[3.7] bpo-28450: Fix and improve the documentation for unknown escape… · python/cpython@95fc8e6 (original) (raw)

`@@ -570,7 +570,8 @@ accepted by the regular expression parser::

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`only inside character classes.)

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``` '\u' and '\U' escape sequences are only recognized in Unicode

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patterns. In bytes patterns they are errors.

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patterns. In bytes patterns they are errors. Unknown escapes of ASCII

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letters are reserved for future use and treated as errors.

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`Octal escapes are included in a limited form. If the first digit is a 0, or if

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`there are three octal digits, it is considered an octal escape. Otherwise, it is

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`@@ -844,7 +845,9 @@ form.

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` *string* is returned unchanged. *repl* can be a string or a function; if it is

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```  a string, any backslash escapes in it are processed. That is, ``\n`` is

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``` converted to a single newline character, \r is converted to a carriage return, and

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so forth. Unknown escapes such as ``\&`` are left alone. Backreferences, such

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so forth. Unknown escapes of ASCII letters are reserved for future use and

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 treated as errors. Other unknown escapes such as ``\&`` are left alone.

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Backreferences, such

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``` as \6, are replaced with the substring matched by group 6 in the pattern.

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` For example::

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``