DropParser.cs

using System;
using Waher.Script.Model;
 
namespace Waher.Script.Persistence.SQL.Parsers
{
    public class DropParser : IKeyWord
    {
        public DropParser()
        {
        }
 
        public string KeyWord => "DROP";
 
        public string[] Aliases => null;
 
        public string[] InternalKeywords => new string[] 
        { 
            "INDEX", 
            "ON" 
        };
 
        public bool TryParse(ScriptParser Parser, out ScriptNode Result)
        {
            Result = null;
 
            string s = Parser.NextToken().ToUpper();
            switch (s)
            {
                case "INDEX":
                    ScriptNode Name = Parser.ParseNoWhiteSpace();
 
                    s = Parser.NextToken().ToUpper();
                    if (s != "ON")
                        return false;
 
                    if (!SelectParser.TryParseSources(Parser, out SourceDefinition Source))
                        return false;
 
                    Result = new DropIndex(Name, Source, Parser.Start, Parser.Length, Parser.Expression);
 
                    return true;
 
                case "TABLE":
                case "COLLECTION":
                    if (!SelectParser.TryParseSources(Parser, out Source))
                        return false;
 
                    Result = new DropCollection(Source, Parser.Start, Parser.Length, Parser.Expression);
 
                    return true;
 
                default:
                    return false;
            }
        }
 
    }
}