# Copyright 2013 Amazon.com, Inc. or its affiliates. All Rights Reserved.

#

# Licensed under the Apache License, Version 2.0 (the "License"). You

# may not use this file except in compliance with the License. A copy of

# the License is located at

#

# http://aws.amazon.com/apache2.0/

#

# or in the "license" file accompanying this file. This file is

# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF

# ANY KIND, either express or implied. See the License for the specific

# language governing permissions and limitations under the License.

import csv

import six

def split_on_commas(value):

if not any(char in value for char in ['"', '\\', "'", ']', '[']):

# No quotes or escaping, just use a simple split.

return value.split(',')

elif not any(char in value for char in ['"', "'", '[', ']']):

# Simple escaping, let the csv module handle it.

return list(csv.reader(six.StringIO(value), escapechar='\\'))[0]

else:

# If there's quotes for the values, we have to handle this

# ourselves.

return _split_with_quotes(value)

def _split_with_quotes(value):

try:

parts = list(csv.reader(six.StringIO(value), escapechar='\\'))[0]

except csv.Error:

raise ValueError("Bad csv value: %s" % value)

iter_parts = iter(parts)

new_parts = []

for part in iter_parts:

# Find the first quote

quote_char = _find_quote_char_in_part(part)

# Find an opening list bracket

list_start = part.find('=[')

if list_start >= 0 and value.find(']') != -1 and \

(quote_char is None or part.find(quote_char) > list_start):

# This is a list, eat all the items until the end

new_chunk = _eat_items(value, iter_parts, part, ']')

list_items = _split_with_quotes(new_chunk[list_start + 2:-1])

new_chunk = new_chunk[:list_start + 1] + ','.join(list_items)

new_parts.append(new_chunk)

continue

elif quote_char is None:

new_parts.append(part)

continue

elif part.count(quote_char) == 2:

# Starting and ending quote are in this part.

# While it's not needed right now, this will

# break down if we ever need to escape quotes while

# quoting a value.

new_parts.append(part.replace(quote_char, ''))

continue

# Now that we've found a starting quote char, we

# need to combine the parts until we encounter an end quote.

new_chunk = _eat_items(value, iter_parts, part, quote_char, quote_char)

new_parts.append(new_chunk)

return new_parts

def _eat_items(value, iter_parts, part, end_char, replace_char=''):

"""

Eat items from an iterator, optionally replacing characters with

a blank and stopping when the end_char has been reached.

"""

current = part

chunks = [current.replace(replace_char, '')]

while True:

try:

current = six.advance_iterator(iter_parts)

except StopIteration:

raise ValueError(value)

chunks.append(current.replace(replace_char, ''))

if end_char in current:

break

return ','.join(chunks)

def _find_quote_char_in_part(part):

if '"' not in part and "'" not in part:

return

quote_char = None

double_quote = part.find('"')

single_quote = part.find("'")

if double_quote >= 0 and single_quote == -1:

quote_char = '"'

elif single_quote >= 0 and double_quote == -1:

quote_char = "'"

elif double_quote < single_quote:

quote_char = '"'

elif single_quote < double_quote:

quote_char = "'"

return quote_char