66 lines
1.5 KiB
Python
66 lines
1.5 KiB
Python
"""
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Sentence: iterate over words using the Iterator Pattern, take #1
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WARNING: the Iterator Pattern is much simpler in idiomatic Python;
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see: sentence_gen*.py.
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"""
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# tag::SENTENCE_ITER[]
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import re
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import reprlib
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RE_WORD = re.compile(r'\w+')
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class Sentence:
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def __init__(self, text):
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self.text = text
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self.words = RE_WORD.findall(text)
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def __repr__(self):
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return f'Sentence({reprlib.repr(self.text)})'
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def __iter__(self): # <1>
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return SentenceIterator(self.words) # <2>
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class SentenceIterator:
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def __init__(self, words):
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self.words = words # <3>
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self.index = 0 # <4>
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def __next__(self):
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try:
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word = self.words[self.index] # <5>
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except IndexError:
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raise StopIteration() # <6>
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self.index += 1 # <7>
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return word # <8>
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def __iter__(self): # <9>
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return self
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# end::SENTENCE_ITER[]
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def main():
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import sys
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import warnings
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try:
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filename = sys.argv[1]
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word_number = int(sys.argv[2])
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except (IndexError, ValueError):
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print(f'Usage: {sys.argv[0]} <file-name> <word-number>')
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sys.exit(2) # command line usage error
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with open(filename, 'rt', encoding='utf-8') as text_file:
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s = Sentence(text_file.read())
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for n, word in enumerate(s, 1):
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if n == word_number:
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print(word)
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break
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else:
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warnings.warn(f'last word is #{n}, {word!r}')
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if __name__ == '__main__':
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main()
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