123 lines
3.8 KiB
Python
123 lines
3.8 KiB
Python
"""
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Functions for working with "safe strings": strings that can be displayed safely
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without further escaping in HTML. Marking something as a "safe string" means
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that the producer of the string has already turned characters that should not
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be interpreted by the HTML engine (e.g. '<') into the appropriate entities.
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"""
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from django.utils.functional import curry, Promise
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class EscapeData(object):
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pass
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class EscapeString(str, EscapeData):
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"""
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A string that should be HTML-escaped when output.
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"""
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pass
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class EscapeUnicode(unicode, EscapeData):
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"""
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A unicode object that should be HTML-escaped when output.
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"""
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pass
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class SafeData(object):
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pass
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class SafeString(str, SafeData):
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"""
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A string subclass that has been specifically marked as "safe" (requires no
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further escaping) for HTML output purposes.
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"""
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def __add__(self, rhs):
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"""
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Concatenating a safe string with another safe string or safe unicode
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object is safe. Otherwise, the result is no longer safe.
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"""
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if isinstance(rhs, SafeUnicode):
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return SafeUnicode(self + rhs)
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elif isinstance(rhs, SafeString):
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return SafeString(self + rhs)
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else:
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return super(SafeString, self).__add__(rhs)
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def __str__(self):
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return self
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def _proxy_method(self, *args, **kwargs):
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"""
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Wrap a call to a normal unicode method up so that we return safe
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results. The method that is being wrapped is passed in the 'method'
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argument.
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"""
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method = kwargs.pop('method')
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data = method(self, *args, **kwargs)
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if isinstance(data, str):
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return SafeString(data)
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else:
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return SafeUnicode(data)
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decode = curry(_proxy_method, method = str.decode)
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class SafeUnicode(unicode, SafeData):
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"""
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A unicode subclass that has been specifically marked as "safe" for HTML
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output purposes.
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"""
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def __add__(self, rhs):
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"""
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Concatenating a safe unicode object with another safe string or safe
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unicode object is safe. Otherwise, the result is no longer safe.
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"""
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if isinstance(rhs, SafeData):
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return SafeUnicode(self + rhs)
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else:
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return super(SafeUnicode, self).__add__(rhs)
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def _proxy_method(self, *args, **kwargs):
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"""
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Wrap a call to a normal unicode method up so that we return safe
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results. The method that is being wrapped is passed in the 'method'
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argument.
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"""
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method = kwargs.pop('method')
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data = method(self, *args, **kwargs)
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if isinstance(data, str):
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return SafeString(data)
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else:
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return SafeUnicode(data)
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encode = curry(_proxy_method, method = unicode.encode)
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def mark_safe(s):
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"""
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Explicitly mark a string as safe for (HTML) output purposes. The returned
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object can be used everywhere a string or unicode object is appropriate.
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Can be called multiple times on a single string.
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"""
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if isinstance(s, SafeData):
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return s
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if isinstance(s, str) or (isinstance(s, Promise) and s._delegate_str):
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return SafeString(s)
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if isinstance(s, (unicode, Promise)):
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return SafeUnicode(s)
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return SafeString(str(s))
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def mark_for_escaping(s):
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"""
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Explicitly mark a string as requiring HTML escaping upon output. Has no
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effect on SafeData subclasses.
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Can be called multiple times on a single string (the resulting escaping is
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only applied once).
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"""
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if isinstance(s, (SafeData, EscapeData)):
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return s
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if isinstance(s, str) or (isinstance(s, Promise) and s._delegate_str):
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return EscapeString(s)
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if isinstance(s, (unicode, Promise)):
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return EscapeUnicode(s)
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return EscapeString(str(s))
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