/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-2016 The eXist Project
* http://exist-db.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.exist.util;
import java.util.Arrays;
/**
* Utility methods for dealing with stack traces
*
* @author Adam Retter <adam.retter@googlemail.com>
*/
public class Stacktrace {
public final static int DEFAULT_STACK_TOP = 10;
/**
* Gets the top N frames from the stack trace and
* returns them as a string
*
* Excludes the callee and self stack frames
*
* @param stack The stack
* @param top The number of frames to examine
*
* @return String representation of the top frames of the stack
*/
public static String top(final StackTraceElement[] stack, final int top) {
final int from = 2;
final int until = stack.length - from < top ? stack.length - from : top + from;
return asString(stack, from, until);
}
/**
* Formats the stack trace as a String
*
* @return A formatted string showing the stack trace
*/
public static String asString(final StackTraceElement[] stack) {
return asString(stack, 0, stack.length);
}
/**
* Formats the stack trace as a String
*
* @param from The most recent frame to start from
* @param until The least recent frame to format until
* @return A formatted string showing the stack trace
*/
public static String asString(final StackTraceElement[] stack, final int from, final int until) {
final StringBuilder builder = new StringBuilder();
for(int i = from; i < until; i++) {
builder
.append(" <- ")
.append(stack[i]);
}
return builder.toString();
}
/**
* Get a subset of the StackTraceElements
*
* @param stack The stack trace
* @param from Starting from HEAD
* @param max The maximum number of elements to take
*
* @return The stack trace elements between from and from+max (or less)
*/
public static StackTraceElement[] substack(final StackTraceElement[] stack, final int from, final int max) {
final int to = stack.length - from < max ? stack.length - from : from + max;
return Arrays.copyOfRange(stack, from, to);
}
}