Prep for sharding gemma.cc: split into kv_cache, tokenizer.

Move activations.h to backprop/ to make space for another activations.h.

PiperOrigin-RevId: 648744500

BUILD.bazel

@@ -94,13 +94,35 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "tokenizer",
+    srcs = ["gemma/tokenizer.cc"],
+    hdrs = ["gemma/tokenizer.h"],
+    deps = [
+        "//compression:io",
+        "@hwy//:hwy",
+        "@hwy//:nanobenchmark",  # timer
+        "@hwy//:profiler",
+        "@com_google_sentencepiece//:sentencepiece_processor",
+    ],
+)
+
+cc_library(
+    name = "kv_cache",
+    srcs = ["gemma/kv_cache.cc"],
+    hdrs = ["gemma/kv_cache.h"],
+    deps = [
+        ":common",
+        "@hwy//:hwy",
+    ],
+)
+
 cc_library(
     name = "gemma_lib",
     srcs = [
         "gemma/gemma.cc",
     ],
     hdrs = [
-        "gemma/activations.h",
         "gemma/gemma.h",
     ],
     exec_properties = {
@@ -114,6 +136,8 @@ cc_library(
     deps = [
         ":common",
         ":ops",
+        ":tokenizer",
+        ":kv_cache",
         ":weights",
         "//compression:compress",
         "//compression:io",
@@ -122,7 +146,6 @@ cc_library(
         "@hwy//:nanobenchmark",  # timer
         "@hwy//:profiler",
         "@hwy//:thread_pool",
-        "@com_google_sentencepiece//:sentencepiece_processor",
     ],
 )
 
@@ -321,6 +344,7 @@ cc_library(
         "backprop/forward.cc",
     ],
     hdrs = [
+        "backprop/activations.h",
         "backprop/backward.h",
         "backprop/backward-inl.h",
         "backprop/forward.h",
@@ -340,6 +364,7 @@ cc_library(
 cc_library(
     name = "backprop_scalar",
     hdrs = [
+        "backprop/activations.h",
         "backprop/backward_scalar.h",
         "backprop/common_scalar.h",
         "backprop/forward_scalar.h",

CMakeLists.txt

@@ -49,6 +49,7 @@ set(SOURCES
   compression/sfp.h
   compression/sfp-inl.h
   compression/test_util.h
+  backprop/activations.h
   backprop/backward.cc
   backprop/backward.h
   backprop/backward-inl.h
@@ -62,18 +63,21 @@ set(SOURCES
   backprop/optimizer.h
   evals/cross_entropy.cc
   evals/cross_entropy.h
-  gemma/configs.h
-  gemma/activations.h
   gemma/benchmark_helper.cc
   gemma/benchmark_helper.h
   gemma/common.cc
   gemma/common.h
+  gemma/configs.h
   gemma/gemma.cc
   gemma/gemma.h
+  gemma/kv_cache.cc
+  gemma/kv_cache.h
   gemma/ops.h
+  gemma/tokenizer.cc
+  gemma/tokenizer.h
+  gemma/weights_raw.h
   gemma/weights.cc
   gemma/weights.h
-  gemma/weights_raw.h
   util/app.h
   util/args.h
   )

backprop/activations.h

@@ -13,8 +13,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#ifndef THIRD_PARTY_GEMMA_CPP_GEMMA_ACTIVATIONS_H_
-#define THIRD_PARTY_GEMMA_CPP_GEMMA_ACTIVATIONS_H_
+#ifndef THIRD_PARTY_GEMMA_CPP_BACKPROP_ACTIVATIONS_H_
+#define THIRD_PARTY_GEMMA_CPP_BACKPROP_ACTIVATIONS_H_
 
 #include <stddef.h>
 
@@ -86,4 +86,4 @@ class ActivationsWrapper {
 
 }  // namespace gcpp
 
-#endif  // THIRD_PARTY_GEMMA_CPP_GEMMA_ACTIVATIONS_H_
+#endif  // THIRD_PARTY_GEMMA_CPP_BACKPROP_ACTIVATIONS_H_

backprop/backward-inl.h

@@ -22,11 +22,11 @@
 
 #include <stddef.h>
 
-#include <algorithm>
 #include <cmath>
+#include <vector>
 
+#include "backprop/activations.h"
 #include "backprop/prompt.h"
-#include "gemma/activations.h"
 #include "gemma/common.h"
 #include "hwy/base.h"
 #include "hwy/contrib/thread_pool/thread_pool.h"

backprop/backward.cc

@@ -15,8 +15,8 @@
 
 #include "backprop/backward.h"
 
