Text::CSV_XS
CSV_XS(3) User Contributed Perl Documentation CSV_XS(3)
NAME
Text::CSV_XS - comma-separated values manipulation routines
SYNOPSIS
use Text::CSV_XS;
$csv = Text::CSV_XS->new (); # create a new object
$csv = Text::CSV_XS->new (\%attr); # create a new object
$status = $csv->combine (@columns); # combine columns into a string
$line = $csv->string (); # get the combined string
$status = $csv->parse ($line); # parse a CSV string into fields
@columns = $csv->fields (); # get the parsed fields
$status = $csv->status (); # get the most recent status
$bad_argument = $csv->error_input (); # get the most recent bad argument
$status = $csv->print ($io, $colref); # Write an array of fields
# immediately to a file $io
$colref = $csv->getline ($io); # Read a line from file $io,
# parse it and return an array
# ref of fields
$eof = $csv->eof (); # Indicate if last parse or
# getline () hit End Of File
$csv->types (\@t_array); # Set column types
DESCRIPTION
Text::CSV_XS provides facilities for the composition and decomposition
of comma-separated values. An instance of the Text::CSV_XS class can
combine fields into a CSV string and parse a CSV string into fields.
The module accepts either strings or files as input and can utilize
any user-specified characters as delimiters, separators, and escapes
so it is perhaps better called ASV (anything separated values) rather
than just CSV.
Embedded newlines
Important Note: The default behavior is to only accept ascii charac-
ters. This means that fields can not contain newlines. If your data
contains newlines embedded in fields, or characters above 0x7e
(tilde), or binary data, you *must* set "binary => 1" in the call to
"new ()". To cover the widest range of parsing options, you will
always want to set binary.
But you still have the problem that you have to pass a correct line to
the "parse ()" method, which is more complicated from the usual point
of usage:
my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
while (<>) { # WRONG!
$csv->parse ($_);
my @fields = $csv->fields ();
will break, as the while might read broken lines, as that doesn’t care
about the quoting. If you need to support embedded newlines, the way
to go is either
use IO::Handle;
my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
while (my $row = $csv->getline (*ARGV)) {
my @fields = @$row;
or, more safely in perl 5.6 and up
my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
open my $io, "<", $file or die "$file: $!";
while (my $row = $csv->getline ($io)) {
my @fields = @$row;
SPECIFICATION
While no formal specification for CSV exists, RFC 4180 1) describes a
common format and establishes "text/csv" as the MIME type registered
with the IANA.
Many informal documents exist that describe the CSV format. How To:
The Comma Separated Value (CSV) File Format 2) provides an overview of
the CSV format in the most widely used applications and explains how
it can best be used and supported.
1) http://tools.ietf.org/html/rfc4180
2) http://www.creativyst.com/Doc/Articles/CSV/CSV01.htm
The basic rules are as follows:
CSV is a delimited data format that has fields/columns separated by
the comma character and records/rows separated by newlines. Fields
that contain a special character (comma, newline, or double quote),
must be enclosed in double quotes. However, if a line contains a sin-
gle entry which is the empty string, it may be enclosed in double
quotes. If a field’s value contains a double quote character it is
escaped by placing another double quote character next to it. The CSV
file format does not require a specific character encoding, byte
order, or line terminator format.
· Each record is one line terminated by a line feed (ASCII/LF=0x0A) or
a carriage return and line feed pair (ASCII/CRLF=0x0D 0x0A), how-
ever, line-breaks can be embedded.
· Fields are separated by commas.
· Allowable characters within a CSV field include 0x09 (tab) and the
inclusive range of 0x20 (space) through 0x7E (tilde). In binary mode
all characters are accepted, at least in quoted fields.
· A field within CSV must be surrounded by double-quotes to contain a
the separator character (comma).
Though this is the most clear and restrictive definition, Text::CSV_XS
is way more liberal than this, and allows extension:
· Line termination by a single carriage return is accepted by default
· The separation-, escape-, and escape- characters can be any ASCII
character in the range from 0x20 (space) to 0x7E (tilde). Characters
outside this range may or may not work as expected. Multibyte char-
acters, like U+060c (ARABIC COMMA), U+FF0C (FULLWIDTH COMMA), U+241B
(SYMBOL FOR ESCAPE), U+2424 (SYMBOL FOR NEWLINE), U+FF02 (FULLWIDTH
QUOTATION MARK), and U+201C (LEFT DOUBLE QUOTATION MARK) (to give
some examples of what might look promising) are therefor not
allowed.
