update from Atlas repo

iterables/fibo_by_hand.py

@@ -0,0 +1,51 @@
+"""
+Fibonacci generator implemented "by hand" without generator objects
+
+    >>> from itertools import islice
+    >>> list(islice(Fibonacci(), 15))
+    [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377]
+
+"""
+
+
+# BEGIN FIBO_BY_HAND
+class Fibonacci:
+
+    def __iter__(self):
+        return FibonacciGenerator()
+
+
+class FibonacciGenerator:
+
+    def __init__(self):
+        self.a = 0
+        self.b = 1
+
+    def __next__(self):
+        result = self.a
+        self.a, self.b = self.b, self.a + self.b
+        return result
+
+    def __iter__(self):
+        return self
+# END FIBO_BY_HAND
+
+# for comparison, this is the usual implementation of a Fibonacci
+# generator in Python:
+
+
+def fibonacci():
+    a, b = 0, 1
+    while True:
+        yield a
+        a, b = b, a + b
+
+
+if __name__ == '__main__':
+
+    for x, y in zip(Fibonacci(), fibonacci()):
+        assert x == y, '%s != %s' % (x, y)
+        print(x)
+        if x > 10**10:
+            break
+    print('etc...')

iterables/paragraph.py

@@ -0,0 +1,48 @@
+"""
+Paragraph: iterate over sentences and words with generator functions.
+The ``.words()`` generator shows the use of ``yield from``.
+
+::
+    >>> p = Paragraph("The cat. The mat. Is the cat on the mat?"
+    ...               " The cat is on the mat.")
+    >>> for s in p:
+    ...     print(s)
+    ...
+    Sentence('The cat.')
+    Sentence('The mat.')
+    Sentence('Is the cat on the mat?')
+    Sentence('The cat is on the mat.')
+    >>> list(p.words())  # doctest: +NORMALIZE_WHITESPACE
+    ['The', 'cat', 'The', 'mat', 'Is', 'the', 'cat', 'on',
+    'the', 'mat', 'The', 'cat', 'is', 'on', 'the', 'mat']
+
+
+.. Note:: sample text from `McGuffey's First Eclectic Reader`__
+
+__ http://www.gutenberg.org/cache/epub/14640/pg14640.txt
+"""
+
+import re
+import reprlib
+
+from sentence_gen import Sentence
+
+
+RE_SENTENCE = re.compile('([^.!?]+[.!?]+)')
+
+
+class Paragraph:
+
+    def __init__(self, text):
+        self.text = text
+
+    def __repr__(self):
+        return 'Paragraph(%s)' % reprlib.repr(self.text)
+
+    def __iter__(self):
+        for match in RE_SENTENCE.finditer(self.text):
+            yield Sentence(match.group().strip())
+
+    def words(self):
+        for sentence in self:
+            yield from sentence

iterables/yield_delegate_fail.py

@@ -0,0 +1,29 @@
+""" Example from `Python: The Full Monty`__ -- A Tested Semantics for the
+Python Programming Language
+
+__ http://cs.brown.edu/~sk/Publications/Papers/Published/pmmwplck-python-full-monty/
+
+"The following program, [...] seems to perform a simple abstraction over the
+process of yielding:"
+
+Citation:
+
+Joe Gibbs Politz, Alejandro Martinez, Matthew Milano, Sumner Warren,
+Daniel Patterson, Junsong Li, Anand Chitipothu, and Shriram Krishnamurthi.
+2013. Python: the full monty. SIGPLAN Not. 48, 10 (October 2013), 217-232.
+DOI=10.1145/2544173.2509536 http://doi.acm.org/10.1145/2544173.2509536
+"""
+
+# BEGIN YIELD_DELEGATE_FAIL
+def f():
+    def do_yield(n):
+        yield n
+    x = 0
+    while True:
+        x += 1
+        do_yield(x)
+# END YIELD_DELEGATE_FAIL
+
+if __name__ == '__main__':
+    print('Invoking f() results in an infinite loop')
+    f()

iterables/yield_delegate_fix.py

@@ -0,0 +1,24 @@
+""" Example adapted from ``yield_delegate_fail.py``
+
+The following program performs a simple abstraction over the process of
+yielding.
+
+"""
+
+# BEGIN YIELD_DELEGATE_FIX
+def f():
+    def do_yield(n):
+        yield n
+    x = 0
+    while True:
+        x += 1
+        yield from do_yield(x)
+# END YIELD_DELEGATE_FIX
+
+if __name__ == '__main__':
+    print('Invoking f() now produces a generator')
+    g = f()
+    print(next(g))
+    print(next(g))
+    print(next(g))
+

sequences/sentence.py

@@ -17,5 +17,8 @@ class Sentence:
     def __getitem__(self, index):
         return self.words[index]  # <2>
 
+    def __len__(self, index):  # <3>
+        return len(self.words)
+
     def __repr__(self):
-        return 'Sentence(%s)' % reprlib.repr(self.text)  # <3>
+        return 'Sentence(%s)' % reprlib.repr(self.text)  # <4>

sequences/sentence_slice.py

@@ -34,6 +34,9 @@ class SentenceSlice:
         else:
             return self.words[position]
 
+    def __len__(self, index):
+        return len(self.words)
+
     # helper functions -- implementation detail
     def _handle_defaults(self, position):
         """handle missing or overflow/underflow start/stop"""