verifier.java

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/* Verifier.java

{{IS_NOTE

	Purpose:
	Description:
	History:
	2001/10/21 17:03:23, Create, Tom M. Yeh.
}}IS_NOTE

Copyright (C) 2001 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
	This program is distributed under GPL Version 2.0 in the hope that
	it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.idom;

import org.xml.sax.Locator;

/**
 * The verifier to verify W3C/DOM related constraints.
 *
 * @author tomyeh
 */
public class Verifier {
	private Verifier() {
	}

	/**
	 * Checks whether an element's name is valid.
	 */
	public static final void checkElementName(String name, Locator loc) {
		if (name.indexOf(":") >= 0)
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"Element or attribute names cannot contain colons", loc);
		checkXMLName(name, loc);
	}

	/**
	 * Checks whether an attribute's name is valid.
	 */
	public static final void checkAttributeName(String name, Locator loc) {
		// Allow xml:space and xml:lang as special cases
		if (!name.equals("xml:space") && !name.equals("xml:lang"))
			checkElementName(name, loc);
	}

	protected static final StringBuffer appendAsHex(StringBuffer sb, char c) {
		return sb.append('\'').append(c)
			.append("' (0x").append(Integer.toHexString(c)).append(')');
	}

	/**
	 * Checks whether a text is valid.
	 */
	public static final void checkCharacterData(String text, Locator loc) {
		if (text == null)
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"A null is not a legal XML value", loc);

		for (int j = 0, len = text.length(); j<len; j++)
			if (!isXMLCharacter(text.charAt(j))) {
				StringBuffer sb = new StringBuffer(40);
				throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
					appendAsHex(sb, text.charAt(j))
					.append(" is not a valid XML character").toString(), loc);
			}
	}

	/**
	 * Checks whether a CDATA is valid.
	 */
	public static final void checkCData(String data, Locator loc) {
		if (data.indexOf("]]>") >= 0)
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"']]>' is not allowed inside a CDATA string", loc);
		checkCharacterData(data, loc);
	}

	/**
	 * Checks whether the prefix of a namespace is valid.
	 */
	public static final void checkNamespacePrefix(String prefix, Locator loc) {
		if (prefix == null || prefix.length() == 0)
			return; //OK: null or empty

		String reason = null;
		char first = prefix.charAt(0);
		if (isXMLDigit(first)) {
			reason = "a number";
		} else if (first == '$') {
			reason = "a dollar sign ($)";
		} else if (first == '-') {
			reason = "a hyphen (-)";
		} else if (first == '.') {
			reason = "a period (.)";
		} else {
			final String s = prefix.toLowerCase();
			if (s.startsWith("xml") && !s.equals("xmlns"))
				reason = "\"xml\" in any combination of case";
		}

		if (reason != null)
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"Namespace prefixes, "+prefix+", cannot begin with " + reason, loc);

		for (int j=0, len = prefix.length(); j<len; j++)
			if (!isXMLNameCharacter(prefix.charAt(j))) {
				StringBuffer sb =
					new StringBuffer("Namespace prefixes cannot contain ");
				throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
					appendAsHex(sb, prefix.charAt(j)).toString(), loc);
			}

		if (prefix.indexOf(":") >= 0)
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"Namespace prefixes cannot contain colons", loc);
	}

	/**
	 * Checks whether the URI of a namespace is valid.
	 */
	public static final void checkNamespaceURI(String uri, Locator loc) {
		if (uri == null || uri.length() == 0)
			return; //OK: null or empty

		String reason = null;
		char first = uri.charAt(0);
		if (Character.isDigit(first))
			reason = "a number";
		else if (first == '$')
			reason = "a dollar sign ($)";
		else if (first == '-')
			reason = "a hyphen (-)";

		if (reason != null)
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"Namespace URIs cannot begin with " + reason, loc);
	}