· A field within CSV must be surrounded by double-quotes to contain an
embedded double-quote, represented by a pair of consecutive dou-
ble-quotes. In binary mode you may additionally use the sequence
""0" for representation of a NULL byte.
· Several violations of the above specification may be allowed by
passing options to the object creator.
FUNCTIONS
version ()
(Class method) Returns the current module version.
new (\%attr)
(Class method) Returns a new instance of Text::CSV_XS. The objects
attributes are described by the (optional) hash ref "\%attr".
Currently the following attributes are available:
eol An end-of-line string to add to rows, usually "undef" (noth-
ing, default), "\012" (Line Feed) or "\015\012" (Carriage
Return, Line Feed). Cannot be longer than 7 (ASCII) charac-
ters.
If both $/ and "eol" equal "\015", parsing lines that end on
only a Carriage Return without Line Feed, will be "parse"d
correct. Line endings, whether in $/ or "eol", other than
"undef", "\n", "\r\n", or "\r" are not (yet) supported for
parsing.
sep_char
The char used for separating fields, by default a comma.
(","). Limited to a single-byte character, usually in the
range from 0x20 (space) to 0x7e (tilde).
The separation character can not be equal to the quote charac-
ter. The separation character can not be equal to the escape
character.
allow_whitespace
When this option is set to true, whitespace (TAB’s and
SPACE’s) surrounding the separation character is removed when
parsing. So lines like:
1 , "foo" , bar , 3 , zapp
are now correctly parsed, even though it violates the CSV
specs. Note that all whitespace is stripped from start and
end of each field. That would make is more a feature than a
way to be able to parse bad CSV lines, as
1, 2.0, 3, ape , monkey
will now be parsed as
("1", "2.0", "3", "ape", "monkey")
even if the original line was perfectly sane CSV.
quote_char
The char used for quoting fields containing blanks, by default
the double quote character ("""). A value of undef suppresses
quote chars. (For simple cases only). Limited to a single-
byte character, usually in the range from 0x20 (space) to 0x7e
(tilde).
The quote character can not be equal to the separation charac-
ter.
allow_loose_quotes
By default, parsing fields that have "quote_char" characters
inside an unquoted field, like
1,foo "bar" baz,42
would result in a parse error. Though it is still bad practice
to allow this format, we cannot help there are some vendors
that make their applications spit out lines styled like this.
escape_char
The character used for escaping certain characters inside
quoted fields. Limited to a single-byte character, usually in
the range from 0x20 (space) to 0x7e (tilde).
The "escape_char" defaults to being the literal double-quote
mark (""") in other words, the same as the default
"quote_char". This means that doubling the quote mark in a
field escapes it:
"foo","bar","Escape ""quote mark"" with two ""quote marks""","baz"
If you change the default quote_char without changing the
default escape_char, the escape_char will still be the quote
mark. If instead you want to escape the quote_char by dou-
bling it, you will need to change the escape_char to be the
same as what you changed the quote_char to.
The escape character can not be equal to the separation char-
acter.
allow_loose_escapes
By default, parsing fields that have "escape_char" characters
that escape characters that do not need to be escaped, like:
my $csv = Text::CSV_XS->new ({ escape_char => "\\" });
$csv->parse (qq{1,"my bar\’s",baz,42});
would result in a parse error. Though it is still bad practice
to allow this format, this option enables you to treat all
escape character sequences equal.
binary
If this attribute is TRUE, you may use binary characters in
quoted fields, including line feeds, carriage returns and NULL
bytes. (The latter must be escaped as ""0".) By default this
feature is off.
types
A set of column types; this attribute is immediately passed to
the types method below. You must not set this attribute other-
wise, except for using the types method. For details see the
description of the types method below.
always_quote
By default the generated fields are quoted only, if they need
to, for example, if they contain the separator. If you set
this attribute to a TRUE value, then all fields will be
quoted. This is typically easier to handle in external appli-
cations. (Poor creatures who aren’t using Text::CSV_XS. :-)
keep_meta_info
By default, the parsing of input lines is as simple and fast
as possible. However, some parsing information - like quota-
tion of the original field - is lost in that process. Set this
flag to true to be able to retrieve that information after
parsing with the methods "meta_info ()", "is_quoted ()", and
"is_binary ()" described below. Default is false.
verbatim
This is a quite controversial attribute to set, but it makes
hard things possible.
The basic thought behind this is to tell the parser that the
normally special characters newline (NL) and Carriage Return
(CR) will not be special when this flag is set, and be dealt
with as being ordinary binary characters. This will ease work-
ing with data with embedded newlines.
When "verbatim" is used with "getline ()", getline
auto-chomp’s every line.
