[Bugfix] Backend option to disable xgrammar any_whitespace (#12744)

Signed-off-by: Wallas Santos <wallashss@ibm.com>
Signed-off-by: Joe Runde <Joseph.Runde@ibm.com>
Co-authored-by: Joe Runde <Joseph.Runde@ibm.com>

tests/entrypoints/llm/test_guided_generate.py

@@ -6,6 +6,7 @@ import weakref
 
 import jsonschema
 import pytest
+from pydantic import BaseModel
 
 from vllm.distributed import cleanup_dist_env_and_memory
 from vllm.entrypoints.llm import LLM
@@ -322,3 +323,56 @@ def test_guided_json_object(llm, guided_decoding_backend: str):
             # Parse to verify it is valid JSON
             parsed_json = json.loads(generated_text)
             assert isinstance(parsed_json, dict)
+
+
+@pytest.mark.skip_global_cleanup
+def test_json_with_any_whitespace_disabled(llm):
+
+    class ResponseSchema(BaseModel):
+        clarifying_question: str
+        cost_per_serving: str
+        calories: str
+        type_dish_ids: str
+        type_meal_ids: str
+        product_ids: list[str]
+        exclude_product_ids: list[str]
+        allergen_ids: list[str]
+        total_cooking_time: str
+        kitchen_ids: str
+        holiday_ids: str
+
+    # Note: Without this setting, the response is sometimes full of `\n`
+    # for some models. This option prevents that.
+    guided_decoding_backend = 'xgrammar:disable-any-whitespace'
+
+    schema = ResponseSchema.model_json_schema()
+    guided_params = GuidedDecodingParams(json=schema,
+                                         backend=\
+                                           guided_decoding_backend)
+    sampling_params = SamplingParams(max_tokens=2000,
+                                     frequency_penalty=0,
+                                     presence_penalty=-1.1,
+                                     repetition_penalty=1.3,
+                                     guided_decoding=guided_params)
+
+    prompt = ("<|im_start|>system\nYou are Qwen, created by Alibaba Cloud. You"
+              "are a helpful assistant.<|im_end|>\n<|im_start|>user\nI want a "
+              "quick launch fast with $10.<|im_end|>\n<|im_start|>assistant\n")
+    outputs = llm.generate(prompts=prompt,
+                           sampling_params=sampling_params,
+                           use_tqdm=True)
+
+    assert outputs is not None
+
+    for output in outputs:
+        assert output is not None
+        assert isinstance(output, RequestOutput)
+
+        generated_text = output.outputs[0].text
+        assert generated_text is not None
+        assert "\n" not in generated_text
+
+        # Parse to verify it is valid JSON
+        parsed_json = json.loads(generated_text)
+        assert isinstance(parsed_json, dict)
+        jsonschema.validate(instance=parsed_json, schema=schema)