oracular (3) HTML::TableParser.3pm.gz
NAME
HTML::TableParser - HTML::TableParser - Extract data from an HTML table
VERSION
version 0.43
SYNOPSIS
use HTML::TableParser;
@reqs = (
{
id => 1.1, # id for embedded table
hdr => \&header, # function callback
row => \&row, # function callback
start => \&start, # function callback
end => \&end, # function callback
udata => { Snack => 'Food' }, # arbitrary user data
},
{
id => 1, # table id
cols => [ 'Object Type',
qr/object/ ], # column name matches
obj => $obj, # method callbacks
},
);
# create parser object
$p = HTML::TableParser->new( \@reqs,
{ Decode => 1, Trim => 1, Chomp => 1 } );
$p->parse_file( 'foo.html' );
# function callbacks
sub start {
my ( $id, $line, $udata ) = @_;
#...
}
sub end {
my ( $id, $line, $udata ) = @_;
#...
}
sub header {
my ( $id, $line, $cols, $udata ) = @_;
#...
}
sub row {
my ( $id, $line, $cols, $udata ) = @_;
#...
}
DESCRIPTION
HTML::TableParser uses HTML::Parser to extract data from an HTML table. The data is returned via a
series of user defined callback functions or methods. Specific tables may be selected either by a
matching a unique table id or by matching against the column names. Multiple (even nested) tables may be
parsed in a document in one pass.
Table Identification
Each table is given a unique id, relative to its parent, based upon its order and nesting. The first top
level table has id 1, the second 2, etc. The first table nested in table 1 has id 1.1, the second 1.2,
etc. The first table nested in table 1.1 has id 1.1.1, etc. These, as well as the tables' column names,
may be used to identify which tables to parse.
Data Extraction
As the parser traverses a selected table, it will pass data to user provided callback functions or
methods after it has digested particular structures in the table. All functions are passed the table id
(as described above), the line number in the HTML source where the table was found, and a reference to
any table specific user provided data.
Table Start
The start callback is invoked when a matched table has been found.
Table End
The end callback is invoked after a matched table has been parsed.
Header The hdr callback is invoked after the table header has been read in. Some tables do not use the
<th> tag to indicate a header, so this function may not be called. It is passed the column
names.
Row The row callback is invoked after a row in the table has been read. It is passed the column
data.
Warn The warn callback is invoked when a non-fatal error occurs during parsing. Fatal errors croak.
New This is the class method to call to create a new object when HTML::TableParser is supposed to
create new objects upon table start.
Callback API
Callbacks may be functions or methods or a mixture of both. In the latter case, an object must be passed
to the constructor. (More on that later.)
The callbacks are invoked as follows:
start( $tbl_id, $line_no, $udata );
end( $tbl_id, $line_no, $udata );
hdr( $tbl_id, $line_no, \@col_names, $udata );
row( $tbl_id, $line_no, \@data, $udata );
warn( $tbl_id, $line_no, $message, $udata );
new( $tbl_id, $udata );
Data Cleanup
There are several cleanup operations that may be performed automatically:
Chomp chomp() the data
Decode Run the data through HTML::Entities::decode.
DecodeNBSP
Normally HTML::Entitites::decode changes a non-breaking space into a character which doesn't seem
to be matched by Perl's whitespace regexp. Setting this attribute changes the HTML "nbsp"
character to a plain 'ol blank.
Trim remove leading and trailing white space.
Data Organization
Column names are derived from cells delimited by the <th> and </th> tags. Some tables have header cells
which span one or more columns or rows to make things look nice. HTML::TableParser determines the actual
number of columns used and provides column names for each column, repeating names for spanned columns and
concatenating spanned rows and columns. For example, if the table header looks like this:
+----+--------+----------+-------------+-------------------+
| | | Eq J2000 | | Velocity/Redshift |
| No | Object |----------| Object Type |-------------------|
| | | RA | Dec | | km/s | z | Qual |
+----+--------+----------+-------------+-------------------+
The columns will be:
No
Object
Eq J2000 RA
Eq J2000 Dec
Object Type
Velocity/Redshift km/s
Velocity/Redshift z
Velocity/Redshift Qual
Row data are derived from cells delimited by the <td> and </td> tags. Cells which span more than one
column or row are handled correctly, i.e. the values are duplicated in the appropriate places.