+#include "backprop/activations.h"
 #include "backprop/prompt.h"
-#include "gemma/activations.h"
 #include "gemma/common.h"
 #include "hwy/contrib/thread_pool/thread_pool.h"
 

backprop/backward_scalar.h

@@ -22,9 +22,9 @@
 #include <cmath>
 #include <vector>
 
+#include "backprop/activations.h"
 #include "backprop/common_scalar.h"
 #include "backprop/prompt.h"
-#include "gemma/activations.h"
 #include "gemma/common.h"  // EmbeddingScaling
 #include "gemma/weights_raw.h"
 

backprop/backward_scalar_test.cc

@@ -26,12 +26,12 @@
 #include <vector>
 
 #include "gtest/gtest.h"
+#include "backprop/activations.h"
 #include "backprop/common_scalar.h"
 #include "backprop/forward_scalar.h"
 #include "backprop/prompt.h"
 #include "backprop/sampler.h"
 #include "backprop/test_util.h"
-#include "gemma/activations.h"
 #include "gemma/configs.h"
 #include "gemma/weights_raw.h"
 

backprop/backward_test.cc

@@ -24,12 +24,12 @@
 #include <random>
 #include <vector>
 
+#include "backprop/activations.h"
 #include "backprop/backward_scalar.h"
 #include "backprop/common_scalar.h"
 #include "backprop/forward_scalar.h"
 #include "backprop/sampler.h"
 #include "backprop/test_util.h"
-#include "gemma/activations.h"
 #include "gemma/configs.h"
 #include "gemma/weights_raw.h"
 #include "hwy/base.h"

backprop/forward-inl.h

@@ -23,7 +23,7 @@
 #include <cmath>
 #include <vector>
 
-#include "gemma/activations.h"
+#include "backprop/activations.h"
 #include "gemma/common.h"
 #include "gemma/configs.h"
 #include "hwy/base.h"

backprop/forward.cc

@@ -15,8 +15,8 @@
 
 #include "backprop/forward.h"
 
+#include "backprop/activations.h"
 #include "backprop/prompt.h"
-#include "gemma/activations.h"
 #include "gemma/common.h"
 #include "hwy/contrib/thread_pool/thread_pool.h"
 

backprop/forward_scalar.h

@@ -23,9 +23,9 @@
 #include <complex>
 #include <vector>
 
+#include "backprop/activations.h"
 #include "backprop/common_scalar.h"
 #include "backprop/prompt.h"
-#include "gemma/activations.h"
 #include "gemma/common.h"  // EmbeddingScaling
 #include "gemma/weights_raw.h"
 

backprop/optimize_test.cc

@@ -20,12 +20,12 @@
 #include <vector>
 
 #include "gtest/gtest.h"
+#include "backprop/activations.h"
 #include "backprop/backward.h"
 #include "backprop/forward.h"
 #include "backprop/optimizer.h"
 #include "backprop/prompt.h"
 #include "backprop/sampler.h"
-#include "gemma/activations.h"
 #include "gemma/common.h"
 #include "gemma/gemma.h"
 #include "gemma/weights.h"

gemma/common.h

@@ -17,6 +17,7 @@
 #define THIRD_PARTY_GEMMA_CPP_GEMMA_COMMON_H_
 
 #include <math.h>  // sqrtf
+#include <stddef.h>
 #include <stdint.h>
 
 #include <string>
@@ -35,6 +36,12 @@ ByteStorageT AllocateSizeof() {
   return hwy::AllocateAligned<uint8_t>(sizeof(T));
 }
 
+constexpr size_t kPrefillBatchSize = 16;
+constexpr size_t kDecodeBatchSize = 1;
+constexpr size_t kBatchedQueryBatchSize = 16;
+constexpr size_t kMinAdjustedPrefillBatchSize =
+    HWY_MAX((size_t)1, kPrefillBatchSize / kBatchedQueryBatchSize);
+
 // Model variants: see configs.h for details.
 enum class Model {
   GEMMA_2B,
@@ -51,6 +58,13 @@ enum class ModelTraining { GEMMA_IT, GEMMA_PT };
 // Tensor types for loading weights.
 enum class Type { kF32, kBF16, kSFP };
 
