Check the full vocab for grammar only if necessary

common/sampling.cpp

@@ -103,7 +103,8 @@ llama_token llama_sampling_sample(
                   struct llama_sampling_context * ctx_sampling,
                   struct llama_context * ctx_main,
                   struct llama_context * ctx_cfg,
-                  const int idx) {
+                  const int idx,
+                  bool is_resampling) {  // Add a parameter to indicate if we are resampling
     const llama_sampling_params & params = ctx_sampling->params;
 
     const int n_vocab = llama_n_vocab(llama_get_model(ctx_main));
@@ -128,8 +129,17 @@ llama_token llama_sampling_sample(
 
     llama_token id = 0;
 
+    // Get a pointer to the logits
     float * logits = llama_get_logits_ith(ctx_main, idx);
 
+    // Declare original_logits at the beginning of the function scope
+    std::vector<float> original_logits;
+
+    if (!is_resampling) {
+        // Only make a copy of the original logits if we are not in the resampling phase, not sure if I actually have to do this.
+        original_logits = std::vector<float>(logits, logits + llama_n_vocab(llama_get_model(ctx_main)));
+    }
+
     // apply params.logit_bias map
     for (auto it = params.logit_bias.begin(); it != params.logit_bias.end(); it++) {
         logits[it->first] += it->second;
@@ -165,7 +175,8 @@ llama_token llama_sampling_sample(
         }
     }
 
-    if (ctx_sampling->grammar != NULL) {
+    // If we are in the resampling phase, apply grammar checks before sampling logic
+    if (is_resampling && ctx_sampling->grammar != NULL) {
         llama_sample_grammar(ctx_main, &cur_p, ctx_sampling->grammar);
     }
 
@@ -212,6 +223,29 @@ llama_token llama_sampling_sample(
         }
     }
 
+    if (ctx_sampling->grammar != NULL && !is_resampling) {
+        // Create an array with a single token data element for the sampled id
+        llama_token_data single_token_data = {id, logits[id], 0.0f};
+        llama_token_data_array single_token_data_array = { &single_token_data, 1, false };
+
+        // Apply grammar constraints to the single token
+        llama_sample_grammar(ctx_main, &single_token_data_array, ctx_sampling->grammar);
+
+        // Check if the token is valid according to the grammar by seeing if its logit has been set to -INFINITY
+        bool is_valid = single_token_data_array.data[0].logit != -INFINITY;
+
+        // If the token is not valid according to the grammar, perform resampling
+        if (!is_valid) {
+            LOG("Resampling because token %d: '%s' does not meet grammar rules\n", id, llama_token_to_piece(ctx_main, id).c_str());
+
+            // Restore logits from the copy
+            std::copy(original_logits.begin(), original_logits.end(), logits);
+
+            // Recursively call llama_sampling_sample to resample with the grammar checks applied first
+            return llama_sampling_sample(ctx_sampling, ctx_main, ctx_cfg, idx, true);  // Pass true for is_resampling
+        }
+    }
+
     return id;
 }
 

common/sampling.h

@@ -92,16 +92,18 @@ std::string llama_sampling_print(const llama_sampling_params & params);
 // optional:
 //  - ctx_cfg:      context to use for classifier-free guidance
 //  - idx:          sample from llama_get_logits_ith(ctx, idx)
+//  - is_resampling: determines whether or not this is a repeated sampling operation due to the ID not matching the grammar
 //
 // returns:
 //  - token:      sampled token
 //  - candidates: vector of candidate tokens
 //
 llama_token llama_sampling_sample(
-        struct llama_sampling_context * ctx_sampling,
-        struct llama_context * ctx_main,
-        struct llama_context * ctx_cfg,
-        int idx = 0);
+    struct llama_sampling_context * ctx_sampling,
+    struct llama_context * ctx_main,
+    struct llama_context * ctx_cfg,
+    const int idx,
+    bool is_resampling = false);
 
 void llama_sampling_accept(
         struct llama_sampling_context * ctx_sampling,

examples/infill/infill.cpp

@@ -527,7 +527,7 @@ int main(int argc, char ** argv) {
 
         if ((int) embd_inp.size() <= n_consumed && !is_interacting) {
 
-            const llama_token id = llama_sampling_sample(ctx_sampling, ctx, ctx_guidance);
+            const llama_token id = llama_sampling_sample(ctx_sampling, ctx, ctx_guidance, 0, false);
 
             llama_sampling_accept(ctx_sampling, ctx, id, true);
 

examples/main/main.cpp

@@ -630,7 +630,7 @@ int main(int argc, char ** argv) {
                 LOG("saved session to %s\n", path_session.c_str());
             }
 
-            const llama_token id = llama_sampling_sample(ctx_sampling, ctx, ctx_guidance);
+            const llama_token id = llama_sampling_sample(ctx_sampling, ctx, ctx_guidance, 0, false);
 
             llama_sampling_accept(ctx_sampling, ctx, id, true);