final concurrency examples

Author: ramalho

futures/callbackhell.js

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+fetch1(request1, function (response1) {
+    // phase 1
+    var request2 = step1(response1);
+
+    fetch2(request2, function (response2) {
+        // phase 2
+        var request3 = step2(response2);
+
+        fetch3(request3, function (response3) {
+            // phase 3
+            step3(response3);
+        });
+    });
+});

futures/callbackhell.py

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+def phase1(response1):
+    request2 = step1(response1)
+    fetch2(request2, phase2)
+
+
+def phase2(response2):
+    request3 = step2(response2)
+    fetch3(request3, phase3)
+
+
+def phase3(response3):
+    step3(response3)
+
+
+fetch1(request1, phase1)

futures/charfinder/charfinder.py

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+#!/usr/bin/env python3
+
+"""
+Unicode character finder utility:
+find characters based on words in their official names.
+
+This can be used from the command line, just pass words as arguments.
+
+Here is the ``main`` function which makes it happen::
+
+    >>> main('rook')  # doctest: +NORMALIZE_WHITESPACE
+    U+2656  ♖  WHITE CHESS ROOK
+    U+265C  ♜  BLACK CHESS ROOK
+    (2 matches for 'rook')
+    >>> main('rook', 'black')  # doctest: +NORMALIZE_WHITESPACE
+    U+265C  ♜  BLACK CHESS ROOK
+    (1 match for 'rook black')
+    >>> main('white bishop')  # doctest: +NORMALIZE_WHITESPACE
+    U+2657  ♗   WHITE CHESS BISHOP
+    (1 match for 'white bishop')
+    >>> main("jabberwocky's vest")
+    (No match for "jabberwocky's vest")
+
+
+For exploring words that occur in the character names, there is the
+``word_report`` function::
+
+    >>> index = UnicodeNameIndex(sample_chars)
+    >>> index.word_report()
+        3 SIGN
+        2 A
+        2 EURO
+        2 LATIN
+        2 LETTER
+        1 CAPITAL
+        1 CURRENCY
+        1 DOLLAR
+        1 SMALL
+    >>> index = UnicodeNameIndex()
+    >>> index.word_report(10)
+    75821 CJK
+    75761 IDEOGRAPH
+    74656 UNIFIED
+    13196 SYLLABLE
+    11735 HANGUL
+     7616 LETTER
+     2232 WITH
+     2180 SIGN
+     2122 SMALL
+     1709 CAPITAL
+
+Note: characters with names starting with 'CJK UNIFIED IDEOGRAPH'
+are indexed with those three words only, excluding the hexadecimal
+codepoint at the end of the name.
+
+"""
+
+import sys
+import re
+import unicodedata
+import pickle
+import warnings
+import itertools
+import functools
+from collections import namedtuple
+
+RE_WORD = re.compile('\w+')
+RE_UNICODE_NAME = re.compile('^[A-Z0-9 -]+$')
+RE_CODEPOINT = re.compile('U\+([0-9A-F]{4,6})')
+
+INDEX_NAME = 'charfinder_index.pickle'
+MINIMUM_SAVE_LEN = 10000
+CJK_UNI_PREFIX = 'CJK UNIFIED IDEOGRAPH'
+CJK_CMP_PREFIX = 'CJK COMPATIBILITY IDEOGRAPH'
+
+sample_chars = [
+    '$',  # DOLLAR SIGN
+    'A',  # LATIN CAPITAL LETTER A
+    'a',  # LATIN SMALL LETTER A
+    '\u20a0',  # EURO-CURRENCY SIGN
+    '\u20ac',  # EURO SIGN
+]
+
+CharDescription = namedtuple('CharDescription', 'code_str char name')
+
+QueryResult = namedtuple('QueryResult', 'count items')
+
+
+def tokenize(text):
+    """return iterable of uppercased words"""
+    for match in RE_WORD.finditer(text):
+        yield match.group().upper()
+
+
+def query_type(text):
+    text_upper = text.upper()
+    if 'U+' in text_upper:
+        return 'CODEPOINT'
+    elif RE_UNICODE_NAME.match(text_upper):
+        return 'NAME'
+    else:
+        return 'CHARACTERS'
+
+
+class UnicodeNameIndex:
+
+    def __init__(self, chars=None):
+        self.load(chars)
+
+    def load(self, chars=None):
+        self.index = None
+        if chars is None:
+            try:
+                with open(INDEX_NAME, 'rb') as fp:
+                    self.index = pickle.load(fp)
+            except OSError:
+                pass
+        if self.index is None:
+            self.build_index(chars)
+        if len(self.index) > MINIMUM_SAVE_LEN:
+            try:
+                self.save()
+            except OSError as exc:
+                warnings.warn('Could not save {!r}: {}'
+                              .format(INDEX_NAME, exc))
+
+    def save(self):
+        with open(INDEX_NAME, 'wb') as fp:
+            pickle.dump(self.index, fp)
+
+    def build_index(self, chars=None):
+        if chars is None:
+            chars = (chr(i) for i in range(32, sys.maxunicode))
+        index = {}
+        for char in chars:
+            try:
+                name = unicodedata.name(char)
+            except ValueError:
+                continue
+            if name.startswith(CJK_UNI_PREFIX):
+                name = CJK_UNI_PREFIX
+            elif name.startswith(CJK_CMP_PREFIX):
+                name = CJK_CMP_PREFIX
+
+            for word in tokenize(name):
+                index.setdefault(word, set()).add(char)
+
+        self.index = index
+
+    def word_rank(self, top=None):
+        res = [(len(self.index[key]), key) for key in self.index]
+        res.sort(key=lambda item: (-item[0], item[1]))
+        if top is not None:
+            res = res[:top]
+        return res
+
+    def word_report(self, top=None):
+        for postings, key in self.word_rank(top):
+            print('{:5} {}'.format(postings, key))
+
+    def find_chars(self, query, start=0, stop=None):
+        stop = sys.maxsize if stop is None else stop
+        result_sets = []
+        for word in tokenize(query):
+            chars = self.index.get(word)
+            if chars is None:  # shorcut: no such word
+                result_sets = []
+                break
+            result_sets.append(chars)
+
+        if not result_sets:
+            return QueryResult(0, ())
+
+        result = functools.reduce(set.intersection, result_sets)
+        result = sorted(result)  # must sort to support start, stop
+        result_iter = itertools.islice(result, start, stop)
+        return QueryResult(len(result),
+                           (char for char in result_iter))
+
+    def describe(self, char):
+        code_str = 'U+{:04X}'.format(ord(char))
+        name = unicodedata.name(char)
+        return CharDescription(code_str, char, name)
+
+    def find_descriptions(self, query, start=0, stop=None):
+        for char in self.find_chars(query, start, stop).items:
+            yield self.describe(char)
+
+    def get_descriptions(self, chars):
+        for char in chars:
+            yield self.describe(char)
+
+    def describe_str(self, char):
+        return '{:7}\t{}\t{}'.format(*self.describe(char))
+
+    def find_description_strs(self, query, start=0, stop=None):
+        for char in self.find_chars(query, start, stop).items:
+            yield self.describe_str(char)
+
+    @staticmethod  # not an instance method due to concurrency
+    def status(query, counter):
+        if counter == 0:
+            msg = 'No match'
+        elif counter == 1:
+            msg = '1 match'
+        else:
+            msg = '{} matches'.format(counter)
+        return '{} for {!r}'.format(msg, query)
+
+
+def main(*args):
+    index = UnicodeNameIndex()
+    query = ' '.join(args)
+    n = 0
+    for n, line in enumerate(index.find_description_strs(query), 1):
+        print(line)
+    print('({})'.format(index.status(query, n)))
+
+if __name__ == '__main__':
+    if len(sys.argv) > 1:
+        main(*sys.argv[1:])
+    else:
+        print('Usage: {} word1 [word2]...'.format(sys.argv[0]))

