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# -*- tclsh -*-
# FILE: "/diska/home/joze/src/tclreadline/tclreadlineCompleter.tcl"
# LAST MODIFICATION: "Tue Sep 14 16:17:25 1999 (joze)"
# (C) 1998, 1999 by Johannes Zellner, <johannes@zellner.org>
# $Id$
# ---
#
# tclreadline -- gnu readline for tcl
# Copyright (C) 1999  Johannes Zellner
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#
# johannes@zellner.org
# http://www.zellner.org/tclreadline/
#
# ================================================================== 


# TODO:
#
#     - tcltest is missing
#
#     - last try: as for widgets
#



namespace eval tclreadline {

namespace export \
TryFromList CompleteFromList DisplayHints Rehash \
PreviousWord CommandCompletion RemoveUsedOptions \
HostList ChannelId InChannelId OutChannelId \
Lindex Llength CompleteBoolean

#**
# TryFromList will return an empty string, if
# the text typed so far does not match any of the
# elements in list. This might be used to allow
# subsequent filename completion by the builtin
# completer.
#
proc TryFromList {text lst {allow ""}} {

    # puts stderr "(CompleteFromList) \ntext=|$text|"
    # puts stderr "(CompleteFromList) lst=|$lst|"
    set pre [GetQuotedPrefix ${text}]
    set matches [MatchesFromList $text $lst $allow]

    # puts stderr "(CompleteFromList) matches=|$matches|"
    if {1 == [llength $matches]} { ; # unique match
        # puts stderr \nunique=$matches\n
        # puts stderr "\n|${pre}${matches}[Right ${pre}]|\n"
        set null [string index $matches 0]
        if {"<" == $null || "?" == $null} {
            return [string trim "[list $text] $lst"]
        } else {
            return [string trim ${pre}${matches}[Right ${pre}]]
        }
    } elseif {"" != ${matches}} {
        # puts stderr \nmore=$matches\n
        set longest [CompleteLongest ${matches}]
        # puts stderr longest=|$longest|
        if {"" == $longest} {
            return [string trim "[list $text] ${matches}"]
        } else {
            return [string trim "${pre}${longest} ${matches}"]
        }
    } else {
        return ""; # nothing to complete
    }
}

#**
# CompleteFromList will never return an empty string.
# completes, if a completion can be done, or ring
# the bell if not.
#
proc CompleteFromList {text lst} {
    set result [TryFromList ${text} ${lst}]
    if {![llength ${result}]} {
        Alert
        # return [string trim [list ${text}] ${lst}"]
        if {[llength ${lst}]} {
            return [string trim "${text} ${lst}"]
        } else {
            return [string trim [list ${text} {}]]
        }
    } else {
        return ${result}
    }
}

#**
# CompleteBoolean does a CompleteFromList
# with a list of all valid boolean values.
#
proc CompleteBoolean {text} {
    return [CompleteFromList $text {yes no true false 1 0}]
}

#**
# build a list of all executables which can be
# found in $env(PATH). This is (naturally) a bit
# slow, and should not called frequently. Instead
# it is a good idea to check if the variable
# `executables' exists and then just use it's
# content instead of calling Rehash.
# (see complete(exec)).
# 
proc Rehash {} {

    global env
    variable executables

    if {![info exists env] || ![array exists env]} {
        return
    }
    if {![info exists env(PATH)]} {
        return
    }

    set executables 0
    foreach dir [split $env(PATH) :] {
        if {[catch [list set files [glob -nocomplain ${dir}/*]]]} { continue }
        foreach file $files {
            if {[file executable $file]} {
                lappend executables [file tail $file]
            }
        }
    }
}

#**
# build a list hosts from the /etc/hosts file.
# this is only done once. This is sort of a
# dirty hack, /etc/hosts is hardcoded ...
# But on the other side, if the user supplies
# a valid host table in tclreadline::hosts
# before entering the event loop, this proc
# will return this list.
# 
proc HostList {} {
    # read the host table only once.
    #
    variable hosts
    if {![info exists hosts]} {
        catch {
            set hosts ""
            set id [open /etc/hosts r]
            if {0 != ${id}} {
                while {-1 != [gets ${id} line]} {
                    regsub {#.*} ${line} {} line
                    if {[llength ${line}] >= 2} {
                        lappend hosts [lindex ${line} 1]
                    }
                }
                close $id
            } 
        }
    }
    return $hosts
}

#**
# never return an empty string, never complete.
# This is useful for showing options lists for example.
#
proc DisplayHints {lst} {
    return [string trim "{} ${lst}"]
}

#**
# find (partial) matches for `text' in `lst'. Ring
# the bell and return the whole list, if the user
# tries to complete ?..? options or <..> hints.
#
# MatchesFromList returns a list which is not suitable
# for passing to the readline completer. Thus,
# MatchesFromList should not be called directly but
# from formatting routines as TryFromList.
#
proc MatchesFromList {text lst {allow ""}} {
    set result ""
    set text [StripPrefix $text]
    set null [string index $text 0]
    foreach char {< ?} {
        if {$char == $null && -1 == [string first $char $allow]} {
            Alert
            return $lst
        }
    }
    # puts stderr "(MatchesFromList) text=$text"
    # puts stderr "(MatchesFromList) lst=$lst"
    foreach word $lst {
        if {[string match ${text}* ${word}]} {
            lappend result ${word}
        }
    }
    return [string trim $result]
}

#**
# invoke cmd with a (hopefully) invalid string and
# parse the error message to get an option list.
#
# @param cmd
# @return list of options for cmd
# @date Sep-14-1999
#
proc TrySubCmds {cmd} {
    set trystring ____
    set result ""
    if [catch {set result [${cmd} ${trystring}]} msg] {
        if {[regexp {bad *option.*____.*: *must *be( .*$)} ${msg} all raw]} {
            regsub -all -- , ${raw} { } raw
            set len [llength ${raw}]
            set len_2 [expr ${len} - 2]
            for {set i 0} {${i} < ${len}} {incr i} {
                set word [lindex ${raw} ${i}]
                if {"or" != ${word} && ${i} != ${len_2}} {
                    lappend result ${word}
                }

            }
        } else {
            # check, if it's a blt error msg ...
            #
            set msglst [split ${msg} \n]
            foreach line ${msglst} {
                if {[regexp "${cmd}\[ \t\]\+\(\[^ \t\]*\)\[^:\]*$" \
                    ${line} all sub]} {
                    lappend result [list ${sub}]
                }
            }
        }
    }
    return ${result}
}

proc FirstNonOption {line} {
    set expr_pos 1
    foreach word [lrange ${line} 1 end] {; # 0 is the command itself
        if {"-" != [string index ${word} 0]} {
            break
        } else {
            incr expr_pos
        }
    }
    return ${expr_pos}
}

proc RemoveUsedOptions {line opts {terminate {}}} {
    if {[llength ${terminate}]} {
        if {[regexp -- ${terminate} ${line}]} {
            return ""
            # return ${terminate}
        }
    }
    set new ""
    foreach word ${opts} {
        if {-1 == [string first ${word} ${line}]} {
            lappend new ${word}
        }
    }
    return [string trim ${new}]
}

proc Alert {} {
    puts -nonewline \a
    flush stdout
}

#**
# get the longest common completion
# e.g. str == {tcl_version tclreadline_version tclreadline_library}
# --> [CompleteLongest ${str}] == "tcl"
#
proc CompleteLongest {str} {
    # puts stderr str=$str
    set match0 [lindex ${str} 0]
    set len0 [string length $match0]
    set no_matches [llength ${str}]
    set part ""
    for {set i 0} {$i < $len0} {incr i} {
        set char [string index $match0 $i]
        for {set j 1} {$j < $no_matches} {incr j} {
            if {$char != [string index [lindex ${str} $j] $i]} {
                break
            }
        }
        if {$j < $no_matches} {
            break
        } else {
            append part $char
        }
    }
    # puts stderr part=$part
    return ${part}
}

proc SplitLine {start line} {
    set depth 0
    # puts stderr SplitLine
    for {set i $start} {$i >= 0} {incr i -1} {
        set c [string index $line $i]
        if {{;} == $c} {
            incr i; # discard command break character
            return [list [expr $start - $i] [string range $line $i end]]
        } elseif {{]} == $c} {
            incr depth
        } elseif {{[} == $c} {
            incr depth -1
            if {$depth < 0} {
                incr i; # discard command break character
                return [list [expr $start - $i] [string range $line $i end]]
            }
        }
    }
    return ""
}

proc IsWhite {char} {
    if {" " == $char || "\n" == $char || "\t" == $char} {
        return 1
    } else {
        return 0
    }
}

proc PreviousWord {start line} {
    incr start -1
    set found 0
    for {set i $start} {$i > 0} {incr i -1} {
        set c [string index $line $i]
        if {${found} && [IsWhite $c]} {
            break
        } elseif {!${found} && ![IsWhite $c]} {
            set found 1
        }
    }
    return [string trim [string range ${line} $i $start]]
}

proc Quote {value left} {
    set right [Right ${left}]
    if {1 < [llength $value] && "" == $right} {
        return [list \"${value}\"]
    } else {
        return [list ${left}${value}${right}]
    }
}

# the following two channel proc's make use of
# the brandnew (Sep 99) `file channels' command
# but have some fallback behaviour for older
# tcl version.
#
proc InChannelId {text {switches ""}} {
    if [catch {set chs [file channels]}] {
        set chs {stdin}
    }
    set result ""
    foreach ch $chs {
        if {![catch {fileevent $ch readable}]} {
            lappend result $ch
        }
    }
    return [ChannelId ${text} <inChannel> $result $switches]
}

proc OutChannelId {text {switches ""}} {
    if [catch {set chs [file channels]}] {
        set chs {stdout stderr}
    }
    set result ""
    foreach ch $chs {
        if {![catch {fileevent $ch writable}]} {
            lappend result $ch
        }
    }
    return [ChannelId ${text} <outChannel> $result $switches]
}

proc ChannelId {text {descript <channelId>} {chs ""} {switches ""}} {
    if {"" == ${chs}} {
        # the `file channels' command is present
        # only in pretty new versions.
        #
        if [catch {set chs [file channels]}] {
            set chs {stdin stdout stderr}
        }
    }
    if {[llength [set channel [TryFromList ${text} "${chs} ${switches}"]]]} {
        return ${channel}
    } else {
        return [DisplayHints [string trim "${descript} ${switches}"]]
    }
}

proc QuoteQuotes {line} {
    regsub -all -- \" $line {\"} line
    regsub -all -- \{ $line {\{} line; # \}\} (keep the editor happy)
    return $line
}

proc Trace {varT} {
    if {![info exists ::tclreadline::Debug]} {return}
    upvar $varT var
    if {![info exists var]} {
        puts $varT=<notdefined>
    } else {
        puts $varT=|$var|
    }
    # puts $var
}

