pipeline.py

from subprocess import Popen, PIPE, STDOUT
import shlex

import json

class Pipeline:
    def __init__(self, stdin=None):
        self.returncode = None
        self.stdout = stdin
        self.stderr = None

    def __or__(self, args):
        if isinstance(args, str):
            args = shlex.split(args)
        if isinstance(args, list):
            p = Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE)
            self.stdout, self.stderr = p.communicate(self.stdout)
            self.returncode = p.returncode
        elif callable(args):
            self.stdout = args(self.stdout)
        else:
            raise NotImplemented()
        return self


P = Pipeline

def json_parse(o):
    return json.loads(o.decode("utf-8"))

def f(o):
    return "\n".join("{type} : {actor[login]}".format(**x) for x in o).encode("utf-8")

def printb(o):
    print(o.decode("utf-8"))

p = P() | "curl https://api.github.com/orgs/vim-jp/events" | json_parse | f | "grep IssueCommentEvent" | printb