Add locale-independent lowercasing

src/LowercaseTrait.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Nyholm\Psr7;
+
+/**
+ * Trait implementing a locale-independent lowercasing logic.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @internal should not be used outside of Nyholm/Psr7 as it does not fall under our BC promise
+ */
+trait LowercaseTrait
+{
+    private static function lowercase(string $value): string
+    {
+        return strtr($value, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz');
+    }
+}

src/MessageTrait.php

@@ -17,6 +17,8 @@
  */
 trait MessageTrait
 {
+    use LowercaseTrait;
+
     /** @var array Map of all registered headers, as original name => array of values */
     private $headers = [];
 
@@ -53,12 +55,12 @@ public function getHeaders(): array
 
     public function hasHeader($header): bool
     {
-        return isset($this->headerNames[\strtolower($header)]);
+        return isset($this->headerNames[self::lowercase($header)]);
     }
 
     public function getHeader($header): array
     {
-        $header = \strtolower($header);
+        $header = self::lowercase($header);
         if (!isset($this->headerNames[$header])) {
             return [];
         }
@@ -76,7 +78,7 @@ public function getHeaderLine($header): string
     public function withHeader($header, $value): self
     {
         $value = $this->validateAndTrimHeader($header, $value);
-        $normalized = \strtolower($header);
+        $normalized = self::lowercase($header);
 
         $new = clone $this;
         if (isset($new->headerNames[$normalized])) {
@@ -102,7 +104,7 @@ public function withAddedHeader($header, $value): self
 
     public function withoutHeader($header): self
     {
-        $normalized = \strtolower($header);
+        $normalized = self::lowercase($header);
         if (!isset($this->headerNames[$normalized])) {
             return $this;
         }
@@ -139,7 +141,7 @@ private function setHeaders(array $headers): void
     {
         foreach ($headers as $header => $value) {
             $value = $this->validateAndTrimHeader($header, $value);
-            $normalized = \strtolower($header);
+            $normalized = self::lowercase($header);
             if (isset($this->headerNames[$normalized])) {
                 $header = $this->headerNames[$normalized];
                 $this->headers[$header] = \array_merge($this->headers[$header], $value);

src/Uri.php

@@ -17,6 +17,8 @@
  */
 final class Uri implements UriInterface
 {
+    use LowercaseTrait;
+
     private const SCHEMES = ['http' => 80, 'https' => 443];
 
     private const CHAR_UNRESERVED = 'a-zA-Z0-9_\-\.~';
@@ -52,9 +54,9 @@ public function __construct(string $uri = '')
             }
 
             // Apply parse_url parts to a URI.
-            $this->scheme = isset($parts['scheme']) ? \strtolower($parts['scheme']) : '';
+            $this->scheme = isset($parts['scheme']) ? self::lowercase($parts['scheme']) : '';
             $this->userInfo = $parts['user'] ?? '';
-            $this->host = isset($parts['host']) ? \strtolower($parts['host']) : '';
+            $this->host = isset($parts['host']) ? self::lowercase($parts['host']) : '';
             $this->port = isset($parts['port']) ? $this->filterPort($parts['port']) : null;
             $this->path = isset($parts['path']) ? $this->filterPath($parts['path']) : '';
             $this->query = isset($parts['query']) ? $this->filterQueryAndFragment($parts['query']) : '';
@@ -129,7 +131,7 @@ public function withScheme($scheme): self
             throw new \InvalidArgumentException('Scheme must be a string');
         }
 
-        if ($this->scheme === $scheme = \strtolower($scheme)) {
+        if ($this->scheme === $scheme = self::lowercase($scheme)) {
             return $this;
         }
 
@@ -163,7 +165,7 @@ public function withHost($host): self
             throw new \InvalidArgumentException('Host must be a string');
         }
 
-        if ($this->host === $host = \strtolower($host)) {
+        if ($this->host === $host = self::lowercase($host)) {
             return $this;
         }