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package org.scijava.log;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import java.util.StringJoiner;

import java.util.concurrent.ConcurrentMap;

import java.util.concurrent.ConcurrentSkipListMap;

/**

* Identifies where a {@link LogMessage} came from.

*

* @author Matthias Arzt

*/

public class LogSource {

public static final String SEPARATOR = ":";

private final LogSource parent;

private final List<String> path;

private final ConcurrentMap<String, LogSource> children =

new ConcurrentSkipListMap<>();

private String formatted = null;

private Integer logLevel;

private LogSource(LogSource parent, String name) {

this.parent = parent;

List<String> parentPath = parent.path();

List<String> list = new ArrayList<>(parentPath.size() + 1);

list.addAll(parentPath);

list.add(name);

this.path = Collections.unmodifiableList(list);

}

private LogSource() {

this.parent = null;

this.path = Collections.emptyList();

}

/** Returns the root log source. This LogSource represents the empty list. */

public static LogSource newRoot() {

return new LogSource();

}

/**

* Returns a log source with the given path.

*

* @param subPath Relative path to the source, divided by

* {@link LogSource#SEPARATOR}.

*/

public LogSource subSource(final String subPath) {

LogSource result = this;

for (final String name : subPath.split(SEPARATOR))

result = result.child(name);

return result;

}

/** Returns the list of strings which is represented by this LogSource. */

public List<String> path() {

return path;

}

/** Returns the last entry in the list of strings. */

public String name() {

if (path.isEmpty()) return "";

return path.get(path.size() - 1);

}

@Override

public String toString() {

if (formatted != null) return formatted;

StringJoiner joiner = new StringJoiner(SEPARATOR);

path.forEach(s -> joiner.add(s));

formatted = joiner.toString();

return formatted;

}

public boolean isRoot() {

return parent == null;

}

/** Gets the parent of this source, or null if the source is a root. */

public LogSource parent() {

return parent;

}

public void setLogLevel(int logLevel) {

this.logLevel = logLevel;

}

public boolean hasLogLevel() {

return logLevel != null;

}

public int logLevel() {

if (!hasLogLevel()) throw new IllegalStateException();

return logLevel;

}

// -- Helper methods --

private LogSource child(final String name) {

if (name.isEmpty()) return this;

LogSource child = children.get(name);

if (child != null) return child;

child = new LogSource(this, name);

children.putIfAbsent(name, child);

return children.get(name);

}

}