PatternMatch.cs

using System.Collections.Generic;
using System.Threading.Tasks;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
 
namespace Waher.Script.Operators
{
    public class PatternMatch : BinaryOperator
    {
        public PatternMatch(ScriptNode Left, ScriptNode Right, int Start, int Length, Expression Expression)
            : base(Left, Right, Start, Length, Expression)
        {
        }
 
        public override IElement Evaluate(Variables Variables)
        {
            IElement Result = this.right.Evaluate(Variables);
            Match(this.left, Result, Variables, this);
            return Result;
        }
 
        public override async Task<IElement> EvaluateAsync(Variables Variables)
        {
            if (!this.isAsync)
                return this.Evaluate(Variables);
 
            IElement Result = await this.right.EvaluateAsync(Variables);
            Match(this.left, Result, Variables, this);
            return Result;
        }
        public static void Match(ScriptNode Branch, IElement Value, Variables Variables, ScriptNode Node)
        {
            Dictionary<string, IElement> AlreadyFound = new Dictionary<string, IElement>();
 
            switch (Branch.PatternMatch(Value, AlreadyFound))
            {
                case PatternMatchResult.Match:
                    foreach (KeyValuePair<string, IElement> P in AlreadyFound)
                        Variables[P.Key] = P.Value;
                    break;
 
                case PatternMatchResult.NoMatch:
                    throw new ScriptRuntimeException("Pattern mismatch.", Node);
 
                case PatternMatchResult.Unknown:
                default:
                    throw new ScriptRuntimeException("Unable to compute pattern match.", Node);
            }
        }
    }
}