umagesh 02/02/17 16:59:43
Added:
proposal/sandbox/filterreaders/src/main/org/apache/tools/ant/filters
HeadFilter.java
Log:
Filter to read the first 'n' lines.
Revision Changes Path
1.1
jakarta-ant/proposal/sandbox/filterreaders/src/main/org/apache/tools/ant/filters/HeadFilter.java
Index: HeadFilter.java
===================================================================
package org.apache.tools.ant.filters;
import java.io.FilterReader;
import java.io.IOException;
import java.io.Reader;
import org.apache.tools.ant.types.Parameter;
import org.apache.tools.ant.types.Parameterizable;
/**
* Read the first n lines (Default is first 10 lines)
*
* Example:
* =======
*
* <filterreader classname="org.apache.tools.ant.filters.HeadFilter">
* <param name="lines" value="3"/>
* </filterreader>
*
* @author <a href="mailto:[EMAIL PROTECTED]">Magesh Umasankar</a>
*/
public final class HeadFilter
extends FilterReader
implements Parameterizable
{
private static final String LINES_KEY = "lines";
private Parameter[] parameters;
private boolean initialized = false;
private long linesRead = 0;
private long lines = 10;
private boolean ignoreLineFeed = false;
/**
* Create a new filtered reader.
*
* @param in a Reader object providing the underlying stream.
*/
public HeadFilter(final Reader in) {
super(in);
}
public final int read() throws IOException {
if (!initialized) {
initialize();
initialized = true;
}
int ch = -1;
if (linesRead < lines) {
ch = in.read();
if (ignoreLineFeed) {
if (ch == '\n') {
ch = in.read();
}
ignoreLineFeed = false;
}
switch (ch) {
case '\r':
ch = '\n';
ignoreLineFeed = true;
//fall through
case '\n':
linesRead++;
break;
}
}
return ch;
}
public final int read(final char cbuf[], final int off,
final int len) throws IOException {
for (int i = 0; i < len; i++) {
final int ch = read();
if (ch == -1) {
if (i == 0) {
return -1;
} else {
return i;
}
}
cbuf[off + i] = (char) ch;
}
return len;
}
public final long skip(long n) throws IOException {
for (long i = 0; i < n; i++) {
if (in.read() == -1) {
return i;
}
}
return n;
}
/**
* Set Parameters
*/
public final void setParameters(final Parameter[] parameters) {
this.parameters = parameters;
initialized = false;
}
private final void initialize() {
if (parameters != null) {
for (int i = 0; i < parameters.length; i++) {
if (LINES_KEY.equals(parameters[i].getName())) {
lines = new Long(parameters[i].getValue()).longValue();
break;
}
}
}
}
}
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