Fossil Wrapper

namespace eval config {
    set aliases {}
    set filters {};             # registered filters
    set commands {};            # registered interceptors

    proc init {filename} {
        set myname $::argv0
        #if {[file exists $filename] && [file mtime $filename] > [file mtime $myname]} {}
        if {[file exists $filename] } {
	    # an existing config file is used only if it is _newer_ than the
	    # running `fsl' file. otherwise the config file is (re)created
	    # since it's definition in `config::defaults' might have changed.
	    # this makes it probable that changes to this script become
	    # automatically active for other users (as long as they don't happen
	    # to manually modify there config files frequently ...)

        dict set config::commands $command $fn
    }
}

proc intercept {params} {
    set command [first $params]
    if {[interceptor? $command]} {
        set params [apply [dict get $config::commands $command] $params]
    }
    return $params
}

# --( Command triggers )------------------------------------------------

proc prefixes {xs {start 0}} {

interceptor ali:aliases {
    puts "Currently defined expansions:"
    dict for {alias expansion} $config::aliases {
        puts [format "%10s -> %s" $alias $expansion]
    }
}

interceptor df|gdf {
   # ----------------------------------------------------------------------
   # a first stab at getting relative revision numbers working with `diff'.
   # should be called as `fsl {g}df -r n' or `fsl {g}df -r n:m' where `n, m' are
   # counting from 0 (initial checkin). This call which is 
   # be mapped to 
   #
   # fsl {g}di -r sha1_n --to sha1_m
   #
   # where `sha1_n, sha1_m' are the sha1 hashes of the respective checkins.
   # further arguments to `diff' are passed through unmodified (hopefully).
   # ----------------------------------------------------------------------
   set hash2num [computeRevnums {}]
   set dim [dict size $hash2num]

   # exchange keys and values in the above dictonary sha1. at the same time,
   # strip the square brackets around the hash value:
   dict for {key val} $hash2num {
      regexp {[[:alnum:]]+} $key sha1
      dict set num2hash [expr {$dim - $val}] $sha1
   }

   # modification of the `params' list is performed in place and step by
   # step. we use `{g}di' instead of `diff' since only the former triggers the
   # `diff' filter:
   regsub {^(g?d)f} $params {\1i} params
   if {[llength $params] == 1} {return $params}

   # extract the revison number information from `params'. the case where the
   # blank between `-r' and `n:m' is ommitted is handled, too:
   set cnt 0
   set rgxrevnum {[[:digit:]]+(:[[:digit:]]+)?}
   foreach word $params {
      set rgx {^\-r} 

   foreach word $from$to {
      set idx [expr $flagpos + $cnt]
      set params [linsert $params $idx $word]
      incr cnt
   }
   set params [lreplace $params $flagpos $flagpos]

   #puts "executing `fossil $params'"
   return $params
}

proc unwrapTimeline records {
#-----------------------------------------------------------------------
# unwrap `fossil timeline' output, putting each checkin on a single
# line. expected input: currently, a list of \n terminated lines.

    #if `true' generate some noise:
    set debug false

    set candidate [first $args]; # candidate for expansion

    # Alias expansion and command interception:
    set params [intercept [expand $args]]
    ###puts "final pars: $params"
    if {[empty? $params]} {
        return 0;                # params cleared, no need to run fossil
    }
    set command [first $params]; # expanded candidate

    # Prepare filters:
    set chain [chain_for $candidate]