+// TODO(janwas): merge with parser/ToString.
+struct ModelInfo {
+  Model model;
+  ModelTraining training;
+  Type weight;
+};
+
 // Returns the return value of FuncT<Config*<TWeight>>().operator()(args), where
 // Config* is selected via `model`. Typically called by CallForModelAndWeight,
 // but can also be called directly when FuncT does not actually use TWeight.

gemma/gemma.cc

@@ -37,7 +37,6 @@
 
 #include <algorithm>
 #include <array>
-#include <memory>
 #include <string>
 #include <utility>  // std::move
 #include <vector>
@@ -54,14 +53,9 @@
 #include "hwy/contrib/thread_pool/thread_pool.h"
 #include "hwy/profiler.h"
 #include "hwy/timer.h"
-// copybara:import_next_line:sentencepiece
-#include "src/sentencepiece_processor.h"
 
 namespace gcpp {
 
-// Set this to true to debug tokenizer tokens.
-constexpr bool kShowTokenization = false;
-
 // Must be aligned.
 template <class TConfig, size_t kBatchSize>
 struct Activations {
@@ -115,114 +109,22 @@ struct Activations {
       griffin_multiplier;
 };
 
-namespace {
-
-template <class TConfig>
-struct CreateKVCache {
-  KVCache operator()() const {
-    KVCache kv_cache = {};
-
-    const size_t size_cache_pos = CachePosSize<TConfig>()();
-    if (size_cache_pos != 0) {
-      const size_t seq_len =
-          (TConfig::kSeqLen + kPrefillBatchSize);
-      kv_cache.kv_cache = hwy::AllocateAligned<float>(seq_len * size_cache_pos);
-    }
-
-    // TODO(patrickms): Add query batching support for Griffin.
-    if (TConfig::kGriffinLayers) {
-      constexpr size_t kConv1dWidth = TConfig::kConv1dWidth;
-      const size_t conv1d_cache_size =
-          TConfig::kGriffinLayers * (kConv1dWidth == 0 ? 0 : kConv1dWidth - 1) *
-          TConfig::kModelDim;
-      if (conv1d_cache_size != 0) {
-        kv_cache.conv1d_cache = hwy::AllocateAligned<float>(conv1d_cache_size);
-        hwy::ZeroBytes(kv_cache.conv1d_cache.get(),
-                       conv1d_cache_size * sizeof(kv_cache.conv1d_cache[0]));
-      }
-
-      const size_t rglru_cache_size =
-          TConfig::kGriffinLayers * TConfig::kModelDim;
-      if (rglru_cache_size != 0) {
-        kv_cache.rglru_cache = hwy::AllocateAligned<float>(rglru_cache_size);
-        hwy::ZeroBytes(kv_cache.rglru_cache.get(),
-                       rglru_cache_size * sizeof(kv_cache.rglru_cache[0]));
-      }
-    }  // kGriffinLayers
-
-    return kv_cache;
+template <typename TConfig>
+struct AllocateState {
+  void operator()(ByteStorageT& prefill, ByteStorageT& decode) const {
+    // When batching queries, the prefill batch size is reduced by a factor
+    // of kBatchedQueryBatchSize
+    prefill =
+        AllocateSizeof<Activations<TConfig, kMinAdjustedPrefillBatchSize *
+                                                kBatchedQueryBatchSize>>();
+    decode = AllocateSizeof<
+        Activations<TConfig, kDecodeBatchSize * kBatchedQueryBatchSize>>();
   }
 };
 
