SimplePie::get_links( string $rel = 'alternate' ): SimplePie\array<string>|null

2810    public function get_links(string $rel = 'alternate')2811    {2812        if (!isset($this->data['links'])) {2813            $this->data['links'] = [];2814            if ($links = $this->get_channel_tags(self::NAMESPACE_ATOM_10, 'link')) {2815                foreach ($links as $link) {2816                    if (isset($link['attribs']['']['href'])) {2817                        $link_rel = (isset($link['attribs']['']['rel'])) ? $link['attribs']['']['rel'] : 'alternate';2818                        $this->data['links'][$link_rel][] = $this->sanitize($link['attribs']['']['href'], self::CONSTRUCT_IRI, $this->get_base($link));2819                    }2820                }2821            }2822            if ($links = $this->get_channel_tags(self::NAMESPACE_ATOM_03, 'link')) {2823                foreach ($links as $link) {2824                    if (isset($link['attribs']['']['href'])) {2825                        $link_rel = (isset($link['attribs']['']['rel'])) ? $link['attribs']['']['rel'] : 'alternate';2826                        $this->data['links'][$link_rel][] = $this->sanitize($link['attribs']['']['href'], self::CONSTRUCT_IRI, $this->get_base($link));2827                    }2828                }2829            }2830            if ($links = $this->get_channel_tags(self::NAMESPACE_RSS_10, 'link')) {2831                $this->data['links']['alternate'][] = $this->sanitize($links[0]['data'], self::CONSTRUCT_IRI, $this->get_base($links[0]));2832            }2833            if ($links = $this->get_channel_tags(self::NAMESPACE_RSS_090, 'link')) {2834                $this->data['links']['alternate'][] = $this->sanitize($links[0]['data'], self::CONSTRUCT_IRI, $this->get_base($links[0]));2835            }2836            if ($links = $this->get_channel_tags(self::NAMESPACE_RSS_20, 'link')) {2837                $this->data['links']['alternate'][] = $this->sanitize($links[0]['data'], self::CONSTRUCT_IRI, $this->get_base($links[0]));2838            }2839 2840            $keys = array_keys($this->data['links']);2841            foreach ($keys as $key) {2842                if ($this->registry->call(Misc::class, 'is_isegment_nz_nc', [$key])) {2843                    if (isset($this->data['links'][self::IANA_LINK_RELATIONS_REGISTRY . $key])) {2844                        $this->data['links'][self::IANA_LINK_RELATIONS_REGISTRY . $key] = array_merge($this->data['links'][$key], $this->data['links'][self::IANA_LINK_RELATIONS_REGISTRY . $key]);2845                        $this->data['links'][$key] = &$this->data['links'][self::IANA_LINK_RELATIONS_REGISTRY . $key];2846                    } else {2847                        $this->data['links'][self::IANA_LINK_RELATIONS_REGISTRY . $key] = &$this->data['links'][$key];2848                    }2849                } elseif (substr($key, 0, 41) === self::IANA_LINK_RELATIONS_REGISTRY) {2850                    $this->data['links'][substr($key, 41)] = &$this->data['links'][$key];2851                }2852                $this->data['links'][$key] = array_unique($this->data['links'][$key]);2853            }2854        }2855 2856        if (isset($this->data['headers']['link'])) {2857            $link_headers = $this->data['headers']['link'];2858            if (is_array($link_headers)) {2859                $link_headers = implode(',', $link_headers);2860            }2861            // https://datatracker.ietf.org/doc/html/rfc82882862            if (is_string($link_headers) &&2863                preg_match_all('/<(?P<uri>[^>]+)>\s*;\s*rel\s*=\s*(?P<quote>"?)' . preg_quote($rel) . '(?P=quote)\s*(?=,|$)/i', $link_headers, $matches)) {2864                return $matches['uri'];2865            }2866        }2867 2868        if (isset($this->data['links'][$rel])) {2869            return $this->data['links'][$rel];2870        }2871 2872        return null;2873    }