	/**
	 * Checks whether a processing instruction target is valid.
	 */
	public static final void
	checkPITarget(String target, Locator loc) {
		if (target.indexOf(":") >= 0)
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"Processing instruction targets cannot contain colons", loc);
		if (target.equalsIgnoreCase("xml"))
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"Processing instruction targets cannot be " +
				"\"xml\" in any combination of case", loc);

		checkXMLName(target, loc);
	}

	/**
	 * Checks whether a comment data is valid.
	 */
	public static final void checkCommentData(String data, Locator loc) {
		if (data.indexOf("--") >= 0)
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"Comments cannot contain double hyphens (--)", loc);

		checkCharacterData(data, loc);
	}

	/**
	 * Checks whether a name is valid.
	 */
	public static void checkXMLName(String name, Locator loc) {
		if (name == null || name.length() == 0)
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"XML names cannot be null or empty", loc);

		if (!isXMLNameStartCharacter(name.charAt(0)))
			throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
				"XML names cannot begin with \'" + name.charAt(0) + '\'', loc);

		for (int j=0, len = name.length(); j<len; j++)
			if (!isXMLNameCharacter(name.charAt(j)))
				throw new DOMException(DOMException.INVALID_CHARACTER_ERR,
					"XML names cannot contain \'" + name.charAt(j) + '\'', loc);
	}

	/**
	 * Checks whether a character is valid.
	 */
	public static boolean isXMLCharacter(char c) {
		if (c == '\n') return true;
		if (c == '\r') return true;
		if (c == '\t') return true;

		if (c < 0x20) return false;  if (c <= 0xD7FF) return true;
		if (c < 0xE000) return false;  if (c <= 0xFFFD) return true;
		if (c < 0x10000) return false;  if (c <= 0x10FFFF) return true;

		return false;
	}

	/**
	 * Checks whether a character can be part of a name.
	 */
	public static boolean isXMLNameCharacter(char c) {
		return isXMLLetter(c) || isXMLDigit(c) || c == '.' || c == '-'
			|| c == '_' || c == ':' || isXMLCombiningChar(c)
			|| isXMLExtender(c);
	}

	/**
	 * Checks whether a character can be the first character of a name.
	 */
	public static boolean isXMLNameStartCharacter(char c) {
		return isXMLLetter(c) || c == '_' || c ==':';
	}

	/**
	 * Checks whether a character is a letter or digit.
	 */
	public static boolean isXMLLetterOrDigit(char c) {
		return (isXMLLetter(c) || isXMLDigit(c));
	}