-}  // namespace
-
-KVCache KVCache::Create(Model model_type) {
-  // TWeight=float is a placeholder and unused because CreateKVCache does not
-  // use TConfig::Weight.
-  return CallForModel</*TWeight=*/float, CreateKVCache>(model_type);
-}
-
-class GemmaTokenizer::Impl {
- public:
-  Impl() = default;
-  explicit Impl(const Path& tokenizer_path) {
-    PROFILER_ZONE("Startup.tokenizer");
-    spp_ = std::make_unique<sentencepiece::SentencePieceProcessor>();
-    if (!spp_->Load(tokenizer_path.path).ok()) {
-      HWY_ABORT("Failed to load the tokenizer file.");
-    }
-  }
-
-  bool Encode(const std::string& input,
-              std::vector<std::string>* pieces) const {
-    return spp_ && spp_->Encode(input, pieces).ok();
-  }
-
-  bool Encode(const std::string& input, std::vector<int>* ids) const {
-    if constexpr (kShowTokenization) {
-      bool is_ok = spp_ && spp_->Encode(input, ids).ok();
-      for (int i = 0; i < static_cast<int>(ids->size()); i++) {
-        fprintf(stderr, "%3d: %d\n", i, (*ids)[i]);
-      }
-      return is_ok;
-    } else {
-      return spp_ && spp_->Encode(input, ids).ok();
-    }
-  }
-
-  // Given a sequence of ids, decodes it into a detokenized output.
-  bool Decode(const std::vector<int>& ids, std::string* detokenized) const {
-    return spp_ && spp_->Decode(ids, detokenized).ok();
-  }
-
- private:
-  std::unique_ptr<sentencepiece::SentencePieceProcessor> spp_;
-};
-
-GemmaTokenizer::GemmaTokenizer(const Path& tokenizer_path) {
-  impl_ = std::make_unique<Impl>(tokenizer_path);
-}
-
-// Default suffices, but they must be defined after GemmaTokenizer::Impl.
-GemmaTokenizer::GemmaTokenizer() = default;
-GemmaTokenizer::~GemmaTokenizer() = default;
-GemmaTokenizer::GemmaTokenizer(GemmaTokenizer&& other) = default;
-GemmaTokenizer& GemmaTokenizer::operator=(GemmaTokenizer&& other) = default;
-
-bool GemmaTokenizer::Encode(const std::string& input,
-                            std::vector<std::string>* pieces) const {
-  return impl_->Encode(input, pieces);
-}
-
-bool GemmaTokenizer::Encode(const std::string& input,
-                            std::vector<int>* ids) const {
-  return impl_->Encode(input, ids);
-}
-
-// Given a sequence of ids, decodes it into a detokenized output.
-bool GemmaTokenizer::Decode(const std::vector<int>& ids,
-                            std::string* detokenized) const {
-  return impl_->Decode(ids, detokenized);
+template <class TConfig, size_t kBatchSize>
+Activations<TConfig, kBatchSize>& GetActivations(const ByteStorageT& state_u8) {
+  return *reinterpret_cast<Activations<TConfig, kBatchSize>*>(state_u8.get());
 }
 
 // Placeholder for internal test2, do not remove
@@ -797,15 +699,9 @@ void RangeChecks(size_t& max_tokens, size_t& max_generated_tokens,
   HWY_ASSERT(prompt_size > 0);
 }
 
-template <class TConfig, size_t kBatchSize>
-Activations<TConfig, kBatchSize>& GetActivations(
-    const ByteStorageT& state_u8) {
-  return *reinterpret_cast<Activations<TConfig, kBatchSize>*>(
-      state_u8.get());
-}
-
 }  // namespace
 
+// TODO(janwas): move into RuntimeConfig
 bool StreamToken(size_t query_idx, size_t pos, int token, float prob,
                  const RuntimeConfig& runtime_config) {
   if (runtime_config.batch_stream_token) {
@@ -1069,22 +965,6 @@ HWY_AFTER_NAMESPACE();
 #if HWY_ONCE
 namespace gcpp {
 
-namespace {
-template <typename TConfig>
-struct AllocateState {
-  void operator()(ByteStorageT& prefill, ByteStorageT& decode) const {
-    // When batching queries, the prefill batch size is reduced by a factor
-    // of kBatchedQueryBatchSize
-    prefill = AllocateSizeof<
-        Activations<TConfig,
-                    kMinAdjustedPrefillBatchSize * kBatchedQueryBatchSize>>();
-    decode = AllocateSizeof<
-        Activations<TConfig, kDecodeBatchSize * kBatchedQueryBatchSize>>();
-  }
-};
-
-}  // namespace
-
 Gemma::Gemma(const Path& tokenizer_path, const Path& weights,
              const ModelInfo& info, hwy::ThreadPool& pool)
     : pool_(pool), tokenizer_(tokenizer_path), info_(info) {
@@ -1136,6 +1016,7 @@ void Gemma::GenerateBatch(const RuntimeConfig& runtime_config,
   pool_.SetWaitMode(hwy::PoolWaitMode::kBlock);
 }
 
+// TODO(janwas): move to common.h.
 void Wrap(const ModelInfo& info, size_t pos, std::string& prompt) {
 
   // Instruction-tuned models are trained to expect control tokens.

