49     public function hasHeader($header): bool  argument
51         return isset($this->headerNames[strtolower($header)]);
54     public function getHeader($header): array  argument
56         $header = strtolower($header);
58         if (!isset($this->headerNames[$header])) {
62         $header = $this->headerNames[$header];
64         return $this->headers[$header];
67     public function getHeaderLine($header): string  argument
69         return implode(', ', $this->getHeader($header));
72     public function withHeader($header, $value): MessageInterface  argument
74         $this->assertHeader($header);
76         $normalized = strtolower($header);
82         $new->headerNames[$normalized] = $header;
83         $new->headers[$header] = $value;
88     public function withAddedHeader($header, $value): MessageInterface  argument
90         $this->assertHeader($header);
92         $normalized = strtolower($header);
96             $header = $this->headerNames[$normalized];
97             $new->headers[$header] = array_merge($this->headers[$header], $value);
99             $new->headerNames[$normalized] = $header;
100             $new->headers[$header] = $value;
106     public function withoutHeader($header): MessageInterface  argument
108         $normalized = strtolower($header);
114         $header = $this->headerNames[$normalized];
117         unset($new->headers[$header], $new->headerNames[$normalized]);
149         foreach ($headers as $header => $value) {
151             $header = (string) $header;
153             $this->assertHeader($header);
155             $normalized = strtolower($header);
157                 $header = $this->headerNames[$normalized];
158                 $this->headers[$header] = array_merge($this->headers[$header], $value);
160                 $this->headerNames[$normalized] = $header;
161                 $this->headers[$header] = $value;
218      * @param mixed $header
220     private function assertHeader($header): void  argument
222         if (!is_string($header)) {
225                 is_object($header) ? get_class($header) : gettype($header)
229         if (!preg_match('/^[a-zA-Z0-9\'`#$%&*+.^_|~!-]+$/D', $header)) {
231                 sprintf('"%s" is not valid header name.', $header)