DateTimeNode.cs

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using System;
using System.Globalization;
using VDS.RDF.Parsing;
using VDS.RDF.Query;
using VDS.RDF.Query.Expressions;

namespace VDS.RDF.Nodes
{
    /// <summary>
    /// Valued Node representing a Date Time value.
    /// </summary>
    public class DateTimeNode
        : LiteralNode, IValuedNode
    {
        private DateTime _value;
        private DateTimeOffset? _offsetValue;

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="lexicalValue">Lexical Value.</param>
        /// <param name="datatype">Datatype URI.</param>
        protected DateTimeNode(IGraph g, DateTimeOffset value, String lexicalValue, Uri datatype)
            : base(g, lexicalValue, datatype)
        {
            _value = value.UtcDateTime;
            _offsetValue = value;
        }

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="lexicalValue">Lexical Value.</param>
        /// <param name="datatype">Datatype URI.</param>
        protected DateTimeNode(IGraph g, DateTime value, String lexicalValue, Uri datatype)
            : base(g, lexicalValue, datatype)
        {
            _value = value;
            _offsetValue = null;
        }

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="datatype">Datatype URI.</param>
        protected DateTimeNode(IGraph g, DateTimeOffset value, Uri datatype)
            : this(g, value, GetStringForm(value, datatype), datatype) { }

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="datatype">Datatype URI.</param>
        protected DateTimeNode(IGraph g, DateTime value, Uri datatype)
            : this(g, value, GetStringForm(value, datatype), datatype) { }

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        public DateTimeNode(IGraph g, DateTimeOffset value)
            : this(g, value, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDateTime)) { }

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        public DateTimeNode(IGraph g, DateTime value)
            : this(g, value, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDateTime)) { }

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="lexicalValue">Lexical Value.</param>
        public DateTimeNode(IGraph g, DateTimeOffset value, String lexicalValue)
            : this(g, value, lexicalValue, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDateTime)) { }

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="lexicalValue">Lexical Value.</param>
        public DateTimeNode(IGraph g, DateTime value, String lexicalValue)
            : this(g, value, lexicalValue, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDateTime)) { }

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="offsetValue">Date Time offset value.</param>
        /// <param name="lexicalValue">Lexical Value.</param>
        public DateTimeNode(IGraph g, DateTime value, DateTimeOffset offsetValue, String lexicalValue)
            : this(g, value, offsetValue, lexicalValue, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDateTime)) { }

        /// <summary>
        /// Creates a new Date Time valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="offsetValue">Date Time offset value.</param>
        /// <param name="lexicalValue">Lexical Value.</param>
        /// <param name="datatype">Data Type URI.</param>
        public DateTimeNode(IGraph g, DateTime value, DateTimeOffset offsetValue, String lexicalValue, Uri datatype)
            : base(g, lexicalValue, datatype)
        {
            _value = value;
            _offsetValue = offsetValue;
        }

        /// <summary>
        /// Gets the String form of the Date Time.
        /// </summary>
        /// <param name="value">Value.</param>
        /// <param name="datatype">Datatype URI.</param>
        /// <returns></returns>
        private static String GetStringForm(DateTimeOffset value, Uri datatype)
        {
            switch (datatype.ToString())
            {
                case XmlSpecsHelper.XmlSchemaDataTypeDateTime:
                    return value.ToString(XmlSpecsHelper.XmlSchemaDateTimeFormat);
                case XmlSpecsHelper.XmlSchemaDataTypeDate:
                    return value.ToString(XmlSpecsHelper.XmlSchemaDateFormat);
                default:
                    throw new RdfQueryException("Unable to create a DateTimeNode because datatype URI is invalid");
            }
        }

        /// <summary>
        /// Gets the String form of the Date Time.
        /// </summary>
        /// <param name="value">Value.</param>
        /// <param name="datatype">Datatype URI.</param>
        /// <returns></returns>
        private static String GetStringForm(DateTime value, Uri datatype)
        {
            switch (datatype.ToString())
            {
                case XmlSpecsHelper.XmlSchemaDataTypeDateTime:
                    return value.ToString(XmlSpecsHelper.XmlSchemaDateTimeFormat);
                case XmlSpecsHelper.XmlSchemaDataTypeDate:
                    return value.ToString(XmlSpecsHelper.XmlSchemaDateFormat);
                default:
                    throw new RdfQueryException("Unable to create a DateTimeNode because datatype URI is invalid");
            }
        }

