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from os import getenv
from markdown.extensions import Extension
from markdown.inlinepatterns import Pattern
VARIABLE_RE = r'(\$\{)([a-zA-Z_]*)(\})'
class VariablePattern(Pattern):
# need to redefine as an extra attribute needs to be passed
def __init__(self, pattern, variables, enable_env, md=None):
self.variables = variables
self.enable_env = enable_env
super().__init__(pattern, md)
def handleMatch(self, m):
# for some reason the group is offest by 1
variable = m.group(3)
value = ''
if variable in self.variables:
value = self.variables[variable]
else:
if self.enable_env:
value = getenv(variable, '')
return value
class VariableExtension(Extension):
def __init__(self, **kwargs):
self.config = {
'enable_env': [False, 'Enable environment variables parsing.'],
'variables': [dict(), 'Dictionary holding variables to be used.']
}
super().__init__(**kwargs)
def extendMarkdown(self, md):
variables = self.getConfig('variables', dict())
enable_env = self.getConfig('enable_env', False)
variable_pattern = VariablePattern(VARIABLE_RE, variables, enable_env)
md.inlinePatterns.register(variable_pattern, 'variable', 175)
def makeExtension(*args, **kwargs):
return VariableExtension(*args, **kwargs)
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