101 lines
2.4 KiB
Python
101 lines
2.4 KiB
Python
from bonobo.config import Configurable, Option
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from bonobo.context import ContextProcessor
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from bonobo.context.processors import contextual
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from bonobo.util.objects import ValueHolder
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__all__ = [
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'FileReader',
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'FileWriter',
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]
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@contextual
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class FileHandler(Configurable):
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"""
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Abstract component factory for file-related components.
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"""
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path = Option(str, required=True)
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eol = Option(str, default='\n')
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mode = Option(str)
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@ContextProcessor
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def file(self, context):
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with self.open() as file:
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yield file
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def open(self):
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return open(self.path, self.mode)
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class Reader(FileHandler):
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def __call__(self, *args):
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yield from self.read(*args)
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def read(self, *args):
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raise NotImplementedError('Abstract.')
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class Writer(FileHandler):
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def __call__(self, *args):
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return self.write(*args)
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def write(self, *args):
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raise NotImplementedError('Abstract.')
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class FileReader(Reader):
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"""
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Component factory for file-like readers.
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On its own, it can be used to read a file and yield one row per line, trimming the "eol" character at the end if
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present. Extending it is usually the right way to create more specific file readers (like json, csv, etc.)
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"""
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mode = Option(str, default='r')
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def read(self, file):
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"""
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Write a row on the next line of given file.
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Prefix is used for newlines.
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:param ctx:
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:param row:
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"""
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for line in file:
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yield line.rstrip(self.eol)
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@contextual
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class FileWriter(Writer):
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"""
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Component factory for file or file-like writers.
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On its own, it can be used to write in a file one line per row that comes into this component. Extending it is
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usually the right way to create more specific file writers (like json, csv, etc.)
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"""
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mode = Option(str, default='w+')
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@ContextProcessor
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def lineno(self, context, file):
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lineno = ValueHolder(0, type=int)
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yield lineno
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def write(self, file, lineno, row):
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"""
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Write a row on the next line of opened file in context.
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:param file fp:
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:param str row:
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:param str prefix:
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"""
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self._write_line(file, (self.eol if lineno.value else '') + row)
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lineno.value += 1
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def _write_line(self, file, line):
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return file.write(line)
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