sglang/python/sglang/srt/layers/rotary_embedding.py

"""
Copyright 2023-2024 SGLang Team
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.
"""

"""MRotaryEmbedding"""
from typing import Any, Dict, List, Optional, Tuple, Union

import torch


class MRotaryEmbedding:
    """Rotary Embedding with Multimodal Sections."""

    @staticmethod
    def get_input_positions(
        input_tokens: List[int],
        image_grid_thw: Union[List[List[int]], torch.Tensor],
        video_grid_thw: Union[List[List[int]], torch.Tensor],
        image_token_id: int,
        video_token_id: int,
        vision_start_token_id: int,
        vision_end_token_id: int,
        spatial_merge_size: int,
        context_len: int = 0,
        extend_prefix_len: int = 0,
    ) -> Tuple[List[List[int]], int]:
        """Get mrope input positions and delta value."""

        if isinstance(image_grid_thw, torch.Tensor):
            image_grid_thw = image_grid_thw.tolist()
        if isinstance(video_grid_thw, torch.Tensor):
            video_grid_thw = video_grid_thw.tolist()

        input_tokens_tensor = torch.tensor(input_tokens)
        vision_start_indices = torch.argwhere(
            input_tokens_tensor == vision_start_token_id
        ).squeeze(1)
        vision_tokens = input_tokens_tensor[vision_start_indices + 1]
        image_nums = (vision_tokens == image_token_id).sum()
        video_nums = (vision_tokens == video_token_id).sum()
        llm_pos_ids_list: list = []

        st = 0
        remain_images, remain_videos = image_nums, video_nums

        image_index, video_index = 0, 0
        for _ in range(image_nums + video_nums):
            if image_token_id in input_tokens and remain_images > 0:
                ed_image = input_tokens.index(image_token_id, st)
            else:
                ed_image = len(input_tokens) + 1
            if video_token_id in input_tokens and remain_videos > 0:
                ed_video = input_tokens.index(video_token_id, st)
            else:
                ed_video = len(input_tokens) + 1
            if ed_image < ed_video:
                t, h, w = (
                    image_grid_thw[image_index][0],
                    image_grid_thw[image_index][1],
                    image_grid_thw[image_index][2],
                )
                image_index += 1
                remain_images -= 1
                ed = ed_image
            else:
                t, h, w = (
                    video_grid_thw[video_index][0],
                    video_grid_thw[video_index][1],
                    video_grid_thw[video_index][2],
                )
                video_index += 1
                remain_videos -= 1
                ed = ed_video
            llm_grid_t, llm_grid_h, llm_grid_w = (
                t,
                h // spatial_merge_size,
                w // spatial_merge_size,
            )
            text_len = ed - st

            st_idx = llm_pos_ids_list[-1].max() + 1 if len(llm_pos_ids_list) > 0 else 0
            llm_pos_ids_list.append(
                torch.arange(text_len).view(1, -1).expand(3, -1) + st_idx
            )

            t_index = (
                torch.arange(llm_grid_t)
                .view(-1, 1)
                .expand(-1, llm_grid_h * llm_grid_w)
                .flatten()
            )
            h_index = (
                torch.arange(llm_grid_h)
                .view(1, -1, 1)
                .expand(llm_grid_t, -1, llm_grid_w)
                .flatten()
            )
            w_index = (
                torch.arange(llm_grid_w)
                .view(1, 1, -1)
                .expand(llm_grid_t, llm_grid_h, -1)
                .flatten()
            )
            llm_pos_ids_list.append(
                torch.stack([t_index, h_index, w_index]) + text_len + st_idx
            )
            st = ed + llm_grid_t * llm_grid_h * llm_grid_w

        if st < len(input_tokens):
            st_idx = llm_pos_ids_list[-1].max() + 1 if len(llm_pos_ids_list) > 0 else 0
            text_len = len(input_tokens) - st
            llm_pos_ids_list.append(
                torch.arange(text_len).view(1, -1).expand(3, -1) + st_idx
            )

        llm_positions = torch.cat(llm_pos_ids_list, dim=1).reshape(3, -1)
        llm_positions = llm_positions[:, context_len:]
        mrope_position_delta = (llm_positions.max() + 1 - len(input_tokens)).item()
        llm_positions += extend_prefix_len

        return llm_positions.tolist(), mrope_position_delta

    @staticmethod
    def get_next_input_positions(
        mrope_position_delta: int,
        context_len: int,
        seq_len: int,
    ) -> List[List[int]]:
        return [
            list(
                range(
                    context_len + mrope_position_delta, seq_len + mrope_position_delta
                )
            )
            for _ in range(3)
        ]