gemma/gemma.h

@@ -17,59 +17,22 @@
 #define THIRD_PARTY_GEMMA_CPP_GEMMA_GEMMA_H_
 
 #include <functional>
-#include <memory>
 #include <random>
 #include <string>
 #include <vector>
 
+// IWYU pragma: begin_exports
 #include "compression/io.h"  // Path
 #include "gemma/common.h"
+#include "gemma/kv_cache.h"
+#include "gemma/tokenizer.h"
+#include "hwy/contrib/thread_pool/thread_pool.h"
+// IWYU pragma: end_exports
 #include "hwy/aligned_allocator.h"
 #include "hwy/base.h"  // hwy::bfloat16_t
-#include "hwy/contrib/thread_pool/thread_pool.h"
 
 namespace gcpp {
 
-constexpr size_t kPrefillBatchSize = 16;
-constexpr size_t kDecodeBatchSize = 1;
-constexpr size_t kBatchedQueryBatchSize = 16;
-constexpr size_t kMinAdjustedPrefillBatchSize =
-    HWY_MAX((size_t)1, kPrefillBatchSize / kBatchedQueryBatchSize);
-
-struct KVCache {
-  hwy::AlignedFreeUniquePtr<float[]>
-      kv_cache;  // kSeqLen * kGemmaLayers * kKVHeads * kQKVDim * 2
-  hwy::AlignedFreeUniquePtr<float[]>
-      conv1d_cache;  // (kConv1dWidth - 1) * kModelDim * kGriffinLayers
-  hwy::AlignedFreeUniquePtr<float[]>
-      rglru_cache;  // kModelDim * kGriffinLayers
-
-  static KVCache Create(Model type);
-};
-
-// The tokenizer's end of sentence and beginning of sentence token ids.
-constexpr int EOS_ID = 1;
-constexpr int BOS_ID = 2;
-
-class GemmaTokenizer {
- public:
-  GemmaTokenizer();
-  explicit GemmaTokenizer(const Path& tokenizer_path);
-
-  // must come after definition of Impl
-  ~GemmaTokenizer();
-  GemmaTokenizer(GemmaTokenizer&& other);
-  GemmaTokenizer& operator=(GemmaTokenizer&& other);
-
-  bool Encode(const std::string& input, std::vector<std::string>* pieces) const;
-  bool Encode(const std::string& input, std::vector<int>* ids) const;
-  bool Decode(const std::vector<int>& ids, std::string* detokenized) const;
-
- private:
-  class Impl;
-  std::unique_ptr<Impl> impl_;
-};
-
 // StreamFunc is called with (token, probability). For prompt tokens,
 // probability is 0.0f. StreamFunc should return false to stop generation and
 // true to continue generation.
@@ -93,13 +56,6 @@ using SampleFunc = std::function<int(const float*, size_t)>;
 using LayersOutputFunc =
     std::function<void(int, const std::string&, const float*, size_t)>;
 
-// TODO(janwas): move into common.h, merge with parser/ToString.
-struct ModelInfo {
-  Model model;
-  ModelTraining training;
-  Type weight;
-};
-
 struct RuntimeConfig {
   size_t max_tokens;
   size_t max_generated_tokens;

