StringValue.cs

using System;
using System.Reflection;
using Waher.Script.Abstraction.Sets;
using Waher.Script.Abstraction.Elements;
using Waher.Runtime.Collections;
using Waher.Script.Model;
 
namespace Waher.Script.Objects
{
    public sealed class StringValue : SemiGroupElement
    {
        private static readonly StringValues associatedSemiGroup = new StringValues();
        private static readonly CaseInsensitiveStringValues associatedSemiGroupCis = new CaseInsensitiveStringValues();
 
        private string value;
        private string valueLower = null;
        private bool caseInsensitive;
 
        public StringValue(string Value)
        {
            this.value = Value;
            this.caseInsensitive = false;
        }
 
        public StringValue(string Value, bool CaseInsensitive)
        {
            this.value = Value;
            this.caseInsensitive = CaseInsensitive;
        }
 
        public string Value
        {
            get => this.value;
            set => this.value = value;
        }
 
        public bool CaseInsensitive
        {
            get => this.caseInsensitive;
            set => this.caseInsensitive = value;
        }
 
        public override string ToString()
        {
            return Expression.EncodeString(this.value);
        }
 
        public override ISemiGroup AssociatedSemiGroup
        {
            get
            {
                if (this.caseInsensitive)
                    return associatedSemiGroupCis;
                else
                    return associatedSemiGroup;
            }
        }
 
        public override object AssociatedObjectValue => this.value;
 
        public override ISemiGroupElement AddLeft(ISemiGroupElement Element)
        {
            if (Element.IsScalar)
                return new StringValue(ScriptNode.ToString(Element) + this.value, this.caseInsensitive);
            else
            {
                ChunkedList<IElement> Elements = new ChunkedList<IElement>();
                ISemiGroupElement SE;
 
                foreach (IElement E in Element.ChildElements)
                {
                    SE = E as ISemiGroupElement;
                    if (SE is null)
                        Elements.Add(new StringValue(ScriptNode.ToString(E) + this.value, this.caseInsensitive));
                    else
                        Elements.Add(this.AddLeft(SE));
                }
 
                return (ISemiGroupElement)Element.Encapsulate(Elements, null);
            }
        }
 
        public override ISemiGroupElement AddRight(ISemiGroupElement Element)
        {
            if (Element.IsScalar)
                return new StringValue(this.value + ScriptNode.ToString(Element), this.caseInsensitive);
            else
            {
                ChunkedList<IElement> Elements = new ChunkedList<IElement>();
                ISemiGroupElement SE;
 
                foreach (IElement E in Element.ChildElements)
                {
                    SE = E as ISemiGroupElement;
                    if (SE is null)
                        Elements.Add(new StringValue(this.value + ScriptNode.ToString(E), this.caseInsensitive));
                    else
                        Elements.Add(this.AddRight(SE));
                }
 
                return (ISemiGroupElement)Element.Encapsulate(Elements, null);
            }
        }
 
        public override bool Equals(object obj)
        {
            if (obj is StringValue S)
                return string.Compare(this.value, S.value, this.caseInsensitive || S.caseInsensitive) == 0;
 
            if (!(obj is IElement E))
                return false;
 
            if (!(E.AssociatedObjectValue is string s))
                return false;
 
            return string.Compare(this.value, s, this.caseInsensitive) == 0;
        }
 
        public override int GetHashCode()
        {
            if (this.caseInsensitive)
            {
                if (this.valueLower is null)
                    this.valueLower = this.value.ToLower();
 
                return this.valueLower.GetHashCode();
            }
            else
                return this.value.GetHashCode();
        }
 
        public override bool TryConvertTo(Type DesiredType, out object Value)
        {
            if (DesiredType == typeof(string))
            {
                Value = this.value;
                return true;
            }
            else if (DesiredType == typeof(char))
            {
                if (this.value.Length == 1)
                {
                    Value = this.value[0];
                    return true;
                }
                else
                {
                    Value = null;
                    return false;
                }
            }
            else if (DesiredType.IsAssignableFrom(typeof(string).GetTypeInfo()))
            {
                Value = this.value;
                return true;
            }
            else if (DesiredType.IsAssignableFrom(typeof(StringValue).GetTypeInfo()))
            {
                Value = this;
                return true;
            }
            else
                return Expression.TryConvert(this.value, DesiredType, true, out Value);
        }
 
        public static readonly StringValue Empty = new StringValue(string.Empty);
    }
}