ExternalDatabase.cs

using System;
using System.Threading.Tasks;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Operators;
 
namespace Waher.Script.Data.Model
{
    public abstract class ExternalDatabase : IDatabaseConnection
    {
        public ExternalDatabase()
        {
        }
 
        public virtual void Dispose()
        {
        }
 
        public abstract Task<IElement> ExecuteSqlStatement(string Statement);
 
        public abstract Task<IElement> GetSchema(string Name);
 
        public abstract Task<ILambdaExpression> GetProcedure(string Name);
 
        public Task<ILambdaExpression> this[string Name] => this.GetProcedure(Name);
 
        public virtual int NrArguments => 1;
 
        public virtual string[] ArgumentNames => new string[] { "SQL" };
 
        public ArgumentType[] ArgumentTypes => argumentTypes1Parameters;
 
        private static readonly ArgumentType[] argumentTypes1Parameters = new ArgumentType[] { ArgumentType.Scalar };
 
        public bool IsAsynchronous => true;
 
        public IElement Evaluate(IElement[] Arguments, Variables Variables)
        {
            return this.EvaluateAsync(Arguments, Variables).Result;
        }
 
        public Task<IElement> EvaluateAsync(IElement[] Arguments, Variables Variables)
        {
            if (!(Arguments[0]?.AssociatedObjectValue is string SqlStatement))
                throw new ScriptRuntimeException("Argument must be a string.", null);
 
            return this.ExecuteSqlStatement(SqlStatement);
        }
 
        public override string ToString()
        {
            return LambdaDefinition.ToString(this);
        }
    }
}