#**
# get the word position.
# @return the word position
# @note will returned modified values.
# @sa EventuallyEvaluateFirst
# @date Sep-06-1999
#
# % p<TAB>
# % bla put<TAB> $b
# % put<TAB> $b
# part  == put
# start == 0
# end   == 3
# line  == "put $b"
# [PartPosition] should return 0
#
proc PartPosition {partT startT endT lineT} {

    upvar $partT part $startT start $endT end $lineT line
    EventuallyEvaluateFirst part start end line
    return [Llength [string range $line 0 [expr $start - 1]]]

# 
#     set local_start [expr $start - 1]
#     set local_start_chr [string index $line $local_start]
#     if {"\"" == $local_start_chr || "\{" == $local_start_chr} {
#         incr local_start -1
#     }
# 
#     set pre_text [QuoteQuotes [string range $line 0 $local_start]]
#     return [llength $pre_text]
# 
}

proc Right {left} {
    # puts left=$left
    if {"\"" == $left} {
        return "\""
    } elseif {"\\\"" == $left} {
        return "\\\""
    } elseif {"\{" == $left} {
        return "\}"
    } elseif {"\\\{" == $left} {
        return "\\\}"
    }
    return ""
}

proc GetQuotedPrefix {text} {
    set null [string index $text 0]
    if {"\"" == $null || "\{" == $null} {
        return \\$null
    } else {
        return {}
    }
}

proc CountChar {line char} {
    # puts stderr char=|$char|
    set found 0
    set pos 0
    while {-1 != [set pos [string first $char $line $pos]]} {
        incr pos
        incr found
    }
    return $found
}

#**
# make a proper tcl list from an icomplete
# string, that is: remove the junk. This is
# complementary to `IncompleteListRemainder'.
# e.g.:
#       for {set i 1} "
#  -->  for {set i 1}
#
proc ProperList {line} {
    set last [expr [string length $line] - 1]
    for {set i $last} {$i >= 0} {incr i -1} {
        if {![catch {llength [string range $line 0 $i]}]} {
            break
        }
    }
    return [string range $line 0 $i]
}

#**
# return the last part of a line which
# prevents the line from beeing a list.
# This is complementary to `ProperList'.
#
proc IncompleteListRemainder {line} {
    set last [expr [string length $line] - 1]
    for {set i $last} {$i >= 0} {incr i -1} {
        if {![catch {llength [string range $line 0 $i]}]} {
            break
        }
    }
    incr i
    return [string range $line $i end]
}

#**
# save `lindex'. works also for non-complete lines
# with opening parentheses or quotes.
# usage as `lindex'.
# Eventually returns the Rest of an incomplete line,
# if the index is `end' or == [Llength $line].
#
proc Lindex {line pos} {
    if {[catch [list set sub [lindex $line $pos]]]} {
        if {"end" == $pos || [Llength $line] == $pos} {
            return [IncompleteListRemainder $line]
        }
        set line [ProperList $line]
        # puts stderr \nproper_line=|$proper_line|
        if {[catch [list set sub [lindex $line $pos]]]} { return {} }
    }
    return $sub
}

#**
# save `llength' (see above).
#
proc Llength {line} {
    if {[catch [list set len [llength $line]]]} {
        set line [ProperList $line]
        if {[catch [list set len [llength $line]]]} { return {} }
    }
    # puts stderr \nline=$line
    return $len
}

proc StripPrefix {text} {
    # puts "(StripPrefix) text=|$text|"
    set null [string index $text 0]
    if {"\"" == $null || "\{" == $null} {
        return [string range $text 1 end]
    } else {
        return $text
    }
}

proc VarCompletion {text {level -1}} {
    if {-1 == ${level}} {
        set level [info level]
    } else {
        incr level
    }
    set pre [GetQuotedPrefix ${text}]
    set var [StripPrefix ${text}]
    # puts stderr "(VarCompletion) pre=|$pre|"
    # puts stderr "(VarCompletion) var=|$var|"

    # arrays
    #
    if {[regexp {([^(]*)\((.*)} ${var} all array name]} {
        set names [uplevel ${level} array names ${array} ${name}*]
        if {1 == [llength $names]} { ; # unique match
            return "${array}(${names})"
        } elseif {"" != ${names}} {
            return "${array}([CompleteLongest ${names}] ${names}"
        } else {
            return ""; # nothing to complete
        }
    }

    # non-arrays
    #
    regsub ":$" ${var} "::" var
    set namespaces [namespace children :: ${var}*]
    if {[llength ${namespaces}] && "::" != [string range ${var} 0 1]} {
        foreach name ${namespaces} {
            regsub "^::" ${name} "" name
            if {[string length ${name}]} {
                lappend new ${name}::
            }
        }
        set namespaces ${new}
        unset new
    }
    set matches \
    [string trim "[uplevel ${level} info vars ${var}*] ${namespaces}"]
    if {1 == [llength $matches]} { ; # unique match

        # check if this unique match is an
        # array name, (whith no "(" yet).
        #
        if {[uplevel ${level} array exists $matches]} {
            return [VarCompletion ${matches}( ${level}]; # recursion
        } else {
            return ${pre}${matches}[Right ${pre}]
        }
    } elseif {"" != $matches} { ; # more than one match
          return [CompleteFromList ${text} ${matches}]
    } else {
        return ""; # nothing to complete
    }
}

proc CompleteControlStatement {text start end line pos mod pre new_line} {
    set pre [GetQuotedPrefix ${pre}]
    set cmd [Lindex $new_line 0]
    set diff [expr \
    [string length $line] - [string length $new_line]]
    if {$diff == [expr $start + 1]} {
        set mod1 $mod
    } else {
        set mod1 $text
        set pre ""
    }
    set new_end [expr $end - $diff]
    set new_start [expr $new_end - [string length $mod1]]
    # puts ""
    # puts new_start=$new_start
    # puts new_end=$new_end
    # puts new_line=$new_line
    # puts mod1=$mod1
    if {$new_start < 0} {
        return ""; # when does this occur?
    }
    # puts stderr ""
    # puts stderr start=|$start|
    # puts stderr end=|$end|
    # puts stderr mod=|$mod|
    # puts stderr new_start=|$new_start|
    # puts stderr new_end=|$new_end|
    # puts stderr new_line=|$new_line|
    # puts stderr ""
    set res [ScriptCompleter $mod1 $new_start $new_end $new_line]
    # puts stderr \n\${pre}\${res}=|${pre}${res}|
    if {[string length [Lindex ${res} 0]]} {
        return ${pre}${res}
    } else {
        return ${res}
    }
    return ""
}

proc BraceOrControlStatement {text start end line pos mod} {
    if {![string length [Lindex $line $pos]]} {
        return [list \{ {}]; # \}
    } else {
        set new_line [string trim [IncompleteListRemainder $line]]
        if {![regexp {^([\{\"])(.*)$} $new_line all pre new_line]} {
            set pre ""
        }
        return [CompleteControlStatement $text \
        $start $end $line $pos $mod $pre $new_line]
    }
}

proc FullQualifiedMatches {qualifier matchlist} {
    set new ""
    if {"" != $qualifier && ![regexp ::$ $qualifier]} {
        append qualifier ::
    }
    foreach entry ${matchlist} {
        set full ${qualifier}${entry}
        if {"" != [namespace which ${full}]} {
            lappend new ${full}
        }
    }
    return ${new}
}

proc ProcsOnlyCompletion {cmd} {
    return [CommandCompletion ${cmd} procs]
}

proc CommandsOnlyCompletion {cmd} {
    return [CommandCompletion ${cmd} commands]
}

proc CommandCompletion {cmd {action both} {spc ::}} {
    # get the leading colons in `cmd'.
    regexp {^:*} ${cmd} pre
    return [CommandCompletionWithPre $cmd $action $spc $pre]
}

proc CommandCompletionWithPre {cmd action spc pre} {
    # puts stderr "(CommandCompletion) cmd=|$cmd|"
    # puts stderr "(CommandCompletion) action=|$action|"
    # puts stderr "(CommandCompletion) spc=|$spc|"

    set cmd [StripPrefix ${cmd}]
    set quali [namespace qualifiers ${cmd}]
    if {[string length ${quali}]} {
        # puts stderr \nquali=|$quali|
        set matches [CommandCompletionWithPre \
        [namespace tail ${cmd}] ${action} ${spc}${quali} ${pre}]
        # puts stderr \nmatches1=|$matches|
        return $matches
    }
    set cmd [string trim ${cmd}]*
    # puts stderr \ncmd=|$cmd|\n
    if {"procs" != ${action}} {
        set all_commands [namespace eval $spc [list info commands ${cmd}]]
        # puts stderr all_commands=|$all_commands|
        set commands ""
        foreach command $all_commands {
            if {[namespace eval $spc [list namespace origin $command]] == \
                [namespace eval $spc [list namespace which $command]]} {
                lappend commands $command
            }
        }
    } else {
        set commands ""
    }
    if {"commands" != ${action}} {
        set all_procs [namespace eval $spc [list info procs ${cmd}]]
        # puts stderr procs=|$procs|
        set procs ""
        foreach proc $all_procs {
            if {[namespace eval $spc [list namespace origin $proc]] == \
                [namespace eval $spc [list namespace which $proc]]} {
                lappend procs $proc
            }
        }
    } else {
        set procs ""
    }
    set matches [namespace eval $spc concat ${commands} ${procs}]
    set namespaces [namespace children $spc ${cmd}]

    if {![llength ${matches}] && 1 == [llength ${namespaces}]} {
        set matches [CommandCompletionWithPre {} ${action} ${namespaces} ${pre}]
        # puts stderr \nmatches=|$matches|
        return $matches
    }

