Add score_batch to Generator

build.rs

@@ -1,6 +1,6 @@
 // build.rs
 //
-// Copyright (c) 2023-2024 Junpei Kawamoto
+// Copyright (c) 2023-2025 Junpei Kawamoto
 //
 // This software is released under the MIT License.
 //
@@ -106,6 +106,7 @@ fn main() {
     cxx_build::bridges([
         "src/sys/types.rs",
         "src/sys/config.rs",
+        "src/sys/scoring.rs",
         "src/sys/translator.rs",
         "src/sys/generator.rs",
         "src/sys/storage_view.rs",

examples/gpt-2.rs

@@ -1,6 +1,6 @@
 // gpt-2.rs
 //
-// Copyright (c) 2023-2024 Junpei Kawamoto
+// Copyright (c) 2023-2025 Junpei Kawamoto
 //
 // This software is released under the MIT License.
 //
@@ -42,7 +42,7 @@ use std::time;
 use anyhow::Result;
 use clap::Parser;
 
-use ct2rs::{Config, Device, GenerationOptions, Generator};
+use ct2rs::{Config, Device, GenerationOptions, Generator, ScoringOptions};
 
 /// Generate text using GPT-2 models.
 #[derive(Parser, Debug)]
@@ -83,7 +83,7 @@ fn main() -> Result<()> {
 
     let now = time::Instant::now();
     let res = g.generate_batch(
-        &[prompts],
+        &[prompts.clone()],
         &GenerationOptions {
             max_length: 30,
             sampling_topk: 10,
@@ -98,5 +98,9 @@ fn main() -> Result<()> {
     }
     println!("Time taken: {elapsed:?}");
 
+    // Scoring the prompts.
+    let scores = g.score_batch(&[prompts], &ScoringOptions::default())?;
+    println!("{:?}", scores[0]);
+
     Ok(())
 }

include/generator.h

@@ -1,6 +1,6 @@
 // generator.h
 //
-// Copyright (c) 2023-2024 Junpei Kawamoto
+// Copyright (c) 2023-2025 Junpei Kawamoto
 //
 // This software is released under the MIT License.
 //
@@ -21,6 +21,8 @@ struct GenerationOptions;
 struct GenerationResult;
 struct GenerationStepResult;
 struct GenerationCallbackBox;
+struct ScoringOptions;
+struct ScoringResult;
 
 class Generator {
 private:
@@ -37,6 +39,11 @@ class Generator {
         GenerationCallbackBox& callback
     ) const;
 
+    rust::Vec<ScoringResult> score_batch(
+        const rust::Vec<VecStr>& tokens,
+        const ScoringOptions& options
+    ) const;
+
     inline size_t num_queued_batches() const {
         return this->impl->num_queued_batches();
     }

src/generator.rs

@@ -1,6 +1,6 @@
 // generator.rs
 //
-// Copyright (c) 2023-2024 Junpei Kawamoto
+// Copyright (c) 2023-2025 Junpei Kawamoto
 //
 // This software is released under the MIT License.
 //
@@ -17,7 +17,7 @@ pub use sys::GenerationOptions;
 
 use crate::tokenizer::encode_all;
 
-use super::{sys, Config, GenerationStepResult, Tokenizer};
+use super::{sys, Config, GenerationStepResult, ScoringOptions, ScoringResult, Tokenizer};
 
 /// A text generator with a tokenizer.
 ///
@@ -110,7 +110,7 @@ impl<T: Tokenizer> Generator<T> {
     /// occurs during initialization, the function will return an error wrapped in the `Result`.
     ///
     /// # Example
-    /// The following example creates a translator instance with the tokenizer provided by
+    /// The following example creates a generator instance with the tokenizer provided by
     /// [tokenizers](https://huggingface.co/docs/tokenizers).
     ///
     /// ```no_run
@@ -213,6 +213,29 @@ impl<T: Tokenizer> Generator<T> {
         Ok(res)
     }
 
