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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
*/
package scala.tools.nsc.util
private[util] trait StackTracing extends Any {
/** Format a stack trace, returning the prefix consisting of frames that satisfy
* a given predicate.
* The format is similar to the typical case described in the Javadoc
* for [[java.lang.Throwable#printStackTrace]].
* If a stack trace is truncated, it will be followed by a line of the form
* `... 3 elided`, by analogy to the lines `... 3 more` which indicate
* shared stack trace segments.
* @param e the exception
* @param p the predicate to select the prefix
*/
def stackTracePrefixString(e: Throwable)(p: StackTraceElement => Boolean): String = {
import collection.mutable.{ ArrayBuffer, ListBuffer }
import compat.Platform.EOL
type TraceRelation = String
val Self = new TraceRelation("")
val CausedBy = new TraceRelation("Caused by: ")
val Suppressed = new TraceRelation("Suppressed: ")
def clazz(e: Throwable): String = e.getClass.getName
def because(e: Throwable): String = e.getCause match { case null => null ; case c => header(c) }
def msg(e: Throwable): String = e.getMessage match { case null => because(e) ; case s => s }
def txt(e: Throwable): String = msg(e) match { case null => "" ; case s => s": $s" }
def header(e: Throwable): String = s"${clazz(e)}${txt(e)}"
val seen = new ArrayBuffer[Throwable](16)
def unseen(t: Throwable) = {
def inSeen = seen exists (_ eq t)
val interesting = (t != null) && !inSeen
if (interesting) seen += t
interesting
}
val sb = ListBuffer.empty[String]
// format the stack trace, skipping the shared trace
def print(e: Throwable, r: TraceRelation, share: Array[StackTraceElement], indents: Int): Unit = if (unseen(e)) {
val trace = e.getStackTrace
val frames = if (share.isEmpty) trace else {
val spare = share.reverseIterator
val trimmed = trace.reverse dropWhile (spare.hasNext && spare.next == _)
trimmed.reverse
}
val prefix = frames takeWhile p
val margin = " " * indents
val indent = margin + " "
sb append s"${margin}${r}${header(e)}"
prefix foreach (f => sb append s"${margin} at $f")
if (frames.size < trace.size) sb append s"${margin} ... ${trace.size - frames.size} more"
if (r == Self && prefix.size < frames.size) sb append s"${margin} ... ${frames.size - prefix.size} elided"
print(e.getCause, CausedBy, trace, indents)
e.getSuppressed foreach (t => print(t, Suppressed, frames, indents + 1))
}
print(e, Self, share = Array.empty, indents = 0)
sb mkString EOL
}
}
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