private Expr ParseForLoop()
{
var stmt = new ForExpr();
var statements = new List <Expr>();
// While ( condition expression )
// Parse while condition
var start = _parser.ParseStatement();
var condition = _parser.ParseExpression(Terminators.ExpSemicolonEnd);
_tokenIt.Advance();
string name = _tokenIt.ExpectId();
var increment = _parser.ParseUnary(name, false);
_tokenIt.Expect(Tokens.RightParenthesis);
stmt.Init(start, condition, increment);
ParseBlock(stmt);
return(stmt);
}
/// <summary>
/// run step 123.
/// </summary>
/// <returns></returns>
public override Expr Parse()
{
var startToken = _tokenIt.NextToken;
_tokenIt.ExpectIdText("repeat");
Expr varname = 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 = new ConstantExpr(1.0);
_parser.SetScriptPosition(startVal, 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 = new ConstantExpr(num);
_parser.SetScriptPosition(startVal, 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();
varname = new VariableExpr(variableName);
_parser.SetScriptPosition(varname, startToken);
if (_tokenIt.NextToken.Token.Type == TokenTypes.Assignment)
{
_tokenIt.Advance();
// Upto "to"
startVal = ParseExpr(_terminatorForTo);
}
else
{
startVal = new ConstantExpr(0);
_parser.SetScriptPosition(startVal, startToken);
}
var result = ParseTo();
op = result.Item1;
endVal = result.Item2;
incVal = result.Item3;
}
// auto-create variable name.
if (varname == null)
{
varname = new VariableExpr("it");
_parser.SetScriptPosition(varname, startToken);
}
// Now setup the stmts
var ctx = _parser.Context;
var startStmt = new AssignExpr(true, varname, startVal);
_parser.SetScriptPositionFromNode(startStmt, varname);
startStmt.Ctx = ctx;
var condition = new CompareExpr(varname, op, endVal);
_parser.SetScriptPositionFromNode(condition, endVal);
varname.Ctx = ctx;
condition.Ctx = ctx;
var incExp = new UnaryExpr(varname.ToQualifiedName(), incVal, Operator.PlusEqual, _parser.Context);
_parser.SetScriptPositionFromNode(incExp, incVal);
var incStmt = new AssignExpr(false, new VariableExpr(varname.ToQualifiedName()), incExp);
_parser.SetScriptPositionFromNode(incStmt, incExp);
incStmt.Ctx = ctx;
var loopStmt = new ForExpr(startStmt, condition, incStmt);
ParseBlock(loopStmt);
return(loopStmt);
}
