# Brainfuck interpreter in Thutu2.
# Don't do anything before the program is entered.
/=1//
/=9/=!=x/
# Remove comments from the program ASAP.
/[^][,.<>+=-]([^!]*?)=!/$1=!/
/==/=/
/=%//
# =x can screw up looping.
/=x/%x/
/([^%])x/$1/
# Fold later lines after earlier ones.
/^([^x]*)%x([^x]*)%x/$2$1%x/
# If there's an exclamation mark (end of program):
/=!/*
  # Remove any remaining line-end markers.
  /=x//
  # Restore temporary -- for data pointer and/or ? for command being processed
  # and/or {} for [] (used when duplicating loops)
  /\-\-/\+\+/
  /^\?//
  /\{\{/=\[/
  /\}\}/=\]/
  # If the data pointer's at the end, create a new tape cell.
  /\+\+$/\+\+\|/
  /\+\+/!
    # If there isn't a data pointer, create a new empty tape.
    /$/\|\+\+/
  /[^|]$/<
  /^=\+/\+\+/@
    /\+\+/\-\-\./
    /^=\+/\?/
  /^=\-/\+\+/@
    /\+\+\./\-\-/
    /^=\-/\?/
  /^=\>/\+\+/@
    /\|\+\+(\.*?)\|/\|$1\|\-\-/
    /^=\>/\?/
  /^=\</\+\+/@
    /\|(\.*?)\|\+\+/\|\-\-$1\|/
    /^=\</\?/
  /^=\,/\+\+/@
    /^=\,/\?/
    /\+\+\./\+\+/
    /\+\+/\-\-/
    ,
    *
      /=x/%%1%%/
      # 0 on EOF
      /^=9/0%%1%%/
      /%%1%%/*
	/^0%%1%%//
	/^([0-9]+)%%(1)%%/#
        /^[0-9]+%%1%%(.*?)\-\-/$d%%1%%$1\-\-\./
      .
    .
  /^=\./\+\+/@
    /^=\./\?/
    /\+\+(\.*?)(\|)/$
    /\+\+/%%$g%0%%/
    /%%([0-9]+)%(0)%%/#
    /%%[0-9]+%0%%/%%>$c<%%/
    /%%>([^a]|[^b])<%%/|
    /%%>([^a]|[^b])<%%/\-\-/
  /^=!.*$/=9/
  /\-\-/<
  # Delete a [] loop and any loops nested in it if there's a loop at the IP
  # and the data pointer points to a 0.
  /\|\+\+\|/^=\[/^([^]]*)=\[[^][]*?=\]/$1/
  /\|\+\+\|/^=\[[^][]*?=\]//
  # Duplicate a [] loop if it's at the IP and it got this far.
  /^=\[/*
    # Change inner loops to use {} not []
    /^=\[([^]]*)=\[([^][]*?)=\]/=\[$1\{\{$2\}\}/
    # Copy the contents of the loop to the start
    /^=\[([^]]*)=\]/$1=\[$1=\]/
  /=\[.*?=!/<
  .
.