482 lines
15 KiB
Perl
482 lines
15 KiB
Perl
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#!/usr/bin/perl
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use strict;
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package LJ::ParseFeed;
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use XML::RSS;
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use XML::Parser;
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# parse_feed parses an RSS/Atom feed
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# arguments: content and, optionally, type, specifying "atom" or
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# "rss". If type isn't supplied, the function will try to guess it
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# based on contents.
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# It returns $feed, which is a hash
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# with the following keys:
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# type - 'atom' or 'rss'
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# version - version of the feed in its standard
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# link - URL of the feed
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# title - title of the feed
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# description - description of the feed
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# # TODO: more kinds of info?
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#
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# items - arrayref of item hashes, in the same order they were in the feed
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# each item contains:
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# link - URL of the item
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# id - unique identifier (optional)
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# text - text of the item
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# subject - subject
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# time - in format 'yyyy-mm-dd hh:mm' (optional)
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# the second argument returned is $error, which, if defined, is a human-readable
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# error string. the third argument is arrayref of items, same as
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# $feed->{'items'}.
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sub parse_feed
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{
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my ($content, $type) = @_;
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my ($feed, $items, $error);
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my $parser;
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# is it RSS or Atom?
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# Atom feeds are rare for now, so prefer to err in favor of RSS
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# simple heuristic: Atom feeds will have '<feed' somewhere at the beginning
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# TODO: maybe store the feed's type on creation in a userprop and not guess here
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my $cut = substr($content, 0, 255);
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if ($type eq 'atom' || $cut =~ m!\<feed!) {
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# try treating it as an atom feed
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$parser = new XML::Parser(Style=>'Stream', Pkg=>'LJ::ParseFeed::Atom');
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return ("", "failed to create XML parser") unless $parser;
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eval {
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$parser->parse($content);
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};
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if ($@) {
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$error = "XML parser error: $@";
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} else {
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($feed, $items, $error) = LJ::ParseFeed::Atom::results();
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};
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if ($feed || $type eq 'atom') {
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# there was a top-level <feed> there, or we're forced to treat
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# as an Atom feed, so even if $error is set,
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# don't try RSS
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$feed->{'type'} = 'atom';
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return ($feed, $error, $items);
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}
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}
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# try parsing it as RSS
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$parser = new XML::RSS;
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return ("", "failed to create RSS parser") unless $parser;
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eval {
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$parser->parse($content);
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};
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if ($@) {
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$error = "RSS parser error: $@";
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return ("", $error);
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}
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$feed = {};
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$feed->{'type'} = 'rss';
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$feed->{'version'} = $parser->{'version'};
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foreach (qw (link title description)) {
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$feed->{$_} = $parser->{'channel'}->{$_}
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if $parser->{'channel'}->{$_};
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}
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$feed->{'items'} = [];
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foreach(@{$parser->{'items'}}) {
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my $item = {};
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$item->{'subject'} = $_->{'title'};
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$item->{'text'} = $_->{'description'};
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$item->{'link'} = $_->{'link'} if $_->{'link'};
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$item->{'id'} = $_->{'guid'} if $_->{'guid'};
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my $nsdc = 'http://purl.org/dc/elements/1.1/';
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my $nsenc = 'http://purl.org/rss/1.0/modules/content/';
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if ($_->{$nsenc} && ref($_->{$nsenc}) eq "HASH") {
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# prefer content:encoded if present
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$item->{'text'} = $_->{$nsenc}->{'encoded'}
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if defined $_->{$nsenc}->{'encoded'};
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}
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if ($_->{'pubDate'}) {
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my $time = time822_to_time($_->{'pubDate'});
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$item->{'time'} = $time if $time;
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}
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if ($_->{$nsdc} && ref($_->{$nsdc}) eq "HASH") {
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if ($_->{$nsdc}->{date}) {
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my $time = w3cdtf_to_time($_->{$nsdc}->{date});
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$item->{'time'} = $time if $time;
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}
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}
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push @{$feed->{'items'}}, $item;
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}
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return ($feed, undef, $feed->{'items'});
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}
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# convert rfc822-time in RSS's <pubDate> to our time
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# see http://www.faqs.org/rfcs/rfc822.html
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# RFC822 specifies 2 digits for year, and RSS2.0 refers to RFC822,
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# but real RSS2.0 feeds apparently use 4 digits.
