codeviewer.java

BBS论坛设计JSP＋MYSQL

/**
 * $RCSfile: CodeViewer.java,v $
 * $Revision: 1.7 $
 * $Date: 2001/07/31 05:39:19 $
 *
 * Copyright (C) 1999-2001 CoolServlets, Inc. All rights reserved.
 *
 * This software is the proprietary information of CoolServlets, Inc.
 * Use is subject to license terms.
 */

package com.bcxy.bbs.codeviewer;

import java.util.HashMap;
import java.util.Hashtable;

/**
 * A class that syntax highlights Java code into html.
 * <p>
 * A CodeViewer object is created and then keeps state as lines are passed in.
 * Each line passed in as java text, is returned as syntax highlighted html
 * text.
 * <p>
 * Users of the class can set how the java code will be highlighted with setter
 * methods.
 * <p>
 * Only valid java lines should be passed in since the object maintains state
 * and may not handle illegal code gracefully.
 * <p>
 * The actual system is implemented as a series of filters that deal with
 * specific portions of the java code. The filters are as follows:
 * <p>
 * 
 * <pre>
 *   htmlFilter
 *      |__
 *         multiLineCommentFilter
 *            |___
 *                 inlineCommentFilter
 *                    |___
 *                         stringFilter
 *                            |__
 *                                keywordFilter
 * </pre>
 * 
 */
public class CodeViewer {
	private static HashMap reservedWords = new HashMap(150); // >= Java2 only
																// (also, not
																// thread-safe)

	// private static Hashtable reservedWords = new Hashtable(150); // < Java2
	// (thread-safe)
	private boolean inMultiLineComment = false;

	private String backgroundColor = "#e6e6e6";

	private String commentStart = "<font color=\"#aa0000\"><i>";

	private String commentEnd = "</font></i>";

	private String stringStart = "<font color=\"#000099\">";

	private String stringEnd = "</font>";

	private String reservedWordStart = "<b>";

	private String reservedWordEnd = "</b>";

	/**
	 * Load all keywords at class loading time.
	 */
	static {
		loadKeywords();
	}

	/**
	 * Gets the html for the start of a comment block.
	 */
	public String getCommentStart() {
		return commentStart;
	}

	/**
	 * Sets the html for the start of a comment block.
	 */
	public void setCommentStart(String commentStart) {
		this.commentStart = commentStart;
	}

	/**
	 * Gets the html for the end of a comment block.
	 */
	public String getCommentEnd() {
		return commentEnd;
	}

	/**
	 * Sets the html for the end of a comment block.
	 */
	public void setCommentEnd(String commentEnd) {
		this.commentEnd = commentEnd;
	}

	/**
	 * Gets the html for the start of a String.
	 */
	public String getStringStart() {
		return stringStart;
	}

	/**
	 * Sets the html for the start of a String.
	 */
	public void setStringStart(String stringStart) {
		this.stringStart = stringStart;
	}

	/**
	 * Gets the html for the end of a String.
	 */
	public String getStringEnd() {
		return stringEnd;
	}

	/**
	 * Sets the html for the end of a String.
	 */
	public void setStringEnd(String stringEnd) {
		this.stringEnd = stringEnd;
	}

	/**
	 * Gets the html for the start of a reserved word.
	 */
	public String getReservedWordStart() {
		return reservedWordStart;
	}

	/**
	 * Sets the html for the start of a reserved word.
	 */
	public void setReservedWordStart(String reservedWordStart) {
		this.reservedWordStart = reservedWordStart;
	}

	/**
	 * Gets the html for the end of a reserved word.
	 */
	public String getReservedWordEnd() {
		return reservedWordEnd;
	}

	/**
	 * Sets the html for the end of a reserved word.
	 */
	public void setReservedWordEnd(String reservedWordEnd) {
		this.reservedWordEnd = reservedWordEnd;
	}

	/**
	 * Passes off each line to the first filter.
	 * 
	 * @param line
	 *            The line of Java code to be highlighted.
	 */
	public String syntaxHighlight(String line) {
		return htmlFilter(line);
	}

