//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;

namespace System.Xml
{
	/// <summary>
	/// http://www.w3.org/TR/REC-xml
	/// </summary>
	/// <remarks>
	/// Includes code and Ideas from  org.apache.xerces.util.XMLChar class of Xerces 2.0.1
	/// However, No surrogate support is included in this class.
	/// This class is currently public. Make it internal after testing completes
	/// </remarks>
	internal class XmlConstructs
	{
		internal static readonly char [] WhitespaceChars = {' ', '\n', '\t', '\r'};

		/** Character flags. */
		internal static readonly byte [] CHARS = new byte [1 << 16];

		/** Valid character mask. */
		internal const int VALID = 0x01;

		/** Space character mask. */
		internal const int SPACE = 0x02;

		/** Name start character mask. */
		internal const int NAME_START = 0x04;

		/** Name character mask. */
		internal const int NAME = 0x08;

		/** Pubid character mask. */
		internal const int PUBID = 0x10;
		/** 
			 * Content character mask. Special characters are those that can
			 * be considered the start of markup, such as '&lt;' and '&amp;'. 
			 * The various newline characters are considered special as well.
			 * All other valid XML characters can be considered content.
			 * <p>
			 * This is an optimization for the inner loop of character scanning.
			 */
		internal const int CONTENT = 0x20;

		/** NCName start character mask. */
		internal const int NCNAME_START = 0x40;

		/** NCName character mask. */
		internal const int NCNAME = 0x80;
	
		static XmlConstructs ()
		{
			//
			// [2] Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] |
			//              [#xE000-#xFFFD] | [#x10000-#x10FFFF]
			//
			int[] charRange = { 
								  0x0009, 0x000A, 0x000D, 0x000D, 0x0020, 0xD7FF, 0xE000, 0xFFFD,
			};

			//
			// [3] S ::= (#x20 | #x9 | #xD | #xA)+
			//
			int[] spaceChar = { 
								  0x0020, 0x0009, 0x000D, 0x000A,
			};

			//
			// [4] NameChar ::= Letter | Digit | '.' | '-' | '_' | ':' |
			//                  CombiningChar | Extender
			//
			int[] nameChar = { 
								 0x002D, 0x002E, // '-' and '.'
			};

			//
			// [5] Name ::= (Letter | '_' | ':') (NameChar)*
			//

			int[] nameStartChar = { 
									  0x003A, 0x005F, // ':' and '_'
			};

			//
			// [13] PubidChar ::= #x20 | 0xD | 0xA | [a-zA-Z0-9] | [-'()+,./:=?;!*#@$_%]
			//

			int[] pubidChar = {
								  0x000A, 0x000D, 0x0020, 0x0021, 0x0023, 0x0024, 0x0025, 0x003D,
								  0x005F
							  };

			int[] pubidRange = {
								   0x0027, 0x003B, 0x003F, 0x005A, 0x0061, 0x007A
							   };

