Add more notes on regular expressions

Author: gerhynes

.gitignore

@@ -1,2 +1,138 @@
-*/.venv/*
-*/__pycache__
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+.pytest_cache/
+cover/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+.pybuilder/
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+#   For a library or package, you might want to ignore these files since the code is
+#   intended to run in multiple environments; otherwise, check them in:
+# .python-version
+
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don't work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow
+__pypackages__/
+
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# pytype static type analyzer
+.pytype/
+
+# Cython debug symbols
+cython_debug/

README.md

@@ -2861,3 +2861,36 @@ Potential use cases include:
 - advanced find/replace in text
 - formatting text/output
 - syntax highlighting
+
+| Character | Matches                           |
+| --------- | --------------------------------- |
+| \d        | digit 0-9                         |
+| \w        | letter, digit or underscore       |
+| \s        | whitespace character              |
+| \D        | not a digit                       |
+| \W        | not a letter, digit or underscore |
+| \S        | not a whitespace character        |
+| .         | any character except line break   |
+
+| Quantifier | Matches                        |
+| ---------- | ------------------------------ |
+| +          | one or more                    |
+| {3}        | exactly x times. {3} - 3 times |
+| {3,5}      | Three to five times            |
+| {4,}       | Four or more times             |
+| \*         | zero or more times             |
+| ?          | once or none (optional         |
+
+You can create a group of acceptable values using `[]`, for example `[a-zA-Z0-9]`.
+
+Inside `[]` `^` means not, rather than starts with. So `[^@$]` means any character that is not @ or $.
+
+| Character | Sets boundary           |
+| --------- | ----------------------- |
+| ^         | start of string or line |
+| $         | end of string or line   |
+| \b        | word boundary           |
+
+`|` works as logical or. For example `\(\d{3}\)|\d{3}` matches three digits with or without parens.
+
+`()` groups characters. `(\(\d{3}\)|\d{3}) \d{3} \d{4}`