    # make `namespaces' having exactly
    # the same number of colons as `cmd'.
    #
    regsub -all {^:*} $spc $pre spc

    set matches [FullQualifiedMatches ${spc} ${matches}]
    # puts stderr \nmatches3=|$matches|
    return [string trim "${matches} ${namespaces}"]
}

#**
# check, if the first argument starts with a '['
# and must be evaluated before continuing.
# NOTE: trims the `line'.
#       eventually modifies all arguments.
# DATE: Sep-06-1999
#
proc EventuallyEvaluateFirst {partT startT endT lineT} {
    # return; # disabled
    upvar $partT part $startT start $endT end $lineT line

    set oldlen [string length ${line}]
    set line [string trim ${line}]
    set diff [expr [string length $line] - $oldlen]
    incr start $diff
    incr end $diff

    set char [string index ${line} 0]
    if {{[} != ${char} && {$} != ${char}} {return}

    set pos 0
    while {-1 != [set idx [string first {]} ${line} ${pos}]]} {
        set cmd [string range ${line} 0 ${idx}]
        if {[info complete ${cmd}]} {
            break;
        }
        set pos [expr ${idx} + 1]
    }

    if {![info exists cmd]} {return}
    if {![info complete ${cmd}]} {return}
    set cmd [string range ${cmd} 1 [expr [string length ${cmd}] - 2]]
    set rest [string range ${line} [expr ${idx} + 1] end]

    if {[catch [list set result [string trim [eval ${cmd}]]]]} {return}

    set line ${result}${rest}
    set diff [expr [string length ${result}] - ([string length ${cmd}] + 2)]
    incr start ${diff}
    incr end ${diff}
}

# if the line entered so far is
# % puts $b<TAB>
# part  == $b
# start == 5
# end   == 7
# line  == "$puts $b"
#
proc ScriptCompleter {part start end line} {

    # puts stderr "(ScriptCompleter) |$part| $start $end |$line|"

    # if the character before the cursor is a terminating
    # quote and the user wants completion, we insert a white
    # space here.
    #
    set char [string index $line [expr $end - 1]]
    if {"\}" == $char} {
        append $part " "
        return [list $part]
    }

    if {{$} == [string index $part 0]} {

        # check for a !$ history event
        #
        if {$start > 0} {
            if {{!} == [string index $line [expr $start - 1]]} {
                return ""
            }
        }
        # variable completion. Check first, if the
        # variable starts with a plain `$' or should
        # be enclosed in braces.
        #
        set var [string range $part 1 end]

        # check if $var is an array name, which
        # already has already a "(" somewhere inside.
        #
        if {"" != [set vc [VarCompletion $var]]} {
            if {"" == [lindex $vc 0]} {
                return "\$ [lrange ${vc} 1 end]"
            } else {
                return \$${vc}
            }
            # puts stderr vc=|$vc|
        } else {
            return ""
        }

    # SCENARIO:
    #
    # % puts bla; put<TAB> $b
    # part  == put
    # start == 10
    # end   == 13
    # line  == "puts bla; put $b"
    # [SplitLine] --> {1 " put $b"} == sub
    # new_start = [lindex $sub 0] == 1
    # new_end   = [expr $end - ($start - $new_start)] == 4
    # new_part  == $part == put
    # new_line  = [lindex $sub 1] == " put $b"
    # 
    } elseif {"" != [set sub [SplitLine $start $line]]} {

        set new_start [lindex $sub 0]
        set new_end [expr $end - ($start - $new_start)]
        set new_line [lindex $sub 1]
        # puts stderr "(SplitLine) $new_start $new_end $new_line"
        return [ScriptCompleter $part $new_start $new_end $new_line]

    } elseif {0 == [set pos [PartPosition part start end line]]} {

        # puts stderr "(PartPosition) $part $start $end $line"
        set all [CommandCompletion ${part}]
        # puts stderr "(ScriptCompleter) all=$all"
        #puts \nmatches=$matches\n
        # return [Format $all $part]
        return [TryFromList $part $all]

    } else {

        # try to use $pos further ...
        # puts stderr |$line|
        #
        if {"." == [string index [string trim ${line}] 0]} {
            set alias WIDGET
        } else {

            # the double `lindex' strips {} or quotes.
            # the subst enables variables containing
            # command names.
            #
            set alias [uplevel [info level] \
            subst [lindex [lindex [QuoteQuotes ${line}] 0] 0]]

            # make `alias' a fully qualified name.
            # this can raise an error, if alias is
            # no valid command.
            #
            if {[catch [list set alias [namespace origin $alias]]]} {
                return ""
            }

            # strip leading ::'s.
            #
            regsub -all {^::} $alias {} alias
            set namespc [namespace qualifiers $alias]
            set alias [namespace tail $alias]
        }

        foreach cmd [list ${alias} tclreadline_complete_unknown] {
            # puts stderr ${namespc}complete(${cmd})
            if {"" != [namespace eval ::tclreadline::${namespc} \
                [list info procs complete(${cmd})]]
            } {
                # puts found=|complete($cmd)|
                # to be more error-proof, we check here,
                # if complete($cmd) takes exactly 5 arguments.
                #
                if {6 != [set arguments [llength \
                    [namespace eval ::tclreadline::${namespc} \
                    [list info args complete($cmd)]]]]
                } {
                    error [list complete(${cmd}) takes ${arguments} \
                    arguments, but should take exactly 6.]
                }

                # remove leading quotes
                #
                set mod [StripPrefix $part]
                # puts stderr mod=$mod

                if {[catch [list set script_result \
                    [namespace eval ::tclreadline::${namespc} \
                    [list complete(${cmd}) $part $start $end $line $pos $mod]]]\
                    ::tclreadline::errorMsg]
                } {
                    error [list error during evaluation of `complete(${cmd})']
                }
                # puts stderr \nscript_result=|${script_result}|
                return ${script_result}
            }
            # set namespc ""; # no qualifiers for tclreadline_complete_unknown
        }

        # as we've reached here no valid specific completer
        # was found. Check, if it's a proc and return the
        # arguments.
        #
        if {[string length [uplevel [info level] info proc $alias]]} {
            set args [uplevel [info level] info args $alias]
            set arg [lindex $args [expr $pos - 1]]
            if {"" != $arg && "args" != $arg} {
                if {[uplevel [info level] info default $alias $arg junk]} {
                    return [DisplayHints ?$arg?]
                } else {
                    return [DisplayHints <$arg>]
                }
            }
        }


        # Ok, also no proc. Try to do the same as for widgets now:
        # try to get at least the first option from an error output.
        # if the subcommand is configure or cget, try to get the
        # option table.
        #
        switch -- $pos {
            1 {
                set cmds [TrySubCmds ${alias}]
                if {[llength ${cmds}]} {
                    return [TryFromList ${part} ${cmds}]
                }
            }
            default {
                set sub [Lindex $line 1]
                switch -- $sub {
                    configure -
                    cget {
                        if {[OptionTable ${widget} options]} {
                        }
                    }
                }
            }
        }


        # no specific command completer found.
        return ""
    }
    error "{NOTREACHED (this is probably an error)}"
}


# explicit command completers
#

# -------------------------------------
#                 TCL
# -------------------------------------

proc complete(after) {text start end line pos mod} {
    set sub [Lindex $line 1]
    # puts \npos=$pos
    switch -- $pos {
        1 {
            return [CompleteFromList ${text} {<ms> cancel idle info}]
        }
        2 {
            switch -- $sub {
                cancel {
                    return [CompleteFromList $text "<script> [after info]"]
                }
                idle {
                    return [DisplayHints <script>]
                }
                info {
                    return [CompleteFromList $text [after info]]
                }
                default { return [DisplayHints ?script?] }
            }
        }
        default {
            switch -- $sub {
                info { return [DisplayHints {}] }
                default { return [DisplayHints ?script?] }
            }
        }
    }
    return ""
}

proc complete(append) {text start end line pos mod} {
    switch -- $pos {
        1       { return [VarCompletion ${text}] }
        default { return [DisplayHints ?value?] }
    }
    return ""
}

proc complete(array) {text start end line pos mod} {
    switch -- $pos {
        1 {
            set cmds {
                anymore donesearch exists get names
                nextelement set size startsearch
            }
            return [CompleteFromList $text $cmds]
        }
        2 {
            set matches ""
            # set vars [uplevel [info level] info vars ${mod}*]
            #
            # better: this displays a list of array names if the
            # user inters with something which cannot be matched.
            # The matching against `text' is done by CompleteFromList.
            #
            set vars [uplevel [info level] info vars]
            foreach var ${vars} {
                if {[uplevel [info level] array exists ${var}]} {
                    lappend matches ${var}
                }
            }
            return [CompleteFromList ${text} ${matches}]
        }
        3 {
            set cmd [Lindex $line 1]
            set array_name [Lindex $line 2]
            switch -- $cmd {
                get -
                names {
                    set pattern [Lindex $line 3]
                    set matches [uplevel [info level] \
                    array names ${array_name} ${pattern}*]
                    if {![llength $matches]} {
                        return [DisplayHints ?pattern?]
                    } else {
                        return [CompleteFromList ${text} ${matches}]
                    }
                }
                anymore -
                donesearch -
                nextelement { return [DisplayHints <searchId>] }
            }
        }
    }
    return ""
}

# proc complete(bgerror) {text start end line pos mod} {
# }

proc complete(binary) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            return [CompleteFromList $text {format scan}]
        }
        2 {
            switch -- $cmd {
                format { return [DisplayHints <formatString>] }
                scan   { return [DisplayHints <string>] }
            }
        }
        3 {
            switch -- $cmd {
                format { return [DisplayHints ?arg?] }
                scan   { return [DisplayHints <formatString>] }
            }
        }
        default {
            switch -- $cmd {
                format { return [DisplayHints ?arg?] }
                scan   { return [DisplayHints ?varName?] }
            }
        }
    }
    return ""
}