			//
			// [84] Letter ::= BaseChar | Ideographic
			//

			int[] letterRange = {
									// BaseChar
									0x0041, 0x005A, 0x0061, 0x007A, 0x00C0, 0x00D6, 0x00D8, 0x00F6,
									0x00F8, 0x0131, 0x0134, 0x013E, 0x0141, 0x0148, 0x014A, 0x017E,
									0x0180, 0x01C3, 0x01CD, 0x01F0, 0x01F4, 0x01F5, 0x01FA, 0x0217,
									0x0250, 0x02A8, 0x02BB, 0x02C1, 0x0388, 0x038A, 0x038E, 0x03A1,
									0x03A3, 0x03CE, 0x03D0, 0x03D6, 0x03E2, 0x03F3, 0x0401, 0x040C,
									0x040E, 0x044F, 0x0451, 0x045C, 0x045E, 0x0481, 0x0490, 0x04C4,
									0x04C7, 0x04C8, 0x04CB, 0x04CC, 0x04D0, 0x04EB, 0x04EE, 0x04F5,
									0x04F8, 0x04F9, 0x0531, 0x0556, 0x0561, 0x0586, 0x05D0, 0x05EA,
									0x05F0, 0x05F2, 0x0621, 0x063A, 0x0641, 0x064A, 0x0671, 0x06B7,
									0x06BA, 0x06BE, 0x06C0, 0x06CE, 0x06D0, 0x06D3, 0x06E5, 0x06E6,
									0x0905, 0x0939, 0x0958, 0x0961, 0x0985, 0x098C, 0x098F, 0x0990,
									0x0993, 0x09A8, 0x09AA, 0x09B0, 0x09B6, 0x09B9, 0x09DC, 0x09DD,
									0x09DF, 0x09E1, 0x09F0, 0x09F1, 0x0A05, 0x0A0A, 0x0A0F, 0x0A10,
									0x0A13, 0x0A28, 0x0A2A, 0x0A30, 0x0A32, 0x0A33, 0x0A35, 0x0A36,
									0x0A38, 0x0A39, 0x0A59, 0x0A5C, 0x0A72, 0x0A74, 0x0A85, 0x0A8B,
									0x0A8F, 0x0A91, 0x0A93, 0x0AA8, 0x0AAA, 0x0AB0, 0x0AB2, 0x0AB3,
									0x0AB5, 0x0AB9, 0x0B05, 0x0B0C, 0x0B0F, 0x0B10, 0x0B13, 0x0B28,
									0x0B2A, 0x0B30, 0x0B32, 0x0B33, 0x0B36, 0x0B39, 0x0B5C, 0x0B5D,
									0x0B5F, 0x0B61, 0x0B85, 0x0B8A, 0x0B8E, 0x0B90, 0x0B92, 0x0B95,
									0x0B99, 0x0B9A, 0x0B9E, 0x0B9F, 0x0BA3, 0x0BA4, 0x0BA8, 0x0BAA,
									0x0BAE, 0x0BB5, 0x0BB7, 0x0BB9, 0x0C05, 0x0C0C, 0x0C0E, 0x0C10,
									0x0C12, 0x0C28, 0x0C2A, 0x0C33, 0x0C35, 0x0C39, 0x0C60, 0x0C61,
									0x0C85, 0x0C8C, 0x0C8E, 0x0C90, 0x0C92, 0x0CA8, 0x0CAA, 0x0CB3,
									0x0CB5, 0x0CB9, 0x0CE0, 0x0CE1, 0x0D05, 0x0D0C, 0x0D0E, 0x0D10,
									0x0D12, 0x0D28, 0x0D2A, 0x0D39, 0x0D60, 0x0D61, 0x0E01, 0x0E2E,
									0x0E32, 0x0E33, 0x0E40, 0x0E45, 0x0E81, 0x0E82, 0x0E87, 0x0E88,
									0x0E94, 0x0E97, 0x0E99, 0x0E9F, 0x0EA1, 0x0EA3, 0x0EAA, 0x0EAB,
									0x0EAD, 0x0EAE, 0x0EB2, 0x0EB3, 0x0EC0, 0x0EC4, 0x0F40, 0x0F47,
									0x0F49, 0x0F69, 0x10A0, 0x10C5, 0x10D0, 0x10F6, 0x1102, 0x1103,
									0x1105, 0x1107, 0x110B, 0x110C, 0x110E, 0x1112, 0x1154, 0x1155,
									0x115F, 0x1161, 0x116D, 0x116E, 0x1172, 0x1173, 0x11AE, 0x11AF,
									0x11B7, 0x11B8, 0x11BC, 0x11C2, 0x1E00, 0x1E9B, 0x1EA0, 0x1EF9,
									0x1F00, 0x1F15, 0x1F18, 0x1F1D, 0x1F20, 0x1F45, 0x1F48, 0x1F4D,
									0x1F50, 0x1F57, 0x1F5F, 0x1F7D, 0x1F80, 0x1FB4, 0x1FB6, 0x1FBC,
									0x1FC2, 0x1FC4, 0x1FC6, 0x1FCC, 0x1FD0, 0x1FD3, 0x1FD6, 0x1FDB,
									0x1FE0, 0x1FEC, 0x1FF2, 0x1FF4, 0x1FF6, 0x1FFC, 0x212A, 0x212B,
									0x2180, 0x2182, 0x3041, 0x3094, 0x30A1, 0x30FA, 0x3105, 0x312C,
									0xAC00, 0xD7A3,
									// Ideographic
									0x3021, 0x3029, 0x4E00, 0x9FA5,
			};
			int[] letterChar = {
								   // BaseChar
								   0x0386, 0x038C, 0x03DA, 0x03DC, 0x03DE, 0x03E0, 0x0559, 0x06D5,
								   0x093D, 0x09B2, 0x0A5E, 0x0A8D, 0x0ABD, 0x0AE0, 0x0B3D, 0x0B9C,
								   0x0CDE, 0x0E30, 0x0E84, 0x0E8A, 0x0E8D, 0x0EA5, 0x0EA7, 0x0EB0,
								   0x0EBD, 0x1100, 0x1109, 0x113C, 0x113E, 0x1140, 0x114C, 0x114E,
								   0x1150, 0x1159, 0x1163, 0x1165, 0x1167, 0x1169, 0x1175, 0x119E,
								   0x11A8, 0x11AB, 0x11BA, 0x11EB, 0x11F0, 0x11F9, 0x1F59, 0x1F5B,
								   0x1F5D, 0x1FBE, 0x2126, 0x212E,
								   // Ideographic
								   0x3007,
			};