futures/charfinder/http_charfinder.html

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+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <title>Charfinder</title>
+  </head>
+  <body>
+    Examples: {links}
+    <p>
+      <form action="/">
+        <input type="search" name="query" value="{query}">
+        <input type="submit" value="find"> {message}
+      </form>
+    </p>
+    <table>
+      {result}
+    </table>
+  </body>
+</html>

futures/charfinder/http_charfinder.py

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+#!/usr/bin/env python3
+
+import sys
+import asyncio
+from aiohttp import web
+
+from charfinder import UnicodeNameIndex
+
+TEMPLATE_NAME = 'http_charfinder.html'
+CONTENT_TYPE = 'text/html; charset=UTF-8'
+SAMPLE_WORDS = ('bismillah chess cat circled Malayalam digit'
+                ' Roman face Ethiopic black mark symbol dot'
+                ' operator Braille hexagram').split()
+
+ROW_TPL = '<tr><td>{code_str}</td><th>{char}</th><td>{name}</td></tr>'
+LINK_TPL = '<a href="/?query={0}" title="find &quot;{0}&quot;">{0}</a>'
+LINKS_HTML = ', '.join(LINK_TPL.format(word) for word in
+                       sorted(SAMPLE_WORDS, key=str.upper))
+
+
+index = UnicodeNameIndex()
+with open(TEMPLATE_NAME) as tpl:
+    template = tpl.read()
+template = template.replace('{links}', LINKS_HTML)
+
+# BEGIN HTTP_CHARFINDER_HOME
+def home(request):  # <1>
+    query = request.GET.get('query', '').strip()  # <2>
+    print('Query: {!r}'.format(query))  # <3>
+    if query:  # <4>
+        descriptions = list(index.find_descriptions(query))
+        res = '\n'.join(ROW_TPL.format(**vars(descr))
+                        for descr in descriptions)
+        msg = index.status(query, len(descriptions))
+    else:
+        descriptions = []
+        res = ''
+        msg = 'Enter words describing characters.'
+
+    text = template.format(query=query, result=res, message=msg)
+    print('Sending {} results'.format(len(descriptions)))
+    return web.Response(content_type=CONTENT_TYPE, text=text)
+# END HTTP_CHARFINDER_HOME
+
+
+# BEGIN HTTP_CHARFINDER_SETUP
+@asyncio.coroutine
+def init(loop, address, port):  # <1>
+    app = web.Application(loop=loop)  # <2>
+    app.router.add_route('GET', '/', home)  # <3>
+    handler = app.make_handler()  # <4>
+    server = yield from loop.create_server(handler,
+                                           address, port)  # <5>
+    return server.sockets[0].getsockname()  # <6>
+
+def main(address="127.0.0.1", port=8888):
+    port = int(port)
+    loop = asyncio.get_event_loop()
+    host = loop.run_until_complete(init(loop, address, port))  # <7>
+    print('Serving on {}. Hit CTRL-C to stop.'.format(host))
+    try:
+        loop.run_forever()  # <8>
+    except KeyboardInterrupt:  # CTRL+C pressed
+        pass
+    print('Server shutting down.')
+    loop.close()  # <9>
+
+
+if __name__ == '__main__':
+    main(*sys.argv[1:])
+# END HTTP_CHARFINDER_SETUP