# coding: utf-8
# 2019/9/20 @ tongshiwei
r"""
To replace the variable str which is in the pattern r"(\$[A-z_]*)\b" （i.e., `$xxx`)
"""
__all__ = ["variable_replace", "default_variable_replace"]
import re
VARIABLE_REGEX = r"(\$[A-z_]*)"
VARIABLE = re.compile(VARIABLE_REGEX)
[文档]def variable_replace(string: str, key_lower: bool = True, quotation: str = "", **variables):
r"""
Examples
--------
>>> string = "hello $who"
>>> variable_replace(string, who="world")
'hello world'
>>> string = "hello $WHO"
>>> variable_replace(string, key_lower=False, WHO="world")
'hello world'
>>> string = "hello $WHO"
>>> variable_replace(string, who="longling")
'hello longling'
>>> string = "hello $Wh_o"
>>> variable_replace(string, wh_o="longling")
'hello longling'
"""
def replace(match):
variable = string[match.start() + 1:match.end()]
variable = variable.lower() if key_lower else variable
variable = variables[variable]
return quotation + variable + quotation
return VARIABLE.sub(replace, string)
[文档]def default_variable_replace(string: str, default_value: (str, None, dict) = None, key_lower: bool = True,
quotation: str = "",
**variables) -> str:
"""
Examples
--------
>>> string = "hello $who, I am $author"
>>> default_variable_replace(string, default_value={"author": "groot"}, who="world")
'hello world, I am groot'
>>> string = "hello $who, I am $author"
>>> default_variable_replace(string, default_value={"author": "groot"})
'hello , I am groot'
>>> string = "hello $who, I am $author"
>>> default_variable_replace(string, default_value='', who="world")
'hello world, I am '
>>> string = "hello $who, I am $author"
>>> default_variable_replace(string, default_value=None, who="world")
'hello world, I am $author'
"""
if default_value is None or isinstance(default_value, str):
return _default_variable_replace(string, default_value, key_lower, quotation, **variables)
elif isinstance(default_value, dict):
return _dict_variable_replace(string, default_value, key_lower, quotation, **variables)
else:
raise TypeError("cannot handle the type %s for default_value" % type(default_value))
def _dict_variable_replace(string: str, default_value: dict, key_lower: bool = True, quotation: str = "",
**variables) -> str:
def replace(match):
variable = string[match.start() + 1:match.end()]
variable = variable.lower() if key_lower else variable
if variable not in variables:
return default_value.get(variable, "")
return quotation + str(variables[variable]) + quotation
return VARIABLE.sub(replace, string)
def _default_variable_replace(string: str, default_value: (str, None) = "", key_lower: bool = True, quotation: str = "",
**variables) -> str:
def replace(match):
variable = string[match.start() + 1:match.end()]
variable = variable.lower() if key_lower else variable
if variable not in variables:
if default_value is not None:
return default_value
else:
variable = string[match.start():match.end()]
variable = variable.lower() if key_lower else variable
return variable
return quotation + str(variables[variable]) + quotation
return VARIABLE.sub(replace, string)