/// <summary>
/// Assign a value to an expression.
/// </summary>
/// <param name="expr">The assignment expressions</param>
/// <returns></returns>
public object VisitAssign(AssignExpr expr)
{
var ctx = expr.Ctx;
var varExpr = expr.VarExp;
var valueExpr = expr.ValueExp;
var node = expr;
var isDeclaration = expr.IsDeclaration;
// CASE 1: Assign variable. a = 1
if (varExpr.IsNodeType(NodeTypes.SysVariable))
{
AssignHelper.SetVariableValue(ctx, this, node, isDeclaration, varExpr, valueExpr);
}
// CASE 2: Assign member.
// e.g. dictionary : user.name = 'kishore'
// e.g. property on class: user.age = 20
else if (varExpr.IsNodeType(NodeTypes.SysMemberAccess))
{
AssignHelper.SetMemberValue(ctx, this, node, varExpr, valueExpr);
}
// Case 3: Assign value to index: "users[0]" = <expression>;
else if (varExpr.IsNodeType(NodeTypes.SysIndex))
{
AssignHelper.SetIndexValue(ctx, this, node, varExpr, valueExpr);
}
return LObjects.Null;
}
/// <summary>
/// Visits the var statement tree.
/// </summary>
/// <param name="assignExpr"></param>
public object VisitAssign(AssignExpr expr)
{
_callBackOnNodeStart(expr);
expr.VarExp.Visit(this);
if (expr.ValueExp != null)
expr.ValueExp.Visit(this);
return null;
}
/// <summary>
/// Creates a unary expression with symbol scope, context, script refernce set.
/// </summary>
/// <param name="name"></param>
/// <param name="token"></param>
/// <returns></returns>
public static Expr Assign(bool declare, Expr left, Expr right, TokenData token)
{
var exp = new AssignExpr();
exp.IsDeclaration = declare;
exp.VarExp = left;
exp.ValueExp = right;
SetupContext(exp, token);
return exp;
}
/// <summary>
/// Creates a unary expression with symbol scope, context, script refernce set.
/// </summary>
/// <param name="name"></param>
/// <param name="token"></param>
/// <returns></returns>
public Expr ToAssignExpr(bool declare, Expr left, Expr right, TokenData token)
{
var exp = new AssignExpr(declare, left, right);
this.SetupContext(exp, token);
return exp;
}
/// <summary>
/// Parses unary
/// 1. ndx++
/// 2. ndx--
/// 3. ndx += 2
/// 4. ndx -= 2
/// 5. ndx *= 2
/// 6. ndx /= 2
/// </summary>
/// <param name="name"></param>
/// <param name="useSemicolonAsTerminator"></param>
/// <returns></returns>
public Expr ParseUnary(string name, bool useSemicolonAsTerminator = true)
{
var idToken = _tokenIt.LastToken;
var opToken = _tokenIt.NextToken;
var op = Operators.ToOp(_tokenIt.NextToken.Token.Text);
AssignExpr stmt = null;
_tokenIt.Advance();
// 1. Create variable expression from the name
var nameExpr = this.ToIdentExpr(name, idToken);
// ++ --
if (_tokenIt.IsEndOfStmtOrBlock())
{
var unaryVal = this.ToUnaryExpr(name, null, 1.0, op, opToken);
stmt = new AssignExpr(false, nameExpr, unaryVal);
_tokenIt.ExpectEndOfStmt();
}
else // += -= *= -=
{
var endTokens = useSemicolonAsTerminator ? Terminators.ExpStatementEnd : Terminators.ExpParenthesisEnd;
var incExpr = ParseExpression(endTokens);
var unaryVal = this.ToUnaryExpr(name, incExpr, -1, op, opToken);
stmt = new AssignExpr(false, nameExpr, unaryVal);
}
this.SetupContext(stmt, idToken);
return stmt;
}
