tools/outputfile.py

#!/usr/bin/env python
# coding: utf-8
#
#    Copyright 2015 Teemu Piippo
#    All rights reserved.
#
#    Redistribution and use in source and binary forms, with or without
#    modification, are permitted provided that the following conditions
#    are met:
#
#    1. Redistributions of source code must retain the above copyright
#       notice, this list of conditions and the following disclaimer.
#    2. Redistributions in binary form must reproduce the above copyright
#       notice, this list of conditions and the following disclaimer in the
#       documentation and/or other materials provided with the distribution.
#    3. Neither the name of the copyright holder nor the names of its
#       contributors may be used to endorse or promote products derived from
#       this software without specific prior written permission.
#
#    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
#    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
#    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
#    PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER
#    OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
#    EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
#    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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#    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

class OutputFile:
    def __init__(self, filename, *, verbose = False):
        self.filename = filename
        self.verbose = verbose
        self.body = ''
        self.oldsum = ''
    def __enter__(self):
        try:
            with open(self.filename, "r") as file:
                self.oldsum = file.readline().strip().removeprefix('// ')
        except IOError:
            pass
        return self
    def write(self, text):
        self.body += text
    def __exit__(self, *args):
        from hashlib import sha256
        checksum = sha256(self.body.encode('utf-8')).hexdigest()
        if checksum == self.oldsum:
            if self.verbose:
                print(f'{self.filename} is up to date')
            pass
        else:
            with open(self.filename, "w") as file:
                file.write('// %s\n' % checksum)
                file.write('// This file has been automatically generated. Do not edit by hand\n')
                file.write('\n')
                file.write(self.body)
                if self.verbose:
                    print(f'{self.filename} written ({checksum})')