			//
			// [87] CombiningChar ::= ...
			//

			int[] combiningCharRange = {
										   0x0300, 0x0345, 0x0360, 0x0361, 0x0483, 0x0486, 0x0591, 0x05A1,
										   0x05A3, 0x05B9, 0x05BB, 0x05BD, 0x05C1, 0x05C2, 0x064B, 0x0652,
										   0x06D6, 0x06DC, 0x06DD, 0x06DF, 0x06E0, 0x06E4, 0x06E7, 0x06E8,
										   0x06EA, 0x06ED, 0x0901, 0x0903, 0x093E, 0x094C, 0x0951, 0x0954,
										   0x0962, 0x0963, 0x0981, 0x0983, 0x09C0, 0x09C4, 0x09C7, 0x09C8,
										   0x09CB, 0x09CD, 0x09E2, 0x09E3, 0x0A40, 0x0A42, 0x0A47, 0x0A48,
										   0x0A4B, 0x0A4D, 0x0A70, 0x0A71, 0x0A81, 0x0A83, 0x0ABE, 0x0AC5,
										   0x0AC7, 0x0AC9, 0x0ACB, 0x0ACD, 0x0B01, 0x0B03, 0x0B3E, 0x0B43,
										   0x0B47, 0x0B48, 0x0B4B, 0x0B4D, 0x0B56, 0x0B57, 0x0B82, 0x0B83,
										   0x0BBE, 0x0BC2, 0x0BC6, 0x0BC8, 0x0BCA, 0x0BCD, 0x0C01, 0x0C03,
										   0x0C3E, 0x0C44, 0x0C46, 0x0C48, 0x0C4A, 0x0C4D, 0x0C55, 0x0C56,
										   0x0C82, 0x0C83, 0x0CBE, 0x0CC4, 0x0CC6, 0x0CC8, 0x0CCA, 0x0CCD,
										   0x0CD5, 0x0CD6, 0x0D02, 0x0D03, 0x0D3E, 0x0D43, 0x0D46, 0x0D48,
										   0x0D4A, 0x0D4D, 0x0E34, 0x0E3A, 0x0E47, 0x0E4E, 0x0EB4, 0x0EB9,
										   0x0EBB, 0x0EBC, 0x0EC8, 0x0ECD, 0x0F18, 0x0F19, 0x0F71, 0x0F84,
										   0x0F86, 0x0F8B, 0x0F90, 0x0F95, 0x0F99, 0x0FAD, 0x0FB1, 0x0FB7,
										   0x20D0, 0x20DC, 0x302A, 0x302F,
			};

			int[] combiningCharChar = {
										  0x05BF, 0x05C4, 0x0670, 0x093C, 0x094D, 0x09BC, 0x09BE, 0x09BF,
										  0x09D7, 0x0A02, 0x0A3C, 0x0A3E, 0x0A3F, 0x0ABC, 0x0B3C, 0x0BD7,
										  0x0D57, 0x0E31, 0x0EB1, 0x0F35, 0x0F37, 0x0F39, 0x0F3E, 0x0F3F,
										  0x0F97, 0x0FB9, 0x20E1, 0x3099, 0x309A,
			};

			//
			// [88] Digit ::= ...
			//

			int[] digitRange = {
								   0x0030, 0x0039, 0x0660, 0x0669, 0x06F0, 0x06F9, 0x0966, 0x096F,
								   0x09E6, 0x09EF, 0x0A66, 0x0A6F, 0x0AE6, 0x0AEF, 0x0B66, 0x0B6F,
								   0x0BE7, 0x0BEF, 0x0C66, 0x0C6F, 0x0CE6, 0x0CEF, 0x0D66, 0x0D6F,
								   0x0E50, 0x0E59, 0x0ED0, 0x0ED9, 0x0F20, 0x0F29,
			};

