csv.Sniffer.snif doesn't set up the dialect properly for a csv created with dialect=csv.excel_tab and containing quote (") char

[b54bdd18-0ffa-412a-9e55-4a92cef9e562]

BPO	17829
Files	csv_sniffing_excel_tab.py: Exemple of sniffing csv with dialect=csv.excel_tab and quote in data

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GitHub fields: ```python assignee = None closed_at = None created_at = labels = ['type-bug'] title = 'csv.Sniffer.snif doesn\'t set up the dialect properly for a csv created with dialect=csv.excel_tab and containing quote (") char' updated_at = user = 'https://bugs.python.org/GhislainHivon' ``` bugs.python.org fields: ```python activity = actor = 'Antoon.Pardon' assignee = 'none' closed = False closed_date = None closer = None components = [] creation = creator = 'GhislainHivon' dependencies = [] files = ['30001'] hgrepos = [] issue_num = 17829 keywords = [] message_count = 3.0 messages = ['187709', '214800', '215031'] nosy_count = 3.0 nosy_names = ['GhislainHivon', 'Antoon.Pardon', 'dmi.baranov'] pr_nums = [] priority = 'normal' resolution = None stage = None status = 'open' superseder = None type = 'behavior' url = 'https://bugs.python.org/issue17829' versions = ['Python 2.7', 'Python 3.2'] ```

[b54bdd18-0ffa-412a-9e55-4a92cef9e562]

When sniffing the dialect of a file created with the csv module with dialect=csv.excel_tab and one of the row contain a quote ("), the delimiter is set to ' ' instead of '\t'.

[d8900210-577a-44e0-8708-ae85a5913450]

I had a look at this and have the following remarks.

1) the file csv_sniffing_excel_tab.py no longer works with python 3.3. It now produces the folowing traceback:

Traceback (most recent call last):
  File "csv_sniffing_excel_tab.py", line 36, in <module>
    create_file()
  File "csv_sniffing_excel_tab.py", line 23, in create_file
    writer.writerows(test_data)
TypeError: 'str' does not support the buffer interface

2) The problem seems to be in the _guess_quote_and_delimiter method. If you always call _guess_delimiter, the sniffer give the correct result.

3) As far as I understand the problem is the first regular expression: (?P\<delim>[^\w\n"\'])(?P\<space> ?)(?P\<quote>["\']).*?(?P=quote)(?P=delim)

Now if we have a line as the following

273:MVREGR1:ByEuPo:"Baryton ""Euphonium"" populaire"

The delim group will match the space, the space group will match nothing the quote group will match " the non-group pattern will match "Euphonium" followed by the quote group matching " again and the delim group matching the space.

And so we get the wrong delimiter.

[d8900210-577a-44e0-8708-ae85a5913450]

I included a patch (against 2.7) that seems to make the test work.

The patch prohibits the delim group to match a space.

[pradeepkumarai]

I included a patch (against 2.7) that seems to make the test work.

The patch prohibits the delim group to match a space.