The Python Standard Library > 6. Text Processing Services > re
https://docs.python.org/3.4/library/re.html
Regular expressions HOWTO:
https://docs.python.org/3.4/howto/regex.html
For … science underlying regular expressions (deterministic and non-deterministic finite automata), you can refer to almost any textbook on writing compilers.
Metacharacters are not active inside classes: … '$' is usually a metacharacter, but inside a character class it’s stripped of its special nature.
Perhaps the most important metacharacter is the backslash, \.
Some of the special sequences beginning with '\' represent predefined sets of characters
* doesn’t match the literal character *; instead, it specifies that the previous character can be matched zero or more times, instead of exactly once.
Pay careful attention to the difference between * and +;
match() versus search()
========================================
Regular expressions
http://www.pythonlearn.com/html-008/cfbook012.html
Python Regular Expressions
2012
https://developers.google.com/edu/python/regular-expressions
Christopher Potts emoticons
https://class.coursera.org/nlp/lecture/145
Python: Regular expressions
University of Cambridge
http://www.ucs.cam.ac.uk/docs/course-notes/unix-courses/archived/archived-python-courses/PythonRE/files/PythonRE.pdf
regular123