Compute token offsets once instead of rescanning from the first token

src/Parser/TokenIterator.php

@@ -31,6 +31,9 @@ class TokenIterator
 
 	private ?string $newline = null;
 
+	/** @var list<int>|null */
+	private ?array $offsets = null;
+
 	/**
 	 * @param list<array{string, int, int}> $tokens
 	 */
@@ -81,12 +84,16 @@ public function currentTokenType(): int
 
 	public function currentTokenOffset(): int
 	{
-		$offset = 0;
-		for ($i = 0; $i < $this->index; $i++) {
-			$offset += strlen($this->tokens[$i][Lexer::VALUE_OFFSET]);
+		if ($this->offsets === null) {
+			$offset = 0;
+			$this->offsets = [];
+			foreach ($this->tokens as $token) {
+				$this->offsets[] = $offset;
+				$offset += strlen($token[Lexer::VALUE_OFFSET]);
+			}
 		}
 
-		return $offset;
+		return $this->offsets[$this->index];
 	}
 
 	public function currentTokenLine(): int

tests/PHPStan/Parser/TokenIteratorTest.php

@@ -5,6 +5,8 @@
 use PHPStan\PhpDocParser\Lexer\Lexer;
 use PHPStan\PhpDocParser\ParserConfig;
 use PHPUnit\Framework\TestCase;
+use function strlen;
+use function substr;
 use const PHP_EOL;
 
 class TokenIteratorTest extends TestCase
@@ -57,4 +59,19 @@ public function testGetDetectedNewline(string $phpDoc, ?string $expectedNewline)
 		$this->assertSame($expectedNewline, $tokens->getDetectedNewline());
 	}
 
+	public function testCurrentTokenOffset(): void
+	{
+		$lexer = new Lexer(new ParserConfig([]));
+		$phpDoc = "/**\n * @param array{size?: 'sm'|'md', icon: Icon} \$a\n */";
+		$tokens = new TokenIterator($lexer->tokenize($phpDoc));
+
+		do {
+			$this->assertSame($tokens->currentTokenValue(), substr($phpDoc, $tokens->currentTokenOffset(), strlen($tokens->currentTokenValue())));
+			$this->assertSame(strlen($tokens->getContentBetween(0, $tokens->currentTokenIndex())), $tokens->currentTokenOffset());
+			$tokens->next();
+		} while (!$tokens->isCurrentTokenType(Lexer::TOKEN_END));
+
+		$this->assertSame(strlen($phpDoc), $tokens->currentTokenOffset());
+	}
+
 }