+    /// Scores a batch of tokens.
+    ///
+    /// # Arguments
+    /// * `tokens` - Batch of strings to score.
+    ///   If the model expects special start or end tokens, they should also be added to this input.
+    /// * `options` - Settings applied to the scoring process.
+    ///
+    /// # Returns
+    /// Returns a `Result` containing a vector of `ScoringResult` if successful,
+    /// or an error if the generation fails.
+    ///
+    pub fn score_batch<U>(
+        &self,
+        prompts: &[U],
+        options: &ScoringOptions,
+    ) -> Result<Vec<ScoringResult>>
+    where
+        U: AsRef<str>,
+    {
+        self.generator
+            .score_batch(&encode_all(&self.tokenizer, prompts)?, options)
+    }
+
     /// Number of batches in the work queue.
     #[inline]
     pub fn num_queued_batches(&self) -> anyhow::Result<usize> {
@@ -242,16 +265,16 @@ impl<T: Tokenizer> Debug for Generator<T> {
 #[cfg(feature = "hub")]
 mod tests {
     use super::Generator;
+    use crate::tokenizers::auto::Tokenizer;
     use crate::{download_model, Config, Device, GenerationOptions};
+    use anyhow::Result;
+    use std::path::PathBuf;
 
     const MODEL_ID: &str = "jkawamoto/gpt2-ct2";
 
-    #[test]
-    #[ignore]
-    fn test_generate() {
-        let model_path = download_model(MODEL_ID).unwrap();
-        let g = Generator::new(
-            &model_path,
+    fn new_generator(model_path: &PathBuf) -> Result<Generator<Tokenizer>> {
+        Generator::new(
+            model_path,
             &Config {
                 device: if cfg!(feature = "cuda") {
                     Device::CUDA
@@ -261,7 +284,13 @@ mod tests {
                 ..Default::default()
             },
         )
-        .unwrap();
+    }
+
+    #[test]
+    #[ignore]
+    fn test_generate() {
+        let model_path = download_model(MODEL_ID).unwrap();
+        let g = new_generator(&model_path).unwrap();
 
         let prompt = "CTranslate2 is a library";
         let res = g
@@ -278,22 +307,30 @@ mod tests {
         assert!(res[0].0[0].starts_with(prompt));
     }
 
+    #[test]
+    #[ignore]
+    fn test_scoring() {
+        let model_path = download_model(MODEL_ID).unwrap();
+        let g = new_generator(&model_path).unwrap();
+
+        let prompt = "CTranslate2 is a library";
+        let res = g.score_batch(&[prompt], &Default::default()).unwrap();
+
+        assert_eq!(
+            res[0].tokens,
+            vec!["Trans", "late", "2", "Ġis", "Ġa", "Ġlibrary"]
+                .iter()
+                .map(|s| s.to_string())
+                .collect::<Vec<String>>()
+        );
+        assert_ne!(res[0].normalized_score(), 0.0);
+    }
+
     #[test]
     #[ignore]
     fn test_generator_debug() {
         let model_path = download_model(MODEL_ID).unwrap();
-        let g = Generator::new(
-            &model_path,
-            &Config {
-                device: if cfg!(feature = "cuda") {
-                    Device::CUDA
-                } else {
-                    Device::CPU
-                },
-                ..Default::default()
-            },
-        )
-        .unwrap();
+        let g = new_generator(&model_path).unwrap();
 
         assert!(format!("{:?}", g).contains(model_path.file_name().unwrap().to_str().unwrap()));
     }

src/lib.rs

@@ -1,6 +1,6 @@
 // lib.rs
 //
-// Copyright (c) 2023-2024 Junpei Kawamoto
+// Copyright (c) 2023-2025 Junpei Kawamoto
 //
 // This software is released under the MIT License.
 //
@@ -80,7 +80,10 @@ pub use generator::{GenerationOptions, Generator};
 #[cfg_attr(docsrs, doc(cfg(feature = "hub")))]
 pub use hub::download_model;
 pub use result::GenerationStepResult;
-pub use sys::{set_log_level, set_random_seed, BatchType, ComputeType, Config, Device, LogLevel};
+pub use sys::{
+    set_log_level, set_random_seed, BatchType, ComputeType, Config, Device, LogLevel,
+    ScoringOptions, ScoringResult,
+};
 pub use tokenizer::Tokenizer;
 pub use translator::{TranslationOptions, Translator};
 #[cfg(feature = "whisper")]

src/sys.rs

@@ -1,6 +1,6 @@
 // sys.rs
 //
-// Copyright (c) 2023-2024 Junpei Kawamoto
+// Copyright (c) 2023-2025 Junpei Kawamoto
 //
 // This software is released under the MIT License.
 //
@@ -47,13 +47,15 @@
 
