import torch.nn as nn
import torch.nn.functional as F

try:
    from flash_attn.ops.activations import swiglu as flash_swiglu
except ImportError:
    flash_swiglu = None

if flash_swiglu is None:
    # PyTorch implementation of SwiGLU
    class SwiGLU(nn.Module):
        def forward(self, x):
            x, gate = x.chunk(2, dim=-1)
            return F.silu(gate) * x

    def swiglu(x):
        layer = SwiGLU()
        return layer(x)

else:
    # Use Flash Attention's built-in swiglu
    def swiglu(x):
        return flash_swiglu(x)