java-如何在实时语法荧光笔中处理多行注释？
作者：互联网
我正在用Java突出显示语法来编写自己的文本编辑器,此刻,每次用户输入单个字符时,它仅分析并突出显示当前行.虽然可能不是最有效的方法,但它足够好,不会引起任何明显的性能问题.在伪Java中,这将是我的代码的核心概念：
public void textUpdated(String wholeText, int updateOffset, int updateLength) {
int lineStart = getFirstLineStart(wholeText, updateOffset);
int lineEnd = getLastLineEnd(wholeText, updateOffset + updateLength);
List<Token> foundTokens = tokenizeText(wholeText, lineStart, lineEnd);
for(Token token : foundTokens) {
highlightText(token.offset, token.length, token.tokenType);
}
}
真正的问题在于多行注释.为了检查输入的字符是否在多行注释中,该程序将需要解析回最近出现的“ / *”,同时还要知道该出现在文字还是其他注释中.如果文本量很小,这将不是问题,但是如果文本包含20,000行代码,则每次按键时可能不得不扫描并(重新)突出显示20,000行代码,这将非常低效.
因此,我的最终问题是：如何在语法突出显示器中处理多行标记/注释,同时又保持高效？
解决方法:
大约10年前(或更长时间),我尝试这样做(出于娱乐目的).因为代码太旧了,所以我不记得代码的所有细节以及代码中的逻辑条件.这里的所有代码基本上都是蛮力解决方案.它绝不会按照rici的建议尝试保持每行的状态.
我将尝试解释代码的高级概念.希望其中一些对您有意义.
at the moment it simply parses and highlights the current line every time the user enters a single character.
这也是我的代码的基本前提.但是,它也可以处理粘贴多行代码.
how do I handle multi-line tokens/comments in a syntax highlighter while keeping it efficient?
在我的解决方案中,当您输入“ / *”以开始多行注释时,我将注释以下所有代码行,直到找到注释的末尾或另一个多行注释的末尾或文件.然后,当您输入匹配的“ * /”以结束多行注释时,我将重新突出显示以下各行,直到下一个多行注释或文档的末尾.
因此,突出显示的内容取决于多行注释之间的代码量.
这是其工作原理的快速概述.我怀疑它是否100％准确,因为我只玩了一点.应该注意的是,这段代码是在我刚学习Java时编写的,因此我绝不建议这是最好的方法,只是我当时所知道的最好的方法.
这是您的娱乐代码：)
只需运行代码,然后单击按钮即可开始.
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
class SyntaxDocument extends DefaultStyledDocument
{
private DefaultStyledDocument doc;
private Element rootElement;
private boolean multiLineComment;
private MutableAttributeSet normal;
private MutableAttributeSet keyword;
private MutableAttributeSet comment;
private MutableAttributeSet quote;
private Set<String> keywords;
private int lastLineProcessed = -1;
public SyntaxDocument()
{
doc = this;
rootElement = doc.getDefaultRootElement();
putProperty( DefaultEditorKit.EndOfLineStringProperty, "\n" );
normal = new SimpleAttributeSet();
StyleConstants.setForeground(normal, Color.black);
comment = new SimpleAttributeSet();
StyleConstants.setForeground(comment, Color.gray);
StyleConstants.setItalic(comment, true);
keyword = new SimpleAttributeSet();
StyleConstants.setForeground(keyword, Color.blue);
quote = new SimpleAttributeSet();
StyleConstants.setForeground(quote, Color.red);
keywords = new HashSet<String>();
keywords.add( "abstract" );
keywords.add( "boolean" );
keywords.add( "break" );
keywords.add( "byte" );
keywords.add( "byvalue" );
keywords.add( "case" );
keywords.add( "cast" );
keywords.add( "catch" );
keywords.add( "char" );
keywords.add( "class" );
keywords.add( "const" );
keywords.add( "continue" );
keywords.add( "default" );
keywords.add( "do" );
keywords.add( "double" );
keywords.add( "else" );
keywords.add( "extends" );
keywords.add( "false" );
keywords.add( "final" );
keywords.add( "finally" );
keywords.add( "float" );
keywords.add( "for" );
keywords.add( "future" );
keywords.add( "generic" );
keywords.add( "goto" );
keywords.add( "if" );
keywords.add( "implements" );
keywords.add( "import" );
keywords.add( "inner" );
keywords.add( "instanceof" );
keywords.add( "int" );
keywords.add( "interface" );
keywords.add( "long" );
keywords.add( "native" );
keywords.add( "new" );
keywords.add( "null" );
keywords.add( "operator" );
keywords.add( "outer" );
keywords.add( "package" );
keywords.add( "private" );
keywords.add( "protected" );
keywords.add( "public" );
keywords.add( "rest" );
keywords.add( "return" );
keywords.add( "short" );
keywords.add( "static" );
keywords.add( "super" );
keywords.add( "switch" );
keywords.add( "synchronized" );
keywords.add( "this" );
keywords.add( "throw" );
keywords.add( "throws" );
keywords.add( "transient" );
keywords.add( "true" );
keywords.add( "try" );
keywords.add( "var" );
keywords.add( "void" );
keywords.add( "volatile" );
keywords.add( "while" );
}
/*
* Override to apply syntax highlighting after the document has been updated
*/
public void insertString(int offset, String str, AttributeSet a) throws BadLocationException