	/**
	 * Checks whether a character is a letter.
	 */
	public static boolean isXMLLetter(char c) {
		if (c < 0x0041) return false;  if (c <= 0x005a) return true;
		if (c < 0x0061) return false;  if (c <= 0x007A) return true;
		if (c < 0x00C0) return false;  if (c <= 0x00D6) return true;
		if (c < 0x00D8) return false;  if (c <= 0x00F6) return true;
		if (c < 0x00F8) return false;  if (c <= 0x00FF) return true;
		if (c < 0x0100) return false;  if (c <= 0x0131) return true;
		if (c < 0x0134) return false;  if (c <= 0x013E) return true;
		if (c < 0x0141) return false;  if (c <= 0x0148) return true;
		if (c < 0x014A) return false;  if (c <= 0x017E) return true;
		if (c < 0x0180) return false;  if (c <= 0x01C3) return true;
		if (c < 0x01CD) return false;  if (c <= 0x01F0) return true;
		if (c < 0x01F4) return false;  if (c <= 0x01F5) return true;
		if (c < 0x01FA) return false;  if (c <= 0x0217) return true;
		if (c < 0x0250) return false;  if (c <= 0x02A8) return true;
		if (c < 0x02BB) return false;  if (c <= 0x02C1) return true;
		if (c == 0x0386) return true;
		if (c < 0x0388) return false;  if (c <= 0x038A) return true;
		if (c == 0x038C) return true;
		if (c < 0x038E) return false;  if (c <= 0x03A1) return true;
		if (c < 0x03A3) return false;  if (c <= 0x03CE) return true;
		if (c < 0x03D0) return false;  if (c <= 0x03D6) return true;
		if (c == 0x03DA) return true;
		if (c == 0x03DC) return true;
		if (c == 0x03DE) return true;
		if (c == 0x03E0) return true;
		if (c < 0x03E2) return false;  if (c <= 0x03F3) return true;
		if (c < 0x0401) return false;  if (c <= 0x040C) return true;
		if (c < 0x040E) return false;  if (c <= 0x044F) return true;
		if (c < 0x0451) return false;  if (c <= 0x045C) return true;
		if (c < 0x045E) return false;  if (c <= 0x0481) return true;
		if (c < 0x0490) return false;  if (c <= 0x04C4) return true;
		if (c < 0x04C7) return false;  if (c <= 0x04C8) return true;
		if (c < 0x04CB) return false;  if (c <= 0x04CC) return true;
		if (c < 0x04D0) return false;  if (c <= 0x04EB) return true;
		if (c < 0x04EE) return false;  if (c <= 0x04F5) return true;
		if (c < 0x04F8) return false;  if (c <= 0x04F9) return true;
		if (c < 0x0531) return false;  if (c <= 0x0556) return true;
		if (c == 0x0559) return true;
		if (c < 0x0561) return false;  if (c <= 0x0586) return true;
		if (c < 0x05D0) return false;  if (c <= 0x05EA) return true;
		if (c < 0x05F0) return false;  if (c <= 0x05F2) return true;
		if (c < 0x0621) return false;  if (c <= 0x063A) return true;
		if (c < 0x0641) return false;  if (c <= 0x064A) return true;
		if (c < 0x0671) return false;  if (c <= 0x06B7) return true;
		if (c < 0x06BA) return false;  if (c <= 0x06BE) return true;
		if (c < 0x06C0) return false;  if (c <= 0x06CE) return true;
		if (c < 0x06D0) return false;  if (c <= 0x06D3) return true;
		if (c == 0x06D5) return true;
		if (c < 0x06E5) return false;  if (c <= 0x06E6) return true;
		if (c < 0x0905) return false;  if (c <= 0x0939) return true;
		if (c == 0x093D) return true;
		if (c < 0x0958) return false;  if (c <= 0x0961) return true;
		if (c < 0x0985) return false;  if (c <= 0x098C) return true;
		if (c < 0x098F) return false;  if (c <= 0x0990) return true;
		if (c < 0x0993) return false;  if (c <= 0x09A8) return true;
		if (c < 0x09AA) return false;  if (c <= 0x09B0) return true;
		if (c == 0x09B2) return true;
		if (c < 0x09B6) return false;  if (c <= 0x09B9) return true;
		if (c < 0x09DC) return false;  if (c <= 0x09DD) return true;
		if (c < 0x09DF) return false;  if (c <= 0x09E1) return true;
		if (c < 0x09F0) return false;  if (c <= 0x09F1) return true;
		if (c < 0x0A05) return false;  if (c <= 0x0A0A) return true;
		if (c < 0x0A0F) return false;  if (c <= 0x0A10) return true;
		if (c < 0x0A13) return false;  if (c <= 0x0A28) return true;
		if (c < 0x0A2A) return false;  if (c <= 0x0A30) return true;
		if (c < 0x0A32) return false;  if (c <= 0x0A33) return true;
		if (c < 0x0A35) return false;  if (c <= 0x0A36) return true;
		if (c < 0x0A38) return false;  if (c <= 0x0A39) return true;
		if (c < 0x0A59) return false;  if (c <= 0x0A5C) return true;
		if (c == 0x0A5E) return true;
		if (c < 0x0A72) return false;  if (c <= 0x0A74) return true;
		if (c < 0x0A85) return false;  if (c <= 0x0A8B) return true;
		if (c == 0x0A8D) return true;
		if (c < 0x0A8F) return false;  if (c <= 0x0A91) return true;
		if (c < 0x0A93) return false;  if (c <= 0x0AA8) return true;
		if (c < 0x0AAA) return false;  if (c <= 0x0AB0) return true;
		if (c < 0x0AB2) return false;  if (c <= 0x0AB3) return true;
		if (c < 0x0AB5) return false;  if (c <= 0x0AB9) return true;
		if (c == 0x0ABD) return true;
		if (c == 0x0AE0) return true;
		if (c < 0x0B05) return false;  if (c <= 0x0B0C) return true;