Imagine a file format like
M^^Hans^Janssen^Klas 2\n2A^Ja^11-06-2007#\r\n
where, the line ending is a very specific "#\r\n", and the
sep_char is a ^ (caret). None of the fields is quoted, but
embedded binary data is likely to be present. With the spe-
cific line ending, that shouldn’t be too hard to detect.
By default, Text::CSV_XS’ parse function however is instructed
to only know about "\n" and "\r" to be legal line endings, and
so has to deal with the embedded newline as a real
end-of-line, so it can scan the next line if binary is true,
and the newline is inside a quoted field. With this attribute
however, we can tell parse () to parse the line as if \n is
just nothing more than a binary character.
For parse () this means that the parser has no idea about line
ending anymore, and getline () chomps line endings on reading.
To sum it up,
$csv = Text::CSV_XS->new ();
is equivalent to
$csv = Text::CSV_XS->new ({
quote_char => ’"’,
escape_char => ’"’,
sep_char => ’,’,
eol => ’’,
always_quote => 0,
binary => 0,
keep_meta_info => 0,
allow_loose_quotes => 0,
allow_loose_escapes => 0,
allow_whitespace => 0,
verbatim => 0,
});
For all of the above mentioned flags, there is an accessor method
available where you can inquire for the current value, or change
the value
my $quote = $csv->quote_char;
$csv->binary (1);
It is unwise to change these settings halfway through writing CSV
data to a stream. If however, you want to create a new stream
using the available CSV object, there is no harm in changing them.
combine
$status = $csv->combine (@columns);
This object function constructs a CSV string from the arguments,
returning success or failure. Failure can result from lack of
arguments or an argument containing an invalid character. Upon
success, "string ()" can be called to retrieve the resultant CSV
string. Upon failure, the value returned by "string ()" is unde-
fined and "error_input ()" can be called to retrieve an invalid
argument.
print
$status = $csv->print ($io, $colref);
Similar to combine, but it expects an array ref as input (not an
array!) and the resulting string is not really created, but imme-
diately written to the $io object, typically an IO handle or any
other object that offers a print method. Note, this implies that
the following is wrong:
open FILE, ">", "whatever";
$status = $csv->print (\*FILE, $colref);
The glob "\*FILE" is not an object, thus it doesn’t have a print
method. The solution is to use an IO::File object or to hide the
glob behind an IO::Wrap object. See IO::File(3) and IO::Wrap(3)
for details.
For performance reasons the print method doesn’t create a result
string. In particular the $csv->string (), $csv->status (),
$csv-fields ()> and $csv->error_input () methods are meaningless
after executing this method.
string
$line = $csv->string ();
This object function returns the input to "parse ()" or the resul-
tant CSV string of "combine ()", whichever was called more
recently.
parse
$status = $csv->parse ($line);
This object function decomposes a CSV string into fields, return-
ing success or failure. Failure can result from a lack of argu-
ment or the given CSV string is improperly formatted. Upon suc-
cess, "fields ()" can be called to retrieve the decomposed fields
. Upon failure, the value returned by "fields ()" is undefined
and "error_input ()" can be called to retrieve the invalid argu-
ment.
You may use the types () method for setting column types. See the
description below.
getline
$colref = $csv->getline ($io);
This is the counterpart to print, like parse is the counterpart to
combine: It reads a row from the IO object $io using $io->getline
() and parses this row into an array ref. This array ref is
returned by the function or undef for failure.
The $csv->string (), $csv->fields () and $csv->status () methods
are meaningless, again.
eof
$eof = $csv->eof ();
If "parse ()" or "getline ()" was used with an IO stream, this
method will return true (1) if the last call hit end of file,
otherwise it will return false (’’). This is useful to see the
difference between a failure and end of file.
types
$csv->types (\@tref);
This method is used to force that columns are of a given type. For
example, if you have an integer column, two double columns and a
string column, then you might do a
$csv->types ([Text::CSV_XS::IV (),
Text::CSV_XS::NV (),
Text::CSV_XS::NV (),
Text::CSV_XS::PV ()]);
Column types are used only for decoding columns, in other words by
the parse () and getline () methods.
You can unset column types by doing a
$csv->types (undef);
or fetch the current type settings with
$types = $csv->types ();
IV Set field type to integer.
NV Set field type to numeric/float.
PV Set field type to string.
fields
@columns = $csv->fields ();
This object function returns the input to "combine ()" or the
resultant decomposed fields of "parse ()", whichever was called
more recently.
meta_info
@flags = $csv->meta_info ();
This object function returns the flags of the input to "combine
()" or the flags of the resultant decomposed fields of "parse ()",
whichever was called more recently.
