added DRY implementation

Author: l3utterfly

llama.cpp

@@ -13233,6 +13233,90 @@ void llama_sample_min_p(struct llama_context * ctx, llama_token_data_array * can
     }
 }
 
+void llama_sample_dry(struct llama_context * ctx, llama_token_data_array * candidates, const llama_token * last_tokens, int last_tokens_size, float dry_base, float dry_multiplier, int dry_allowed_length, const llama_token * seq_breakers, int seq_breakers_size) {
+    // sanity check
+    GGML_ASSERT(last_tokens_size > 0);
+
+    // get the last token
+    auto last_token = last_tokens[last_tokens_size - 1];
+
+    // if last token is part of the sequence breakers, skip whole sampler
+    if(std::find(seq_breakers, seq_breakers + seq_breakers_size, last_token) != seq_breakers + seq_breakers_size) {
+        return;
+    }
+
+    // create an unordered map of "next tokens" <-> max match length
+    std::unordered_map<llama_token, size_t> match_lengths;
+
+    // loop through each previous token (exclude the last token)
+    for (size_t i = 0; i < last_tokens_size - 1; ++i) {
+        // skip if the compare token if it's not the same as the last token
+        if(last_tokens[i] != last_token) {
+            continue;
+        }
+
+        // get the next token (i + 1 is always less than last_tokens_size)
+        auto next_token = last_tokens[i + 1];
+
+        // try to extend the match backwards (match length starts a 1 because last token is already matched)
+        size_t match_length = 1;
+
+        // loop through the previous tokens
+        for(;; match_length++) {
+            // if we have reached the start of our last tokens, break
+            if(i < match_length) break;
+
+            // compare token starts at our prev index, going backwards by match length
+            auto compare_token = last_tokens[i - match_length];
+
+            // head token starts at the end of last tokens, going backwards by match length, minus 1 because we start at the last token itself
+            auto head_token = last_tokens[last_tokens_size - 1 - match_length];
+
+            // if compare token is part of the sequence breakers, break out of the match
+            if(std::find(seq_breakers, seq_breakers + seq_breakers_size, compare_token) != seq_breakers + seq_breakers_size)
+                break;
+
+            // break out of the match if any tokens don't match
+            if(compare_token != head_token)
+                break;
+        }
+
+        // Check if the next token exists in the map
+        auto it = match_lengths.find(next_token);
+
+        if (it == match_lengths.end()) {
+            // Key does not exist, insert the new value
+            match_lengths[next_token] = match_length;
+        } else {
+            // Key exists, update it with the max of the new value or the existing value
+            it->second = std::max(it->second, match_length);
+        }
+    }
+
+    // apply penalties
+    for (const auto& pair : match_lengths) {
+        auto next_token = pair.first;
+        auto match_length = pair.second;
+
+        // if the match length is greater than our allowed length in config, we apply penalities
+        if(match_length > dry_allowed_length) {
+
+            // find our next token in the candidates->data
+            size_t i = 0;
+            for (; i < candidates->size; ++i) {
+                if (candidates->data[i].id == next_token) {
+                    // calculate the penalty
+                    float penalty = dry_multiplier * pow(dry_base, match_length - dry_allowed_length);
+
+                    // apply the dry penalty
+                    candidates->data[i].logit -= penalty;
+                    break;
+                }
+            }
+        }
+    }
+}
+
 void llama_sample_tail_free(struct llama_context * ctx, llama_token_data_array * candidates, float z, size_t min_keep) {
     if (z >= 1.0f || candidates->size <= 2) {
         return;