feat: Add support for PostProcessor Sequence

src/PostProcessors/PostProcessor.php

@@ -28,6 +28,7 @@ public static function fromConfig(?array $config): ?self
             'ByteLevel' => new ByteLevelPostProcessor($config),
             'TemplateProcessing' => new TemplateProcessing($config),
             'RobertaProcessing' => new RobertaProcessing($config),
+            'Sequence' => new PostProcessorSequence($config),
             default => throw new \InvalidArgumentException("Unknown post-processor type {$config['type']}"),
         };
     }

src/PostProcessors/PostProcessorSequence.php

@@ -0,0 +1,68 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Codewithkyrian\Transformers\PostProcessors;
+
+/**
+ * A post-processor that applies multiple post-processors in sequence.
+ */
+class PostProcessorSequence extends PostProcessor
+{
+
+    /**
+     * List of post-processors to apply.
+     */
+    protected array $processors;
+
+    /**
+     * Creates a new instance of PostProcessorSequence.
+     *
+     * @param array $config The configuration array.
+     *  - 'processors' (array): The list of post-processors to apply.
+     */
+    public function __construct(array $config)
+    {
+        parent::__construct($config);
+
+        $this->processors = array_map(
+            fn ($processorConfig) => PostProcessor::fromConfig($processorConfig),
+            $config['processors']
+        );
+    }
+
+    /**
+     * Post-process the given tokens.
+     *
+     * @param array $tokens The list of tokens for the first sequence.
+     * @param string[]|null $tokenPair The input tokens for the second sequence in a pair.
+     * * @param bool $addSpecialTokens Whether to add the special tokens associated with the corresponding model.
+     *
+     * @return PostProcessedOutput An array containing the post-processed tokens and token_type_ids.
+     */
+    public function postProcess(array $tokens, ?array $tokenPair = null, bool $addSpecialTokens = true): PostProcessedOutput
+    {
+        $tokenTypeIds = null;
+
+        foreach ($this->processors as $processor) {
+            if ($processor instanceof ByteLevelPostProcessor) {
+                // Special case where we need to pass the tokens_pair to the post-processor
+                $output = $processor->postProcess($tokens);
+                $tokens = $output->tokens;
+
+                if ($tokenPair !== null) {
+                    $pairOutput = $processor->postProcess($tokenPair);
+                    $tokenPair = $pairOutput->tokens;
+                }
+            } else {
+                $output = $processor->postProcess($tokens, $tokenPair, $addSpecialTokens);
+                $tokens = $output->tokens;
+                $tokenTypeIds = $output->tokenTypeIds;
+            }
+        }
+
+        return new PostProcessedOutput($tokens, $tokenTypeIds);
+    }
+}
+
+?>

src/Utils/AutoConfig.php

@@ -16,7 +16,7 @@ class AutoConfig implements ArrayAccess
 
     protected array $architectures = [];
 
-    public int $padTokenId;
+    public int|array $padTokenId;
 
     protected int $vocabSize;
 

src/Utils/GenerationConfig.php

@@ -124,8 +124,8 @@ class GenerationConfig implements \ArrayAccess
     /** @var bool Whether or not to return a `ModelOutput` instead of a plain tuple. */
     public bool $return_dict_in_generate;
 
-    /** @var int|null The id of the *padding* token. */
-    public ?int $pad_token_id;
+    /** @var int|int[]|null The id of the *padding* token. */
+    public int|array|null $pad_token_id;
 
     /** @var int|null The id of the *beginning-of-sequence* token. */
     public ?int $bos_token_id;