[TASK] Mark parsing-internal classes and methods as @internal

Code that uses this library is not expected to call internal parsing
functionality. Communicate this with the corresponding `@internal`
annotation.

This allows us to boldly refactor the parser code.

Part of #668

CHANGELOG.md

@@ -15,6 +15,7 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ### Changed
 
+- Mark parsing-internal classes and methods as `@internal` (#674)
 - Block installations on unsupported higher PHP versions (#691)
 - Improve performance of Value::parseValue with many delimiters by refactoring to remove array_search() (#413)
 - Add visibility to all class/interface constants (#469)

src/Parser.php

@@ -33,6 +33,8 @@ public function __construct($sText, ?Settings $oParserSettings = null, $iLineNo
      * Sets the charset to be used if the CSS does not contain an `@charset` declaration.
      *
      * @param string $sCharset
+     *
+     * @internal
      */
     public function setCharset($sCharset): void
     {
@@ -41,6 +43,8 @@ public function setCharset($sCharset): void
 
     /**
      * Returns the charset that is used if the CSS does not contain an `@charset` declaration.
+     *
+     * @internal
      */
     public function getCharset(): void
     {

src/Parsing/Anchor.php

@@ -2,6 +2,9 @@
 
 namespace Sabberworm\CSS\Parsing;
 
+/**
+ * @internal
+ */
 class Anchor
 {
     /**

src/Parsing/OutputException.php

@@ -4,6 +4,8 @@
 
 /**
  * Thrown if the CSS parser attempts to print something invalid.
+ *
+ * @internal
  */
 class OutputException extends SourceException
 {

src/Parsing/ParserState.php

@@ -5,6 +5,9 @@
 use Sabberworm\CSS\Comment\Comment;
 use Sabberworm\CSS\Settings;
 
+/**
+ * @internal
+ */
 class ParserState
 {
     /**

src/Parsing/SourceException.php

@@ -2,6 +2,9 @@
 
 namespace Sabberworm\CSS\Parsing;
 
+/**
+ * @internal
+ */
 class SourceException extends \Exception
 {
     /**

src/Parsing/UnexpectedEOFException.php

@@ -6,5 +6,7 @@
  * Thrown if the CSS parser encounters end of file it did not expect.
  *
  * Extends `UnexpectedTokenException` in order to preserve backwards compatibility.
+ *
+ * @internal
  */
 class UnexpectedEOFException extends UnexpectedTokenException {}

src/Parsing/UnexpectedTokenException.php

@@ -4,6 +4,8 @@
 
 /**
  * Thrown if the CSS parser encounters a token it did not expect.
+ *
+ * @internal
  */
 class UnexpectedTokenException extends SourceException
 {