Add some optional repeat penalty. (#623)

* Add some optional repeat penalty.

* Add the missing files.

candle-transformers/src/lib.rs

@@ -1,3 +1,4 @@
 pub mod generation;
 pub mod models;
 pub mod pipelines;
+pub mod utils;

candle-transformers/src/utils.rs

@@ -0,0 +1,18 @@
+use candle::{Result, Tensor};
+
+pub fn apply_repeat_penalty(logits: &Tensor, penalty: f32, context: &[u32]) -> Result<Tensor> {
+    let device = logits.device();
+    let mut logits = logits.to_vec1::<f32>()?;
+    let context: std::collections::HashSet<_> = context.iter().collect();
+    for (token_id, logit) in logits.iter_mut().enumerate() {
+        if context.contains(&(token_id as u32)) {
+            if *logit >= 0. {
+                *logit /= penalty
+            } else {
+                *logit *= penalty
+            }
+        }
+    }
+    let logits_len = logits.len();
+    Tensor::from_vec(logits, logits_len, device)
+}