 pub use config::*;
 pub use generator::*;
+pub use scoring::*;
 pub use storage_view::*;
 pub use translator::*;
 pub use types::*;
 pub use whisper::*;
 
 mod config;
 mod generator;
+mod scoring;
 mod storage_view;
 mod translator;
 mod types;

src/sys/generator.cpp

@@ -1,6 +1,6 @@
 // generator.cpp
 //
-// Copyright (c) 2023-2024 Junpei Kawamoto
+// Copyright (c) 2023-2025 Junpei Kawamoto
 //
 // This software is released under the MIT License.
 //
@@ -97,3 +97,30 @@ Generator::generate_batch(
 
     return res;
 }
+
+Vec<ScoringResult>
+Generator::score_batch(
+    const Vec<VecStr>& tokens,
+    const ScoringOptions& options
+) const {
+    auto futures = this->impl->score_batch_async(
+        from_rust(tokens),
+        ctranslate2::ScoringOptions {
+            options.max_input_length,
+            options.offset,
+        },
+        options.max_batch_size,
+        options.batch_type
+    );
+
+    Vec<ScoringResult> res;
+    for (auto& future : futures) {
+        const auto& r = future.get();
+        res.push_back(ScoringResult {
+            to_rust(r.tokens),
+            to_rust(r.tokens_score),
+        });
+    }
+
+    return res;
+}

src/sys/generator.rs

@@ -1,6 +1,6 @@
 // generator.rs
 //
-// Copyright (c) 2023-2024 Junpei Kawamoto
+// Copyright (c) 2023-2025 Junpei Kawamoto
 //
 // This software is released under the MIT License.
 //
@@ -17,7 +17,8 @@ use anyhow::{anyhow, Error, Result};
 use cxx::UniquePtr;
 
 use super::{
-    config, vec_ffi_vecstr, BatchType, Config, GenerationStepResult, VecStr, VecString, VecUSize,
+    config, vec_ffi_vecstr, BatchType, Config, GenerationStepResult, ScoringOptions, ScoringResult,
+    VecStr, VecString, VecUSize,
 };
 
 trait GenerationCallback {
@@ -93,6 +94,7 @@ mod ffi {
     unsafe extern "C++" {
         include!("ct2rs/include/generator.h");
         include!("ct2rs/src/sys/types.rs.h");
+        include!("ct2rs/src/sys/scoring.rs.h");
 
         type VecString = super::VecString;
         type VecStr<'a> = super::VecStr<'a>;
@@ -102,6 +104,9 @@ mod ffi {
         type BatchType = super::BatchType;
         type GenerationStepResult = super::GenerationStepResult;
 
+        type ScoringOptions = super::ScoringOptions;
+        type ScoringResult = super::ScoringResult;
+
         type Generator;
 
         fn generator(model_path: &str, config: UniquePtr<Config>) -> Result<UniquePtr<Generator>>;
@@ -114,6 +119,12 @@ mod ffi {
             callback: &mut GenerationCallbackBox,
         ) -> Result<Vec<GenerationResult>>;
 
+        fn score_batch(
+            self: &Generator,
+            tokens: &Vec<VecStr>,
+            options: &ScoringOptions,
+        ) -> Result<Vec<ScoringResult>>;
+
         fn num_queued_batches(self: &Generator) -> Result<usize>;
 
         fn num_active_batches(self: &Generator) -> Result<usize>;
@@ -260,6 +271,26 @@ impl Generator {
             .collect())
     }
 
+    /// Scores a batch of tokens.
+    ///
+    /// # Arguments
+    /// * `tokens` - Batch of tokens to score.
+    ///   If the model expects special start or end tokens, they should also be added to this input.
+    /// * `options` - Settings applied to the scoring process.
+    ///
+    /// # Returns
+    /// Returns a `Result` containing a vector of `ScoringResult` if successful,
+    /// or an error if the generation fails.
+    pub fn score_batch<T: AsRef<str>>(
+        &self,
+        tokens: &[Vec<T>],
+        options: &ScoringOptions,
+    ) -> Result<Vec<ScoringResult>> {
+        self.ptr
+            .score_batch(&vec_ffi_vecstr(tokens), options)
+            .map_err(Error::from)
+    }
+
     /// Number of batches in the work queue.
     #[inline]
     pub fn num_queued_batches(&self) -> Result<usize> {