targets.py

from __future__ import annotations

import torch

from model import DIV_MAP
from tokenizer import (
    PAD, RST, SIM_BEG, SIM_END, SLD_BEG, DUR, SIM_COUNT_2,
    BRK_BASE, BRK_END, HLD_BASE, HLD_END, ID_TO_DIV,
    DUR_NUM_TO_ID, DUR_DEN_TO_ID,
    SLD_BASE, SLD_END, TAP_BASE, TAP_END, TCH_BASE, TCH_END,
    CONFIG_BASE,
)

TYPE_REST = 0
TYPE_TAP = 1
TYPE_HOLD = 2
TYPE_SLIDE = 3
TYPE_BREAK = 4
TYPE_TOUCH = 5
TYPE_CONTROL = 6
NUM_TOKEN_TYPES = 7

DIV_VALUES = [1, 2, 4, 8, 16, 32, 48, 64, 128, 192, 384]
DIV_VALUE_TO_CLASS = {v: i for i, v in enumerate(DIV_VALUES)}
NUM_DIV_CLASSES = len(DIV_VALUES)


def build_aux_targets(tokens: torch.Tensor) -> dict[str, torch.Tensor]:
    """Build auxiliary labels from next-token targets.

    Args:
        tokens: [B, T] target token ids, usually chart_tokens[:, 1:].
    """
    device = tokens.device
    B, T = tokens.shape

    presence = torch.zeros(B, T, dtype=torch.long, device=device)
    token_type = torch.full((B, T), TYPE_CONTROL, dtype=torch.long, device=device)
    position = torch.full((B, T), -100, dtype=torch.long, device=device)
    division = torch.full((B, T), -100, dtype=torch.long, device=device)
    is_sim = torch.zeros(B, T, dtype=torch.long, device=device)
    needs_duration = torch.zeros(B, T, dtype=torch.long, device=device)

    is_pad = tokens == PAD
    token_type = torch.where(tokens == RST, torch.full_like(token_type, TYPE_REST), token_type)

    ranges = [
        (TAP_BASE, TAP_END, TYPE_TAP),
        (HLD_BASE, HLD_END, TYPE_HOLD),
        (SLD_BASE, SLD_END, TYPE_SLIDE),
        (BRK_BASE, BRK_END, TYPE_BREAK),
        (TCH_BASE, TCH_END, TYPE_TOUCH),
    ]
    for start, end, typ in ranges:
        mask = (tokens >= start) & (tokens < end)
        token_type = torch.where(mask, torch.full_like(token_type, typ), token_type)
        presence = torch.where(mask, torch.ones_like(presence), presence)
        position = torch.where(mask, (tokens - start) % 8, position)

    group_event = (tokens == SIM_BEG) | (tokens == SLD_BEG)
    presence = torch.where(group_event, torch.ones_like(presence), presence)
    config_event = tokens >= CONFIG_BASE
    presence = torch.where(config_event, torch.ones_like(presence), presence)
    sim_event = (tokens == SIM_BEG) | (tokens == SIM_COUNT_2) | (tokens == SIM_END)
    is_sim = torch.where(sim_event, torch.ones_like(is_sim), is_sim)
    duration_tokens = {DUR} | set(DUR_NUM_TO_ID.values()) | set(DUR_DEN_TO_ID.values())
    duration_event = torch.zeros_like(needs_duration, dtype=torch.bool)
    for tok in duration_tokens:
        duration_event |= tokens == tok
    needs_duration = torch.where(duration_event, torch.ones_like(needs_duration), needs_duration)

    for div_id, div_value in ID_TO_DIV.items():
        mask = tokens == div_id
        division = torch.where(mask, torch.full_like(division, DIV_VALUE_TO_CLASS[div_value]), division)

    token_type = torch.where(is_pad, torch.full_like(token_type, -100), token_type)
    presence = torch.where(is_pad, torch.full_like(presence, -100), presence)
    is_sim = torch.where(is_pad, torch.full_like(is_sim, -100), is_sim)
    needs_duration = torch.where(is_pad, torch.full_like(needs_duration, -100), needs_duration)

    return {
        "presence": presence,
        "type": token_type,
        "position": position,
        "division": division,
        "sim": is_sim,
        "duration": needs_duration,
    }