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#!/usr/local/bin/tclsh
# demonstration application, encodes the incoming byte stream to base64
package require Trf
# line buffer for parcel below.
set line ""
proc parcel {max cmd buffer} {
# this transformation takes the incoming byte stream and parcels it into
# lines of at most $max characters each. The last line is possibly shorter.
# only the write part is implemented.
#
# hm, this could be generalized into a transformation parceling the input
# into packets and adding some sort of frame around these.
#puts stderr "$max $cmd [string length $buffer]"
global line
switch -- $cmd {
create/write {
set line ""
}
delete/write {
set line ""
}
write {
append line $buffer
set res ""
while {[string length $line] > $max} {
append res "[string range $line 0 [expr {$max-1}]]\n"
set line [string range $line $max end]
}
return $res
}
flush/write {
if {[string length $line] > 0} {
set res "$line\n"
set line ""
return $res
} else {
return {}
}
}
clear/write {
set line ""
}
}
}
transform -attach stdout -command {parcel 72}
base64 -attach stdout -mode encode
fconfigure stdin -translation binary
fcopy stdin stdout
close stdout
# close is *required* to flush out the internal buffers.
# This is not done during a simple exit :-(
exit
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