Optimize isString

Signed-off-by: Kamil Tekiela <tekiela246@gmail.com>

Author: kamil-tekiela

psalm-baseline.xml

@@ -232,7 +232,6 @@
       <code><![CDATA[! $flags]]></code>
       <code><![CDATA[! $flags]]></code>
       <code><![CDATA[! $flags]]></code>
-      <code><![CDATA[! $flags]]></code>
       <code><![CDATA[Context::isComment($token)]]></code>
       <code><![CDATA[Context::isComment($token)]]></code>
       <code><![CDATA[Context::isComment($token, $end)]]></code>

src/Context.php

@@ -469,25 +469,17 @@ public static function isSymbol(string $string): int|null
     /**
      * Checks if the given character is the beginning of a string.
      *
-     * @param string $string string to be checked
+     * @param string $character a character to be checked
      *
      * @return int|null the appropriate flag for the string type
      */
-    public static function isString(string $string): int|null
+    public static function isString(string $character): int|null
     {
-        if ($string === '') {
-            return null;
-        }
-
-        if (str_starts_with($string, '\'')) {
-            return Token::FLAG_STRING_SINGLE_QUOTES;
-        }
-
-        if (str_starts_with($string, '"')) {
-            return Token::FLAG_STRING_DOUBLE_QUOTES;
-        }
-
-        return null;
+        return match ($character) {
+            '\'' => Token::FLAG_STRING_SINGLE_QUOTES,
+            '"' => Token::FLAG_STRING_DOUBLE_QUOTES,
+            default => null,
+        };
     }
 
     /**

src/Lexer.php

@@ -868,7 +868,7 @@ public function parseString(string $quote = ''): Token|null
         $token = $this->str[$this->last];
         $flags = Context::isString($token);
 
-        if (! $flags && $token !== $quote) {
+        if ($flags === null && $token !== $quote) {
             return null;
         }
 

tests/Lexer/IsMethodsTest.php

@@ -107,11 +107,8 @@ public function testIsString(): void
         $this->assertEquals(Token::FLAG_STRING_SINGLE_QUOTES, Context::isString("'"));
         $this->assertEquals(Token::FLAG_STRING_DOUBLE_QUOTES, Context::isString('"'));
 
-        $this->assertEquals(Token::FLAG_STRING_SINGLE_QUOTES, Context::isString("'foo bar'"));
-        $this->assertEquals(Token::FLAG_STRING_DOUBLE_QUOTES, Context::isString('"foo bar"'));
-
         $this->assertNull(Context::isString(''));
-        $this->assertNull(Context::isString('foo bar'));
+        $this->assertNull(Context::isString('f'));
     }
 
     public function testIsSymbol(): void