org.unix4j.unix.tail.TailOption Maven / Gradle / Ivy
package org.unix4j.unix.tail;
import java.util.Collections;
import java.util.EnumSet;
import java.util.Iterator;
import org.unix4j.option.Option;
import org.unix4j.unix.Tail;
/**
* Options for the {@link Tail tail} command.
*
* For most applications, it may be more convenient to use {@link Tail#Options}
* instead of the option constants defined here.
*
*
* {@code -c} {@code --chars} The {@code count} argument is in units of characters instead of
lines. Starts from 1 and includes line ending characters. {@code -q} {@code --suppressHeaders} Suppresses printing of headers when multiple files are being
examined. {@code -s} {@code --countFromStart} The {@code count} argument is relative to the beginning of the file
instead of counting from the end of the file. For instance,
{@code tail -s 10} prints the lines starting from line 10;
{@code tail -s 1} prints the whole file.
*/
public enum TailOption implements Option, TailOptions {
/**
* Option {@code --chars}, {@code -c}:
* The {@code count} argument is in units of characters instead of
lines. Starts from 1 and includes line ending characters.
*/
chars('c'),
/**
* Option {@code --suppressHeaders}, {@code -q}:
* Suppresses printing of headers when multiple files are being
examined.
*/
suppressHeaders('q'),
/**
* Option {@code --countFromStart}, {@code -s}:
* The {@code count} argument is relative to the beginning of the file
instead of counting from the end of the file. For instance,
{@code tail -s 10} prints the lines starting from line 10;
{@code tail -s 1} prints the whole file.
*/
countFromStart('s');
private final char acronym;
private TailOption(char acronym) {
this.acronym = acronym;
}
@Override
public Class optionType() {
return TailOption.class;
}
/**
* Returns the option with the given {@code acronym}, or {@code null} if no
* such option is found.
*
* @param acronym the option {@link #acronym() acronym}
* @return the option with the given {@code acronym} or {@code null} if it
* is not found
*/
public static TailOption findByAcronym(char acronym) {
for (final TailOption opt : values()) {
if (opt.acronym() == acronym) return opt;
}
return null;
}
@Override
public char acronym() {
return acronym;
}
@Override
public boolean isSet(TailOption option) {
return equals(option);
}
/**
* Returns a new set with {@code this} active option.
*
* @return a new set containing this option
*/
@Override
public EnumSet asSet() {
return EnumSet.of(this);
}
/**
* Returns an immutable iterator returning o single element: {@code this}
* option.
*
* @return an immutable iterator with {@code this} active option.
*/
@Override
public Iterator iterator() {
return Collections.singleton(this).iterator();
}
/**
* Returns 1 as this is a set with a single element: {@code this} option
*
* @return one
*/
@Override
public int size() {
return 1;
}
/**
* Returns true if the {@link Option#acronym() acronym} should be used for
* the specified {@code option} in string representations.
*
* This method returns always true for all options.
*
* @param option
* the option of interest
* @return always true indicating that option acronyms should be used in
* string representations for all options
*/
@Override
public boolean useAcronymFor(TailOption option) {
return true;
}
}