# proc complete(break) {text start end line pos mod} {
# }

proc complete(catch) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <script>] }
        2 { return [DisplayHints ?varName?] }
    }
    return ""
}

proc complete(cd) {text start end line pos mod} {
    return ""
}

proc complete(clock) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            return [CompleteFromList $text {clicks format scan seconds}]
        }
        2 {
            switch -- $cmd {
                format  { return [DisplayHints <clockValue>] }
                scan    { return [DisplayHints <dateString>] }
                clicks  -
                seconds {}
            }
        }
        3 -
        5 {
            switch -- $cmd {
                format {
                    set subcmds [RemoveUsedOptions $line {-format -gmt}]
                    return [TryFromList $text $subcmds]
                }
                scan {
                    set subcmds [RemoveUsedOptions $line {-base -gmt}]
                    return [TryFromList $text $subcmds]
                }
                clicks  -
                seconds {}
            }
        }
        4 -
        6 {
            set sub [Lindex $line [expr $pos - 1]]
            switch -- $cmd {
                format {
                    switch -- $sub {
                        -format { return [DisplayHints <string>] }
                        -gmt    { return [DisplayHints <boolean>] }
                    }
                }
                scan {
                    switch -- $sub {
                        -base { return [DisplayHints <clockVal>] }
                        -gmt  { return [DisplayHints <boolean>] }
                    }
                }
                clicks  -
                seconds {}
            }
        }
    }
    return ""
}

proc complete(close) {text start end line pos mod} {
    switch -- $pos {
        1 { return [ChannelId $text] }
    }
    return ""
}

proc complete(concat) {text start end line pos mod} {
    return [DisplayHints ?arg?]
}

# proc complete(continue) {text start end line pos mod} {
# }

# proc complete(dde) {text start end line pos mod} {
#     We're not on windoze here ...
# }

proc complete(encoding) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            return [CompleteFromList $text {convertfrom convertto names system}]
        }
        2 {
            switch -- $cmd {
                convertfrom -
                convertto -
                system {
                    return [CompleteFromList ${text} [encoding names]]
                }
            }
        }
        3 {
            switch -- $cmd {
                convertfrom { return [DisplayHints <data>] }
                convertto { return [DisplayHints <string>] }
            }
        }
    }
    return ""
}

proc complete(eof) {text start end line pos mod} {
    switch -- $pos {
        1 { return [InChannelId $text] }
    }
    return ""
}

proc complete(error) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <message>] }
        2 { return [DisplayHints ?info?] }
        3 { return [DisplayHints ?code?] }
    }
    return ""
}

proc complete(eval) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <arg>] }
        default { return [DisplayHints ?arg?] }
    }
    return ""
}

proc complete(exec) {text start end line pos mod} {
    set redir [list | |& < <@ << > 2> >& >> 2>> >>& >@ 2>@ >&@]
    variable executables
    if {![info exists executables]} {
        Rehash
    }
    switch -- $pos {
        1 {
            return [TryFromList $text "-keepnewline -- $executables"]
        }
        default {
            set prev [PreviousWord ${start} ${line}]
            if {"-keepnewline" == $prev && 2 == $pos} {
                return [TryFromList $text "-- $executables"]
            }
            switch -exact -- $prev {
                | -
                |& { return [TryFromList $text $executables] }
                < -
                > -
                2> -
                >& -
                >> -
                2>> -
                >>& { return "" }
                <@ -
                >@ -
                2>@ -
                >&@ { return [ChannelId $text] }
                << { return [DisplayHints <value>] }
                default { return [TryFromList $text $redir "<>"] }
            }
        }
    }
    return ""
}

proc complete(exit) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints ?returnCode?] }
    }
    return ""
}

proc complete(expr) {text start end line pos mod} {
    set left $text
    set right ""
    set substitution [regexp -- {(.*)(\(.*)} $text all left right]; #-)

    set cmds {
        - + ~ !  * / % + - << >> < > <= >= == != & ^ | && || <x?y:z>
        acos    cos     hypot   sinh 
        asin    cosh    log     sqrt 
        atan    exp     log10   tan 
        atan2   floor   pow     tanh 
        ceil    fmod    sin     abs 
        double  int     rand    round 
        srand 
    }

    if {")" == [string index $text end] && -1 != [lsearch $cmds $left]} {
        return "$text "; # append a space after a closing ')'
    }

    switch -- $left {
        rand { return "rand() " }

        abs  -
        acos -
        asin -
        atan -
        ceil  -
        cos -
        cosh -
        double -
        exp -
        floor -
        int -
        log -
        log10 -
        round  -
        sin  -
        sinh  -
        sqrt  -
        srand  -
        tan  -
        tanh { return [DisplayHints <value>] }


        atan2 -
        fmod -
        hypot -
        pow { return [DisplayHints <value>,<value>] }
    }

    set completions [TryFromList $left $cmds <>]
    if {1 == [llength $completions]} {
        if {!$substitution} {
            if {"rand" == $completions} {
                return "rand() "; # rand() takes no arguments
            }
            append completions (; #-)
            return [list $completions {}]
        }
    } else {
        return $completions
    }
    return ""
}

proc complete(fblocked) {text start end line pos mod} {
    switch -- $pos {
        1 { return [InChannelId $text] }
    }
    return ""
}

proc complete(fconfigure) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            return [ChannelId ${text}]
        }
        default {
            set option [PreviousWord ${start} ${line}]
            switch -- $option {
                -blocking {
                    return [CompleteBoolean ${text}]
                }
                -buffering {
                    return [CompleteFromList ${text} {full line none}]
                }
                -buffersize {
                    if {![llength ${text}]} {
                        return [DisplayHints <newSize>]
                    }
                }
                -encoding {
                    return [CompleteFromList ${text} [encoding names]]
                }
                -eofchar {
                    return [DisplayHints {\{<inChar>\ <outChar>\}}]
                }
                -translation {
                    return [CompleteFromList ${text} {auto binary cr crlf lf}]
                }
                default {return [CompleteFromList $text \
                    [RemoveUsedOptions $line {
                    -blocking -buffering -buffersize
                    -encoding -eofchar -translation}]]
                }
            }
        }
    }
    return ""
}

proc complete(fcopy) {text start end line pos mod} {
    switch -- $pos {
        1 {
            return [InChannelId ${text}]
        }
        2 {
            return [OutChannelId ${text}]
        }
        default {
            set option [PreviousWord ${start} ${line}]
            switch -- $option {
                -size    { return [DisplayHints <size>] }
                -command { return [DisplayHints <callback>] }
                default  { return [CompleteFromList $text \
                    [RemoveUsedOptions $line {-size -command}]]
                }
            }
        }
    }
    return ""
}

proc complete(file) {text start end line pos mod} {
    switch -- $pos {
        1 {
            set cmds {
                atime attributes copy delete dirname executable exists
                extension isdirectory isfile join lstat mkdir mtime
                nativename owned pathtype readable readlink rename
                rootname size split stat tail type volumes writable
            }
            return [TryFromList $text $cmds]
        }
        2 {
            set cmd [Lindex $line 1]
            switch -- $cmd {
                atime -
                attributes -
                dirname -
                executable -
                exists -
                extension -
                isdirectory -
                isfile -
                join -
                lstat -
                mtime -
                mkdir -
                nativename -
                owned -
                pathtype -
                readable -
                readlink -
                rootname -
                size -
                split -
                stat -
                tail -
                type -
                volumes -
                writable {
                    return ""
                }

                copy -
                delete -
                rename {
                    # return [TryFromList $text "-force [glob *]"]
                    # this is not perfect. The  `-force' and `--'
                    # options will not be displayed.
                    return ""
                }
            }
        }
    }
    return ""
}

proc complete(fileevent) {text start end line pos mod} {
    switch -- $pos {
        1 {
            return [ChannelId ${text}]
        }
        2 {
            return [CompleteFromList ${text} {readable writable}]
        }
        3 {
            return [DisplayHints ?script?]
        }
    }
    return ""
}

proc complete(flush) {text start end line pos mod} {
    switch -- $pos {
        1 { return [OutChannelId ${text}] }
    }
    return ""
}

proc complete(for) {text start end line pos mod} {
    switch -- $pos {
        1 -
        2 -
        3 -
        4 {
            return [BraceOrControlStatement $text $start $end $line $pos $mod]
        }
    }
    return ""
}

proc complete(foreach) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <varname>] }
        2 { return [DisplayHints <list>] }
        default {
            if {[expr $pos % 2]} {
                return [DisplayHints [list ?varname? <body>]]
            } else {
                return [DisplayHints ?list?]
            }
        }
    }
    return ""
}

proc complete(format) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <formatString>] }
        default { return [DisplayHints ?arg?] }
    }
    return ""
}

proc complete(gets) {text start end line pos mod} {
    switch -- $pos {
        1 { return [InChannelId ${text}] }
        2 { return [VarCompletion ${text}]}
    }
    return ""
}

proc complete(glob) {text start end line pos mod} {
    switch -- $pos {
        1 {
            # This also is not perfect.
            # This will not display the options as hints!
            set matches [TryFromList ${text} {-nocomplain --}]
            if {[llength [string trim ${text}]] && [llength ${matches}]} {
                return ${matches}
            }
        }
    }
    return ""
}

proc complete(global) {text start end line pos mod} {
    return [VarCompletion ${text}]
}

proc complete(history) {text start end line pos mod} {
    switch -- $pos {
        1 {
            set cmds {add change clear event info keep nextid redo}
            return [TryFromList $text $cmds]
        }
        2 {
            set cmd [Lindex $line 1]
            switch -- $cmd {
                add { return [DisplayHints <command>] }
                change { return [DisplayHints <newValue>] }

                info -
                keep { return [DisplayHints ?count?] }

                event -
                redo { return [DisplayHints ?event?] }

                clear -
                nextid { return "" }
            }
        }
    }
    return ""
}