	/*
	 * Filter html tags that appear in the java source into more benign text
	 * that won't disrupt the output.
	 */
	private String htmlFilter(String line) {
		if (line == null || line.equals("")) {
			return "";
		}
		// replace ampersands with HTML escape sequence for ampersand;
		line = replace(line, "&", "&#38;");
		// replace \" sequences with HTML escape sequences;
		line = replace(line, "\\\"", "&#92;&#34");
		// replace the \\ with HTML escape sequences. fixes a problem when
		// backslashes preceed quotes.
		line = replace(line, "\\\\", "&#92;&#92;");
		// replace less-than signs which might be confused
		// by HTML as tag angle-brackets;
		line = replace(line, "<", "&#60;");
		// replace greater-than signs which might be confused
		// by HTML as tag angle-brackets;
		line = replace(line, ">", "&#62;");
		return multiLineCommentFilter(line);
	}

	/*
	 * Filter out multiLine comments. State is kept with a private boolean
	 * variable.
	 */
	private String multiLineCommentFilter(String line) {
		if (line == null || line.equals("")) {
			return "";
		}
		StringBuffer buf = new StringBuffer();
		int index;
		// First, check for the end of a multi-line comment.
		if (inMultiLineComment && (index = line.indexOf("*/")) > -1
				&& !isInsideString(line, index)) {
			inMultiLineComment = false;
			buf.append(line.substring(0, index));
			buf.append("*/").append(commentEnd);
			if (line.length() > index + 2) {
				buf.append(inlineCommentFilter(line.substring(index + 2)));
			}
			return buf.toString();
		}
		// If there was no end detected and we're currently in a multi-line
		// comment, we don't want to do anymore work, so return line.
		else if (inMultiLineComment) {
			return line;
		}
		// We're not currently in a comment, so check to see if the start
		// of a multi-line comment is in this line.
		else if ((index = line.indexOf("/*")) > -1
				&& !isInsideString(line, index)) {
			inMultiLineComment = true;
			// Return result of other filters + everything after the start
			// of the multiline comment. We need to pass the through the
			// to the multiLineComment filter again in case the comment ends
			// on the same line.
			buf.append(inlineCommentFilter(line.substring(0, index)));
			buf.append(commentStart).append("/*");
			buf.append(multiLineCommentFilter(line.substring(index + 2)));
			return buf.toString();
		}
		// Otherwise, no useful multi-line comment information was found so
		// pass the line down to the next filter for processesing.
		else {
			return inlineCommentFilter(line);
		}
	}

	/*
	 * Filter inline comments from a line and formats them properly.
	 */
	private String inlineCommentFilter(String line) {
		if (line == null || line.equals("")) {
			return "";
		}
		StringBuffer buf = new StringBuffer();
		int index;
		if ((index = line.indexOf("//")) > -1 && !isInsideString(line, index)) {
			buf.append(stringFilter(line.substring(0, index)));
			buf.append(commentStart);
			buf.append(line.substring(index));
			buf.append(commentEnd);
		} else {
			buf.append(stringFilter(line));
		}
		return buf.toString();
	}

	/*
	 * Filters strings from a line of text and formats them properly.
	 */
	private String stringFilter(String line) {
		if (line == null || line.equals("")) {
			return "";
		}
		StringBuffer buf = new StringBuffer();
		if (line.indexOf("\"") <= -1) {
			return keywordFilter(line);
		}
		int start = 0;
		int startStringIndex = -1;
		int endStringIndex = -1;
		int tempIndex;
		// Keep moving through String characters until we want to stop...
		while ((tempIndex = line.indexOf("\"")) > -1) {
			// We found the beginning of a string
			if (startStringIndex == -1) {
				startStringIndex = 0;
				buf.append(stringFilter(line.substring(start, tempIndex)));
				buf.append(stringStart).append("\"");
				line = line.substring(tempIndex + 1);
			}
			// Must be at the end
			else {
				startStringIndex = -1;
				endStringIndex = tempIndex;
				buf.append(line.substring(0, endStringIndex + 1));
				buf.append(stringEnd);
				line = line.substring(endStringIndex + 1);
			}
		}
		buf.append(keywordFilter(line));
		return buf.toString();
	}

