InsertParser.cs

using System;
using Waher.Script.Model;
using Waher.Script.Operators;
 
namespace Waher.Script.Persistence.SQL.Parsers
{
    public class InsertParser : IKeyWord
    {
        public InsertParser()
        {
        }
 
        public string KeyWord => "INSERT";
 
        public string[] Aliases => null;
 
        public string[] InternalKeywords => new string[] 
        { 
            "LAZY", 
            "INTO", 
            "VALUES", 
            "OBJECT", 
            "OBJECTS" 
        };
 
        public bool TryParse(ScriptParser Parser, out ScriptNode Result)
        {
            Result = null;
 
            string s = Parser.NextToken().ToUpper();
            bool Lazy = s == "LAZY";
 
            if (Lazy)
                s = Parser.NextToken().ToUpper();
 
            if (s != "INTO")
                return false;
 
            if (!SelectParser.TryParseSources(Parser, out SourceDefinition Source))
                return false;
 
            switch (Parser.PeekNextToken().ToUpper())
            {
                case "(":
                    Parser.NextToken();
 
                    ScriptNode Node = Parser.ParseList();
                    if (!(Node is ElementList Columns))
                        Columns = new ElementList(new ScriptNode[] { Node }, Node.Start, Node.Length, Node.Expression);
 
                    if (Parser.NextToken() != ")")
                        return false;
 
                    if (string.Compare(Parser.NextToken(), "VALUES", true) != 0)
                        return false;
 
                    if (Parser.NextToken() != "(")
                        return false;
 
                    Node = Parser.ParseList();
                    if (!(Node is ElementList Values))
                        Values = new ElementList(new ScriptNode[] { Node }, Node.Start, Node.Length, Node.Expression);
 
                    if (Values.Elements.Length != Columns.Elements.Length)
                        return false;
 
                    if (Parser.NextToken() != ")")
                        return false;
 
                    Result = new InsertValues(Source, Columns, Values, Lazy, Parser.Start, Parser.Length, Parser.Expression);
                    return true;
 
                case "SELECT":
                    Node = Parser.ParseStatement();
                    if (!(Node is Select Select))
                        return false;
 
                    Result = new InsertSelect(Source, Select, Lazy, Parser.Start, Parser.Position, Parser.Expression);
                    return true;
 
                case "OBJECT":
                case "OBJECTS":
                    Parser.NextToken();
 
                    Node = Parser.ParseList();
                    if (!(Node is ElementList Objects))
                        Objects = new ElementList(new ScriptNode[] { Node }, Node.Start, Node.Length, Node.Expression);
 
                    Result = new InsertObjects(Source, Objects, Lazy, Parser.Start, Parser.Length, Parser.Expression);
                    return true;
 
                default:
                    return false;
            }
        }
 
    }
}