# --- HTTP PACKAGE ---

# create a http namespace inside
# tclreadline and import some commands.
#
namespace eval http {
    catch {
        namespace import \
        ::tclreadline::DisplayHints ::tclreadline::PreviousWord \
        ::tclreadline::CompleteFromList ::tclreadline::CommandCompletion \
        ::tclreadline::RemoveUsedOptions ::tclreadline::HostList \
        ::tclreadline::ChannelId ::tclreadline::Lindex \
        ::tclreadline::CompleteBoolean
    }
}

proc http::complete(config) {text start end line pos mod} {
    set prev [PreviousWord ${start} ${line}]
    switch -- $prev {
        -accept { return [DisplayHints <mimetypes>] }
        -proxyhost {
            return [CompleteFromList $text [HostList]]
        }
        -proxyport { return [DisplayHints <number>] }
        -proxyfilter {
            return [CompleteFromList $text [CommandCompletion $text]]
        }
        -useragent { return [DisplayHints <string>] }
        default {
            return [CompleteFromList $text [RemoveUsedOptions $line {
                -accept -proxyhost -proxyport -proxyfilter -useragent
            }]]
        }
    }
    return ""
}

proc http::complete(geturl) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <url>] }
        default {
            set prev [PreviousWord ${start} ${line}]
            switch -- $prev {
                -blocksize { return [DisplayHints <size>] }
                -channel { return [ChannelId ${text}] }
                -command -
                -handler -
                -progress {
                    return [CompleteFromList $text [CommandCompletion $text]]
                }
                -headers { return [DisplayHints <keyvaluelist>] }
                -query { return [DisplayHints <query>] }
                -timeout { return [DisplayHints <milliseconds>] }
                -validate { return [CompleteBoolean $text] }
                default {
                    return [CompleteFromList $text [RemoveUsedOptions $line {
                        -blocksize -channel -command -handler -headers
                        -progress -query -timeout -validate
                    }]]
                }
            }
        }
    }
    return ""
}

proc http::complete(formatQuery) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <key>] }
        2 { return [DisplayHints <value>] }
        default {
            switch [expr $pos % 2] {
                0 { return [DisplayHints ?value?] }
                1 { return [DisplayHints ?key?] }
            }
        }
    }
    return ""
}

proc http::complete(reset) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <token>] }
        2 { return [DisplayHints ?why?] }
    }
    return ""
}

# the unknown proc handles the rest
#
proc \
http::complete(tclreadline_complete_unknown) {text start end line pos mod} {
    set cmd [Lindex $line 0]
    regsub -all {^.*::} $cmd "" cmd
    switch -- $pos {
        1 {
            switch -- $cmd {
                reset -
                wait -
                data -
                status -
                code -
                size -
                cleanup {
                    return [DisplayHints <token>]
                }
            }
        }
    }
    return ""
}

# --- END OF HTTP PACKAGE ---

proc complete(if) {text start end line pos mod} {
    # we don't offer the completion `then':
    # it's optional, more difficult to parse
    # and who uses it anyway?
    #
    switch -- $pos {
        1 -
        2 {
            return [BraceOrControlStatement $text $start $end $line $pos $mod]
        }
        default {
            set prev [PreviousWord ${start} ${line}]
            switch -- $prev {
                then -
                else -
                elseif {
                    return [BraceOrControlStatement \
                    $text $start $end $line $pos $mod]
                }
                default {
                    if {-1 == [lsearch [ProperList $line] else]} {
                        return [CompleteFromList $text {else elseif}]
                    }
                }
            }
        }
    }
    return ""
}

proc complete(incr) {text start end line pos mod} {
    switch -- $pos {
        1 {
            set matches [uplevel [info level] info vars ${mod}*]
            set integers ""
            # check for integers
            #
            foreach match $matches {
                if {[uplevel [info level] array exists $match]} {
                    continue
                }
                if {[regexp {^[0-9]+$} [uplevel [info level] set $match]]} {
                    lappend integers $match
                }
            }
            return [CompleteFromList ${text} ${integers}]
        }
        2 { return [DisplayHints ?increment?] }
    }
    return ""
}

proc complete(info) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            set cmds {
                args body cmdcount commands complete default exists
                globals hostname level library loaded locals nameofexecutable
                patchlevel procs script sharedlibextension tclversion vars}
            return [CompleteFromList $text $cmds]
        }
        2 {
            switch -- $cmd {
                args -
                body -
                default -
                procs { return [complete(proc) ${text} 0 0 ${line} 1 ${mod}] }
                complete { return [DisplayHints <command>] }
                level { return [DisplayHints ?number?] }
                loaded { return [DisplayHints ?interp?] }
                commands -
                exists -
                globals -
                locals -
                vars {
                    if {"exists" == $cmd} {
                        set do vars
                    } else {
                        set do $cmd
                    }
                    # puts stderr [list complete(info) level = [info level]]
                    return \
                    [CompleteFromList ${text} [uplevel [info level] info ${do}]]
                }
            }
        }
        3 {
            switch -- $cmd {
                default {
                    set proc [Lindex $line 2]
                    return [CompleteFromList ${text} \
                    [uplevel [info level] info args $proc]]
                }
                default {}
            }
        }
        4 {
            switch -- $cmd {
                default {
                    return [VarCompletion ${text}]
                }
                default {}
            }
        }
    }
    return ""
}

proc complete(interp) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            set cmds {
                alias aliases create delete eval exists expose hide hidden
                invokehidden issafe marktrusted share slaves target transfer}
            return [TryFromList $text $cmds]
        }
        2 {
            switch -- $cmd {

                create {
                    set cmds [RemoveUsedOptions ${line} {-save --} {--}]
                    if {[llength $cmds]} {
                        return [CompleteFromList $text "$cmds ?path?"]
                    } else {
                        return [DisplayHints ?path?]
                    }
                }

                eval -
                exists -
                expose -
                hide -
                hidden -
                invokehidden -
                marktrusted -
                target { return [CompleteFromList ${text} [interp slaves]] }

                aliases -
                delete -
                issafe -
                slaves { return [CompleteFromList ${text} [interp slaves]] }

                alias -
                share -
                transfer { return [DisplayHints <srcPath>] }
            }
        }
        3 {
            switch -- $cmd {

                alias { return [DisplayHints <srcCmd>] }

                create {
                    set cmds [RemoveUsedOptions ${line} {-save --} {--}]
                    if {[llength $cmds]} {
                        return [CompleteFromList $text "$cmds ?path?"]
                    } else {
                        return [DisplayHints ?path?]
                    }
                }

                eval { return [DisplayHints <arg>] }
                delete { return [CompleteFromList ${text} [interp slaves]] }

                expose { return [DisplayHints <hiddenName>] }
                hide { return [DisplayHints <exposedCmdName>] }

                invokehidden {
                    return \
                    [CompleteFromList $text {?-global? <hiddenCmdName>}]
                }

                target { return [DisplayHints <alias>] }

                exists {}
                hidden {}
                marktrusted {}
                aliases {}
                issafe {}
                slaves {}

                share -
                transfer {return [ChannelId ${text}]}
            }
        }
        4 {
            switch -- $cmd {

                alias { return [DisplayHints <targetPath>] }
                eval { return [DisplayHints ?arg?] }

                invokehidden {
                    return [CompleteFromList $text {<hiddenCmdName> ?arg?}]
                }

                create {
                    set cmds [RemoveUsedOptions ${line} {-save --} {--}]
                    if {[llength $cmds]} {
                        return [CompleteFromList $text "$cmds ?path?"]
                    } else {
                        return [DisplayHints ?path?]
                    }
                }

                expose { return [DisplayHints ?exposedCmdName?] }
                hide { return [DisplayHints ?hiddenCmdName?] }

                share -
                transfer { return [CompleteFromList ${text} [interp slaves]] }
            }
        }
        5 {
            switch -- $cmd {

                alias { return [DisplayHints <targetCmd>] }
                invokehidden -
                eval { return [DisplayHints ?arg?] }

                expose { return [DisplayHints ?exposedCmdName?] }
                hide { return [DisplayHints ?hiddenCmdName?] }

                share -
                transfer { return [CompleteFromList ${text} [interp slaves]] }
            }
        }
    }
    return ""
}

proc complete(join) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <list>] }
        2 { return [DisplayHints ?joinString?] }
    }
    return ""
}

proc complete(lappend) {text start end line pos mod} {
    switch -- $pos {
        1 { return [VarCompletion ${text}] }
        default { return [DisplayHints ?value?] }
    }
    return ""
}

# the following routines are described in the
# `library' man page.
# --- LIBRARY ---

proc complete(auto_execok) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <cmd>] }
    }
    return ""
}

proc complete(auto_load) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <cmd>] }
    }
    return ""
}

proc complete(auto_mkindex) {text start end line pos mod} {
    switch -- $pos {
        1 { return "" }
        default { return [DisplayHints ?pattern?] }
    }
    return ""
}

# proc complete(auto_reset) {text start end line pos mod} {
# }

proc complete(tcl_findLibrary) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <basename>] }
        2 { return [DisplayHints <version>] }
        3 { return [DisplayHints <patch>] }
        4 { return [DisplayHints <initScript>] }
        5 { return [DisplayHints <enVarName>] }
        6 { return [DisplayHints <varName>] }
    }
    return ""
}

proc complete(parray) {text start end line pos mod} {
    switch -- $pos {
        1 {
            set vars [uplevel [info level] info vars]
            foreach var ${vars} {
                if {[uplevel [info level] array exists ${var}]} {
                    lappend matches ${var}
                }
            }
            return [CompleteFromList $text $matches]
        }
    }
    return ""
}

proc complete(tcl_endOfWord) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <str>] }
        2 { return [DisplayHints <start>] }
    }
    return ""
}

proc complete(tcl_startOfNextWord) {text start end line pos mod} {
    return [complete(tcl_endOfWord) $text $start $end $line $pos $mod]
}

proc complete(tcl_startOfPreviousWord) {text start end line pos mod} {
    return [complete(tcl_endOfWord) $text $start $end $line $pos $mod]
}

proc complete(tcl_wordBreakAfter) {text start end line pos mod} {
    return [complete(tcl_endOfWord) $text $start $end $line $pos $mod]
}

proc complete(tcl_wordBreakBefore) {text start end line pos mod} {
    return [complete(tcl_endOfWord) $text $start $end $line $pos $mod]
}

