/// <summary>
/// run step 123.
/// </summary>
/// <returns></returns>
public override Expr Parse()
{
var startToken = _tokenIt.NextToken;
var conditionToken = startToken;
var assignToken = startToken;
var incToken = startToken;
var loopToken = startToken;
var varToken = startToken;
_tokenIt.ExpectIdText("repeat");
Expr varnameExpr = null;
Expr startVal = null;
Expr endVal = null;
Expr incVal = null;
Operator op = Operator.LessThanEqual;
// Case 1: repeat to 10
if (_tokenIt.NextToken.Token.Text == "to")
{
var result = ParseTo();
startVal = Exprs.Const(new LNumber(1.0), startToken);
op = result.Item1;
endVal = result.Item2;
incVal = result.Item3;
}
// Case 2: repeat 1 to 10
else if (_tokenIt.NextToken.Token.Kind == TokenKind.LiteralNumber)
{
var num = _tokenIt.ExpectNumber();
var result = ParseTo();
startVal = Exprs.Const(new LNumber(num), startToken);
op = result.Item1;
endVal = result.Item2;
incVal = result.Item3;
}
// Case 3: repeat ndx to 10
else if (_tokenIt.NextToken.Token.Kind == TokenKind.Ident)
{
var variableName = _tokenIt.ExpectId();
varnameExpr = Exprs.Ident(variableName, _tokenIt.LastToken);
if (_tokenIt.NextToken.Token.Type == TokenTypes.Assignment)
{
_tokenIt.Advance();
// Upto "to"
startVal = ParseExpr(_terminatorForTo);
}
else
{
startVal = Exprs.Const(new LNumber(0), startToken);
}
var result = ParseTo();
op = result.Item1;
endVal = result.Item2;
incVal = result.Item3;
}
// auto-create variable name.
if (varnameExpr == null)
{
varnameExpr = Exprs.Ident("it", _tokenIt.LastToken);
}
// Now setup the stmts
var start = Exprs.Assign(true, varnameExpr, startVal, varToken);
var condition = Exprs.Compare(varnameExpr, op, endVal, varToken);
var incExp = Exprs.Unary(varnameExpr.ToQualifiedName(), incVal, 0, Operator.PlusEqual, incToken);
var incStmt = Exprs.Assign(false, varnameExpr, incExp, assignToken);
var loopStmt = Exprs.For(start, condition, incStmt, loopToken);
ParseBlock(loopStmt as BlockExpr);
return(loopStmt);
}
