47 lines
1.4 KiB
Python
47 lines
1.4 KiB
Python
from io import StringIO
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class BaseCommand(object):
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"""Commands can be used to chain the execution of multiple programs
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together. You can chain multiple commands together using commands
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For example:
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ls = RawCommand(["ls"])
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grep = RawCommand(["grep", "potato"])
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printer = Printer()
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ls.chain(grep).chain(printer).call()
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"""
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def __init__(self, args=None):
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self.cmd_args = args
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self.prev_cmd = None
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def call(self, *args, **kwargs):
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"""Implicitly calls any chained commands, returning a function
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to make an input generator."""
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raise NotImplementedError("Must implement call")
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def get_input_generator(self):
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"""Gets the input generator from the previous command, if it
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exists. If it doesn't exist, we just return an empy list so that
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when you iterate over it, it does nothing."""
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if self.prev_cmd is not None:
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make_input_generator = self.prev_cmd.call()
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input_generator = make_input_generator()
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else:
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input_generator = []
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return input_generator
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def chain(self, cmd):
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"""Chains a command to another command, returning the other command"""
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cmd.prev_cmd = self
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return cmd
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registered_cmds = []
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def register_cmd(cls):
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"""Decorator for putting all of the commands in one nice place."""
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registered_cmds.append(cls.__name__)
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return cls
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