For each field, a meta_info field will hold flags that tell some-
thing about the field returned by the "fields ()" method or passed
to the "combine ()" method. The flags are bitwise-or’d like:
0x0001
The field was quoted.
0x0002
The field was binary.
See the "is_*** ()" methods below.
is_quoted
my $quoted = $csv->is_quoted ($column_idx);
Where $column_idx is the (zero-based) index of the column in the
last result of "parse ()".
This returns a true value if the data in the indicated column was
enclosed in "quote_char" quotes. This might be important for data
where ",20070108," is to be treated as a numeric value, and where
","20070108"," is explicitly marked as character string data.
is_binary
my $binary = $csv->is_binary ($column_idx);
Where $column_idx is the (zero-based) index of the column in the
last result of "parse ()".
This returns a true value if the data in the indicated column con-
tained any byte in the range [\x00-\x08,\x10-\x1F,\x7F-\xFF]
status
$status = $csv->status ();
This object function returns success (or failure) of "combine ()"
or "parse ()", whichever was called more recently.
error_input
$bad_argument = $csv->error_input ();
This object function returns the erroneous argument (if it exists)
of "combine ()" or "parse ()", whichever was called more recently.
error_diag
$csv->error_diag ();
$error_code = 0 + $csv->error_diag ();
$error_str = "" . $csv->error_diag ();
($cde, $str) = $csv->error_diag ();
If (and only if) an error occured, this function returns the diag-
nostics of that error.
If called in void context, it will print the internal error code
and the associated error message to STDERR.
If called in list context, it will return the error code and the
error message in that order.
If called in scalar context, it will return the diagnostics in a
single scalar, a-la $!. It will contain the error code in numeric
context, and the diagnostics message in string context.
INTERNALS
Combine (...)
Parse (...)
The arguments to these two internal functions are deliberately not
described or documented to enable the module author(s) to change it
when they feel the need for it and using them is highly discouraged as
the API may change in future releases.
EXAMPLES
An example for creating CSV files:
use Text::CSV_XS;
my $csv = Text::CSV_XS->new;
open my $csv_fh, ">", "hello.csv" or die "hello.csv: $!";
my @sample_input_fields = (
’You said, "Hello!"’, 5.67,
’"Surely"’, ’’, ’3.14159’);
if ($csv->combine (@sample_input_fields)) {
my $string = $csv->string;
print $csv_fh "$string\n";
}
else {
my $err = $csv->error_input;
print "combine () failed on argument: ", $err, "\n";
}
close $csv_fh;
An example for parsing CSV lines:
use Text::CSV_XS;
my $csv = Text::CSV_XS->new ({ keep_meta_info => 1, binary => 1 });
my $sample_input_string =
qq{"I said, ""Hi!""",Yes,"",2.34,,"1.09","\x{20ac}",};
if ($csv->parse ($sample_input_string)) {
my @field = $csv->fields;
foreach my $col (0 .. $#field) {
my $quo = $csv->is_quoted ($col) ? $csv->{quote_char} : "";
printf "%2d: %s%s%s\n", $col, $quo, $field[$col], $quo;
}
}
else {
my $err = $csv->error_input;
print STDERR "parse () failed on argument: ", $err, "\n";
$csv->error_diag ();
}
TODO
More Errors & Warnings
At current, it is hard to tell where or why an error occured (if at
all). New extensions ought to be clear and concise in reporting what
error occurred where and why, and possibly also tell a remedy to the
problem. error_diag is a (very) good start, but there is more work
to be done here.
Basic calls should croak or warn on illegal parameters. Errors
should be documented.
eol
Discuss an option to make the eol honor the $/ setting. Maybe
my $csv = Text::CSV_XS->new ({ eol => $/ });
is already enough, and new options only make things less opaque.
setting meta info
Future extensions might include extending the "meta_info ()",
"is_quoted ()", and "is_binary ()" to accept setting these flags for
fields, so you can specify which fields are quoted in the combine
()/string () combination.
$csv->meta_info (0, 1, 1, 3, 0, 0);
$csv->is_quoted (3, 1);
parse returning undefined fields
Adding an option that enables the parser to distinguish between
empty fields and undefined fields, like
$csv->always_quote (1);
$csv->allow_undef (1);
$csv->parse (qq{,"",1,"2",,""});
my @fld = $csv->fields ();
Then would return (undef, "", "1", "2", undef, "") in @fld, instead
of the current ("", "", "1", "2", "", "").
combined methods
Requests for adding means (methods) that combine "combine ()" and
"string ()" in a single call will not be honored. Likewise for
"parse ()" and "fields ()". Given the trouble with embedded new-
lines, using "getline ()" and "print ()" instead is the prefered way
to go.
