95 lines
2.5 KiB
Java
95 lines
2.5 KiB
Java
|
Grep
|
||
|
|
|
||
|
|
import java.io.*;
|
||
|
|
import java.nio.*;
|
||
|
|
import java.nio.channels.*;
|
||
|
|
import java.nio.charset.*;
|
||
|
|
import java.util.regex.*;
|
||
|
|
|
||
|
|
|
||
|
|
public class Grep {
|
||
|
|
|
||
|
|
// Charset and decoder for ISO-8859-15
|
||
|
|
private static Charset charset = Charset.forName("ISO-8859-15");
|
||
|
|
private static CharsetDecoder decoder = charset.newDecoder();
|
||
|
|
|
||
|
|
// Pattern used to parse lines
|
||
|
|
private static Pattern linePattern
|
||
|
|
= Pattern.compile(".*
|
||
|
|
?
|
||
|
|
");
|
||
|
|
|
||
|
|
// The input pattern that we're looking for
|
||
|
|
private static Pattern pattern;
|
||
|
|
|
||
|
|
// Compile the pattern from the command line
|
||
|
|
//
|
||
|
|
private static void compile(String pat) {
|
||
|
|
try {
|
||
|
|
pattern = Pattern.compile(pat);
|
||
|
|
} catch (PatternSyntaxException x) {
|
||
|
|
System.err.println(x.getMessage());
|
||
|
|
System.exit(1);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Use the linePattern to break the given CharBuffer into lines, applying
|
||
|
|
// the input pattern to each line to see if we have a match
|
||
|
|
//
|
||
|
|
private static void grep(File f, CharBuffer cb) {
|
||
|
|
Matcher lm = linePattern.matcher(cb); // Line matcher
|
||
|
|
Matcher pm = null; // Pattern matcher
|
||
|
|
int lines = 0;
|
||
|
|
while (lm.find()) {
|
||
|
|
lines++;
|
||
|
|
CharSequence cs = lm.group(); // The current line
|
||
|
|
if (pm == null)
|
||
|
|
pm = pattern.matcher(cs);
|
||
|
|
else
|
||
|
|
pm.reset(cs);
|
||
|
|
if (pm.find())
|
||
|
|
System.out.print(f + ":" + lines + ":" + cs);
|
||
|
|
if (lm.end() == cb.limit())
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Search for occurrences of the input pattern in the given file
|
||
|
|
//
|
||
|
|
private static void grep(File f) throws IOException {
|
||
|
|
|
||
|
|
// Open the file and then get a channel from the stream
|
||
|
|
FileInputStream fis = new FileInputStream(f);
|
||
|
|
FileChannel fc = fis.getChannel();
|
||
|
|
|
||
|
|
// Get the file's size and then map it into memory
|
||
|
|
int sz = (int)fc.size();
|
||
|
|
MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY, 0, sz);
|
||
|
|
|
||
|
|
// Decode the file into a char buffer
|
||
|
|
CharBuffer cb = decoder.decode(bb);
|
||
|
|
|
||
|
|
// Perform the search
|
||
|
|
grep(f, cb);
|
||
|
|
|
||
|
|
// Close the channel and the stream
|
||
|
|
fc.close();
|
||
|
|
}
|
||
|
|
|
||
|
|
public static void main(String[] args) {
|
||
|
|
if (args.length < 2) {
|
||
|
|
System.err.println("Usage: java Grep pattern file...");
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
compile(args[0]);
|
||
|
|
for (int i = 1; i < args.length; i++) {
|
||
|
|
File f = new File(args[i]);
|
||
|
|
try {
|
||
|
|
grep(f);
|
||
|
|
} catch (IOException x) {
|
||
|
|
System.err.println(f + ": " + x);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|