67 lines
2.0 KiB
Python
67 lines
2.0 KiB
Python
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"""
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Defines utilities useful for performing standard "configuration" style tasks.
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"""
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import re
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import os
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def configure_file(input_path, output_path, substitutions):
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"""configure_file(input_path, output_path, substitutions) -> bool
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Given an input and output path, "configure" the file at the given input path
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by replacing variables in the file with those given in the substitutions
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list. Returns true if the output file was written.
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The substitutions list should be given as a list of tuples (regex string,
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replacement), where the regex and replacement will be used as in 're.sub' to
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execute the variable replacement.
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The output path's parent directory need not exist (it will be created).
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If the output path does exist and the configured data is not different than
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it's current contents, the output file will not be modified. This is
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designed to limit the impact of configured files on build dependencies.
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"""
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# Read in the input data.
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f = open(input_path, "rb")
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try:
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data = f.read()
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finally:
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f.close()
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# Perform the substitutions.
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for regex_string,replacement in substitutions:
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regex = re.compile(regex_string)
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data = regex.sub(replacement, data)
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# Ensure the output parent directory exists.
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output_parent_path = os.path.dirname(os.path.abspath(output_path))
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if not os.path.exists(output_parent_path):
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os.makedirs(output_parent_path)
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# If the output path exists, load it and compare to the configured contents.
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if os.path.exists(output_path):
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current_data = None
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try:
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f = open(output_path, "rb")
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try:
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current_data = f.read()
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except:
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current_data = None
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f.close()
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except:
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current_data = None
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if current_data is not None and current_data == data:
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return False
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# Write the output contents.
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f = open(output_path, "wb")
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try:
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f.write(data)
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finally:
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f.close()
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return True
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