98 lines
2.2 KiB
Python
98 lines
2.2 KiB
Python
"""
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Helper functions.
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"""
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from __future__ import absolute_import
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from __future__ import print_function
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import contextlib
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import os.path
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import sys
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import yaml
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@contextlib.contextmanager
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def open_or_use_stdout(filename):
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"""
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Opens the specified file for writing, or returns sys.stdout if filename is "-".
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"""
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if filename == "-":
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yield sys.stdout
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return
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line_buffered = 1
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try:
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fp = open(filename, "w", line_buffered)
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except IOError:
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print("Could not open file {}".format(filename), file=sys.stderr)
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sys.exit(1)
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try:
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yield fp
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finally:
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fp.close()
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def default_if_none(value, default):
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return value if value is not None else default
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def is_string_list(lst):
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"""
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Returns true if 'lst' is a list of strings, and false otherwise.
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"""
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return isinstance(lst, list) and all(isinstance(x, basestring) for x in lst)
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def is_string_set(value):
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"""
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Returns true if 'value' is a set of strings, and false otherwise.
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"""
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return isinstance(value, set) and all(isinstance(x, basestring) for x in value)
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def is_js_file(filename):
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"""
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Returns true if 'filename' ends in .js, and false otherwise.
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"""
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return os.path.splitext(filename)[1] == ".js"
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def is_yaml_file(filename):
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"""
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Returns true if 'filename' ends in .yml or .yaml, and false
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otherwise.
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"""
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return os.path.splitext(filename)[1] in (".yaml", ".yml")
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def load_yaml_file(filename):
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"""
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Attempts to read 'filename' as YAML.
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"""
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try:
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with open(filename, "r") as fp:
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return yaml.safe_load(fp)
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except yaml.YAMLError as err:
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raise ValueError("File '%s' contained invalid YAML: %s" % (filename, err))
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def dump_yaml(value):
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"""
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Returns 'value' formatted as YAML.
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"""
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# Use block (indented) style for formatting YAML.
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return yaml.safe_dump(value, default_flow_style=False).rstrip()
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def load_yaml(value):
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"""
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Attempts to parse 'value' as YAML.
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"""
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try:
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return yaml.safe_load(value)
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except yaml.YAMLError as err:
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raise ValueError("Attempted to parse invalid YAML value '%s': %s" % (value, err))
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