Unicode
Make "parse ()" and "combine ()" do the right thing for Unicode
(UTF-8) if requested. See t/50_utf8.t. More complicated, but evenly
important, also for "getline ()" and "print ()".
Probably the best way to do this is to make a subclass
Text::CSV_XS::Encoded that can be passed the required encoding and
then behaves transparently (but slower).
Double double quotes
There seem to be applications around that write their dates like
1,4,""12/11/2004"",4,1
If we would support that, probably through allow_double_quoted Defi-
nitely belongs in t/65_allow.t
Parse the whole file at once
Implement a new methods that enables the parsing of a complete file
at once, returning a lis of hashes. Possible extension to this could
be to enable a column selection on the call:
my @AoH = $csv->parse_file ($filename, { cols => [ 1, 4..8, 12 ]});
Returning something like
[ { fields => [ 1, 2, "foo", 4.5, undef, "", 8 ],
flags => [ ... ],
errors => [ ... ],
},
{ fields => [ ... ],
.
.
},
]
EBCDIC
The hard-coding of characters and character ranges makes this module
unusable on EBCDIC system. Using some #ifdef structure could enable
these again without loosing speed. Testing would be the hard part.
Release plan
No guarantees, but this is what I have in mind right now:
0.31
- croak / carp
- error cause, check if error_diag () is enough
- return undef
- DIAGNOSTICS setction in pod to *describe* the errors
0.32
- allow_double_quoted
- Text::CSV_XS::Encoded (maybe)
0.33
- csv2csv - a script to regenerate a CSV file to follow standards
- EBCDIC support
DIAGNOSTICS
Still under construction ...
If an error occured, $csv->error_diag () can be used to get more
information on the cause of the failure. Note that for speed reasons,
the internal value is never cleared on success, so using the value
returned by error_diag () in normal cases - when no error occured -
may cause unexpected results.
Currently these errors are available:
1001 "sep_char is equal to quote_char or escape_char"
2010 "ECR - QUO char inside quotes followed by CR not part of EOL"
2011 "ECR - Characters after end of quoted field"
2012 "EOF - End of data in parsing input stream"
2021 "EIQ - NL char inside quotes, binary off"
2022 "EIQ - CR char inside quotes, binary off"
2023 "EIQ - QUO ..."
2024 "EIQ - EOF cannot be escaped, not even inside quotes"
2025 "EIQ - Loose unescaped escape"
2026 "EIQ - Binary character inside quoted field, binary off"
2027 "EIQ - Quoted field not terminated"
2030 "EIF - NL char inside unquoted verbatim, binary off"
2031 "EIF - CR char is first char of field, not part of EOL"
2032 "EIF - CR char inside unquoted, not part of EOL"
2033 "EIF - QUO, QUO != ESC, binary off"
2034 "EIF - Loose unescaped quote"
2035 "EIF - Escaped EOF in unquoted field"
2036 "EIF - ESC error"
2037 "EIF - Binary character in unquoted field, binary off"
2110 "ECB - Binary character in Combine, binary off"
SEE ALSO
perl(1), IO::File(3), L{IO::Handle(3)>, IO::Wrap(3), Text::CSV(3),
Text::CSV_PP(3). and Spreadsheet::Read(3).
AUTHORS and MAINTAINERS
Alan Citterman <alan@mfgrtl.com> wrote the original Perl module.
Please don’t send mail concerning Text::CSV_XS to Alan, as he’s not
involved in the C part which is now the main part of the module.
Jochen Wiedmann <joe@ispsoft.de> rewrote the encoding and decoding in
C by implementing a simple finite-state machine and added the variable
quote, escape and separator characters, the binary mode and the print
and getline methods. See ChangeLog releases 0.10 through 0.23.
H.Merijn Brand <h.m.brand@xs4all.nl> cleaned up the code, added the
field flags methods, wrote the major part of the test suite, completed
the documentation, fixed some RT bugs. See ChangeLog releases 0.25 and
on.
COPYRIGHT AND LICENSE
Copyright (C) 2007-2007 H.Merijn Brand for PROCURA B.V. Copyright (C)
1998-2001 Jochen Wiedmann. All rights reserved. Portions Copyright
(C) 1997 Alan Citterman. All rights reserved.
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
perl v5.8.8 2007-06-21 CSV_XS(3)
