arctic_inference/vllm/structured_output.py

# Copyright 2025 Snowflake Inc.
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from vllm.logger import init_logger
from vllm.v1.structured_output.backend_xgrammar import XgrammarBackend

from arctic_inference.patching import ArcticPatch

logger = init_logger(__name__)


class XgrammarBackendPatch(ArcticPatch[XgrammarBackend]):
    """Patch for XgrammarBackend to handle additional structured output."""

    _orig_post_init = XgrammarBackend.__post_init__

    def __post_init__(self):
        self._orig_post_init()

        if self.vllm_config.speculative_config is not None:
            self.num_speculative_tokens = \
                max(self.vllm_config.speculative_config.num_speculative_tokens,
                    self.vllm_config.speculative_config.suffix_speculative_tokens)

        logger.info(f"XgrammarBackendPatch: num_speculative_tokens="
                    f"{self.num_speculative_tokens}")