{
if (str.equals("{"))
str = addMatchingBrace(offset);
super.insertString(offset, str, a);
processChangedLines(offset, str.length());
}
/*
* Override to apply syntax highlighting after the document has been updated
*/
public void remove(int offset, int length) throws BadLocationException
{
super.remove(offset, length);
processChangedLines(offset, 0);
}
/*
* Determine how many lines have been changed,
* then apply highlighting to each line
*/
public void processChangedLines(int offset, int length)
throws BadLocationException
{
String content = doc.getText(0, doc.getLength());
// The lines affected by the latest document update
int startLine = rootElement.getElementIndex(offset);
int endLine = rootElement.getElementIndex(offset + length);
if (startLine > endLine)
startLine = endLine;
// Make sure all comment lines prior to the start line are commented
// and determine if the start line is still in a multi line comment
if (startLine != lastLineProcessed
&& startLine != lastLineProcessed + 1)
{
setMultiLineComment( commentLinesBefore( content, startLine ) );
}
// Do the actual highlighting
for (int i = startLine; i <= endLine; i++)
{
applyHighlighting(content, i);
}
// Resolve highlighting to the next end multi line delimiter
if (isMultiLineComment())
commentLinesAfter(content, endLine);
else
highlightLinesAfter(content, endLine);
}
/*
* Highlight lines when a multi line comment is still 'open'
* (ie. matching end delimiter has not yet been encountered)
*/
private boolean commentLinesBefore(String content, int line)
{
int offset = rootElement.getElement( line ).getStartOffset();
// Start of comment not found, nothing to do
int startDelimiter = lastIndexOf( content, getStartDelimiter(), offset - 2 );
if (startDelimiter < 0)
return false;
// Matching start/end of comment found, nothing to do
int endDelimiter = indexOf( content, getEndDelimiter(), startDelimiter );
if (endDelimiter < offset & endDelimiter != -1)
return false;
// End of comment not found, highlight the lines
doc.setCharacterAttributes(startDelimiter, offset - startDelimiter + 1, comment, false);
return true;
}
/*
* Highlight comment lines to matching end delimiter
*/
private void commentLinesAfter(String content, int line)
{
int offset = rootElement.getElement( line ).getStartOffset();
// End of comment and Start of comment not found
// highlight until the end of the Document
int endDelimiter = indexOf( content, getEndDelimiter(), offset );
if (endDelimiter < 0)
{
endDelimiter = indexOf( content, getStartDelimiter(), offset + 2);
if (endDelimiter < 0)
{
doc.setCharacterAttributes(offset, content.length() - offset + 1, comment, false);
return;
}
}
// Matching start/end of comment found, comment the lines
int startDelimiter = lastIndexOf( content, getStartDelimiter(), endDelimiter );
if (startDelimiter < 0 || startDelimiter >= offset)
{
doc.setCharacterAttributes(offset, endDelimiter - offset + 1, comment, false);
}
}
/*
* Highlight lines to start or end delimiter
*/
private void highlightLinesAfter(String content, int line)
throws BadLocationException
{
int offset = rootElement.getElement( line ).getEndOffset();
// Start/End delimiter not found, nothing to do
int startDelimiter = indexOf( content, getStartDelimiter(), offset );
int endDelimiter = indexOf( content, getEndDelimiter(), offset );
if (startDelimiter < 0)
startDelimiter = content.length();
if (endDelimiter < 0)
endDelimiter = content.length();
int delimiter = Math.min(startDelimiter, endDelimiter);
if (delimiter < offset)
return;
// Start/End delimiter found, reapply highlighting
int endLine = rootElement.getElementIndex( delimiter );
for (int i = line + 1; i <= endLine; i++)
{
Element branch = rootElement.getElement( i );
Element leaf = doc.getCharacterElement( branch.getStartOffset() );
AttributeSet as = leaf.getAttributes();
if ( as.isEqual(comment) )
{
applyHighlighting(content, i);
}
}
}
/*
* Parse the line to determine the appropriate highlighting
*/
private void applyHighlighting(String content, int line)