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sub time822_to_time {
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my $t822 = shift;
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# remove day name if present
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$t822 =~ s/^\s*\w+\s*,//;
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# remove whitespace
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$t822 =~ s/^\s*//;
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# break it up
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if ($t822 =~ m!(\d?\d)\s+(\w+)\s+(\d\d\d\d)\s+(\d?\d):(\d\d)!) {
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my ($day, $mon, $year, $hour, $min) = ($1,$2,$3,$4,$5);
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$day = "0" . $day if length($day) == 1;
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$hour = "0" . $hour if length($hour) == 1;
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$mon = {'Jan'=>'01', 'Feb'=>'02', 'Mar'=>'03', 'Apr'=>'04',
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'May'=>'05', 'Jun'=>'06', 'Jul'=>'07', 'Aug'=>'08',
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'Sep'=>'09', 'Oct'=>'10', 'Nov'=>'11', 'Dec'=>'12'}->{$mon};
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return undef unless $mon;
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return "$year-$mon-$day $hour:$min";
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} else {
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return undef;
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}
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}
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# convert W3C-DTF to our internal format
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# see http://www.w3.org/TR/NOTE-datetime
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# Based very loosely on code from DateTime::Format::W3CDTF,
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# which isn't stable yet so we can't use it directly.
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sub w3cdtf_to_time {
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my $tw3 = shift;
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# TODO: Should somehow return the timezone offset
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# so that it can stored... but we don't do timezones
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# yet anyway. For now, just strip the timezone
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# portion if it is present, along with the decimal
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# fractions of a second.
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$tw3 =~ s/(?:\.\d+)?(?:[+-]\d{1,2}:\d{1,2}|Z)$//;
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$tw3 =~ s/^\s*//; $tw3 =~ s/\s*$//; # Eat any superflous whitespace
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# We can only use complete times, so anything which
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# doesn't feature the time part is considered invalid.
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# This is working around clients that don't implement W3C-DTF
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# correctly, and only send single digit values in the dates.
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# 2004-4-8T16:9:4Z vs 2004-04-08T16:09:44Z
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# If it's more messed up than that, reject it outright.
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$tw3 =~ /^(\d{4})-(\d{1,2})-(\d{1,2})T(\d{1,2}):(\d{1,2})(?::(\d{1,2}))?$/
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or return undef;
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my %pd; # parsed date
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$pd{Y} = $1; $pd{M} = $2; $pd{D} = $3;
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$pd{h} = $4; $pd{m} = $5; $pd{s} = $6;
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# force double digits
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foreach (qw/ M D h m s /) {
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next unless defined $pd{$_};
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$pd{$_} = sprintf "%02d", $pd{$_};
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}
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return $pd{s} ? "$pd{Y}-$pd{M}-$pd{D} $pd{h}:$pd{m}:$pd{s}" :
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"$pd{Y}-$pd{M}-$pd{D} $pd{h}:$pd{m}";
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}
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package LJ::ParseFeed::Atom;
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our ($feed, $item, $data);
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our ($ddepth, $dholder); # for accumulating;
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our @items;
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our $error;
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sub err {
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$error = shift unless $error;
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}
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sub results {
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return ($feed, \@items, $error);
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}
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# $name under which we'll store accumulated data may be different
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# from $tag which causes us to store it
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# $name may be a scalarref pointing to where we should store
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# swallowing is achieved by calling startaccum('');
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sub startaccum {
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my $name = shift;
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return err("Tag found under neither <feed> nor <entry>")
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unless $feed || $item;
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$data = ""; # defining $data triggers accumulation
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$ddepth = 1;
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$dholder = undef
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unless $name;
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# if $name is a scalarref, it's actually our $dholder
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if (ref($name) eq 'SCALAR') {
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$dholder = $name;
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} else {
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$dholder = ($item ? \$item->{$name} : \$feed->{$name})
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if $name;
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}
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return;
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}
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sub swallow {
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return startaccum('');
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}
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sub StartDocument {
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($feed, $item, $data) = (undef, undef, undef);
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@items = ();
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undef $error;
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}
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sub StartTag {
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# $_ carries the unparsed tag
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my ($p, $tag) = @_;
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my $holder;
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# do nothing if there has been an error
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return if $error;
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# are we just accumulating data?