METHODS
new
$p = HTML::TableParser->new( \@reqs, \%attr );
This is the class constructor. It is passed a list of table requests as well as attributes which
specify defaults for common operations. Table requests are documented in "Table Requests".
The %attr hash provides default values for some of the table request attributes, namely the data
cleanup operations ( "Chomp", "Decode", "Trim" ), and the multi match attribute "MultiMatch",
i.e.,
$p = HTML::TableParser->new( \@reqs, { Chomp => 1 } );
will set Chomp on for all of the table requests, unless overridden by them. The data cleanup
operations are documented above; "MultiMatch" is documented in "Table Requests".
Decode defaults to on; all of the others default to off.
parse_file
This is the same function as in HTML::Parser.
parse This is the same function as in HTML::Parser.
Table Requests
A table request is a hash used by HTML::TableParser to determine which tables are to be parsed, the
callbacks to be invoked, and any data cleanup. There may be multiple requests processed by one call to
the parser; each table is associated with a single request (even if several requests match the table).
A single request may match several tables, however unless the MultiMatch attribute is specified for that
request, it will be used for the first matching table only.
A table request which matches a table id of "DEFAULT" will be used as a catch-all request, and will match
all tables not matched by other requests. Please note that tables are compared to the requests in the
order that the latter are passed to the new() method; place the DEFAULT method last for proper behavior.
Identifying tables to parse
HTML::TableParser needs to be told which tables to parse. This can be done by matching table ids or
column names, or a combination of both. The table request hash elements dedicated to this are:
id This indicates a match on table id. It can take one of these forms:
exact match
id => $match
id => '1.2'
Here $match is a scalar which is compared directly to the table id.
regular expression
id => $re
id => qr/1\.\d+\.2/
$re is a regular expression, which must be constructed with the "qr//" operator.
subroutine
id => \&my_match_subroutine
id => sub { my ( $id, $oids ) = @_ ;
$oids[0] > 3 && $oids[1] < 2 }
Here "id" is assigned a coderef to a subroutine which returns true if the table matches,
false if not. The subroutine is passed two arguments: the table id as a scalar string (
e.g. 1.2.3) and the table id as an arrayref (e.g. "$oids = [ 1, 2, 3]").
"id" may be passed an array containing any combination of the above:
id => [ '1.2', qr/1\.\d+\.2/, sub { ... } ]
Elements in the array may be preceded by a modifier indicating the action to be taken if the
table matches on that element. The modifiers and their meanings are:
"-" If the id matches, it is explicitly excluded from being processed by this request.
"--" If the id matches, it is skipped by all requests.
"+" If the id matches, it will be processed by this request. This is the default action.
An example:
id => [ '-', '1.2', 'DEFAULT' ]
indicates that this request should be used for all tables, except for table 1.2.
id => [ '--', '1.2' ]
Table 2 is just plain skipped altogether.
cols This indicates a match on column names. It can take one of these forms:
exact match
cols => $match
cols => 'Snacks01'
Here $match is a scalar which is compared directly to the column names. If any column
matches, the table is processed.
regular expression
cols => $re
cols => qr/Snacks\d+/
$re is a regular expression, which must be constructed with the "qr//" operator. Again,
a successful match against any column name causes the table to be processed.
subroutine
cols => \&my_match_subroutine
cols => sub { my ( $id, $oids, $cols ) = @_ ;
... }
Here "cols" is assigned a coderef to a subroutine which returns true if the table
matches, false if not. The subroutine is passed three arguments: the table id as a
scalar string ( e.g. 1.2.3), the table id as an arrayref (e.g. "$oids = [ 1, 2, 3]"), and
the column names, as an arrayref (e.g. "$cols = [ 'col1', 'col2' ]"). This option gives
the calling routine the ability to make arbitrary selections based upon table id and
columns.
