective.ConditionalPart.IFDEF:
// We must note IFs in excluded code to respect nesting (avoid misinterpreting inner ENDIF)
if (InExcludedCode)
{
If_EnterExcludedIf();
}
else
{
ifCondition = If_SymbolExists(directive);
if (ifCondition == null)
{
error = new Error(ErrorCode.If_Missing_Condition, Error.Msg_MissingCondition, directive.SourceLine);
return;
}
If_EnterIf((bool)ifCondition);
}
break;
case ConditionalDirective.ConditionalPart.IFNDEF:
// We must note IFs in excluded code to respect nesting (avoid misinterpreting inner ENDIF)
if (InExcludedCode)
{
If_EnterExcludedIf();
}
else
{
ifCondition = If_SymbolExists(directive);
if (ifCondition == null)
{
error = new Error(ErrorCode.If_Missing_Condition, Error.Msg_MissingCondition, directive.SourceLine);
return;
}
If_EnterIf(!(bool)ifCondition);
}
break;
case ConditionalDirective.ConditionalPart.ENDIF:
If_CloseIf();
break;
default:
error = new Error(ErrorCode.Engine_Error, "Unexpected IF block tiye in Pass.ProcessIfBlockDirective");
break;
}
}