	/*
	 * Filters keywords from a line of text and formats them properly.
	 */
	private String keywordFilter(String line) {
		if (line == null || line.equals("")) {
			return "";
		}
		StringBuffer buf = new StringBuffer();
		// HashMap usedReservedWords = new HashMap(); // >= Java2 only (not
		// thread-safe)
		Hashtable usedReservedWords = new Hashtable(); // < Java2 (thread-safe)
		int i = 0, startAt = 0;
		char ch;
		StringBuffer temp = new StringBuffer();
		while (i < line.length()) {
			temp.setLength(0);
			ch = line.charAt(i);
			startAt = i;
			// 65-90, uppercase letters
			// 97-122, lowercase letters
			while (i < line.length()
					&& ((ch >= 65 && ch <= 90) || (ch >= 97 && ch <= 122))) {
				temp.append(ch);
				i++;
				if (i < line.length()) {
					ch = line.charAt(i);
				}
			}
			String tempString = temp.toString();
			if (reservedWords.containsKey(tempString)
					&& !usedReservedWords.containsKey(tempString)) {
				usedReservedWords.put(tempString, tempString);
				line = replace(line, tempString, (reservedWordStart
						+ tempString + reservedWordEnd));
				i += (reservedWordStart.length() + reservedWordEnd.length());
			} else {
				i++;
			}
		}
		buf.append(line);
		return buf.toString();
	}

	/**
	 * Replaces all instances of oldString with newString in line.
	 */
	private static final String replace(String line, String oldString,
			String newString) {
		int i = 0;
		if ((i = line.indexOf(oldString, i)) >= 0) {
			char[] line2 = line.toCharArray();
			char[] newString2 = newString.toCharArray();
			int oLength = oldString.length();
			StringBuffer buf = new StringBuffer(line2.length);
			buf.append(line2, 0, i).append(newString2);
			i += oLength;
			int j = i;
			while ((i = line.indexOf(oldString, i)) > 0) {
				buf.append(line2, j, i - j).append(newString2);
				i += oLength;
				j = i;
			}
			buf.append(line2, j, line2.length - j);
			return buf.toString();
		}
		return line;
	}

	/*
	 * Checks to see if some position in a line is between String start and
	 * ending characters. Not yet used in code or fully working :)
	 */
	private boolean isInsideString(String line, int position) {
		if (line.indexOf("\"") < 0) {
			return false;
		}
		int index;
		String left = line.substring(0, position);
		String right = line.substring(position);
		int leftCount = 0;
		int rightCount = 0;
		while ((index = left.indexOf("\"")) > -1) {
			leftCount++;
			left = left.substring(index + 1);
		}
		while ((index = right.indexOf("\"")) > -1) {
			rightCount++;
			right = right.substring(index + 1);
		}
		if (rightCount % 2 != 0 && leftCount % 2 != 0) {
			return true;
		} else {
			return false;
		}
	}

	/*
	 * Load Hashtable (or HashMap) with Java reserved words. Improved list in
	 * version 1.1 taken directly from Java language spec.
	 */
	private static void loadKeywords() {
		reservedWords.put("abstract", "abstract");
		reservedWords.put("boolean", "boolean");
		reservedWords.put("break", "break");
		reservedWords.put("byte", "byte");
		reservedWords.put("case", "case");
		reservedWords.put("catch", "catch");
		reservedWords.put("char", "char");
		reservedWords.put("class", "class");
		reservedWords.put("const", "const");
		reservedWords.put("continue", "continue");
		reservedWords.put("default", "default");
		reservedWords.put("do", "do");
		reservedWords.put("double", "double");
		reservedWords.put("else", "else");
		reservedWords.put("extends", "extends");
		reservedWords.put("false", "false");
		reservedWords.put("final", "final");
		reservedWords.put("finally", "finally");
		reservedWords.put("float", "float");
		reservedWords.put("for", "for");
		reservedWords.put("goto", "goto");
		reservedWords.put("if", "if");
		reservedWords.put("implements", "implements");
		reservedWords.put("import", "import");
		reservedWords.put("instanceof", "instanceof");
		reservedWords.put("int", "int");
		reservedWords.put("interface", "interface");
		reservedWords.put("long", "long");
		reservedWords.put("native", "native");
		reservedWords.put("new", "new");
		reservedWords.put("package", "package");
		reservedWords.put("private", "private");
		reservedWords.put("protected", "protected");
		reservedWords.put("public", "public");
		reservedWords.put("return", "return");
		reservedWords.put("short", "short");
		reservedWords.put("static", "static");
		reservedWords.put("strictfp", "strictfp");
		reservedWords.put("super", "super");
		reservedWords.put("switch", "switch");
		reservedWords.put("synchronized", "synchronized");
		reservedWords.put("this", "this");
		reservedWords.put("throw", "throw");
		reservedWords.put("throws", "throws");
		reservedWords.put("transient", "transient");
		reservedWords.put("true", "true");
		reservedWords.put("try", "try");
		reservedWords.put("void", "void");
		reservedWords.put("volatile", "volatile");
		reservedWords.put("while", "while");
	}
}