Refactor sliding window configuration to Transformers best practice (#21927)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

vllm/model_executor/models/exaone4.py

@@ -159,25 +159,12 @@ class Exaone4Attention(nn.Module):
         if quant_config is not None and quant_config.get_name() == "gguf":
             is_neox_style = False
 
-        self.apply_all_layers = False  # apply rotary embeddings to every layer.
         layer_idx = extract_layer_index(prefix)
-        interleaved_sliding_window = getattr(config,
-                                             "interleaved_sliding_window",
-                                             4096)
-        sliding_window_pattern = getattr(config, "sliding_window_pattern",
-                                         "LLLG")
+        is_sliding = config.layer_types[layer_idx] == "sliding_attention"
+        self.sliding_window = config.sliding_window if is_sliding else None
 
-        if sliding_window_pattern:
-            layer_has_sliding_window = (
-                layer_idx + 1) % sliding_window_pattern.__len__() != 0
-        else:
-            layer_has_sliding_window = False
-            self.apply_all_layers = True
-
-        if layer_has_sliding_window:
-            self.sliding_window = interleaved_sliding_window
-        else:
-            self.sliding_window = None
+        # apply rotary embeddings to every layer
+        self.apply_all_layers = not is_sliding
 
         self.rotary_emb = get_rope(
             self.head_dim,