############################################################################
#
#       File:     filenseq.icn
#
#       Subject:  Procedure to get highest numbered filename in a sequence
#
#       Author:   David A. Gamey
#
#       Date:     May 2, 2001
#
###########################################################################
#
#   This file is in the public domain.
#
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#
#  This procedure is useful when you need to create the next file 
#  in a series of files (such as successive log files).
#
#  Usage:
#
#  fn := nextseqfilename( ".", "$", "log")
#
#  returns the (non-existent) filename next in the sequence .\$*.log
#  (where the * represents 1, 2, 3, ...) or fails
#
#
############################################################################
#
#  Requires:  MS-DOS or another congenial operating system
#
############################################################################
#
#  Links:  io
#
############################################################################

link io

procedure nextseqfilename(dir,pre,ext)

local s,f,n,wn

static wf
initial wf := 8                   # filename width

dir ||:= ( dir[-1] ~== "\\" ) 

s := set( dosdirlist( dir, pre || "*." || ext || " /a:-d" ) )

n := integer( repl( '9', wn := wf - *pre ) )

every f := map( dir || pre || right( 1 to n, wn,"0") || "." || ext )  do 
	if not member(s,f) then return f
	
end