REBOL functions profiler

〈Overview〉 ≡

profiler-table: context [ ]
profiler-call-stack: [ ]
in-func: func [name /local w stats] [
 if not word? name [exit]
 if not empty? profiler-call-stack [
  if w: in profiler-table last profiler-call-stack [
   stats: get w
   if stats/start [
    stats/time: stats/time + difference now/precise stats/start
    stats/start: none
   ]
  ]
 ]
 append profiler-call-stack name
 either w: in profiler-table name [
  stats: get w
  stats/start: now/precise
 ] [
  profiler-table: make profiler-table reduce [
   to set-word! name context [
    start: now/precise
    time: 0:00 count: 0
   ]
  ]
 ]
]
out-func: func [name /local t w stats] [
 t: now/precise
 if not word? name [exit]
 stats: get w: in profiler-table name
 if stats/start [
  stats/time: stats/time + difference t stats/start
  stats/count: stats/count + 1
  stats/start: none
 ]
 remove back tail profiler-call-stack
 if not empty? profiler-call-stack [
  if w: in profiler-table last profiler-call-stack [
   stats: get w
   stats/start: now/precise
  ]
 ]
]

-left: func [str n] [head insert/dup tail str " " n - length? str]
-right: func [str n] [head insert/dup str " " n - length? str]

reset-profiler: does [
 foreach stats next second profiler-table [
  stats/time: 0:00
  stats/count: 0
 ]
]

show-profiler-results: has [res stats str total-time total-calls] [
 res: clear [ ]
 str: copy { Top ten functions by total time: +------------------------------+------------------+---------+ | Name | Time | Calls | +------------------------------+------------------+---------+ }
 foreach w next first profiler-table [
  stats: get in profiler-table w
  append/only res reduce [stats/time stats/count w]
 ]
 sort/reverse res
 foreach row copy/part res 10 [
  append str reduce [
   "| " -left form row/3 28 " | " -right form row/1 16 " | " -right form row/2 7 " |^/"
  ]
 ]
 clear res
 foreach w next first profiler-table [
  stats: get in profiler-table w
  if stats/count > 0 [append/only res reduce [stats/time / stats/count w]]
 ]
 sort/reverse res
 append str {+------------------------------+------------------+---------+ Top ten functions by average time: +------------------------------+------------------+ | Name | Time | +------------------------------+------------------+ }
 foreach row copy/part res 10 [
  append str reduce [
   "| " -left form row/2 28 " | " -right form row/1 16 " |^/"
  ]
 ]
 append str {+------------------------------+------------------+ Total execution time: }
 total-time: 0:00
 total-calls: 0
 foreach stats next second profiler-table [
  if stats/time [total-time: total-time + stats/time]
  if stats/count [total-calls: total-calls + stats/count]
 ]
 repend str [total-time " for " total-calls " function calls."]
]