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Edit File: inplace.awk

# inplace --- load and invoke the inplace extension.
# 
# Copyright (C) 2013, 2017, 2019 the Free Software Foundation, Inc.
# 
# This file is part of GAWK, the GNU implementation of the
# AWK Programming Language.
# 
# GAWK 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 3 of the License, or
# (at your option) any later version.
# 
# GAWK 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
#
# Andrew J. Schorr, aschorr@telemetry-investments.com
# January 2013
#
# Revised for namespaces
# Arnold Robbins, arnold@skeeve.com
# July 2017
# June 2019, add backwards compatibility

@load "inplace"

# Please set inplace::suffix to make a backup copy.  For example, you may
# want to set inplace::suffix to .bak on the command line or in a BEGIN rule.

# Before there were namespaces in gawk, this extension used
# INPLACE_SUFFIX as the variable for making backup copies. We allow this
# too, so that any code that used the previous version continues to work.

# By default, each filename on the command line will be edited inplace.
# But you can selectively disable this by adding an inplace::enable=0 argument
# prior to files that you do not want to process this way.  You can then
# reenable it later on the commandline by putting inplace::enable=1 before files
# that you wish to be subject to inplace editing.

# N.B. We call inplace::end() in the BEGINFILE and END rules so that any
# actions in an ENDFILE rule will be redirected as expected.

@namespace "inplace"

BEGIN {
    enable = 1         # enabled by default
}

BEGINFILE {
    sfx = (suffix ? suffix : awk::INPLACE_SUFFIX)
    if (filename != "")
        end(filename, sfx)
    if (enable)
        begin(filename = FILENAME, sfx)
    else
        filename = ""
}

END {
    if (filename != "")
        end(filename, (suffix ? suffix : awk::INPLACE_SUFFIX))
}