Fossil Wrapper

            set line [$filter $line]
        }
        # Prevent broken pipe error from propagating:
        catch {puts -nonewline $line}
    }
}

# --( Interceptors )----------------------------------------------------

# - Interceptors can refer to the current parameter list via an
#   implicitly defined $params variable in their bodies. (See `Builtin
#   interceptors' below for usage.)
#
# - If an interceptor returns an empty list, the wrapper is expected
#   to exit without calling Fossil, thereby fully intercepting the
#   query. Otherwise, it acts as a pre-processor: the returned list is
#   treated as a revised parameter list and will be supplied to
#   `fossil'.
#
#   rephrased: 
#      interceptor modifies `params' (the current command line arguments
#      of the `fsl' call) and returns the modified list which is then
#      used in further processing and the final call to `fossil'. if
#      the interceptor returns nothing, `fsl' exits immediately.
#      in this case the only performed actions are those executed
#      by the interceptor itself.
#

proc interceptor {command_spec body} {
    # cf. `apply' documentation: the anonymous function for `apply'
    # has to be specified in the form {args body namespace} where
    # `args' spefifies the formal arguments of the function. in the
    # present case `args' is identical to `params'. in the current setup
    # the `namespace' argument is apparently redundant and could be
    # ommitted:

    set fn [list {params} $body [uplevel 1 {namespace current}]]
    
    foreach command [triggers_for $command_spec] {
       # this loop sets up the dictionary `config::commands' whose
       # keys are the known interceptor commands and whose values are
       # the corresponding anonymous function definitions. note that each
       # alternate name in `commands_spec (e.g., a, ali, alias etc.)
       # generates a further entry (with identical value).
       dict set config::commands $command $fn
    }
}

proc intercept {params} {
    global dbglvl
    set command [first $params]
    if {[interceptor? $command]} {

        if {$dbglvl > 0} { puts "*** `$command' interceptor triggered" }
        # here, the interceptor definition is retrieved from the
        # `commands' dictionary and used as the anonymous function
        # argument for `apply' (and `params' as its concrete argument). 
        set params [apply [dict get $config::commands $command] $params]
    }
    return $params
}

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

proc prefixes {xs {start 0}} {
    # Return the prefix list of string $xs.
    for {set right $start} {$right < [string length $xs]} {incr right} {
        lappend parts [string range $xs 0 $right]
    }

        yellow  33       blue   34        purple  35
        magenta 35       cyan   36        grey    37
    }
    ansi $colour $colours $text
}

proc alias?       {name} { dict exists $config::aliases  $name }
proc filter?      {name} { dict exists $config::filters  $name }
proc interceptor? {name} { dict exists $config::commands $name }

# --( Builtin interceptors )--------------------------------------------

interceptor wr:wrapper {
    set fmt "=> %s:\n   %s"
    puts [format $fmt "Aliases"      [dict keys $config::aliases]]
    puts [format $fmt "Filters"      [dict keys $config::filters]]
    puts [format $fmt "Interceptors" [dict keys $config::commands]]
}

interceptor he:help {
    # Wrap builtin help command by expanding its argument list. This
    # allows us provide help on aliased commands transparently. When
    # the expanded command is an interceptor, simply print its body.
    set expansion [expand [lrange $params 1 end] 1]
    set command   [first $expansion]
    if {![prefix? $command "help"] && [interceptor? $command]} {
        puts "'$command' is an interceptor defined as follows:"
        puts [lindex [dict get $config::commands $command] 1]
    } else {
        concat help $expansion
    }
}

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

interceptor df|gdf {
   # ------------------------------------------------------------------------
   # drop-in replacement for `fsl (g)di' using hg/svn-style relative revision
   # numbers. call as
   #
   # fsl (g)df ... -r n(:m) ...
   #
   # where n, m are counting from 0 (initial checkin) and `...' denotes
   # further `diff' arguments.
   # This call is mapped to
   #
   # fsl (g)di ... -r sha1_n (--to sha1_m) ...
   #
   # where `sha1_n, sha1_m' are the sha1 hashes of the respective checkins.
   # ------------------------------------------------------------------------
   # map this interceptor command to `fossil (g)diff'. actually, we use `di'
   # instead of `diff' since only the former will trigger the `diff' filter:
   regsub {^(g?d)f} $params {\1i} params

   # extract the revison number information from `params'. contrary to
   # `fossil' it is acceptable to omit blanks between `-r' and `n:m':
   set rgx { \-r[[:blank:]]*}
   set rgxrevnum {[[:digit:]]+(:[[:digit:]]+)?}
   set rgx $rgx$rgxrevnum

   # without `-r' argument we can return already:
   if {![regexp $rgx $params revarg]} {return $params}

   set hash2num [computeRevnums {}]
   set dim [dict size $hash2num]

   # exchange keys and values in the above dictonary. at the same time,
   # strip the square brackets around the hash value:
   dict for {key val} $hash2num {
      regexp {[a-f\d]{10}} $key sha1
      dict set num2hash [expr {$dim - $val}] $sha1
   }

   # translate rev. numbers to sha1 hashes and construct the 
   # required `diff' arguments:
   regexp $rgxrevnum $revarg numbers
   set revs [split $numbers :]
   set to {}
   set cnt 0
   set fromto [list from to]
   foreach rev $revs {
      set optarg [lindex $fromto $cnt] 
      # this evals in turn to define variables `from' and `to', respectively,
      # which contain the respective `diff' arguments:
      set $optarg " --$optarg [dict get $num2hash $rev]"
      incr cnt
   } 

   #replace `-r n:m' by the constructed `diff' arguments: 
   regsub $revarg $params $from$to params
   return $params
}

# --( further procs )---------------------------------------------------

proc unwrapTimeline records {
#-----------------------------------------------------------------------
# unwrap `fossil timeline' output, putting each checkin on a single
# line. expected input: currently, a list of \n terminated lines.
# (maybe the \n should go away?). continuation lines belonging
# to the checkin message (including the trailing user/tags info)

  
   set dbgpat {\--debug[[:blank:]]+([[:digit:]]+[ ]*)}
   regexp $dbgpat $argv dum dbglvl
   regsub $dbgpat $argv "" argv

   return $argv
}














































































































































# --( Fossil )----------------------------------------------------------

proc fossil {args} {
    global dbglvl

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

    }

    log_user $prior_log;              # revert Expect settings
    return [spawned_errno $spawn_id]; # return with fossil error code
}

# --( Entry )-----------------------------------------------------------

set argv [preparse $argv]
config::init ~/.fslrc
exit [fossil {*}$argv]