"cols" may be passed an arrayref containing any combination of the above:
cols => [ 'Snacks01', qr/Snacks\d+/, sub { ... } ]
Elements in the array may be preceded by a modifier indicating the action to be taken if the
table matches on that element. They are the same as the table id modifiers mentioned above.
colre This is deprecated, and is present for backwards compatibility only. An arrayref containing the
regular expressions to match, or a scalar containing a single reqular expression
More than one of these may be used for a single table request. A request may match more than one table.
By default a request is used only once (even the "DEFAULT" id match!). Set the "MultiMatch" attribute to
enable multiple matches per request.
When attempting to match a table, the following steps are taken:
1. The table id is compared to the requests which contain an id match. The first such match is used
(in the order given in the passed array).
2. If no explicit id match is found, column name matches are attempted. The first such match is
used (in the order given in the passed array)
3. If no column name match is found (or there were none requested), the first request which matches
an id of "DEFAULT" is used.
Specifying the data callbacks
Callback functions are specified with the callback attributes "start", "end", "hdr", "row", and "warn".
They should be set to code references, i.e.
%table_req = ( ..., start => \&start_func, end => \&end_func )
To use methods, specify the object with the "obj" key, and the method names via the callback attributes,
which should be set to strings. If you don't specify method names they will default to (you guessed it)
"start", "end", "hdr", "row", and "warn".
$obj = SomeClass->new();
# ...
%table_req_1 = ( ..., obj => $obj );
%table_req_2 = ( ..., obj => $obj, start => 'start',
end => 'end' );
You can also have HTML::TableParser create a new object for you for each table by specifying the "class"
attribute. By default the constructor is assumed to be the class new() method; if not, specify it using
the "new" attribute:
use MyClass;
%table_req = ( ..., class => 'MyClass', new => 'mynew' );
To use a function instead of a method for a particular callback, set the callback attribute to a code
reference:
%table_req = ( ..., obj => $obj, end => \&end_func );
You don't have to provide all the callbacks. You should not use both "obj" and "class" in the same table
request.
HTML::TableParser automatically determines if your object or class has one of the required methods. If
you wish it not to use a particular method, set it equal to "undef". For example
%table_req = ( ..., obj => $obj, end => undef )
indicates the object's end method should not be called, even if it exists.
You can specify arbitrary data to be passed to the callback functions via the "udata" attribute:
%table_req = ( ..., udata => \%hash_of_my_special_stuff )
Specifying Data cleanup operations
Data cleanup operations may be specified uniquely for each table. The available keys are "Chomp",
"Decode", "Trim". They should be set to a non-zero value if the operation is to be performed.
Other Attributes
The "MultiMatch" key is used when a request is capable of handling multiple tables in the document.
Ordinarily, a request will process a single table only (even "DEFAULT" requests). Set it to a non-zero
value to allow the request to handle more than one table.
BUGS
Please report any bugs or feature requests on the bugtracker website
<https://rt.cpan.org/Public/Dist/Display.html?Name=HTML-TableParser> or by email to
bug-HTML-TableParser@rt.cpan.org <mailto:bug-HTML-TableParser@rt.cpan.org>.
When submitting a bug or request, please include a test-file or a patch to an existing test-file that
illustrates the bug or desired feature.
SOURCE
The development version is on github at <https://github.com/djerius/html-tableparser> and may be cloned
from <git://github.com/djerius/html-tableparser.git>
AUTHOR
Diab Jerius <djerius@cpan.org>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2018 by Smithsonian Astrophysical Observatory.
This is free software, licensed under:
The GNU General Public License, Version 3, June 2007