python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Tools/demo/markov.py

@@ -0,0 +1,125 @@
+#!/usr/bin/env python3
+
+"""
+Markov chain simulation of words or characters.
+"""
+
+class Markov:
+    def __init__(self, histsize, choice):
+        self.histsize = histsize
+        self.choice = choice
+        self.trans = {}
+
+    def add(self, state, next):
+        self.trans.setdefault(state, []).append(next)
+
+    def put(self, seq):
+        n = self.histsize
+        add = self.add
+        add(None, seq[:0])
+        for i in range(len(seq)):
+            add(seq[max(0, i-n):i], seq[i:i+1])
+        add(seq[len(seq)-n:], None)
+
+    def get(self):
+        choice = self.choice
+        trans = self.trans
+        n = self.histsize
+        seq = choice(trans[None])
+        while True:
+            subseq = seq[max(0, len(seq)-n):]
+            options = trans[subseq]
+            next = choice(options)
+            if not next:
+                break
+            seq += next
+        return seq
+
+
+def test():
+    import sys, random, getopt
+    args = sys.argv[1:]
+    try:
+        opts, args = getopt.getopt(args, '0123456789cdwq')
+    except getopt.error:
+        print('Usage: %s [-#] [-cddqw] [file] ...' % sys.argv[0])
+        print('Options:')
+        print('-#: 1-digit history size (default 2)')
+        print('-c: characters (default)')
+        print('-w: words')
+        print('-d: more debugging output')
+        print('-q: no debugging output')
+        print('Input files (default stdin) are split in paragraphs')
+        print('separated blank lines and each paragraph is split')
+        print('in words by whitespace, then reconcatenated with')
+        print('exactly one space separating words.')
+        print('Output consists of paragraphs separated by blank')
+        print('lines, where lines are no longer than 72 characters.')
+        sys.exit(2)
+    histsize = 2
+    do_words = False
+    debug = 1
+    for o, a in opts:
+        if '-0' <= o <= '-9': histsize = int(o[1:])
+        if o == '-c': do_words = False
+        if o == '-d': debug += 1
+        if o == '-q': debug = 0
+        if o == '-w': do_words = True
+    if not args:
+        args = ['-']
+
+    m = Markov(histsize, random.choice)
+    try:
+        for filename in args:
+            if filename == '-':
+                f = sys.stdin
+                if f.isatty():
+                    print('Sorry, need stdin from file')
+                    continue
+            else:
+                f = open(filename, 'r')
+            if debug: print('processing', filename, '...')
+            text = f.read()
+            f.close()
+            paralist = text.split('\n\n')
+            for para in paralist:
+                if debug > 1: print('feeding ...')
+                words = para.split()
+                if words:
+                    if do_words:
+                        data = tuple(words)
+                    else:
+                        data = ' '.join(words)
+                    m.put(data)
+    except KeyboardInterrupt:
+        print('Interrupted -- continue with data read so far')
+    if not m.trans:
+        print('No valid input files')
+        return
+    if debug: print('done.')
+
+    if debug > 1:
+        for key in m.trans.keys():
+            if key is None or len(key) < histsize:
+                print(repr(key), m.trans[key])
+        if histsize == 0: print(repr(''), m.trans[''])
+        print()
+    while True:
+        data = m.get()
+        if do_words:
+            words = data
+        else:
+            words = data.split()
+        n = 0
+        limit = 72
+        for w in words:
+            if n + len(w) > limit:
+                print()
+                n = 0
+            print(w, end=' ')
+            n += len(w) + 1
+        print()
+        print()
+
+if __name__ == "__main__":
+    test()