string: Add basic constant definitions.

string/metadata.txt

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+srctype=micropython-lib
+type=module
+version=0.0.1

string/setup.py

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+import sys
+# Remove current dir from sys.path, otherwise setuptools will peek up our
+# module instead of system.
+sys.path.pop(0)
+from setuptools import setup
+
+
+setup(name='micropython-string',
+      version='0.0.1',
+      description='string module for MicroPython',
+      long_description="This is a module reimplemented specifically for MicroPython standard library,\nwith efficient and lean design in mind. Note that this module is likely work\nin progress and likely supports just a subset of CPython's corresponding\nmodule. Please help with the development if you are interested in this\nmodule.",
+      url='https://github.com/micropython/micropython/issues/405',
+      author='MicroPython Developers',
+      author_email='micro-python@googlegroups.com',
+      maintainer='MicroPython Developers',
+      maintainer_email='micro-python@googlegroups.com',
+      license='MIT',
+      py_modules=['string'])

string/string.py

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+# Some strings for ctype-style character classification
+whitespace = ' \t\n\r\v\f'
+ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
+ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+ascii_letters = ascii_lowercase + ascii_uppercase
+digits = '0123456789'
+hexdigits = digits + 'abcdef' + 'ABCDEF'
+octdigits = '01234567'
+punctuation = """!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~"""
+printable = digits + ascii_letters + punctuation + whitespace