Fossil Wrapper

         regexp $rgxrev $line rev
         dict set revnums $rev [expr {$numrev - $revcnt}]
      }
   }
   return $revnums
}

proc fixGrep {lines params grepflags} {
   proc cihashLookup {lines} {
      set cihashes {}
      foreach line $lines {
         # FIXME: there must be a nicer way to handle `grep -l' as well,
         # no?
         set fhash [string trimright [first [split $line :]]]

         if { [catch {dict get $cihashes $fhash}] }  {
            # no entry, yet, for this file artifact, so we do the lookup.
            # this is the rate limiting step by a large maring here.
            # hopefully `fossil grep' will report the checkin hash itself
            # at some time in the future.
            set report [split [exec fossil whatis $fhash] \n]
            set rgxpat {^[^[]+(\[[a-f\d]{10}\])}
            regexp $rgxpat [lindex $report 4] _ cihash
            dict set cihashes $fhash $cihash
         }
      }
      return $cihashes
   }
   set f1 [last $grepflags]
   set f2 [first $grepflags]
   if {$f1 + $f2 > 0} {
      set buf $lines
      set lines {}
      if {$f1} { lappend lines [first $buf] } 
      if {$f2} { lappend lines [last $buf] } 
   }
   set cihashes [cihashLookup $lines]
   set revnums [computeRevnums {}]
   set greppat [lindex $params end-1]
   foreach line $lines {
      set fhash [string trimright [first [split $line :]]]
      set cihash [dict get $cihashes $fhash]
      set revnum [dict get $revnums $cihash]
      # for now, we just preprend the chronological revision numbers and
      # add a bit of colour
      regsub -all "(.*?)($greppat)(.*)" $line \\1[coloured redbold \\2]\\3 line
      lappend out [coloured magenta $revnum]:$line
   }
   return $out
}
proc fixGrep {lines params grepflags} {
   # alternative implementation avoiding `whatis' and using `finfo'
   # output instead to map file hash to checkin hash. this is faster
   # when having lots of matching revisions but slower when `-F -L'
   # are used since we always have to process the complete `finfo'
   # output.
   set fname [last $params]
   set finfo [lrange [split [exec fossil finfo -W 0 $fname] \n] 1 end]
   set rgxdate {^\d{4}-\d\d-\d\d}
   set rgxhash {\[([a-f\d]{10})\]}
   foreach line $finfo {
      regexp "$rgxdate $rgxhash" $line _ cihash
      regexp ", artifact: $rgxhash, branch: .*\\)" $line _ fhash
      dict set cihashes $fhash \[$cihash\]
   }
   set revnums [computeRevnums {}]
   set f1 [last $grepflags]
   set f2 [first $grepflags]
   if {$f1 + $f2 > 0} {
      set buf $lines
      set lines {}
      if {$f1} { lappend lines [first $buf] } 
      if {$f2} { lappend lines [last $buf] } 
   }



   set greppat [lindex $params end-1]
   foreach line $lines {
      set fhash [string trimright [first [split $line :]]]
      set cihash [dict get $cihashes $fhash]
      set revnum [dict get $revnums $cihash]
      # for now, we just preprend the chronological revision numbers and
      # add a bit of colour

# ------------------------------------------------------------------------
# Extend `grep' by options
#   -F
#   -L
# to report only _f_irst (oldest) and _l_ast (newest) checkin matching
# the pattern. This is frequently what one is interested in.
# ------------------------------------------------------------------------
   # THINK: one might consider to convert this to a complete
   # interceptor, moving all processing from the expect/filter block
   # here. The benefit would be the added capability to make 'grep'
   # work on multiple input files (or the whole '[fsl] ls' output).

   # we set up a 2-element list `grepflags' with 0/1 entries
   # indicating whether F and L are set. this list is put into the
   # `config' namespace to make it accessible elsewhere.

   set grepopts [lrange $params 1 end-2]
   set grepflags [regexp -- -F $grepopts]
   lappend grepflags [regexp -- -L $grepopts] 

    # Prepare filters:
    set chain [chain_for $candidate]
    set chain [expr {[empty? $chain] ? [chain_for $command] : $chain}]
    set chain [string trimright $chain]

    # Expect settings:
    set prior_log [log_user];   # to be reverted before returning

    # FIXME: reconcider the overall logic of how to handle log_user
    # on/off. it is slowly becoming a mess. previously 'log_user 0'
    # had to be called only if filter chain is non-empty (indicating
    # that the usual fossil output is going to be processed prior to
    # display). redefining this filter chain further down to
    # `passthrough' then is not a problem (as is done for 'timeline'
    # etc. where the output modifcation is not done by any filter but
    # in a proc prior to final filtering) but it _is_ a problem for
    # commands that lead to an empty filter chain (which usually
    # indicates that one wants just to see the raw fossil output)
    # while something is still done to their output as is the case for
    # `grep' now. maybe we can put everything in a grep filter
    # instead so that this explicit test for 'grep' becomes obsolete:
    if {![empty? $chain] || $command == "grep"} { 
        log_user 0; # disable logging to stdout
    }

    if {![interactive? $params]} {
        set stty_init -onlcr;   # do not map LF to CRLF on output
    }












    #ensure that `lines' always exists:
    set lines {}
    # Call to `fossil' binary:
    spawn -noecho fossil {*}$params
    while 1 {
        if {[interactive? $params]} {
            interact; break