SyntaxHighlighter.java

/*
Copyright (c) 2013, Fivium Ltd.
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice, 
      this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice, 
      this list of conditions and the following disclaimer in the documentation 
      and/or other materials provided with the distribution.
    * Neither the name of Fivium Ltd nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON 
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
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 */
package net.foxopen.foxydocs.view;

import static net.foxopen.foxydocs.FoxyDocs.*;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import net.vzurczak.main.*;

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.Bullet;
import org.eclipse.swt.custom.LineStyleEvent;
import org.eclipse.swt.custom.LineStyleListener;
import org.eclipse.swt.custom.ST;
import org.eclipse.swt.custom.StyleRange;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.graphics.GlyphMetrics;

public class SyntaxHighlighter {

  private final static HashMap<String, StyleRange[]> cache = new HashMap<String, StyleRange[]>();

  public static String getHash(String input) throws NoSuchAlgorithmException, UnsupportedEncodingException {
    MessageDigest digest = MessageDigest.getInstance("SHA-256");
    digest.update(input.getBytes("UTF-8"));
    return new String(digest.digest());
  }

  public static StyleRange[] getStyle(final StyledText target) {
    String hash = "";
    try {
      hash = getHash(target.getText());
    } catch (NoSuchAlgorithmException e) {
      e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    }
    if (hash != "" && cache.containsKey(hash)) {
      return cache.get(hash);
    }
    ArrayList<StyleRange> ranges = new ArrayList<StyleRange>();
    XmlRegionAnalyzer analyzer = new XmlRegionAnalyzer();
    String xml = target.getText();
    List<XmlRegion> regions = analyzer.analyzeXml(xml);
    for (XmlRegion xr : regions) {
      // Create a collection to hold the StyleRanges
      int regionLength = xr.getEnd() - xr.getStart();
      switch (xr.getXmlRegionType()) {
      case MARKUP:
        // Name is red
        ranges.add(new StyleRange(xr.getStart(), regionLength, DARK_RED, null));
        // <, > and / in blue
        char[] cArray = xml.substring(xr.getStart(), xr.getEnd()).toCharArray();
        for (int i = 0; i < cArray.length; i++) {
          switch (cArray[i]) {
          case '<':
          case '>':
          case '/':
            ranges.add(new StyleRange(xr.getStart() + i, 0, BLUE, null)); // Last
            break;
          default:
            break;
          }
        }

        break;
      case ATTRIBUTE:
        ranges.add(new StyleRange(xr.getStart(), regionLength, RED, null));
        break;
      case ATTRIBUTE_VALUE:
        // Color the two first and the last char in blue
        ranges.add(new StyleRange(xr.getStart(), 2, BLUE, null));
        ranges.add(new StyleRange(xr.getStart() + regionLength - 1, 1, BLUE, null));
        break;
      case MARKUP_VALUE:
        // Default
        break;
      case COMMENT:
        ranges.add(new StyleRange(xr.getStart(), regionLength, GREY, null));
        break;
      case INSTRUCTION:
        ranges.add(new StyleRange(xr.getStart(), regionLength, GREEN, null));
        break;
      case CDATA:
        // Default
        break;
      case WHITESPACE:
        // Nothing
        break;
      case UNEXPECTED:
        ranges.add(new StyleRange(xr.getStart(), regionLength, PURPLE, null, SWT.BOLD));
        break;
      default:
        break;
      }
    }
    StyleRange[] styles = ranges.toArray(new StyleRange[0]);
    cache.put(hash, styles);
    return styles;
  }

  public static void addSyntaxHighligherListener(final StyledText target) {
    // Line number
    target.addLineStyleListener(new LineStyleListener() {

      @Override
      public void lineGetStyle(LineStyleEvent event) {
        event.bulletIndex = target.getLineAtOffset(event.lineOffset);
        StyleRange style = new StyleRange();
        style.metrics = new GlyphMetrics(0, 0, Integer.toString(target.getLineCount() + 1).length() * 12);
        // Line number
        event.bullet = new Bullet(ST.BULLET_NUMBER, style);
        // Colours
        event.styles = getStyle(target);
      }
    });

  }

}