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if (defined $data) {
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$data .= $_;
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$ddepth++;
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return;
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}
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# where we'll usually store info
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$holder = $item ? $item : $feed;
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TAGS: {
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if ($tag eq 'feed') {
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return err("Nested <feed> tags")
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if $feed;
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$feed = {};
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$feed->{'standard'} = 'atom';
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$feed->{'version'} = $_{'version'};
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return err("No version specified in <feed>")
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unless $feed->{'version'};
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return err("Incompatible version specified in <feed>")
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unless $feed->{'version'} eq '0.3';
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last TAGS;
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}
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if ($tag eq 'entry') {
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return err("Nested <entry> tags")
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if $item;
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$item = {};
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last TAGS;
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}
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# at this point, we must have a top-level <feed> or <entry>
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# to write into
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return err("Tag found under neither <feed> nor <entry>")
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unless $holder;
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if ($tag eq 'link') {
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# ignore links with rel= anything but alternate
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unless ($_{'rel'} eq 'alternate') {
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swallow();
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last TAGS;
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}
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$holder->{'link'} = $_{'href'};
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return err("No href attribute in <link>")
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unless $holder->{'link'};
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last TAGS;
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}
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if ($tag eq 'content') {
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return err("<content> outside <entry>")
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unless $item;
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# if type is multipart/alternative, we continue recursing
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# otherwise we accumulate
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my $type = $_{'type'} || "text/plain";
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unless ($type eq "multipart/alternative") {
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push @{$item->{'contents'}}, [$type, ""];
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startaccum(\$item->{'contents'}->[-1]->[1]);
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last TAGS;
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}
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# it's multipart/alternative, so recurse, but don't swallow
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last TAGS;
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}
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# store tags which should require no further
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# processing as they are, and others under _atom_*, to be processed
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# in EndTag under </entry>
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if ($tag eq 'title') {
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if ($item) { # entry's subject
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startaccum("subject");
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} else { # feed's title
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startaccum($tag);
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}
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last TAGS;
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}
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if ($tag eq 'id') {
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unless ($item) {
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swallow(); # we don't need feed-level <id>
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} else {
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startaccum($tag);
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}
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last TAGS;
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}
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if ($tag eq 'tagline' && !$item) { # feed's tagline, our "description"
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startaccum("description");
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last TAGS;
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}
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# accumulate and store
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startaccum("_atom_" . $tag);
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last TAGS;
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}
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return;
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}
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sub EndTag {
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# $_ carries the unparsed tag
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my ($p, $tag) = @_;
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# do nothing if there has been an error
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return if $error;
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# are we accumulating data?
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if (defined $data) {
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$ddepth--;
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if ($ddepth == 0) { # stop accumulating
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$$dholder = $data
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if $dholder;
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undef $data;
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return;
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}
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$data .= $_;
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return;
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}
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TAGS: {
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if ($tag eq 'entry') {
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# finalize item...
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# generate suitable text from $item->{'contents'}
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my $content;
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$item->{'contents'} ||= [];
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unless (scalar(@{$item->{'contents'}}) >= 1) {
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# this item had no <content>
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# maybe it has <summary>? if so, use <summary>
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# TODO: type= or encoding issues here? perhaps unite
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# handling of <summary> with that of <content>?
