ANTLR PlSqlParser VisitAssignment_statement override

VisitAssignment_statement.cs

private static readonly Regex _reFrom = new Regex(@"[\n\r\s]+FROM[\n\r\s]+");

public override object VisitAssignment_statement(PlSqlParser.Assignment_statementContext context)
{
    if (context.general_element().GetText() is var varName && !_assignments.ContainsKey(varName))
    {
        var selectQuery = context.expression().GetText().Trim('\'').Trim();

        if (selectQuery.StartsWith("SELECT", StringComparison.InvariantCultureIgnoreCase) ||
            selectQuery.StartsWith("WITH", StringComparison.InvariantCultureIgnoreCase))
        {
            if (selectQuery.LastIndexOf("WHERE", StringComparison.InvariantCultureIgnoreCase) is var i and >0)
            {
                selectQuery = selectQuery.Substring(0, i)
                    .Replace("''", "'");
            }

            if (!_reFrom.IsMatch(selectQuery))
            {
                selectQuery = $"{selectQuery} FROM X";
            }

            _assignments.Add(varName, selectQuery);
        }
    }

    return null;
}