git.gag.com Git - debian/openrocket/blob - core/src/net/sf/openrocket/gui/help/tours/TextLineReader.java

   1 package net.sf.openrocket.gui.help.tours;
   2
   3 import java.io.BufferedReader;
   4 import java.io.IOException;
   5 import java.io.InputStream;
   6 import java.io.InputStreamReader;
   7 import java.io.Reader;
   8 import java.nio.charset.Charset;
   9 import java.util.Iterator;
  10 import java.util.NoSuchElementException;
  11
  12 import net.sf.openrocket.util.BugException;
  13
  14 /**
  15  * Read from a Reader object one line at a time, ignoring blank lines,
  16  * preceding and trailing whitespace and comment lines starting with '#'.
  17  *
  18  * @author Sampo Niskanen <sampo.niskanen@iki.fi>
  19  */
  20 public class TextLineReader implements Iterator<String> {
  21
  22         private static final Charset UTF8 = Charset.forName("UTF-8");
  23
  24
  25
  26         private final BufferedReader reader;
  27
  28         private String next = null;
  29
  30         /**
  31          * Read from an input stream with UTF-8 character encoding.
  32          */
  33         public TextLineReader(InputStream inputStream) {
  34                 this(new InputStreamReader(inputStream, UTF8));
  35         }
  36
  37
  38         /**
  39          * Read from a reader.
  40          */
  41         public TextLineReader(Reader reader) {
  42                 if (reader instanceof BufferedReader) {
  43                         this.reader = (BufferedReader) reader;
  44                 } else {
  45                         this.reader = new BufferedReader(reader);
  46                 }
  47         }
  48
  49
  50         /**
  51          * Test whether the file has more lines available.
  52          */
  53         @Override
  54         public boolean hasNext() {
  55                 if (next != null) {
  56                         return true;
  57                 }
  58
  59                 try {
  60                         next = readLine();
  61                 } catch (IOException e) {
  62                         throw new BugException(e);
  63                 }
  64
  65                 return next != null;
  66         }
  67
  68
  69         /**
  70          * Retrieve the next non-blank, non-comment line.
  71          */
  72         @Override
  73         public String next() {
  74                 if (hasNext()) {
  75                         String ret = next;
  76                         next = null;
  77                         return ret;
  78                 }
  79
  80                 throw new NoSuchElementException("End of file reached");
  81         }
  82
  83
  84         /**
  85          * Peek what the next line would be.
  86          */
  87         public String peek() {
  88                 if (hasNext()) {
  89                         return next;
  90                 }
  91
  92                 throw new NoSuchElementException("End of file reached");
  93         }
  94
  95
  96         private String readLine() throws IOException {
  97
  98                 while (true) {
  99                         // Read the next line
 100                         String line = reader.readLine();
 101                         if (line == null) {
 102                                 return null;
 103                         }
 104
 105                         // Check whether to accept the line
 106                         line = line.trim();
 107                         if (line.length() > 0 && line.charAt(0) != '#') {
 108                                 return line;
 109                         }
 110                 }
 111
 112         }
 113
 114
 115         @Override
 116         public void remove() {
 117                 throw new UnsupportedOperationException("Remove not supported");
 118         }
 119
 120 }