			//
			// [89] Extender ::= ...
			//

			int[] extenderRange = {
									  0x3031, 0x3035, 0x309D, 0x309E, 0x30FC, 0x30FE,
			};

			int[] extenderChar = {
									 0x00B7, 0x02D0, 0x02D1, 0x0387, 0x0640, 0x0E46, 0x0EC6, 0x3005,
			};

			//
			// SpecialChar ::= '<', '&', '\n', '\r', ']'
			//

			int[] specialChar = {
									'<', '&', '\n', '\r', ']',
			};

			//
			// Initialize
			//

			// set valid characters
			for (int i = 0; i < charRange.Length; i += 2) 
			{
				for (int j = charRange[i]; j <= charRange[i + 1]; j++) 
				{
					CHARS[j] = (byte)(CHARS[j] | VALID | CONTENT);
				}
			}

			// remove special characters
			for (int i = 0; i < specialChar.Length; i++) 
			{
				CHARS[specialChar[i]] = (byte)(CHARS[specialChar[i]] & ~CONTENT);
			}

			// set space characters
			for (int i = 0; i < spaceChar.Length; i++) 
			{
				CHARS[spaceChar[i]] = (byte)(CHARS[spaceChar[i]] | SPACE);
			}

			// set name start characters
			for (int i = 0; i < nameStartChar.Length; i++) 
			{
				CHARS[nameStartChar[i]] = (byte)(CHARS[nameStartChar[i]] | NAME_START | NAME | 
					NCNAME_START | NCNAME);
			}
			for (int i = 0; i < letterRange.Length; i += 2) 
			{
				for (int j = letterRange[i]; j <= letterRange[i + 1]; j++) 
				{
					CHARS[j] = (byte)(CHARS[j] | NAME_START | NAME |	NCNAME_START | NCNAME);
				}
			}
			for (int i = 0; i < letterChar.Length; i++) 
			{
				CHARS[letterChar[i]] = (byte)(CHARS[letterChar[i]] | NAME_START | NAME |
					NCNAME_START | NCNAME);
			}

			// set name characters
			for (int i = 0; i < nameChar.Length; i++) 
			{
				CHARS[nameChar[i]] = (byte)(CHARS[nameChar[i]] | NAME | NCNAME);
			}
			for (int i = 0; i < digitRange.Length; i += 2) 
			{
				for (int j = digitRange[i]; j <= digitRange[i + 1]; j++) 
				{
					CHARS[j] = (byte)(CHARS[j] | NAME | NCNAME);
				}
			}
			for (int i = 0; i < combiningCharRange.Length; i += 2) 
			{
				for (int j = combiningCharRange[i]; j <= combiningCharRange[i + 1]; j++) 
				{
					CHARS[j] = (byte)(CHARS[j] | NAME | NCNAME);
				}
			}
			for (int i = 0; i < combiningCharChar.Length; i++) 
			{
				CHARS[combiningCharChar[i]] = (byte)(CHARS[combiningCharChar[i]] | NAME | NCNAME);
			}
			for (int i = 0; i < extenderRange.Length; i += 2) 
			{
				for (int j = extenderRange[i]; j <= extenderRange[i + 1]; j++) 
				{
					CHARS[j] = (byte)(CHARS[j] | NAME | NCNAME);
				}
			}
			for (int i = 0; i < extenderChar.Length; i++) 
			{
				CHARS[extenderChar[i]] = (byte)(CHARS[extenderChar[i]] | NAME | NCNAME);
			}

			// remove ':' from allowable NCNAME_START and NCNAME chars
			CHARS[':'] = (byte)(CHARS[':'] & ~(NCNAME_START | NCNAME));

			// set Pubid characters
			for (int i = 0; i < pubidChar.Length; i++) 
			{
				CHARS[pubidChar[i]] = (byte)(CHARS[pubidChar[i]] | PUBID);
			}
			for (int i = 0; i < pubidRange.Length; i += 2) 
			{
				for (int j = pubidRange[i]; j <= pubidRange[i + 1]; j++) 
				{
					CHARS[j] = (byte)(CHARS[j] | PUBID);
				}
			}
		}

		//Static Methods

		/// <summary>
		/// Returns true if the specified character is valid.
		/// </summary>
		/// <param name="c">The character to check.</param>
		public static bool IsValid(char c) 
		{
			return c > 0 && ((CHARS[c] & VALID) != 0);
		}

		public static bool IsValid (int c) 
		{
			if (c > 0xffff)
				return c < 0x110000;
			return c > 0 && ((CHARS[c] & VALID) != 0);
		}

