uuid: Provide UUID class and uuid4() implementation using os.urandom().

Includes unit test.

uuid/metadata.txt

@@ -1,3 +1,6 @@
-srctype=dummy
-type=module
-version = 0.0.1
+srctype = micropython-lib
+type = module
+version = 0.1
+author = Andrew Leech
+author_email = andrew@alelec.net
+depends = os

uuid/setup.py

@@ -7,14 +7,15 @@
 import sdist_upip
 
 setup(name='micropython-uuid',
-      version='0.0.1',
-      description='Dummy uuid module for MicroPython',
-      long_description='This is a dummy implementation of a module for MicroPython standard library.\nIt contains zero or very little functionality, and primarily intended to\navoid import errors (using idea that even if an application imports a\nmodule, it may be not using it onevery code path, so may work at least\npartially). It is expected that more complete implementation of the module\nwill be provided later. Please help with the development if you are\ninterested in this module.',
+      version='0.1',
+      description='uuid 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/pfalcon/micropython-lib',
-      author='Paul Sokolovsky',
-      author_email='micropython-lib@googlegroups.com',
+      author='Andrew Leech',
+      author_email='andrew@alelec.net',
       maintainer='Paul Sokolovsky',
       maintainer_email='micropython-lib@googlegroups.com',
       license='MIT',
       cmdclass={'sdist': sdist_upip.sdist},
-      py_modules=['uuid'])
+      py_modules=['uuid'],
+      install_requires=['micropython-os'])

uuid/test_uuid.py

@@ -0,0 +1,15 @@
+import uuid
+
+u1 = uuid.uuid4()
+u2 = uuid.uuid4()
+
+assert str(u1) != str(u2), "Two uuid4 should not match"
+
+assert len(str(u1)) == len(str(u1)) == 36
+
+assert str(repr(u1)).startswith("<UUID")
+assert str(repr(u1)).endswith(">")
+
+assert len(u1.hex) == 32
+
+print("OK")

uuid/uuid.py

@@ -0,0 +1,28 @@
+import os
+import ubinascii
+
+
+class UUID:
+    def __init__(self, bytes):
+        if len(bytes) != 16:
+            raise ValueError('bytes arg must be 16 bytes long')
+        self._bytes = bytes
+
+    @property
+    def hex(self):
+        return ubinascii.hexlify(self._bytes).decode()
+
+    def __str__(self):
+        h = self.hex
+        return '-'.join((h[0:8], h[8:12], h[12:16], h[16:20], h[20:32]))
+
+    def __repr__(self):
+        return "<UUID: %s>" % str(self)
+
+
+def uuid4():
+    """Generates a random UUID compliant to RFC 4122 pg.14"""
+    random = bytearray(os.urandom(16))
+    random[6] = (random[6] & 0x0F) | 0x40
+    random[8] = (random[8] & 0x3F) | 0x80
+    return UUID(bytes=random)