feat: add preview count_tokens method to CodeGenerationModel

PiperOrigin-RevId: 575318395

Author: sararob

tests/unit/aiplatform/test_language_models.py

@@ -2771,6 +2771,43 @@ def test_code_generation_multiple_candidates(self):
             response.candidates[0].text == _TEST_CODE_GENERATION_PREDICTION["content"]
         )
 
+    def test_code_generation_preview_count_tokens(self):
+        """Tests the count_tokens method in CodeGenerationModel."""
+        aiplatform.init(
+            project=_TEST_PROJECT,
+            location=_TEST_LOCATION,
+        )
+        with mock.patch.object(
+            target=model_garden_service_client.ModelGardenServiceClient,
+            attribute="get_publisher_model",
+            return_value=gca_publisher_model.PublisherModel(
+                _CODE_COMPLETION_BISON_PUBLISHER_MODEL_DICT
+            ),
+        ):
+            model = preview_language_models.CodeGenerationModel.from_pretrained(
+                "code-gecko@001"
+            )
+
+        gca_count_tokens_response = gca_prediction_service_v1beta1.CountTokensResponse(
+            total_tokens=_TEST_COUNT_TOKENS_RESPONSE["total_tokens"],
+            total_billable_characters=_TEST_COUNT_TOKENS_RESPONSE[
+                "total_billable_characters"
+            ],
+        )
+
+        with mock.patch.object(
+            target=prediction_service_client_v1beta1.PredictionServiceClient,
+            attribute="count_tokens",
+            return_value=gca_count_tokens_response,
+        ):
+            response = model.count_tokens("def reverse_string(s):")
+
+            assert response.total_tokens == _TEST_COUNT_TOKENS_RESPONSE["total_tokens"]
+            assert (
+                response.total_billable_characters
+                == _TEST_COUNT_TOKENS_RESPONSE["total_billable_characters"]
+            )
+
     def test_code_completion(self):
         """Tests code completion with the code generation model."""
         aiplatform.init(

vertexai/language_models/_language_models.py

@@ -2648,7 +2648,47 @@ async def predict_streaming_async(
             yield _parse_text_generation_model_response(prediction_obj)
 
 
-class _PreviewCodeGenerationModel(CodeGenerationModel, _TunableModelMixin):
+class _CountTokensCodeGenerationMixin(_LanguageModel):
+    """Mixin for code generation models that support the CountTokens API"""
+
+    def count_tokens(
+        self,
+        prefix: str,
+        *,
+        suffix: Optional[str] = None,
+    ) -> CountTokensResponse:
+        """Counts the tokens and billable characters for a given code generation prompt.
+
+        Note: this does not make a prediction request to the model, it only counts the tokens
+        in the request.
+
+        Args:
+            prefix (str): Code before the current point.
+            suffix (str): Code after the current point.
+
+        Returns:
+            A `CountTokensResponse` object that contains the number of tokens
+            in the text and the number of billable characters.
+        """
+        prediction_request = {"prefix": prefix, "suffix": suffix}
+
+        count_tokens_response = self._endpoint._prediction_client.select_version(
+            "v1beta1"
+        ).count_tokens(
+            endpoint=self._endpoint_name,
+            instances=[prediction_request],
+        )
+
+        return CountTokensResponse(
+            total_tokens=count_tokens_response.total_tokens,
+            total_billable_characters=count_tokens_response.total_billable_characters,
+            _count_tokens_response=count_tokens_response,
+        )
+
+
+class _PreviewCodeGenerationModel(
+    CodeGenerationModel, _TunableModelMixin, _CountTokensCodeGenerationMixin
+):
     __name__ = "CodeGenerationModel"
     __module__ = "vertexai.preview.language_models"