		/// <summary>
		/// Returns true if the specified character is invalid.
		/// </summary>
		/// <param name="c">The character to check.</param>
		public static bool IsInvalid(char c) 
		{
			return !IsValid(c);
		}

		public static bool IsInvalid(int c) 
		{
			return !IsValid(c);
		}

		/// <summary>
		/// Returns true if the specified character can be considered content.
		/// </summary>
		/// <param name="c">The character to check.</param>
		public static bool IsContent(char c) 
		{
			return (CHARS[c] & CONTENT) != 0;
		}

		public static bool IsContent(int c) 
		{
			return c > 0 && c < CHARS.Length && (CHARS[c] & CONTENT) != 0;
		}

		/// <summary>
		/// Returns true if the specified character can be considered markup.
		/// Markup characters include '&lt;', '&amp;', and '%'.
		/// </summary>
		/// <param name="c">The character to check.</param>
		public static bool IsMarkup(char c) 
		{
			return c == '<' || c == '&' || c == '%';
		}

		public static bool IsMarkup(int c) 
		{
			return c > 0 && c < CHARS.Length && (c == '<' || c == '&' || c == '%');
		}

		/// <summary>
		/// Returns true if the specified character is a space character
		/// as defined by production [3] in the XML 1.0 specification. 
		/// </summary>
		/// <param name="c">The character to check.</param>
		/// <returns></returns>
		public static bool IsWhitespace (char c) 
		{
			return (CHARS[c] & SPACE) != 0;
		}

		public static bool IsWhitespace (int c) 
		{
			return c > 0 && c < CHARS.Length && (CHARS[c] & SPACE) != 0;
		}

		/// <summary>
		/// Returns true if the specified character is a valid name start
		/// character as defined by production [5] in the XML 1.0 specification.
		/// </summary>
		/// <param name="c">The character to check.</param>
		public static bool IsFirstNameChar (char c) 
		{
			return (CHARS[c] & NAME_START) != 0;
		} 

		public static bool IsFirstNameChar (int c) 
		{
			return c > 0 && c < CHARS.Length && (CHARS[c] & NAME_START) != 0;
		} 

		/// <summary>
		/// Returns true if the specified character is a valid name
		/// character as defined by production [4] in the XML 1.0 specification.
		/// </summary>
		/// <param name="c">The character to check.</param>
		public static bool IsNameChar(char c) 
		{
			return (CHARS[c] & NAME) != 0;
		} 

		public static bool IsNameChar(int c) 
		{
			return c > 0 && c < CHARS.Length && (CHARS[c] & NAME) != 0;
		} 

		/// <summary>
		/// Returns true if the specified character is a valid NCName start
		/// character as defined by production [4] in Namespaces in XML
		/// recommendation.
		/// </summary>
		/// <param name="c">The character to check.</param>
		/// <returns></returns>
		public static bool IsNCNameStart(char c) 
		{
			return (CHARS[c] & NCNAME_START) != 0;
		}

		public static bool IsNCNameStart(int c) 
		{
			return c > 0 && c < CHARS.Length && (CHARS[c] & NCNAME_START) != 0;
		}

		/// <summary>
		/// Returns true if the specified character is a valid NCName
		/// character as defined by production [5] in Namespaces in XML
		/// recommendation.
		/// </summary>
		/// <param name="c"></param>
		/// <returns></returns>
		public static bool IsNCNameChar(char c) 
		{
			return (CHARS[c] & NCNAME) != 0;
		} 

		public static bool IsNCNameChar(int c) 
		{
			return c > 0 && c < CHARS.Length && (CHARS[c] & NCNAME) != 0;
		} 

		/// <summary>
		/// Returns true if the specified character is a valid Pubid
		/// character as defined by production [13] in the XML 1.0 specification.
		/// </summary>
		/// <param name="c">The character to check</param>
		public static bool IsPubidChar (char c) 
		{
			return (CHARS[c] & PUBID) != 0;
		}

		public static bool IsPubidChar (int c) 
		{
			return c > 0 && c < CHARS.Length && (CHARS[c] & PUBID) != 0;
		}