# --- END OF `LIBRARY' ---

proc complete(lindex) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <list>] }
        2 { return [DisplayHints <index>] }
    }
    return ""
}

proc complete(linsert) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <list>] }
        2 { return [DisplayHints <index>] }
        3 { return [DisplayHints <element>] }
        default { return [DisplayHints ?element?] }
    }
    return ""
}

proc complete(list) {text start end line pos mod} {
    return [DisplayHints ?arg?]
}

proc complete(llength) {text start end line pos mod} {
    switch -- $pos {
        1 {
            return [DisplayHints <list>]
        }
    }
    return ""
}

proc complete(load) {text start end line pos mod} {
    switch -- $pos {
        1 {
            return ""; # filename
        }
        2 {
            if {![llength ${mod}]} {
                return [DisplayHints ?packageName?]
            }
        }
        3 {
            if {![llength ${mod}]} {
                return [DisplayHints ?interp?]
            }
        }
    }
    return ""
}

proc complete(lrange) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <list>] }
        2 { return [DisplayHints <first>] }
        3 { return [DisplayHints <last>] }
    }
    return ""
}

proc complete(lreplace) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <list>] }
        2 { return [DisplayHints <first>] }
        3 { return [DisplayHints <last>] }
        default { return [DisplayHints ?element?] }
    }
    return ""
}

proc complete(lsearch) {text start end line pos mod} {
    set options {-exact -glob -regexp}
    switch -- $pos {
        1 {
            return [CompleteFromList ${text} "$options <list>"]
        }
        2 -
        3 -
        4 {
            set sub [Lindex $line 1]
            if {-1 != [lsearch $options $sub]} {
                incr pos -1
            }
            switch -- $pos {
                1 { return [DisplayHints <list>] }
                2 { return [DisplayHints <pattern>] }
            }
        }
    }
    return ""
}

proc complete(lsort) {text start end line pos mod} {
    set options [RemoveUsedOptions ${line} {
        -ascii -dictionary -integer -real -command
        -increasing -decreasing -index <list>
    }]
    switch -- $pos {
        1 { return [CompleteFromList ${text} ${options}] }
        default {
            switch -- [PreviousWord ${start} ${line}] {
                -command {
                    return [CompleteFromList $text [CommandCompletion $text]]
                }
                -index { return [DisplayHints <index>] }
                default { return [CompleteFromList ${text} ${options}] }
            }
        }
    }
    return ""
}

# --- MSGCAT PACKAGE ---

# create a msgcat namespace inside
# tclreadline and import some commands.
#
namespace eval msgcat {
    catch {namespace import ::tclreadline::DisplayHints}
}

proc msgcat::complete(mc) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <src-string>] }
    }
    return ""
}

proc msgcat::complete(mclocale) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints ?newLocale?] }
    }
    return ""
}

# proc msgcat::complete(mcpreferences) {text start end line pos mod} {
# }

proc msgcat::complete(mcload) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <dirname>] }
    }
    return ""
}

proc msgcat::complete(mcset) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <locale>] }
        2 { return [DisplayHints <src-string>] }
        3 { return [DisplayHints ?translate-string?] }
    }
    return ""
}

proc msgcat::complete(mcunknown) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <locale>] }
        2 { return [DisplayHints <src-string>] }
    }
    return ""
}

# --- END OF MSGCAT PACKAGE ---

# TODO import ! -force
proc complete(namespace) {text start end line pos mod} {
    # TODO dosn't work ???
    set space_matches [namespace children :: [string trim ${mod}*]]
    # puts \nspace_matches=|${space_matches}|
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            set cmds {
                children code current delete eval export forget
                import inscope origin parent qualifiers tail which}
            return [TryFromList $text $cmds]
        }
        2 {
            switch -- $cmd {
                children -
                delete -
                eval -
                inscope -
                forget -
                parent -
                qualifiers -
                tail {
                    regsub {^([^:])} ${mod} {::\1} mod; # full qual. name
                    return [TryFromList ${mod} $space_matches]
                }
                code { return [DisplayHints <script> ] }
                current {}
                export { return [CompleteFromList ${text} {-clear ?pattern?}] }
                import {
                    if {"-" != [string index ${mod} 0]} {
                        regsub {^([^:])} ${mod} {::\1} mod; # full qual. name
                    }
                    return [CompleteFromList ${mod} "-force $space_matches"]
                }
                origin { return [DisplayHints <command>] }
                # qualifiers -
                # tail { return [DisplayHints <string>] }
                which { return [CompleteFromList ${mod} {
                    -command -variable <name>}] }
            }
        }
        3 {
            switch -- $cmd {
                children -
                export -
                forget -
                import { return [DisplayHints ?pattern?] }
                delete { return [TryFromList ${mod} $space_matches] }
                eval -
                inscope { return [DisplayHints <arg>] }
                which { return [CompleteFromList ${mod} {-variable <name>}] }
            }
        }
        4 {
            switch -- $cmd {
                export -
                forget -
                import { return [DisplayHints ?pattern?] }
                delete { return [TryFromList ${mod} $space_matches] }
                eval -
                inscope { return [DisplayHints ?arg?] }
                which { return [CompleteFromList ${mod} {<name>}] }
            }
        }
    }
    return ""
}

proc complete(open) {text start end line pos mod} {
        # 2 { return [DisplayHints ?access?] }
    switch -- $pos {
        2 {
            set access {r r+ w w+ a a+ 
                RDONLY WRONLY RDWR APPEND CREAT EXCL NOCTTY NONBLOCK TRUNC}
            return [CompleteFromList ${text} $access]
        }
        3 { return [DisplayHints ?permissions?] }
    }
    return ""
}

proc complete(package) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            set cmds {
                forget ifneeded names present provide require
                unknown vcompare versions vsatisfies}
            return [TryFromList $text $cmds]
        }
        2 {
            switch -- $cmd {
                forget -
                ifneeded -
                provide -
                versions { return [CompleteFromList ${mod} [package names]] }
                present -
                require {
                    return [CompleteFromList ${mod} "-exact [package names]"] }
                names {}
                unknown { return [DisplayHints ?command?] }
                vcompare -
                vsatisfies { return [DisplayHints <version1>] }
            }
        }
        3 {
            set versions ""
            catch [list set versions [package versions [Lindex $line 2]]]
            switch -- $cmd {
                forget {}
                ifneeded {
                    if {"" != $versions} {
                        return [CompleteFromList ${text} $versions]
                    } else {
                        return [DisplayHints <version>]
                    }
                }
                provide {
                    if {"" != $versions} {
                        return [CompleteFromList ${text} $versions]
                    } else {
                        return [DisplayHints ?version?]
                    }
                }
                versions {}
                present -
                require {
                    if {"-exact" == [PreviousWord ${start} ${line}]} {
                        return [CompleteFromList ${mod} [package names]]
                    } else {
                        if {"" != $versions} {
                            return [CompleteFromList ${text} $versions]
                        } else {
                            return [DisplayHints ?version?]
                        }
                    }
                }
                names {}
                unknown {}
                vcompare -
                vsatisfies { return [DisplayHints <version2>] }
            }
        }
    }
    return ""
}

proc complete(pid) {text start end line pos mod} {
    switch -- $pos {
        1 { return [ChannelId ${text}] }
    }
}

proc complete(pkg_mkIndex) {text start end line pos mod} {
    set cmds [RemoveUsedOptions ${line} {-direct -load -verbose -- <dir>} {--}]
    set res [string trim [TryFromList $text $cmds]]
    set prev [PreviousWord ${start} ${line}]
    if {"-load" == $prev} {
        return [DisplayHints <pkgPat>]
    } elseif {"--" == $prev} {
        return [TryFromList ${text} <dir>]
    }
    return ${res}
}

proc complete(proc) {text start end line pos mod} {
    switch -- $pos {
        1 {
            set known_procs [ProcsOnlyCompletion ${text}]
            return [CompleteFromList ${text} ${known_procs}]
        }
        2 {
            set proc [Lindex $line 1]
            if {[catch {set args [uplevel [info level] info args ${proc}]}]} {
                return [DisplayHints <args>]
            } else {
                return [list "\{${args}\}"]
            }
        }
        3 {
            if {![string length [Lindex $line $pos]]} {
                return [list \{ {}]; # \}
            } else {
                return [DisplayHints <body>]
            }
        }
    }
    return ""
}

proc complete(puts) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            return [OutChannelId ${text} "-nonewline"]
        }
        2 {
            switch -- $cmd {
                -nonewline { return [OutChannelId ${text}] }
                default { return [DisplayHints <string>] }
            }
        }
        3 {
            switch -- $cmd {
                -nonewline { return [DisplayHints <string>] }
            }
        }
    }
    return ""
}

# proc complete(pwd) {text start end line pos mod} {
# }

proc complete(read) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 {
            return [InChannelId ${text} "-nonewline"]
        }
        2 {
            switch -- $cmd {
                -nonewline { return [InChannelId ${text}] }
                default { return [DisplayHints <numChars>] }
            }
        }
    }
    return ""
}

proc complete(regexp) {text start end line pos mod} {
    set prev [PreviousWord ${start} ${line}]
    if {[llength ${prev}] && "--" != $prev && \
        ("-" == [string index ${prev} 0] || 1 == $pos)} {
        set cmds [RemoveUsedOptions ${line} {
            -nocase -indices -expanded -line 
            -linestop -lineanchor -about <expression> --} {--}]
        if {[llength ${cmds}]} {
            return [string trim [CompleteFromList $text $cmds]]
        }
    } else {
        set virtual_pos [expr ${pos} - [FirstNonOption ${line}]]
        switch -- ${virtual_pos} {
            0 { return [DisplayHints <string>] }
            1 { return [DisplayHints ?matchVar?] }
            default { return [DisplayHints ?subMatchVar?] }
        }
    }
    return ""
}

# proc complete(regexp) {text start end line pos mod} {
#     We're not on windoze here ...
# }

proc complete(regsub) {text start end line pos mod} {
    set prev [PreviousWord ${start} ${line}]
    if {[llength ${prev}] && "--" != $prev && \
        ("-" == [string index ${prev} 0] || 1 == $pos)} {
        set cmds [RemoveUsedOptions ${line} {
            -all -nocase --} {--}]
        if {[llength ${cmds}]} {
            return [string trim [CompleteFromList $text $cmds]]
        }
    } else {
        set virtual_pos [expr ${pos} - [FirstNonOption ${line}]]
        switch -- ${virtual_pos} {
            0 { return [DisplayHints <expression>] }
            1 { return [DisplayHints <string>] }
            2 { return [DisplayHints <subSpec>] }
            3 { return [DisplayHints <varName>] }
        }
    }
    return ""
}

proc complete(rename) {text start end line pos mod} {
    switch -- $pos {
        1 {
            return [CompleteFromList $text [CommandCompletion $text]]
        }
        2 {
            return [DisplayHints <newName>]
        }
    }
    return ""
}

