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Java > Open Source Codes > org > jedit > syntax > TextUtilities


1 package org.jedit.syntax;
2
3 /*
4  * TextUtilities.java - Utility functions used by the text area classes
5  * Copyright (C) 1999 Slava Pestov
6  *
7  * You may use and modify this package for any purpose. Redistribution is
8  * permitted, in both source and binary form, provided that this notice
9  * remains intact in all source distributions of this package.
10  */
11
12 import javax.swing.text.*;
13
14 /**
15  * Class with several utility functions used by the text area component.
16  * @author Slava Pestov
17  * @version $Id: TextUtilities.java,v 1.1 2003/12/14 16:29:49 daggerrz Exp $
18  */
19 public class TextUtilities
20 {
21    /**
22     * Returns the offset of the bracket matching the one at the
23     * specified offset of the document, or -1 if the bracket is
24     * unmatched (or if the character is not a bracket).
25     * @param doc The document
26     * @param offset The offset
27     * @exception BadLocationException If an out-of-bounds access
28     * was attempted on the document text
29     */
30    public static int findMatchingBracket(Document doc, int offset)
31       throws BadLocationException
32    {
33       if(doc.getLength() == 0)
34          return -1;
35       char c = doc.getText(offset,1).charAt(0);
36       char cprime; // c` - corresponding character
37 boolean direction; // true = back, false = forward
38
39       switch(c)
40       {
41       case '(': cprime = ')'; direction = false; break;
42       case ')': cprime = '('; direction = true; break;
43       case '[': cprime = ']'; direction = false; break;
44       case ']': cprime = '['; direction = true; break;
45       case '{': cprime = '}'; direction = false; break;
46       case '}': cprime = '{'; direction = true; break;
47       default: return -1;
48       }
49
50       int count;
51
52       // How to merge these two cases is left as an exercise
53 // for the reader.
54
55       // Go back or forward
56 if(direction)
57       {
58          // Count is 1 initially because we have already
59 // `found' one closing bracket
60 count = 1;
61
62          // Get text[0,offset-1];
63 String JavaDoc text = doc.getText(0,offset);
64
65          // Scan backwards
66 for(int i = offset - 1; i >= 0; i--)
67          {
68             // If text[i] == c, we have found another
69 // closing bracket, therefore we will need
70 // two opening brackets to complete the
71 // match.
72 char x = text.charAt(i);
73             if(x == c)
74                count++;
75
76             // If text[i] == cprime, we have found a
77 // opening bracket, so we return i if
78 // --count == 0
79 else if(x == cprime)
80             {
81                if(--count == 0)
82                   return i;
83             }
84          }
85       }
86       else
87       {
88          // Count is 1 initially because we have already
89 // `found' one opening bracket
90 count = 1;
91
92          // So we don't have to + 1 in every loop
93 offset++;
94
95          // Number of characters to check
96 int len = doc.getLength() - offset;
97
98          // Get text[offset+1,len];
99 String JavaDoc text = doc.getText(offset,len);
100
101          // Scan forwards
102 for(int i = 0; i < len; i++)
103          {
104             // If text[i] == c, we have found another
105 // opening bracket, therefore we will need
106 // two closing brackets to complete the
107 // match.
108 char x = text.charAt(i);
109
110             if(x == c)
111                count++;
112
113             // If text[i] == cprime, we have found an
114 // closing bracket, so we return i if
115 // --count == 0
116 else if(x == cprime)
117             {
118                if(--count == 0)
119                   return i + offset;
120             }
121          }
122       }
123
124       // Nothing found
125 return -1;
126    }
127
128    /**
129     * Locates the start of the word at the specified position.
130     * @param line The text
131     * @param pos The position
132     */
133    public static int findWordStart(String JavaDoc line, int pos, String JavaDoc noWordSep)
134    {
135       char ch = line.charAt(pos - 1);
136
137       if(noWordSep == null)
138          noWordSep = "";
139       boolean selectNoLetter = (!Character.isLetterOrDigit(ch)
140          && noWordSep.indexOf(ch) == -1);
141
142       int wordStart = 0;
143       for(int i = pos - 1; i >= 0; i--)
144       {
145          ch = line.charAt(i);
146          if(selectNoLetter ^ (!Character.isLetterOrDigit(ch) &&
147             noWordSep.indexOf(ch) == -1))
148          {
149             wordStart = i + 1;
150             break;
151          }
152       }
153
154       return wordStart;
155    }
156
157    /**
158     * Locates the end of the word at the specified position.
159     * @param line The text
160     * @param pos The position
161     */
162    public static int findWordEnd(String JavaDoc line, int pos, String JavaDoc noWordSep)
163    {
164       char ch = line.charAt(pos);
165
166       if(noWordSep == null)
167          noWordSep = "";
168       boolean selectNoLetter = (!Character.isLetterOrDigit(ch)
169          && noWordSep.indexOf(ch) == -1);
170
171       int wordEnd = line.length();
172       for(int i = pos; i < line.length(); i++)
173       {
174          ch = line.charAt(i);
175          if(selectNoLetter ^ (!Character.isLetterOrDigit(ch) &&
176             noWordSep.indexOf(ch) == -1))
177          {
178             wordEnd = i;
179             break;
180          }
181       }
182       return wordEnd;
183    }
184 }
185
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