        /// <summary>
        /// Gets the date time value as a string.
        /// </summary>
        /// <returns></returns>
        public string AsString()
        {
            return Value;
        }

        /// <summary>
        /// Throws an error as date times cannot be converted to integers.
        /// </summary>
        /// <returns></returns>
        public long AsInteger()
        {
            throw new RdfQueryException("Cannot convert Date Times to other types");
        }

        /// <summary>
        /// Throws an error as date times cannot be converted to decimals.
        /// </summary>
        /// <returns></returns>
        public decimal AsDecimal()
        {
            throw new RdfQueryException("Cannot convert Date Times to other types");
        }

        /// <summary>
        /// Throws an error as date times cannot be converted to floats.
        /// </summary>
        /// <returns></returns>
        public float AsFloat()
        {
            throw new RdfQueryException("Cannot convert Date Times to other types");
        }

        /// <summary>
        /// Throws an error as date times cannot be converted to doubles.
        /// </summary>
        /// <returns></returns>
        public double AsDouble()
        {
            throw new RdfQueryException("Cannot convert Date Times to other types");
        }

        /// <summary>
        /// Throws an error as date times cannot be converted to booleans.
        /// </summary>
        /// <returns></returns>
        public bool AsBoolean()
        {
            throw new RdfQueryException("Cannot convert Date Times to other types");
        }

        /// <summary>
        /// Gets the date time value of the node.
        /// </summary>
        /// <returns></returns>
        public DateTime AsDateTime()
        {
            return _value;
        }

        /// <summary>
        /// Gets the date time value of the node.
        /// </summary>
        /// <returns></returns>
        public DateTimeOffset AsDateTimeOffset()
        {
            if (_offsetValue.HasValue)
            {
                return _offsetValue.Value;
            }
            else
            {
                // Create the offset
                DateTimeOffset offset;
                _offsetValue = DateTimeOffset.TryParse(Value, null, DateTimeStyles.AssumeUniversal, out offset)
                                        ? offset
                                        : new DateTimeOffset(_value);
                return _offsetValue.Value;
            }
        }

        /// <summary>
        /// Throws an error as date times cannot be cast to a time span.
        /// </summary>
        /// <returns></returns>
        public TimeSpan AsTimeSpan()
        {
            throw new RdfQueryException("Cannot convert Date Times to other types");
        }

        /// <summary>
        /// Gets the URI of the datatype this valued node represents as a String.
        /// </summary>
        public String EffectiveType
        {
            get
            {
                return DataType.AbsoluteUri;
            }
        }

        /// <summary>
        /// Gets the numeric type of the node.
        /// </summary>
        public SparqlNumericType NumericType
        {
            get 
            {
                return SparqlNumericType.NaN;
            }
        }
    }

    /// <summary>
    /// Valued Node representing a Date value.
    /// </summary>
    public class DateNode
        : DateTimeNode
    {
        /// <summary>
        /// Creates a new Date valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        public DateNode(IGraph g, DateTimeOffset value)
            : base(g, value, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDate)) { }

        /// <summary>
        /// Creates a new Date valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="lexicalValue">Lexical Value.</param>
        public DateNode(IGraph g, DateTimeOffset value, String lexicalValue)
            : base(g, value, lexicalValue, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDate)) { }

        /// <summary>
        /// Creates a new Date valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        public DateNode(IGraph g, DateTime value)
            : base(g, value, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDate)) { }

        /// <summary>
        /// Creates a new Date valued node.
        /// </summary>
        /// <param name="g">Graph the node belongs to.</param>
        /// <param name="value">Date Time value.</param>
        /// <param name="lexicalValue">Lexical Value.</param>
        public DateNode(IGraph g, DateTime value, String lexicalValue)
            : base(g, value, UriFactory.Create(XmlSpecsHelper.XmlSchemaDataTypeDate)) { }
    }
}