# proc complete(resource) {text start end line pos mod} {
#     This is not a mac ...
# }

proc complete(return) {text start end line pos mod} {
    # TODO this is not perfect yet
    set cmds {-code -errorinfo -errorcode ?string?}
    set res [PreviousWord ${start} ${line}]
    switch -- ${res} {
        -errorinfo { return [DisplayHints <info>] }
        -code -
        -errorcode {
            set codes {ok error return break continue}
            return [TryFromList ${mod} ${codes}]
        }
    }
    return [CompleteFromList ${text} [RemoveUsedOptions ${line} ${cmds}]]
}

# --- SAFE PACKAGE ---

# create a safe namespace inside
# tclreadline and import some commands.
#
namespace eval safe {
    catch {
        namespace import \
        ::tclreadline::DisplayHints ::tclreadline::PreviousWord \
        ::tclreadline::CompleteFromList ::tclreadline::CommandCompletion \
        ::tclreadline::RemoveUsedOptions ::tclreadline::HostList \
        ::tclreadline::ChannelId ::tclreadline::Lindex \
        ::tclreadline::CompleteBoolean
    }
    variable opts
    set opts {
        -accessPath -statics -noStatics -nested -nestedLoadOk -deleteHook
    }
    proc SlaveOrOpts {text start line pos slave} {
        set prev [PreviousWord ${start} ${line}]
        variable opts
        if {$pos > 1} {
            set slave ""
        }
        switch -- $prev {
            -accessPath { return [DisplayHints <directoryList>] }
            -statics { return [CompleteBoolean $text] }
            -nested { return [CompleteBoolean $text] }
            -deleteHook { return [DisplayHints <script>] }
            default {
                return [CompleteFromList ${text} \
                [RemoveUsedOptions ${line} "${opts} $slave"]]
            }
        }
    }
}

proc safe::complete(interpCreate) {text start end line pos mod} {
    return [SlaveOrOpts $text $start $line $pos ?slave?]
}

proc safe::complete(interpInit) {text start end line pos mod} {
    return [SlaveOrOpts $text $start $line $pos [interp slaves]]
}

proc safe::complete(interpConfigure) {text start end line pos mod} {
    return [SlaveOrOpts $text $start $line $pos [interp slaves]]
}

proc safe::complete(interpDelete) {text start end line pos mod} {
    return [CompleteFromList $text [interp slaves]]
}

proc safe::complete(interpAddToAccessPath) {text start end line pos mod} {
    switch -- $pos {
        1 { return [CompleteFromList $text [interp slaves]] }
    }
}

proc safe::complete(interpFindInAccessPath) {text start end line pos mod} {
    switch -- $pos {
        1 { return [CompleteFromList $text [interp slaves]] }
    }
}

proc safe::complete(setLogCmd) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints ?cmd?] }
        default { return [DisplayHints ?arg?] }
    }
}

# --- END OF SAFE PACKAGE ---

proc complete(scan) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <string>] }
        2 { return [DisplayHints <format>] }
        default { return [VarCompletion ${text}] }
    }
    return ""
}

proc complete(seek) {text start end line pos mod} {
    switch -- $pos {
        1 { return [ChannelId ${text}] }
        2 { return [DisplayHints <offset>] }
        3 { return [TryFromList ${text} {start current end}] }
    }
    return ""
}

proc complete(set) {text start end line pos mod} {
    switch -- $pos {
        1 { return [VarCompletion ${text}] }
        2 {
            if {$text == "" || $text == "\"" || $text == "\{"} {
                set line [QuoteQuotes $line]
                if {[catch [list set value [list [uplevel [info level] \
                    set [Lindex $line 1]]]] msg]
                } {
                    return ""
                } else {
                    return [Quote $value ${text}]
                }
            }
        }
    }
    return ""
}

proc complete(socket) {text start end line pos mod} {
    set cmd [Lindex ${line} 1]
    set prev [PreviousWord ${start} ${line}]
    if {"-server" == ${cmd}} {
        # server sockets
        #
        switch -- $pos {
            2 { return [DisplayHints <command>] }
            default {
                if {"-myaddr" == $prev} {
                    return [DisplayHints <addr>]
                } else {
                    return [CompleteFromList ${mod} \
                    [RemoveUsedOptions $line {-myaddr -error -sockname <port>}]]
                }
            }
        }
    } else {
        # client sockets
        #
        switch -- ${prev} {
            -myaddr { return [DisplayHints <addr>] }
            -myport { return [DisplayHints <port>] }
        }

        set hosts [HostList]
        set cmds {-myaddr -myport -async -myaddr -error -sockname -peername}
        if {$pos <= 1} {
            lappend cmds -server
        }
        set cmds [RemoveUsedOptions $line $cmds]
        if {-1 != [lsearch $hosts $prev]} {
            return [DisplayHints <port>]
        } else {
            return [CompleteFromList ${mod} [concat ${cmds} ${hosts}]]
        }
    }
    return ""
}

# proc complete(source) {text start end line pos mod} {
# }

proc complete(split) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <string>] }
        2 { return [DisplayHints ?splitChars?] }
    }
}

proc complete(string) {text start end line pos mod} {
    set cmd [Lindex ${line} 1]
    set prev [PreviousWord ${start} ${line}]
    set cmds {
        bytelength compare equal first index is last length map match
        range repeat replace tolower toupper totitle trim trimleft
        trimright wordend wordstart}
    switch -- $pos {
        1 {
            return [CompleteFromList ${text} ${cmds}]
        }
        2 {
            switch -- $cmd {
                compare -
                equal {
                    return [CompleteFromList ${text} {
                        -nocase -length <string> }]
                }

                first -
                last { return [DisplayHints <string1>] }

                map { return [CompleteFromList ${text} {-nocase <charMap>]} }
                match { return [CompleteFromList ${text} {-nocase <pattern>]} }

                is {
                    return [CompleteFromList ${text} {
                        alnum alpha ascii boolean control digit double 
                        false graph integer lower print punct space 
                        true upper wordchar xdigit 
                    }]
                }

                bytelength -
                index -
                length -
                range -
                repeat -
                replace -
                tolower -
                totitle -
                toupper -
                trim -
                trimleft -
                trimright -
                wordend -
                wordstart { return [DisplayHints <string>] }
            }
        }
        3 {
            switch -- $cmd {
                compare -
                equal {
                    if {"-length" == $prev} {
                        return [DisplayHints <int>]
                    }
                    return [CompleteFromList ${text} \
                    [RemoveUsedOptions $line {-nocase -length <string>}]]
                }

                first -
                last { return [DisplayHints <string2>] }

                map {
                    if {"-nocase" == $prev} {
                        return [DisplayHints <charMap>]
                    } else {
                        return [DisplayHints <string>]
                    }
                }
                match {
                    if {"-nocase" == $prev} {
                        return [DisplayHints <pattern>]
                    } else {
                        return [DisplayHints <string>]
                    }
                }

                is {
                    return [CompleteFromList ${text} \
                    [RemoveUsedOptions $line {-strict -failindex <string>}]]
                }

                bytelength {}
                index -
                wordend -
                wordstart { return [DisplayHints <charIndex>] }
                range -
                replace { return [DisplayHints <first>] }
                repeat { return [DisplayHints <count>] }
                tolower -
                totitle -
                toupper { return [DisplayHints ?first?] }
                trim -
                trimleft -
                trimright { return [DisplayHints ?chars?] }
            }
        }
        4 {
            switch -- $cmd {
                compare -
                equal {
                    if {"-length" == $prev} {
                        return [DisplayHints <int>]
                    }
                    return [CompleteFromList ${text} \
                    [RemoveUsedOptions $line {-nocase -length <string>}]]
                }

                first -
                last { return [DisplayHints ?startIndex?] }

                map -
                match { return [DisplayHints <string>] }

                is {
                    if {"-failindex" == $prev} {
                        return [VarCompletion ${text}]
                    }
                    return [CompleteFromList ${text} \
                    [RemoveUsedOptions $line {-strict -failindex <string>}]]
                }

                bytelength {}
                index {}
                length {}
                range -
                replace { return [DisplayHints <last>] }
                repeat {}
                tolower -
                totitle -
                toupper { return [DisplayHints ?last?] }
                trim -
                trimleft -
                trimright {}
                wordend -
                wordstart {}
            }
        }
        default {
            switch -- $cmd {
                compare -
                equal {
                    if {"-length" == $prev} {
                        return [DisplayHints <int>]
                    }
                    return [CompleteFromList ${text} \
                    [RemoveUsedOptions $line {-nocase -length <string>}]]
                }

                is {
                    if {"-failindex" == $prev} {
                        return [VarCompletion ${text}]
                    }
                    return [CompleteFromList ${text} \
                    [RemoveUsedOptions $line {-strict -failindex <string>}]]
                }

                replace { return [DisplayHints ?newString?] }
            }
        }
    }
    return ""
}

proc complete(subst) {text start end line pos mod} {
    return [CompleteFromList ${text} [RemoveUsedOptions $line {
        -nobackslashes -nocommands -novariables <string>}]]
}

proc complete(switch) {text start end line pos mod} {
    set prev [PreviousWord ${start} ${line}]
    if {[llength ${prev}] && "--" != $prev && \
        ("-" == [string index ${prev} 0] || 1 == $pos)} {
        set cmds [RemoveUsedOptions ${line} {
            -exact -glob -regexp --} {--}]
        if {[llength ${cmds}]} {
            return [string trim [CompleteFromList $text $cmds]]
        }
    } else {
        set virtual_pos [expr ${pos} - [FirstNonOption ${line}]]
        switch -- ${virtual_pos} {
            0 { return [DisplayHints <string>] }
            1 { return [DisplayHints <pattern>] }
            2 { return [DisplayHints <body>] }
            default { 
                switch [expr $virtual_pos % 2] {
                    0 { return [DisplayHints ?body?] }
                    1 { return [DisplayHints ?pattern?] }
                }
            }
        }
    }
    return ""
}