throws BadLocationException
{
lastLineProcessed = line;
int startOffset = rootElement.getElement( line ).getStartOffset();
int endOffset = rootElement.getElement( line ).getEndOffset() - 1;
int lineLength = endOffset - startOffset;
int contentLength = content.length();
if (endOffset >= contentLength)
endOffset = contentLength - 1;
// check for multi line comments
// (always set the comment attribute for the entire line)
if (endingMultiLineComment(content, startOffset, endOffset)
|| isMultiLineComment()
|| startingMultiLineComment(content, startOffset, endOffset) )
{
doc.setCharacterAttributes(startOffset, endOffset - startOffset + 1, comment, false);
lastLineProcessed = -1;
return;
}
// set normal attributes for the line
doc.setCharacterAttributes(startOffset, lineLength, normal, true);
// check for single line comment
int index = content.indexOf(getSingleLineDelimiter(), startOffset);
if ( (index > -1) && (index < endOffset) )
{
doc.setCharacterAttributes(index, endOffset - index + 1, comment, false);
endOffset = index - 1;
}
// check for tokens
checkForTokens(content, startOffset, endOffset);
}
/*
* Does this line contain the start delimiter
*/
private boolean startingMultiLineComment(String content, int startOffset, int endOffset)
throws BadLocationException
{
int index = indexOf( content, getStartDelimiter(), startOffset );
if ( (index < 0) || (index > endOffset) )
return false;
else
{
setMultiLineComment( true );
return true;
}
}
/*
* Does this line contain the end delimiter
*/
private boolean endingMultiLineComment(String content, int startOffset, int endOffset)
throws BadLocationException
{
int index = indexOf( content, getEndDelimiter(), startOffset );
if ( (index < 0) || (index > endOffset) )
return false;
else
{
setMultiLineComment( false );
return true;
}
}
/*
* We have found a start delimiter
* and are still searching for the end delimiter
*/
private boolean isMultiLineComment()
{
return multiLineComment;
}
private void setMultiLineComment(boolean value)
{
multiLineComment = value;
}
/*
* Parse the line for tokens to highlight
*/
private void checkForTokens(String content, int startOffset, int endOffset)
{
while (startOffset <= endOffset)
{
// skip the delimiters to find the start of a new token
while ( isDelimiter( content.substring(startOffset, startOffset + 1) ) )
{
if (startOffset < endOffset)
startOffset++;
else
return;
}
// Extract and process the entire token
if ( isQuoteDelimiter( content.substring(startOffset, startOffset + 1) ) )
startOffset = getQuoteToken(content, startOffset, endOffset);
else
startOffset = getOtherToken(content, startOffset, endOffset);
}
}
/*
*
*/
private int getQuoteToken(String content, int startOffset, int endOffset)
{
String quoteDelimiter = content.substring(startOffset, startOffset + 1);
String escapeString = getEscapeString(quoteDelimiter);
int index;
int endOfQuote = startOffset;
// skip over the escape quotes in this quote
index = content.indexOf(escapeString, endOfQuote + 1);
while ( (index > -1) && (index < endOffset) )
{
endOfQuote = index + 1;
index = content.indexOf(escapeString, endOfQuote);
}
// now find the matching delimiter
index = content.indexOf(quoteDelimiter, endOfQuote + 1);
if ( (index < 0) || (index > endOffset) )
endOfQuote = endOffset;
else
endOfQuote = index;
doc.setCharacterAttributes(startOffset, endOfQuote - startOffset + 1, quote, false);
return endOfQuote + 1;
}
/*
*
*/
private int getOtherToken(String content, int startOffset, int endOffset)
{
int endOfToken = startOffset + 1;
while ( endOfToken <= endOffset )
{
if ( isDelimiter( content.substring(endOfToken, endOfToken + 1) ) )
break;
endOfToken++;
}
String token = content.substring(startOffset, endOfToken);
if ( isKeyword( token ) )
{
doc.setCharacterAttributes(startOffset, endOfToken - startOffset, keyword, false);
}
return endOfToken + 1;
}
/*
* Assume the needle will be found at the start/end of the line
*/
private int indexOf(String content, String needle, int offset)