		/// <summary>
		/// Check to see if a string is a valid Name according to [5]
		/// in the XML 1.0 Recommendation
		/// </summary>
		/// <param name="name">The string to check</param>
		public static bool IsValidName(String name, out Exception err) 
		{
			err = null;
			if (name.Length == 0)
			{
				err = new XmlException("Name can not be an empty string",null);
				return false;
			}
			char ch = name[0];
			if( IsFirstNameChar (ch) == false)
			{
				err = new XmlException("The character '"+ch+"' cannot start a Name",null);
				return false;
			}
			for (int i = 1; i < name.Length; i++ ) 
			{
				ch = name[i];
				if( IsNameChar (ch) == false )
				{
					err = new XmlException("The character '"+ch+"' is not allowed in a Name",null);
					return false;
				}
			}
			return true;
		}

		public static int IsValidName (string name)
		{
			if (name.Length == 0)
				return 0;
			if (!IsFirstNameChar (name [0]))
				return 0;
			for (int i=1; i<name.Length; i++)
				if (!IsNameChar (name [i]))
					return i;
			return -1;
		}

		/// <summary>
		/// Check to see if a string is a valid NCName according to [4]
		/// from the XML Namespaces 1.0 Recommendation
		/// </summary>
		/// <param name="ncName">The string to check</param>
		public static bool IsValidNCName(String ncName, out Exception err) 
		{
			err = null;
			if (ncName.Length == 0)
			{
				err = new XmlException("NCName can not be an empty string",null);
				return false;
			}
			char ch = ncName[0];
			if( IsNCNameStart(ch) == false)
			{
				err = new XmlException("The character '"+ch+"' cannot start a NCName",null);
				return false;
			}
			for (int i = 1; i < ncName.Length; i++ ) 
			{
				ch = ncName[i];
				if( IsNCNameChar (ch) == false )
				{
					err = new XmlException("The character '"+ch+"' is not allowed in a NCName",null);
					return false;
				}
			}
			return true;
		}

		/// <summary>
		/// Check to see if a string is a valid Nmtoken according to [7]
		/// in the XML 1.0 Recommendation
		/// </summary>
		/// <param name="nmtoken">The string to check.</param>
		public static bool IsValidNmtoken(String nmtoken, out Exception err) 
		{
			err = null;
			if (nmtoken.Length == 0)
			{
				err = new XmlException("NMTOKEN can not be an empty string", null);
				return false;
			}
			for (int i = 0; i < nmtoken.Length; i++ ) 
			{
				char ch = nmtoken[i];
				if(  ! IsNameChar (ch) )
				{
					err = new XmlException("The character '"+ch+"' is not allowed in a NMTOKEN",null);
					return false;
				}
			}
			return true;
		}

		// encodings

		/// <summary>
		/// Returns true if the encoding name is a valid IANA encoding.
		/// This method does not verify that there is a decoder available
		/// for this encoding, only that the characters are valid for an
		/// IANA encoding name.
		/// </summary>
		/// <param name="ianaEncoding">The encoding to check.</param>
		/// <returns></returns>
		public static bool IsValidIANAEncoding(String ianaEncoding) 
		{
			if (ianaEncoding != null) 
			{
				int length = ianaEncoding.Length;
				if (length > 0) 
				{
					char c = ianaEncoding[0];
					if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) 
					{
						for (int i = 1; i < length; i++) 
						{
							c = ianaEncoding[i];
							if ((c < 'A' || c > 'Z') && (c < 'a' || c > 'z') &&
								(c < '0' || c > '9') && c != '.' && c != '_' &&
								c != '-') 
							{
								return false;
							}
						}
						return true;
					}
				}
			}
			return false;
		}

		public static bool IsName (string str)
		{
			if (str.Length == 0)
				return false;
			if (!IsFirstNameChar (str [0]))
				return false;
			for (int i = 1; i < str.Length; i++)
				if (!IsNameChar (str [i]))
					return false;
			return true;
		}

		public static bool IsNCName (string str)
		{
			if (str.Length == 0)
				return false;
			if (!IsFirstNameChar (str [0]))
				return false;
			for (int i = 0; i < str.Length; i++)
				if (!IsNCNameChar (str [i]))
					return false;
			return true;
		}

		public static bool IsNmToken (string str)
		{
			if (str.Length == 0)
				return false;
			for (int i = 0; i < str.Length; i++)
				if (!IsNameChar (str [i]))
					return false;
			return true;
		}

		public static bool IsWhitespace (string str)
		{
			for (int i = 0; i < str.Length; i++)
				if (!IsWhitespace (str [i])) return false;
				
			return true;
		}

		public static int GetPredefinedEntity (string name)
		{
			switch (name) {
			case "amp":
				return '&';
			case "lt":
				return '<';
			case "gt":
				return '>';
			case "quot":
				return '"';
			case "apos":
				return '\'';
			default:
				return -1;
			}
		}
	}
}