public override Expression VisitExprSlice([NotNull] LogicScriptParser.ExprSliceContext context)
{
// Create a new unbounded expression visitor, since we only care about the slice length, not the operand's
var operand = new ExpressionVisitor(Context).Visit(context.expression());
var start = context.indexer().lr?.Text switch
{
">" => IndexStart.Right,
"<" or null => IndexStart.Left,
_ => throw new ParseException("Unknown index start position", context.indexer().Span())
};
Expression offset;
if (context.indexer().offset == null)
{
Context.Errors.AddError("Missing indexer offset", context.indexer().Span());
offset = new NumberLiteralExpression(context.indexer().Span(), BitsValue.Zero);
}
else
{
offset = new ExpressionVisitor(Context).Visit(context.indexer().offset);
}
var length = context.indexer().len == null ? 1 : context.indexer().len.GetConstantValue(Context.Outer);
var sliceExpr = new SliceExpression(context.Span(), operand, start, offset, length);
if (length == 0)
{
Context.Errors.AddError("Slice length cannot be zero", context.indexer().len.Span());
}
if (offset.IsConstant)
{
//TODO Figure out the logic for left-indexed slices
var offsetValue = (int)offset.GetConstantValue().Number;
if (offsetValue >= operand.BitSize)
{
Context.Errors.AddError("Offset is out of bounds", context.indexer().offset.Span());
}
if (offsetValue + length > operand.BitSize)
{
Context.Errors.AddError("Slice is out of bounds", context.indexer().Span());
}
}
if (MaxBitSize != 0 && length > MaxBitSize)
{
Context.Errors.AddError($"Cannot fit a {length} bits long number into {MaxBitSize} bits", sliceExpr);
}
return(sliceExpr);
}
public BitsValue Visit(Expression expr)
{
return(expr switch
{
NumberLiteralExpression lit => lit.Value,
BinaryOperatorExpression binOp => Visit(binOp),
ReferenceExpression refExpr => Visit(refExpr),
TernaryOperatorExpression tern => Visit(tern),
UnaryOperatorExpression unary => Visit(unary),
TruncateExpression trunc => Visit(trunc),
SliceExpression slice => Visit(slice),
_ => throw new InterpreterException("Unknown expression", expr.Span.Start),
});
private Expression DoExpression(bool doOperator = true)
{
Expression ret = null;
if (Take(LexemeKind.LeftParenthesis, out _))
{
ret = DoExpression();
if (Take(LexemeKind.QuestionMark, out _))
{
ret = DoTernaryOperator(ret);
}
Take(LexemeKind.RightParenthesis, "closing parentheses");
}
else if (Take(LexemeKind.String, out var str))
{
if (float.TryParse(str.Content, NumberStyles.Float, CultureInfo.InvariantCulture, out var f))
{
ret = new NumberLiteralExpression(f);
}
else if (Current.Kind == LexemeKind.Exclamation)
{
ret = DoFunctionCall(str.Content);
}
else
{
if (Current.Kind == LexemeKind.LeftParenthesis)
{
ret = DoCommandExpression(str.Content);
}
else
{
Error($"unxpected string '{str.Content}' found");
}
}
}
else if (Take(LexemeKind.QuotedString, out var quotedStr))
{
ret = new StringLiteralExpression(quotedStr.Content);
}
else if (Take(LexemeKind.Exclamation, out _))
{
ret = DoNegateOperator();
}
else if (Take(LexemeKind.Keyword, out var keyword))
{
if (keyword.Content == "null")
{
ret = new NullExpression();
}
else if (keyword.Content == "true")
{
ret = new BooleanLiteralExpression(true);
}
else if (keyword.Content == "false")
{
ret = new BooleanLiteralExpression(false);
}
else
{
Error($"unexpected keyword: '{keyword.Content}'");
}
}
else if (Take(LexemeKind.Dollar, out _))
{
Push();
if (Take(LexemeKind.String, out _) && Take(LexemeKind.EqualsAssign, out _))
{
Pop();
ret = DoVariableAssign();
}
else
{
Pop();
string name = Take(LexemeKind.String, "variable name").Content;
ret = new VariableAccessExpression(name);
if (Take(LexemeKind.Increment, out _))
{
ret = new UnaryOperatorExpression(Operator.IncrementByOne, ret);
}
else if (Take(LexemeKind.Decrement, out _))
{
ret = new UnaryOperatorExpression(Operator.DecrementByOne, ret);
}
}
}
while (Take(LexemeKind.Dot, out _))
{
ret = new MemberAccessExpression(ret, Take(LexemeKind.String, "member name").Content);
if (Take(LexemeKind.Exclamation, out _))
{
ret = DoMemberCall(ret);
}
}
if (ret != null && doOperator)
{
ret = Take(LexemeKind.QuestionMark, out _)
? DoTernaryOperator(ret)
: (DoOperatorChain(ret) ?? ret);
}
return(ret);
}
public override object Visit(NumberLiteralExpression ex)
{
return(ex.Value);
}
public virtual object Visit(NumberLiteralExpression ex)
{
return(null);
}
private void Visit(NumberLiteralExpression expr)
{
LoadBitsValue(expr.Value);
}
public override object Visit(NumberLiteralExpression ex)
{
return(DataType.Number);
}