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cli.py
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cli.py
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#!/usr/bin/env python
import argparse
import bz2
import gzip
import os.path
import sys
from csvkit import CSVKitReader
from csvkit.exceptions import ColumnIdentifierError
def lazy_opener(fn):
def wrapped(self, *args, **kwargs):
self._lazy_open()
fn(*args, **kwargs)
return wrapped
class LazyFile(object):
"""
A proxy for a File object that delays opening it until
a read method is called.
Currently this implements only the minimum methods to be useful,
but it could easily be expanded.
"""
def __init__(self, init, *args, **kwargs):
self.init = init
self.f = None
self._is_lazy_opened = False
self._lazy_args = args
self._lazy_kwargs = kwargs
def __getattr__(self, name):
if not self._is_lazy_opened:
self.f = self.init(*self._lazy_args, **self._lazy_kwargs)
self._is_lazy_opened = True
return getattr(self.f, name)
def __iter__(self):
return self
def close(self):
self.f.close()
self.f = None
self._is_lazy_opened = False
def next(self):
if not self._is_lazy_opened:
self.f = self.init(*self._lazy_args, **self._lazy_kwargs)
self._is_lazy_opened = True
return self.f.next()
class CSVFileType(object):
"""
An argument factory like argparse.FileType with compression support.
"""
def __init__(self, mode='rb'):
"""
Initialize the factory.
"""
self._mode = mode
def __call__(self, path):
"""
Build a file-like object from the specified path.
"""
if path == '-':
if 'r' in self._mode:
return sys.stdin
elif 'w' in self._mode:
return sys.stdout
else:
raise ValueError('Invalid path "-" with mode {0}'.format(self._mode))
else:
(_, extension) = os.path.splitext(path)
if extension == '.gz':
return LazyFile(gzip.open, path, self._mode)
if extension == '.bz2':
return LazyFile(bz2.BZ2File, path, self._mode)
else:
return LazyFile(open, path, self._mode)
class CSVKitUtility(object):
description = ''
epilog = ''
override_flags = ''
def __init__(self, args=None, output_file=None):
"""
Perform argument processing and other setup for a CSVKitUtility.
"""
self._init_common_parser()
self.add_arguments()
self.args = self.argparser.parse_args(args)
self.reader_kwargs = self._extract_csv_reader_kwargs()
self.writer_kwargs = self._extract_csv_writer_kwargs()
self._install_exception_handler()
if output_file is None:
self.output_file = sys.stdout
else:
self.output_file = output_file
# Ensure SIGPIPE doesn't throw an exception
# Prevents [Errno 32] Broken pipe errors, e.g. when piping to 'head'
# To test from the shell:
# python -c "for i in range(5000): print 'a,b,c'" | csvlook | head
# Without this fix you will see at the end:
# [Errno 32] Broken pipe
# With this fix, there should be no error
# For details on Python and SIGPIPE, see http://bugs.python.org/issue1652
try:
import signal
signal.signal(signal.SIGPIPE, signal.SIG_DFL)
except (ImportError, AttributeError):
#Do nothing on platforms that don't have signals or don't have SIGPIPE
pass
def add_arguments(self):
"""
Called upon initialization once the parser for common arguments has been constructed.
Should be overriden by individual utilities.
"""
raise NotImplementedError('add_arguments must be provided by each subclass of CSVKitUtility.')
def main(self):
"""
Main loop of the utility.
Should be overriden by individual utilities and explicitly called by the executing script.
"""
raise NotImplementedError(' must be provided by each subclass of CSVKitUtility.')
def _init_common_parser(self):
"""
Prepare a base argparse argument parser so that flags are consistent across different shell command tools.
If you want to constrain which common args are present, you can pass a string for 'omitflags'. Any argument
whose single-letter form is contained in 'omitflags' will be left out of the configured parser. Use 'f' for
file.
"""
self.argparser = argparse.ArgumentParser(description=self.description, epilog=self.epilog)
# Input
if 'f' not in self.override_flags:
self.argparser.add_argument('file', metavar="FILE", nargs='?', type=CSVFileType(), default=sys.stdin,
help='The CSV file to operate on. If omitted, will accept input on STDIN.')
if 'd' not in self.override_flags:
self.argparser.add_argument('-d', '--delimiter', dest='delimiter',
help='Delimiting character of the input CSV file.')
if 't' not in self.override_flags:
self.argparser.add_argument('-t', '--tabs', dest='tabs', action='store_true',
help='Specifies that the input CSV file is delimited with tabs. Overrides "-d".')
if 'q' not in self.override_flags:
self.argparser.add_argument('-q', '--quotechar', dest='quotechar',
help='Character used to quote strings in the input CSV file.')
if 'u' not in self.override_flags:
self.argparser.add_argument('-u', '--quoting', dest='quoting', type=int, choices=[0,1,2,3],
help='Quoting style used in the input CSV file. 0 = Quote Minimal, 1 = Quote All, 2 = Quote Non-numeric, 3 = Quote None.')
if 'b' not in self.override_flags:
self.argparser.add_argument('-b', '--doublequote', dest='doublequote', action='store_true',
help='Whether or not double quotes are doubled in the input CSV file.')
if 'p' not in self.override_flags:
self.argparser.add_argument('-p', '--escapechar', dest='escapechar',
help='Character used to escape the delimiter if quoting is set to "Quote None" and the quotechar if doublequote is not specified.')
if 'z' not in self.override_flags:
self.argparser.add_argument('-z', '--maxfieldsize', dest='maxfieldsize', type=int,
help='Maximum length of a single field in the input CSV file.')
if 'e' not in self.override_flags:
self.argparser.add_argument('-e', '--encoding', dest='encoding', default='utf-8',
help='Specify the encoding the input CSV file.')
if 'v' not in self.override_flags:
self.argparser.add_argument('-v', '--verbose', dest='verbose', action='store_true',
help='Print detailed tracebacks when errors occur.')