{
int index;
while ( (index = content.indexOf(needle, offset)) != -1 )
{
String text = getLine( content, index ).trim();
if (text.startsWith(needle) || text.endsWith(needle))
break;
else
offset = index + 1;
}
return index;
}
/*
* Assume the needle will the found at the start/end of the line
*/
private int lastIndexOf(String content, String needle, int offset)
{
int index;
while ( (index = content.lastIndexOf(needle, offset)) != -1 )
{
String text = getLine( content, index ).trim();
if (text.startsWith(needle) || text.endsWith(needle))
break;
else
offset = index - 1;
}
return index;
}
private String getLine(String content, int offset)
{
int line = rootElement.getElementIndex( offset );
Element lineElement = rootElement.getElement( line );
int start = lineElement.getStartOffset();
int end = lineElement.getEndOffset();
return content.substring(start, end - 1);
}
/*
* Override for other languages
*/
protected boolean isDelimiter(String character)
{
String operands = ";:{}()[]+-/%<=>!&|^~*";
if (Character.isWhitespace( character.charAt(0) )
|| operands.indexOf(character) != -1 )
return true;
else
return false;
}
/*
* Override for other languages
*/
protected boolean isQuoteDelimiter(String character)
{
String quoteDelimiters = "\"'";
if (quoteDelimiters.indexOf(character) < 0)
return false;
else
return true;
}
/*
* Override for other languages
*/
protected boolean isKeyword(String token)
{
return keywords.contains( token );
}
/*
* Override for other languages
*/
protected String getStartDelimiter()
{
return "/*";
}
/*
* Override for other languages
*/
protected String getEndDelimiter()
{
return "*/";
}
/*
* Override for other languages
*/
protected String getSingleLineDelimiter()
{
return "//";
}
/*
* Override for other languages
*/
protected String getEscapeString(String quoteDelimiter)
{
return "\\" + quoteDelimiter;
}
/*
*
*/
protected String addMatchingBrace(int offset) throws BadLocationException
{
StringBuffer whiteSpace = new StringBuffer();
int line = rootElement.getElementIndex( offset );
int i = rootElement.getElement(line).getStartOffset();
while (true)
{
String temp = doc.getText(i, 1);
if (temp.equals(" ") || temp.equals("\t"))
{
whiteSpace.append(temp);
i++;
}
else
break;
}
return "{\n" + whiteSpace.toString() + "\t\n" + whiteSpace.toString() + "}";
}
/*
public void setCharacterAttributes(int offset, int length, AttributeSet s, boolean replace)
{
super.setCharacterAttributes(offset, length, s, replace);
}
*/
public static void main(String a[])
{
EditorKit editorKit = new StyledEditorKit()
{
public Document createDefaultDocument()
{
return new SyntaxDocument();
}
};
// final JEditorPane edit = new JEditorPane()
final JTextPane edit = new JTextPane();
// LinePainter painter = new LinePainter(edit, Color.cyan);
// LinePainter2 painter = new LinePainter2(edit, Color.cyan);
// edit.setEditorKitForContentType("text/java", editorKit);
// edit.setContentType("text/java");
edit.setEditorKit(editorKit);
JButton button = new JButton("Load SyntaxDocument.java");
button.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
try
{
long startTime = System.currentTimeMillis();
FileReader fr = new FileReader( "SyntaxDocument.java" );
// FileReader fr = new FileReader( "C:\\Java\\j2sdk1.4.2\\src\\javax\\swing\\JComponent.java" );
BufferedReader br = new BufferedReader(fr);
edit.read( br, null );
System.out.println("Load: " + (System.currentTimeMillis() - startTime));
System.out.println("Document contains: " + edit.getDocument().getLength() + " characters");
edit.requestFocus();
}
catch(Exception e2) {}
}
});
JFrame frame = new JFrame("Syntax Highlighting");
frame.getContentPane().add( new JScrollPane(edit) );
frame.getContentPane().add(button, BorderLayout.SOUTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(800,300);
frame.setVisible(true);
}
}
注意：此代码不会检查注释定界符是否在文字内,因此需要对其进行改进.
我并不是真的希望您使用此代码,但是我认为它可以使您了解使用蛮力方法时可能获得的性能.
标签：lexer,java,tokenize,parsing,syntax-highlighting 来源： https://codeday.me/bug/20191009/1880579.html