RecordParser.cs

using Waher.Script.Model;
using Waher.Script.Operators;
 
namespace Waher.Script.Persistence.SQL.Parsers
{
    public enum RecordOperation
    {
        New,
 
        Update,
 
        Delete
    }
 
    public class RecordParser : IKeyWord
    {
        public RecordParser()
        {
        }
 
        public string KeyWord => "RECORD";
 
        public string[] Aliases => null;
 
        public string[] InternalKeywords => new string[] 
        { 
            "INTO", 
            "NEW", 
            "UPDATE",
            "DELETE",
            "OBJECT", 
            "OBJECTS" 
        };
 
        public bool TryParse(ScriptParser Parser, out ScriptNode Result)
        {
            Result = null;
 
            string s = Parser.NextToken().ToUpper();
 
            if (s != "INTO")
                return false;
 
            if (!SelectParser.TryParseSources(Parser, out SourceDefinition Source))
                return false;
 
            RecordOperation? Operation = null;
 
            while (true)
            {
                switch (Parser.PeekNextToken().ToUpper())
                {
                    case "NEW":
                        if (Operation.HasValue)
                            return false;
 
                        Parser.NextToken();
                        Operation = RecordOperation.New;
                        continue;
 
                    case "UPDATE":
                        if (Operation.HasValue)
                            return false;
 
                        Parser.NextToken();
                        Operation = RecordOperation.Update;
                        continue;
 
                    case "DELETE":
                        if (Operation.HasValue)
                            return false;
 
                        Parser.NextToken();
                        Operation = RecordOperation.Delete;
                        continue;
 
                    case "OBJECT":
                    case "OBJECTS":
                        Parser.NextToken();
 
                        ScriptNode Node = Parser.ParseList();
                        if (!(Node is ElementList Objects))
                            Objects = new ElementList(new ScriptNode[] { Node }, Node.Start, Node.Length, Node.Expression);
 
                        Result = new RecordObjects(Source, Operation ?? RecordOperation.New,
                            Objects, Parser.Start, Parser.Length, Parser.Expression);
                        return true;
 
                    default:
                        return false;
                }
            }
        }
 
    }
}