diff options
| author | Guido van Rossum <guido@python.org> | 2000-11-08 15:17:49 (GMT) |
|---|---|---|
| committer | Guido van Rossum <guido@python.org> | 2000-11-08 15:17:49 (GMT) |
| commit | f4e13a45639e906691690afa6281dba2103247a9 (patch) | |
| tree | 93c328a86fb0babb62f28d35ee09dd62d50a301c /Demo/threads/squasher.py | |
| parent | 704925c774c5802e5175b77251e49af5530c94fd (diff) | |
| download | cpython-f4e13a45639e906691690afa6281dba2103247a9.zip cpython-f4e13a45639e906691690afa6281dba2103247a9.tar.gz cpython-f4e13a45639e906691690afa6281dba2103247a9.tar.bz2 | |
Add 1994 Coroutine module by Tim Peters
Diffstat (limited to 'Demo/threads/squasher.py')
| -rw-r--r-- | Demo/threads/squasher.py | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/Demo/threads/squasher.py b/Demo/threads/squasher.py new file mode 100644 index 0000000..3d5ea00 --- /dev/null +++ b/Demo/threads/squasher.py @@ -0,0 +1,104 @@ +# Coroutine example: general coroutine transfers +# +# The program is a variation of a Simula 67 program due to Dahl & Hoare, +# who in turn credit the original example to Conway. +# +# We have a number of input lines, terminated by a 0 byte. The problem +# is to squash them together into output lines containing 72 characters +# each. A semicolon must be added between input lines. Runs of blanks +# and tabs in input lines must be squashed into single blanks. +# Occurrences of "**" in input lines must be replaced by "^". +# +# Here's a test case: + +test = """\ + d = sqrt(b**2 - 4*a*c) +twoa = 2*a + L = -b/twoa + R = d/twoa + A1 = L + R + A2 = L - R\0 +""" + +# The program should print: + +# d = sqrt(b^2 - 4*a*c);twoa = 2*a; L = -b/twoa; R = d/twoa; A1 = L + R; +#A2 = L - R +#done + +# getline: delivers the next input line to its invoker +# disassembler: grabs input lines from getline, and delivers them one +# character at a time to squasher, also inserting a semicolon into +# the stream between lines +# squasher: grabs characters from disassembler and passes them on to +# assembler, first replacing "**" with "^" and squashing runs of +# whitespace +# assembler: grabs characters from squasher and packs them into lines +# with 72 character each, delivering each such line to putline; +# when it sees a null byte, passes the last line to putline and +# then kills all the coroutines +# putline: grabs lines from assembler, and just prints them + +from Coroutine import * + +def getline(text): + for line in string.splitfields(text, '\n'): + co.back(line) + +def disassembler(): + while 1: + card = co.tran(cogetline) + for i in range(len(card)): + co.tran(cosquasher, card[i]) + co.tran(cosquasher, ';') + +def squasher(): + while 1: + ch = co.tran(codisassembler) + if ch == '*': + ch2 = co.tran(codisassembler) + if ch2 == '*': + ch = '^' + else: + co.tran(coassembler, ch) + ch = ch2 + if ch in ' \t': + while 1: + ch2 = co.tran(codisassembler) + if ch2 not in ' \t': + break + co.tran(coassembler, ' ') + ch = ch2 + co.tran(coassembler, ch) + +def assembler(): + line = '' + while 1: + ch = co.tran(cosquasher) + if ch == '\0': + break + if len(line) == 72: + co.tran(coputline, line) + line = '' + line = line + ch + line = line + ' ' * (72 - len(line)) + co.tran(coputline, line) + co.kill() + +def putline(): + while 1: + line = co.tran(coassembler) + print line + +import string +co = Coroutine() +cogetline = co.create(getline, test) +coputline = co.create(putline) +coassembler = co.create(assembler) +codisassembler = co.create(disassembler) +cosquasher = co.create(squasher) + +co.tran(coputline) +print 'done' + +# end of example |