48 lines
1.7 KiB
Python
48 lines
1.7 KiB
Python
def coerce_scalar(value):
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'''
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Given a configuration value, coerce it to an integer or a boolean as appropriate and return the
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result.
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'''
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try:
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return int(value)
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except (TypeError, ValueError):
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pass
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if value == 'true' or value == 'True':
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return True
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if value == 'false' or value == 'False':
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return False
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return value
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def apply_constants(value, constants):
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'''
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Given a configuration value (bool, dict, int, list, or string) and a dict of named constants,
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replace any configuration string values of the form "{constant}" (or containing it) with the
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value of the correspondingly named key from the constants. Recurse as necessary into nested
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configuration to find values to replace.
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For instance, if a configuration value contains "{foo}", replace it with the value of the "foo"
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key found within the configuration's "constants".
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Return the configuration value and modify the original.
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'''
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if not value or not constants:
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return value
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if isinstance(value, str):
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for constant_name, constant_value in constants.items():
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value = value.replace('{' + constant_name + '}', str(constant_value))
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# Support constants within non-string scalars by coercing the value to its appropriate type.
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value = coerce_scalar(value)
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elif isinstance(value, list):
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for index, list_value in enumerate(value):
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value[index] = apply_constants(list_value, constants)
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elif isinstance(value, dict):
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for option_name, option_value in value.items():
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value[option_name] = apply_constants(option_value, constants)
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return value
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