# Output
if 'l' not in self.override_flags:
self.argparser.add_argument('-l', '--linenumbers', dest='line_numbers', action='store_true',
help='Insert a column of line numbers at the front of the output. Useful when piping to grep or as a simple primary key.')
# Input/Output
if 'zero' not in self.override_flags:
self.argparser.add_argument('--zero', dest='zero_based', action='store_true',
help='When interpreting or displaying column numbers, use zero-based numbering instead of the default 1-based numbering.')
def _extract_csv_reader_kwargs(self):
"""
Extracts those from the command-line arguments those would should be passed through to the input CSV reader(s).
"""
kwargs = {}
if self.args.encoding:
kwargs['encoding'] = self.args.encoding
if self.args.tabs:
kwargs['delimiter'] = '\t'
elif self.args.delimiter:
kwargs['delimiter'] = self.args.delimiter
if self.args.quotechar:
kwargs['quotechar'] = self.args.quotechar
if self.args.quoting:
kwargs['quoting'] = self.args.quoting
if self.args.doublequote:
kwargs['doublequote'] = self.args.doublequote
if self.args.escapechar:
kwargs['escapechar'] = self.args.escapechar
if self.args.maxfieldsize:
kwargs['maxfieldsize'] = self.args.maxfieldsize
return kwargs
def _extract_csv_writer_kwargs(self):
"""
Extracts those from the command-line arguments those would should be passed through to the output CSV writer.
"""
kwargs = {}
if 'l' not in self.override_flags and self.args.line_numbers:
kwargs['line_numbers'] = True
return kwargs
def _install_exception_handler(self):
"""
Installs a replacement for sys.excepthook, which handles pretty-printing uncaught exceptions.
"""
def handler(t, value, traceback):
if self.args.verbose:
sys.__excepthook__(t, value, traceback)
else:
# Special case handling for Unicode errors, which behave very strangely
# when cast with unicode()
if t == UnicodeDecodeError:
sys.stderr.write('Your file is not "%s" encoded. Please specify the correct encoding with the -e flag. Use the -v flag to see the complete error.\n' % self.args.encoding)
else:
sys.stderr.write('%s\n' % unicode(value).encode('utf-8'))
sys.excepthook = handler
def print_column_names(self):
"""
Pretty-prints the names and indices of all columns to a file-like object (usually sys.stdout).
"""
f = self.args.file
output = self.output_file
try:
zero_based=self.args.zero_based
except:
zero_based=False
rows = CSVKitReader(f, **self.reader_kwargs)
column_names = rows.next()
for i, c in enumerate(column_names):
if not zero_based:
i += 1
output.write('%3i: %s\n' % (i, c))
def match_column_identifier(column_names, c, zero_based=False):
"""
Determine what column a single column id (name or index) matches in a series of column names.
Note that integer values are *always* treated as positional identifiers. If you happen to have
column names which are also integers, you must specify them using a positional index.
"""
if isinstance(c, basestring) and not c.isdigit() and c in column_names:
return column_names.index(c)
else:
try:
c = int(c)
if not zero_based:
c -= 1
# Fail out if neither a column name nor an integer
except:
raise ColumnIdentifierError('Column identifier "%s" is neither an integer, nor a existing column\'s name.' % c)
# Fail out if index is 0-based
if c < 0:
raise ColumnIdentifierError('Column 0 is not valid; columns are 1-based.')
# Fail out if index is out of range
if c >= len(column_names):
raise ColumnIdentifierError('Index %i is beyond the last named column, "%s" at index %i.' % (c, column_names[-1], len(column_names) - 1))
return c
def parse_column_identifiers(ids, column_names, zero_based=False, excluded_columns=None):
"""
Parse a comma-separated list of column indices AND/OR names into a list of integer indices.
Ranges of integers can be specified with two integers separated by a '-' or ':' character. Ranges of
non-integers (e.g. column names) are not supported.
Note: Column indices are 1-based.
"""
columns = []
# If not specified, start with all columns
if not ids:
columns = range(len(column_names))
if columns and not excluded_columns:
return columns
if not columns:
for c in ids.split(','):
c = c.strip()
try:
columns.append(match_column_identifier(column_names, c, zero_based))
except ColumnIdentifierError:
if ':' in c:
a,b = c.split(':',1)
elif '-' in c:
a,b = c.split('-',1)
else:
raise
try:
if a:
a = int(a)
else:
a = 1
if b:
b = int(b) + 1
else:
b = len(column_names)
except ValueError:
raise ColumnIdentifierError("Invalid range %s. Ranges must be two integers separated by a - or : character.")
for x in range(a,b):
columns.append(match_column_identifier(column_names, x, zero_based))
excludes = []
if excluded_columns:
for c in excluded_columns.split(','):
c = c.strip()
try:
excludes.append(match_column_identifier(column_names, c, zero_based))
except ColumnIdentifierError:
if ':' in c:
a,b = c.split(':',1)
elif '-' in c:
a,b = c.split('-',1)
else:
raise
try:
if a:
a = int(a)
else:
a = 1
if b:
b = int(b) + 1
else:
b = len(column_names)
except ValueError:
raise ColumnIdentifierError("Invalid range %s. Ranges must be two integers separated by a - or : character.")
for x in range(a,b):
excludes.append(match_column_identifier(column_names, x, zero_based))
return [c for c in columns if c not in excludes]