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# history.tcl --
#
# Implementation of the history command.
#
# Copyright (c) 1997 Sun Microsystems, Inc.
#
# See the file "license.terms" for information on usage and redistribution of
# this file, and for a DISCLAIMER OF ALL WARRANTIES.
#
# The tcl::history array holds the history list and some additional
# bookkeeping variables.
#
# nextid the index used for the next history list item.
# keep the max size of the history list
# oldest the index of the oldest item in the history.
namespace eval ::tcl {
variable history
if {![info exists history]} {
array set history {
nextid 0
keep 20
oldest -20
}
}
namespace ensemble create -command ::tcl::history -map {
add ::tcl::HistAdd
change ::tcl::HistChange
clear ::tcl::HistClear
event ::tcl::HistEvent
info ::tcl::HistInfo
keep ::tcl::HistKeep
nextid ::tcl::HistNextID
redo ::tcl::HistRedo
}
}
# history --
#
# This is the main history command. See the man page for its interface.
# This does some argument checking and calls the helper ensemble in the
# tcl namespace.
proc ::history {args} {
# If no command given, we're doing 'history info'. Can't be done with an
# ensemble unknown handler, as those don't fire when no subcommand is
# given at all.
if {![llength $args]} {
set args info
}
# Tricky stuff needed to make stack and errors come out right!
tailcall apply {arglist {tailcall history {*}$arglist} ::tcl} $args
}
# (unnamed) --
#
# Callback when [::history] is destroyed. Destroys the implementation.
#
# Parameters:
# oldName what the command was called.
# newName what the command is now called (an empty string).
# op the operation (= delete).
#
# Results:
# none
#
# Side Effects:
# The implementation of the [::history] command ceases to exist.
trace add command ::history delete [list apply {{oldName newName op} {
variable history
unset -nocomplain history
foreach c [info procs ::tcl::Hist*] {
rename $c {}
}
rename ::tcl::history {}
} ::tcl}]
# tcl::HistAdd --
#
# Add an item to the history, and optionally eval it at the global scope
#
# Parameters:
# event the command to add
# exec (optional) a substring of "exec" causes the command to
# be evaled.
# Results:
# If executing, then the results of the command are returned
#
# Side Effects:
# Adds to the history list
proc ::tcl::HistAdd {event {exec {}}} {
variable history
if {
[prefix longest {exec {}} $exec] eq ""
&& [llength [info level 0]] == 3
} then {
return -code error "bad argument \"$exec\": should be \"exec\""
}
# Do not add empty commands to the history
if {[string trim $event] eq ""} {
return ""
}
# Maintain the history
set history([incr history(nextid)]) $event
unset -nocomplain history([incr history(oldest)])
# Only execute if 'exec' (or non-empty prefix of it) given
if {$exec eq ""} {
return ""
}
tailcall eval $event
}
# tcl::HistKeep --
#
# Set or query the limit on the length of the history list
#
# Parameters:
# limit (optional) the length of the history list
#
# Results:
# If no limit is specified, the current limit is returned
#
# Side Effects:
# Updates history(keep) if a limit is specified
proc ::tcl::HistKeep {{count {}}} {
variable history
if {[llength [info level 0]] == 1} {
return $history(keep)
}
if {![string is integer -strict $count] || ($count < 0)} {
return -code error "illegal keep count \"$count\""
}
set oldold $history(oldest)
set history(oldest) [expr {$history(nextid) - $count}]
for {} {$oldold <= $history(oldest)} {incr oldold} {
unset -nocomplain history($oldold)
}
set history(keep) $count
}
# tcl::HistClear --
#
# Erase the history list
#
# Parameters:
# none
#
# Results:
# none
#
# Side Effects:
# Resets the history array, except for the keep limit
proc ::tcl::HistClear {} {
variable history
set keep $history(keep)
unset history
array set history [list \
nextid 0 \
keep $keep \
oldest -$keep \
]
}
# tcl::HistInfo --
#
# Return a pretty-printed version of the history list
#
# Parameters:
# num (optional) the length of the history list to return
#
# Results:
# A formatted history list
proc ::tcl::HistInfo {{count {}}} {
variable history
if {[llength [info level 0]] == 1} {
set count [expr {$history(keep) + 1}]
} elseif {![string is integer -strict $count]} {
return -code error "bad integer \"$count\""
}
set result {}
set newline ""
for {set i [expr {$history(nextid) - $count + 1}]} \
{$i <= $history(nextid)} {incr i} {
if {![info exists history($i)]} {
continue
}
set cmd [string map [list \n \n\t] [string trimright $history($i) \ \n]]
append result $newline[format "%6d %s" $i $cmd]
set newline \n
}
return $result
}
# tcl::HistRedo --
#
# Fetch the previous or specified event, execute it, and then replace
# the current history item with that event.
#
# Parameters:
# event (optional) index of history item to redo. Defaults to -1,
# which means the previous event.
#
# Results:
# Those of the command being redone.
#
# Side Effects:
# Replaces the current history list item with the one being redone.
proc ::tcl::HistRedo {{event -1}} {
variable history
set i [HistIndex $event]
if {$i == $history(nextid)} {
return -code error "cannot redo the current event"
}
set cmd $history($i)
HistChange $cmd 0
tailcall eval $cmd
}
# tcl::HistIndex --
#
# Map from an event specifier to an index in the history list.
#
# Parameters:
# event index of history item to redo.
# If this is a positive number, it is used directly.
# If it is a negative number, then it counts back to a previous
# event, where -1 is the most recent event.
# A string can be matched, either by being the prefix of a
# command or by matching a command with string match.
#
# Results:
# The index into history, or an error if the index didn't match.
proc ::tcl::HistIndex {event} {
variable history
if {![string is integer -strict $event]} {
for {set i [expr {$history(nextid)-1}]} {[info exists history($i)]} \
{incr i -1} {
if {[string match $event* $history($i)]} {
return $i
}
if {[string match $event $history($i)]} {
return $i
}
}
return -code error "no event matches \"$event\""
} elseif {$event <= 0} {
set i [expr {$history(nextid) + $event}]
} else {
set i $event
}
if {$i <= $history(oldest)} {
return -code error "event \"$event\" is too far in the past"
}
if {$i > $history(nextid)} {
return -code error "event \"$event\" hasn't occured yet"
}
return $i
}
# tcl::HistEvent --
#
# Map from an event specifier to the value in the history list.
#
# Parameters:
# event index of history item to redo. See index for a description of
# possible event patterns.
#
# Results:
# The value from the history list.
proc ::tcl::HistEvent {{event -1}} {
variable history
set i [HistIndex $event]
if {![info exists history($i)]} {
return ""
}
return [string trimright $history($i) \ \n]
}
# tcl::HistChange --
#
# Replace a value in the history list.
#
# Parameters:
# newValue The new value to put into the history list.
# event (optional) index of history item to redo. See index for a
# description of possible event patterns. This defaults to 0,
# which specifies the current event.
#
# Side Effects:
# Changes the history list.
proc ::tcl::HistChange {newValue {event 0}} {
variable history
set i [HistIndex $event]
set history($i) $newValue
}
# tcl::HistNextID --
#
# Returns the number of the next history event.
#
# Parameters:
# None.
#
# Side Effects:
# None.
proc ::tcl::HistNextID {} {
variable history
return [expr {$history(nextid) + 1}]
}
return
# Local Variables:
# mode: tcl
# fill-column: 78
# End:
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