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if ($item->{'_atom_summary'}) {
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$item->{'text'} = $item->{'_atom_summary'};
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delete $item->{'contents'};
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} else {
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# nothing to display, so ignore this entry
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undef $item;
|
||
|
|
last TAGS;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
unless ($item->{'text'}) { # unless we already have text
|
||
|
|
if (scalar(@{$item->{'contents'}}) == 1) {
|
||
|
|
# only one <content> section
|
||
|
|
$content = $item->{'contents'}->[0];
|
||
|
|
} else {
|
||
|
|
# several <content> section, must choose the best one
|
||
|
|
foreach (@{$item->{'contents'}}) {
|
||
|
|
if ($_->[0] eq "application/xhtml+xml") { # best match
|
||
|
|
$content = $_;
|
||
|
|
last; # don't bother to look at others
|
||
|
|
}
|
||
|
|
if ($_->[0] =~ m!html!) { # some kind of html/xhtml/html+xml, etc.
|
||
|
|
# choose this unless we've already chosen some html
|
||
|
|
$content = $_
|
||
|
|
unless $content->[0] =~ m!html!;
|
||
|
|
next;
|
||
|
|
}
|
||
|
|
if ($_->[0] eq "text/plain") {
|
||
|
|
# choose this unless we have some html already
|
||
|
|
$content = $_
|
||
|
|
unless $content->[0] =~ m!html!;
|
||
|
|
next;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
# if we didn't choose anything, pick the first one
|
||
|
|
$content = $item->{'contents'}->[0]
|
||
|
|
unless $content;
|
||
|
|
}
|
||
|
|
|
||
|
|
# we ignore the 'mode' attribute of <content>. If it's "xml", we've
|
||
|
|
# stringified it by accumulation; if it's "escaped", our parser
|
||
|
|
# unescaped it
|
||
|
|
# TODO: handle mode=base64?
|
||
|
|
|
||
|
|
$item->{'text'} = $content->[1];
|
||
|
|
delete $item->{'contents'};
|
||
|
|
}
|
||
|
|
|
||
|
|
# generate time
|
||
|
|
my $w3time = $item->{'_atom_modified'} || $item->{'_atom_created'};
|
||
|
|
my $time;
|
||
|
|
if ($w3time) {
|
||
|
|
# see http://www.w3.org/TR/NOTE-datetime for format
|
||
|
|
# we insist on having granularity up to a minute,
|
||
|
|
# and ignore finer data as well as the timezone, for now
|
||
|
|
if ($w3time =~ m!^(\d\d\d\d)-(\d\d)-(\d\d)T(\d\d):(\d\d)!) {
|
||
|
|
$time = "$1-$2-$3 $4:$5";
|
||
|
|
}
|
||
|
|
}
|
||
|
|
if ($time) {
|
||
|
|
$item->{'time'} = $time;
|
||
|
|
}
|
||
|
|
|
||
|
|
# get rid of all other tags we don't need anymore
|
||
|
|
foreach (keys %$item) {
|
||
|
|
delete $item->{$_} if substr($_, 0, 6) eq '_atom_';
|
||
|
|
}
|
||
|
|
|
||
|
|
push @items, $item;
|
||
|
|
undef $item;
|
||
|
|
last TAGS;
|
||
|
|
}
|
||
|
|
if ($tag eq 'feed') {
|
||
|
|
# finalize feed
|
||
|
|
# get rid of all other tags we don't need anymore
|
||
|
|
foreach (keys %$feed) {
|
||
|
|
delete $feed->{$_} if substr($_, 0, 6) eq '_atom_';
|
||
|
|
}
|
||
|
|
|
||
|
|
# link the feed with its itms
|
||
|
|
$feed->{'items'} = \@items
|
||
|
|
if $feed;
|
||
|
|
last TAGS;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
sub Text {
|
||
|
|
my $p = shift;
|
||
|
|
|
||
|
|
# do nothing if there has been an error
|
||
|
|
return if $error;
|
||
|
|
|
||
|
|
$data .= $_ if defined $data;
|
||
|
|
}
|
||
|
|
|
||
|
|
sub PI {
|
||
|
|
# ignore processing instructions
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
sub EndDocument {
|
||
|
|
# if we parsed a feed, link items to it
|
||
|
|
$feed->{'items'} = \@items
|
||
|
|
if $feed;
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
1;
|