/// <summary>
/// Evaluate object[index]
/// </summary>
/// <returns></returns>
public object VisitIndex(IndexExpr expr)
{
var ndxVal = expr.IndexExp.Evaluate(this);
var listObject = expr.VarExp.Evaluate(this);
// Check for empty objects.
ExceptionHelper.NotNull(expr, listObject, "indexing");
ExceptionHelper.NotNull(expr, ndxVal, "indexing");
var lobj = (LObject)listObject;
// CASE 1. Access
// e.g. Array: users[0]
// e.g. Map: users['total']
if (!expr.IsAssignment)
{
var result = EvalHelper.AccessIndex(Ctx.Methods, expr, lobj, (LObject)ndxVal);
return result;
}
// CASE 2. Assignment
// e.g. Array: users[0] = 'john'
// e.g. Map: users['total'] = 200
// NOTE: In this case of assignment, return back a MemberAccess object descripting what is assign
var indexAccess = new IndexAccess();
indexAccess.Instance = lobj;
indexAccess.MemberName = (LObject)ndxVal;
return indexAccess;
}
/// <summary>
/// Creates an index expression from the parameters supplied.
/// </summary>
/// <param name="varExp"></param>
/// <param name="indexExp"></param>
/// <param name="isAssignment"></param>
/// <param name="token"></param>
/// <returns></returns>
public static Expr Index(Expr varExp, Expr indexExp, bool isAssignment, TokenData token)
{
var exp = new IndexExpr();
exp.IsAssignment = isAssignment;
exp.VarExp = varExp;
exp.IndexExp = indexExp;
SetupContext(exp, token);
return exp;
}
/// <summary>
/// Visits the function call expression tree
/// </summary>
/// <param name="exp"></param>
public object VisitIndex(IndexExpr exp)
{
_callBackOnNodeStart(exp);
_callBackOnNodeStart(exp.VarExp);
_callBackOnNodeStart(exp.IndexExp);
return null;
}