# --- TCLREADLINE PACKAGE ---

# create a tclreadline namespace inside
# tclreadline and import some commands.
#
namespace eval tclreadline {
    catch {
        namespace import \
        ::tclreadline::DisplayHints \
        ::tclreadline::CompleteFromList \
        ::tclreadline::Lindex
    }
}

proc tclreadline::complete(readline) {text start end line pos mod} {
    set cmd [Lindex $line 1]
    switch -- $pos {
        1 { return [CompleteFromList ${text} {
            read initialize write add complete
            customcompleter builtincompleter eofchar}]
        }
        2 {
            switch -- $cmd {
                read {}
                initialize {}
                write {}
                add { return [DisplayHints <completerLine>] }
                completer { return [DisplayHints <line>] }
                customcompleter { return [DisplayHints ?scriptCompleter?] }
                builtincompleter { return [DisplayHints ?boolean?] }
                eofchar { return [DisplayHints ?script?] }
            }
        }
    }
    return ""
}

# --- END OF TCLREADLINE PACKAGE ---

proc complete(tell) {text start end line pos mod} {
    switch -- $pos {
        1 { return [ChannelId ${text}] }
    }
    return ""
}

proc complete(time) {text start end line pos mod} {
    switch -- $pos {
        1 { return [DisplayHints <script>] }
        2 { return [DisplayHints ?count?] }
    }
    return ""
}

proc complete(trace) {text start end line pos mod} {
    set cmd [Lindex ${line} 1]
    switch -- $pos {
        1 {
            return [CompleteFromList ${mod} {variable vdelete vinfo}]
        }
        2 {
            return [CompleteFromList ${text} \
            [uplevel [info level] info vars "${mod}*"]]
        }
        3 {
            switch -- $cmd {
                variable -
                vdelete { return [CompleteFromList ${text} {r w u}] }
            }
        }
        4 {
            switch -- $cmd {
                variable -
                vdelete {
                    return [CompleteFromList $text [CommandCompletion $text]]
                }
            }
        }
    }
    return ""
}

proc complete(unknown) {text start end line pos mod} {
    switch -- $pos {
        1 {
            return [CompleteFromList $text [CommandCompletion $text]]
        }
        default { return [DisplayHints ?arg?] }
    }
    return ""
}

proc complete(unset) {text start end line pos mod} {
    return [VarCompletion ${text}]
}

proc complete(update) {text start end line pos mod} {
    switch -- $pos {
        1 { return idletasks }
    }
    return ""
}

proc complete(uplevel) {text start end line pos mod} {
    set one [Lindex ${line} 1]
    switch -- $pos {
        1 {
            return [CompleteFromList $text "?level? [CommandCompletion $text]"]
        }
        2 {
            if {"#" == [string index $one 0] || [regexp {^[0-9]*$} $one]} {
                return [CompleteFromList $text [CommandCompletion $text]]
            } else {
                return [DisplayHints ?arg?]
            }
        }
        default { return [DisplayHints ?arg?] }
    }
    return ""
}

proc complete(upvar) {text start end line pos mod} {
    set one [Lindex ${line} 1]
    switch -- $pos {
        1 {
            return [DisplayHints {?level? <otherVar>}]
        }
        2 {
            if {"#" == [string index $one 0] || [regexp {^[0-9]*$} $one]} {
                return [DisplayHints <otherVar>]
            } else {
                return [DisplayHints <myVar>]
            }
        }
        3 {
            if {"#" == [string index $one 0] || [regexp {^[0-9]*$} $one]} {
                return [DisplayHints <myVar>]
            } else {
                return [DisplayHints ?otherVar?]
            }
        }
        default {
            set virtual_pos $pos
            if {"#" == [string index $one 0] || [regexp {^[0-9]*$} $one]} {
                incr virtual_pos
            }
            switch [expr $virtual_pos % 2] {
                0 { return [DisplayHints ?myVar?] }
                1 { return [DisplayHints ?otherVar?] }
            }
        }
    }
    return ""
}

proc complete(variable) {text start end line pos mod} {
    set modulo [expr $pos % 2]
    switch -- $modulo {
        1 { return [VarCompletion ${text}] }
        0 {
            if {$text == "" || $text == "\"" || $text == "\{"} {
                set line [QuoteQuotes $line]
                if {[catch [list set value [list [uplevel [info level] \
                    set [PreviousWord $start $line]]]] msg]
                } {
                    return ""
                } else {
                    return [Quote $value ${text}]
                }
            }
        }
    }
    return ""
}

proc complete(vwait) {text start end line pos mod} {
    switch -- $pos {
        1 { return [VarCompletion ${mod}] }
    }
    return ""
}

proc complete(while) {text start end line pos mod} {
    switch -- $pos {
        1 -
        2 {
            return [BraceOrControlStatement $text $start $end $line $pos $mod]
        }
    }
    return ""
}

# -------------------------------------
#                  TK
# -------------------------------------

# GENERIC WIDGET CONFIGURATION

proc WidgetChildren {pattern} {
    regsub {^([^\.])} ${pattern} {\.\1} pattern
    if {![string length ${pattern}]} {
        set pattern .
    }
    if {[winfo exists ${pattern}]} {
        return [winfo children ${pattern}]
    } else {
        regsub {.[^.]*$} $pattern {} pattern
        if {[winfo exists ${pattern}]} {
            return [winfo children ${pattern}]
        } else {
            return ""
        }
    }
}

proc WidgetDescendants {pattern} {
    set tree [WidgetChildren ${pattern}]
    foreach widget $tree {
        append tree " [WidgetDescendants $widget]"
    }
    return $tree
}

proc ToplevelWindows {} {
    set children [WidgetChildren ""]
    set toplevels ""
    foreach widget $children {
        set toplevel [winfo toplevel $widget]
        if {-1 == [lsearch $toplevels $toplevel]} {
            lappend toplevels $toplevel
        }
    }
    return $toplevels
}

#**
# try to get options for commands which
# allow `configure' (cget).
# @param command.
# @param optionsT where the table will be stored.
# @return number of options
# @date Sep-14-1999
#
proc OptionTable {cmd optionsT} {
    upvar $optionsT options
    # first we build an option table
    #
    if {[catch [list set option_table [${widget} configure]] msg]} {
        return 0
    }
    foreach optline ${option_table} {
        if {5 != [llength ${optline}]} continue else {
            lappend options(switches) [lindex ${optline} 0]
            lappend options(value)    [lindex ${optline} 4]
        }
    }
    return [llength ${option_table}
}

#**
# :xa
# @param
# @return
# @warning
# @sa
# @author Johannes Zellner
# @date Sep-14-1999
#
proc CompleteFromOptions {text start line cmd} {
    OptionTable ${widget} options
    set prev [PreviousWord ${start} ${line}]
    #puts \nprev=|$prev|
    #puts switches=|$options(switches)|
    #puts found=[lsearch -exact ${prev} $options(switches)]
    if {-1 != [set found \
        [lsearch -exact $options(switches) ${prev}]]
    } {
        if {![llength ${text}]} {
            return [list "[lindex $options(value) ${found}]"]
        }
    } else {
        return [TryFromList ${text} $options(switches)]
    }
}

proc complete(WIDGET) {text start end line pos mod} {
    set widget [lindex ${line} 0]
    set cmd [lindex ${line} 1]

    switch -- $pos {
        1 {
            set cmds [TrySubCmds ${widget}]
            if {[llength ${cmds}]} {
                return [TryFromList ${mod} ${cmds}]
            }
        }
        2 {
            if {([string match ${cmd}* cget] || \
                [string match ${cmd}* configure])
            } {
                return [CompleteFromOptions ${text} ${start} ${line} ${widget}]
            }
        }
    }
    return ""
}

# SPECIFIC TK COMMAND COMPLETERS

proc complete(bell) {text start end line pos mod} {
    switch -- $pos {
        1 { return [CompleteFromList ${text} -displayof] }
        2 {
            if {"-displayof" == [PreviousWord ${start} ${line}]} {
                return [CompleteFromList ${text} [ToplevelWindows]]
            }
        }
    }
}

# proc complete(bind) {text start end line pos mod} {
#     TODO
#     return ""
# }

proc complete(image) {text start end line pos mod} {
    set sub [Lindex $line 1]
    switch -- $pos {
        1 { return [CompleteFromList ${text} [TrySubCmds image]] }
        2 {
            switch -- $sub {
                create { return [CompleteFromList ${text} [image types]] }
                delete -
                height -
                type -
                width { return [CompleteFromList ${text} [image names]] }
                names {}
                types {}
            }
        }
        3 {
            switch -- $sub {
                create {
                    set type [Lindex $line 2]
                    switch -- $type {
                        bitmap {
                            return [CompleteFromList ${text} {
                                ?name? -background -data -file
                                -foreground -maskdata -maskfile
                            }]
                        }
                        photo {
                            # TODO
                        }
                        default {}
                    }
                }
                default {}
            }
        }
        default {
            switch -- $sub {
                create {
                    set type [Lindex $line 2]
                    set prev [PreviousWord $start $line]
                    # puts stderr prev=$prev
                    switch -- $type {
                        bitmap {
                            switch -- $prev {
                                -background -
                                -foreground { return [DisplayHints <color>] }
                                -data -
                                -maskdata { return [DisplayHints <string>] }
                                -file -
                                -maskfile { return "" }
                                default {
                                    return [CompleteFromList ${text} \
                                    [RemoveUsedOptions ${line} {
                                        -background -data -file
                                        -foreground -maskdata -maskfile
                                    }]]
                                }
                            }
                        }
                        photo {
                            # TODO
                        }
                    }
                }
            }
        }
    }
}

proc complete(winfo) {text start end line pos mod} {
    set cmd [lindex ${line} 1]
    switch -- $pos {
        1 {
            set cmds [TrySubCmds winfo]
            if {[llength ${cmds}]} {
                return [TryFromList ${text} ${cmds}]
            }
        }
        2 {
            return [TryFromList ${text} [WidgetChildren ${text}]]
        }
    }
    return ""
}

}; # namespace tclreadline