@@ -55,6 +55,7 @@ package org.apache.tools.ant.filters;
import java.io.IOException;
import java.io.Reader;
import java.util.LinkedList;
import org.apache.tools.ant.types.Parameter;
/**
@@ -90,18 +91,22 @@ public final class TailFilter
/** Number of lines to be skipped. */
private long skip = 0;
/** Buffer to hold in characters read ahead. */
private char[] buffer = new char[4096];
/** The character position that has been returned from the buffer. */
private int returnedCharPos = -1;
/** Whether or not read-ahead been completed. */
private boolean completedReadAhead = false;
/** Current index position on the buffer. */
private int bufferPos = 0;
/** A line tokenizer */
private TokenFilter.LineTokenizer lineTokenizer = null;
/** the current line from the input stream */
private String line = null;
/** the position in the current line */
private int linePos = 0;
private LinkedList lineList = new LinkedList();
/**
* Constructor for "dummy" instances.
*
@@ -119,6 +124,8 @@ public final class TailFilter
*/
public TailFilter(final Reader in) {
super(in);
lineTokenizer = new TokenFilter.LineTokenizer();
lineTokenizer.setIncludeDelims(true);
}
/**
@@ -140,74 +147,19 @@ public final class TailFilter
setInitialized(true);
}
if (!completedReadAhead) {
int ch = -1;
while ((ch = in.read()) != -1) {
if (buffer.length == bufferPos) {
if (returnedCharPos != -1) {
final char[] tmpBuffer = new char[buffer.length];
System.arraycopy(buffer, returnedCharPos + 1, tmpBuffer,
0, buffer.length - (returnedCharPos + 1));
buffer = tmpBuffer;
bufferPos = bufferPos - (returnedCharPos + 1);
returnedCharPos = -1;
} else {
final char[] tmpBuffer = new char[buffer.length * 2];
System.arraycopy(buffer, 0, tmpBuffer, 0, bufferPos);
buffer = tmpBuffer;
}
}
if (lines > 0) {
if (ch == '\n' || ch == -1) {
++linesRead;
if ((linesRead == lines + skip)) {
int i = 0;
for (i = returnedCharPos + 1;
buffer[i] != 0 && buffer[i] != '\n'; i++) {
}
returnedCharPos = i;
--linesRead;
}
}
}
if (ch == -1) {
break;
}
buffer[bufferPos] = (char) ch;
bufferPos++;
}
completedReadAhead = true;
}
// Because the complete stream is read into the buffer I can delete
// the "skip lines" from back to the beginning.
if (skip > 0) {
// searching...
int i;
for (i = buffer.length - 1; skip > 0; i--) {
if (buffer[i]=='\n') {
skip--;
}
}
// cut the buffer to the new length
char[] newBuffer = new char[i];
System.arraycopy(buffer, 0, newBuffer, 0, i);
buffer = newBuffer;
// don´t forget to set the "lastposition" new
bufferPos = i;
while (line == null || line.length() == 0) {
line = lineTokenizer.getToken(in);
line = tailFilter(line);
if (line == null)
return -1;
linePos = 0;
}
++returnedCharPos;
if (returnedCharPos >= bufferPos) {
return -1;
} else {
return buffer[returnedCharPos];
}
int ch = line.charAt(linePos);
linePos++;
if (linePos == line.length())
line = null;
return ch;
}
/**
@@ -267,6 +219,7 @@ public final class TailFilter
/**
* Scans the parameters list for the "lines" parameter and uses
* it to set the number of lines to be returned in the filtered stream.
* also scan for "skip" parameter.
*/
private final void initialize() {
Parameter[] params = getParameters();
@@ -274,13 +227,55 @@ public final class TailFilter
for (int i = 0; i < params.length; i++) {
if (LINES_KEY.equals(params[i].getName())) {
setLines(new Long(params[i].getValue()).longValue());
break ;
continue ;
}
if (SKIP_KEY.equals(params[i].getName())) {
skip = new Long(params[i].getValue()).longValue();
break;
continue;
}
}
}
}
/**
* implement a tail filter on a stream of lines.
* line = null is the end of the stream.
* @return "" while reading in the lines,
* line while outputing the lines
* null at the end of outputting the lines
*/
private String tailFilter(String line) {
if (! completedReadAhead) {
if (line != null) {
lineList.add(line);
if (lines == -1) {
if (lineList.size() > skip) {
return (String) lineList.removeFirst();
}
}
else {
long linesToKeep = lines + (skip > 0 ? skip : 0);
if (linesToKeep < lineList.size()) {
lineList.removeFirst();
}
}
return "";
}
completedReadAhead = true;
if (skip > 0) {
for (int i = 0; i < skip; ++i) {
lineList.removeLast();
}
}
if (lines > -1) {
while (lineList.size() > lines) {
lineList.removeFirst();
}
}
}
if (lineList.size() > 0) {
return (String) lineList.removeFirst();
}
return null;
}
}
Magesh Umasankar