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