HtmlAttribute.cs

// HtmlAgilityPack V1.0 - Simon Mourier <simon underscore mourier at hotmail dot com>

#region

using System;
using System.Diagnostics;

#endregion

namespace HtmlAgilityPack
{
	/// <summary>
	/// Represents an HTML attribute.
	/// </summary>
	[DebuggerDisplay("Name: {OriginalName}, Value: {Value}")]
	public class HtmlAttribute : IComparable
	{
		#region Fields

		int _line;
		internal int _lineposition;
		internal string _name;
		internal int _namelength;
		internal int _namestartindex;
		internal HtmlDocument _ownerdocument; // attribute can exists without a node
		internal HtmlNode _ownernode;
		AttributeValueQuote _quoteType = AttributeValueQuote.DoubleQuote;
		internal int _streamposition;
		internal string _value;
		internal int _valuelength;
		internal int _valuestartindex;

		#endregion

		#region Constructors

		internal HtmlAttribute(HtmlDocument ownerdocument)
		{
			_ownerdocument = ownerdocument;
		}

		#endregion

		#region Properties

		/// <summary>
		/// Gets the line number of this attribute in the document.
		/// </summary>
		public int Line
		{
			get { return _line; }
			internal set { _line = value; }
		}

		/// <summary>
		/// Gets the column number of this attribute in the document.
		/// </summary>
		public int LinePosition
		{
			get { return _lineposition; }
		}

		/// <summary>
		/// Gets the qualified name of the attribute.
		/// </summary>
		public string Name
		{
			get
			{
				if (_name == null)
				{
					_name = _ownerdocument._text.Substring(_namestartindex, _namelength);
				}
				return _name.ToLower();
			}
			set
			{
				if (value == null)
				{
					throw new ArgumentNullException("value");
				}
				_name = value;
				if (_ownernode != null)
				{
					_ownernode._innerchanged = true;
					_ownernode._outerchanged = true;
				}
			}
		}

		/// <summary>
		/// Name of attribute with original case
		/// </summary>
		public string OriginalName
		{
			get { return _name; }
		}

		/// <summary>
		/// Gets the HTML document to which this attribute belongs.
		/// </summary>
		public HtmlDocument OwnerDocument
		{
			get { return _ownerdocument; }
		}

		/// <summary>
		/// Gets the HTML node to which this attribute belongs.
		/// </summary>
		public HtmlNode OwnerNode
		{
			get { return _ownernode; }
		}

		/// <summary>
		/// Specifies what type of quote the data should be wrapped in
		/// </summary>
		public AttributeValueQuote QuoteType
		{
			get { return _quoteType; }
			set { _quoteType = value; }
		}

		/// <summary>
		/// Gets the stream position of this attribute in the document, relative to the start of the document.
		/// </summary>
		public int StreamPosition
		{
			get { return _streamposition; }
		}

		/// <summary>
		/// Gets or sets the value of the attribute.
		/// </summary>
		public string Value
		{
			get
			{
				if (_value == null)
				{
					_value = _ownerdocument._text.Substring(_valuestartindex, _valuelength);
				}
				return _value;
			}
			set
			{
				_value = value;
				if (_ownernode != null)
				{
					_ownernode._innerchanged = true;
					_ownernode._outerchanged = true;
				}
			}
		}

		internal string XmlName
		{
			get { return HtmlDocument.GetXmlName(Name); }
		}

		internal string XmlValue
		{
			get { return Value; }
		}

		/// <summary>
		/// Gets a valid XPath string that points to this Attribute
		/// </summary>
		public string XPath
		{
			get
			{
				string basePath = (OwnerNode == null) ? "/" : OwnerNode.XPath + "/";
				return basePath + GetRelativeXpath();
			}
		}

		#endregion

		#region IComparable Members

		/// <summary>
		/// Compares the current instance with another attribute. Comparison is based on attributes' name.
		/// </summary>
		/// <param name="obj">An attribute to compare with this instance.</param>
		/// <returns>A 32-bit signed integer that indicates the relative order of the names comparison.</returns>
		public int CompareTo(object obj)
		{
			HtmlAttribute att = obj as HtmlAttribute;
			if (att == null)
			{
				throw new ArgumentException("obj");
			}
			return Name.CompareTo(att.Name);
		}

		#endregion

		#region Public Methods

		/// <summary>
		/// Creates a duplicate of this attribute.
		/// </summary>
		/// <returns>The cloned attribute.</returns>
		public HtmlAttribute Clone()
		{
			HtmlAttribute att = new HtmlAttribute(_ownerdocument);
			att.Name = Name;
			att.Value = Value;
			return att;
		}

		/// <summary>
		/// Removes this attribute from it's parents collection
		/// </summary>
		public void Remove()
		{
			_ownernode.Attributes.Remove(this);
		}

		#endregion

		#region Private Methods

		private string GetRelativeXpath()
		{
			if (OwnerNode == null)
				return Name;

			int i = 1;
			foreach (HtmlAttribute node in OwnerNode.Attributes)
			{
				if (node.Name != Name) continue;

				if (node == this)
					break;

				i++;
			}
			return "@" + Name + "[" + i + "]";
		}

		#endregion
	}

	/// <summary>
	/// An Enum representing different types of Quotes used for surrounding attribute values
	/// </summary>
	public enum AttributeValueQuote
	{
		/// <summary>
		/// A single quote mark '
		/// </summary>
		SingleQuote,
		/// <summary>
		/// A double quote mark "
		/// </summary>
		DoubleQuote
	}
}