gemma/kv_cache.cc

@@ -0,0 +1,67 @@
+// Copyright 2024 Google LLC
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "gemma/kv_cache.h"
+
+#include "gemma/common.h"  // CallForModel
+#include "hwy/aligned_allocator.h"
+#include "hwy/base.h"  // ZeroBytes
+
+namespace gcpp {
+namespace {
+template <class TConfig>
+struct CreateKVCache {
+  KVCache operator()() const {
+    KVCache kv_cache = {};
+
+    const size_t size_cache_pos = CachePosSize<TConfig>()();
+    if (size_cache_pos != 0) {
+      const size_t seq_len = (TConfig::kSeqLen + kPrefillBatchSize);
+      kv_cache.kv_cache = hwy::AllocateAligned<float>(seq_len * size_cache_pos);
+    }
+
+    // TODO(patrickms): Add query batching support for Griffin.
+    if (TConfig::kGriffinLayers) {
+      constexpr size_t kConv1dWidth = TConfig::kConv1dWidth;
+      const size_t conv1d_cache_size =
+          TConfig::kGriffinLayers * (kConv1dWidth == 0 ? 0 : kConv1dWidth - 1) *
+          TConfig::kModelDim;
+      if (conv1d_cache_size != 0) {
+        kv_cache.conv1d_cache = hwy::AllocateAligned<float>(conv1d_cache_size);
+        hwy::ZeroBytes(kv_cache.conv1d_cache.get(),
+                       conv1d_cache_size * sizeof(kv_cache.conv1d_cache[0]));
+      }
+
+      const size_t rglru_cache_size =
+          TConfig::kGriffinLayers * TConfig::kModelDim;
+      if (rglru_cache_size != 0) {
+        kv_cache.rglru_cache = hwy::AllocateAligned<float>(rglru_cache_size);
+        hwy::ZeroBytes(kv_cache.rglru_cache.get(),
+                       rglru_cache_size * sizeof(kv_cache.rglru_cache[0]));
+      }
+    }  // kGriffinLayers
+
+    return kv_cache;
+  }
+};
+}  // namespace
+
+KVCache KVCache::Create(Model model_type) {
+  // TWeight=float is a placeholder and unused because CreateKVCache does not
+  // use TConfig::Weight.
+  return CallForModel</*TWeight=*/float, CreateKVCache>(model_type);
+}
+
+}  // namespace gcpp

gemma/kv_cache.h

@@ -0,0 +1,39 @@
+// Copyright 2024 Google LLC
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef THIRD_PARTY_GEMMA_CPP_GEMMA_KV_CACHE_H_
+#define THIRD_PARTY_GEMMA_CPP_GEMMA_KV_CACHE_H_
+
+#include "gemma/common.h"  // Model
+#include "hwy/aligned_allocator.h"
+
+namespace gcpp {
+
+struct KVCache {
+  // kSeqLen * kGemmaLayers * kKVHeads * kQKVDim * 2
+  hwy::AlignedFreeUniquePtr<float[]> kv_cache;
+
+  // (kConv1dWidth - 1) * kModelDim * kGriffinLayers
+  hwy::AlignedFreeUniquePtr<float[]> conv1d_cache;
+
+  // kModelDim * kGriffinLayers
+  hwy::AlignedFreeUniquePtr<float[]> rglru_cache;
+
+  static KVCache Create(Model type);
+};
+
+}  // namespace gcpp
+
+#endif  // THIRD_PARTY_GEMMA_CPP_GEMMA_KV_CACHE_H_

gemma/tokenizer.cc

@@ -0,0 +1,98 @@
+// Copyright 2024 Google LLC
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "gemma/tokenizer.h"
+
+#include <stdio.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "compression/io.h"  // Path
+#include "hwy/base.h"
+#include "hwy/profiler.h"
+// copybara:import_next_line:sentencepiece
+#include "src/sentencepiece_processor.h"
+
+namespace gcpp {
+
+// Set this to true to debug tokenizer tokens.
+constexpr bool kShowTokenization = false;
+
+class GemmaTokenizer::Impl {
+ public:
+  Impl() = default;
+  explicit Impl(const Path& tokenizer_path) {
+    PROFILER_ZONE("Startup.tokenizer");
+    spp_ = std::make_unique<sentencepiece::SentencePieceProcessor>();
+    if (!spp_->Load(tokenizer_path.path).ok()) {
+      HWY_ABORT("Failed to load the tokenizer file.");
+    }
+  }
+
+  bool Encode(const std::string& input,
+              std::vector<std::string>* pieces) const {
+    return spp_ && spp_->Encode(input, pieces).ok();
+  }
+
+  bool Encode(const std::string& input, std::vector<int>* ids) const {
+    if constexpr (kShowTokenization) {
+      bool is_ok = spp_ && spp_->Encode(input, ids).ok();
+      for (int i = 0; i < static_cast<int>(ids->size()); i++) {
+        fprintf(stderr, "%3d: %d\n", i, (*ids)[i]);
+      }
+      return is_ok;
+    } else {
+      return spp_ && spp_->Encode(input, ids).ok();
+    }
+  }
+
+  // Given a sequence of ids, decodes it into a detokenized output.
+  bool Decode(const std::vector<int>& ids, std::string* detokenized) const {
+    return spp_ && spp_->Decode(ids, detokenized).ok();
+  }
+
+ private:
+  std::unique_ptr<sentencepiece::SentencePieceProcessor> spp_;
+};
+
+GemmaTokenizer::GemmaTokenizer(const Path& tokenizer_path) {
+  impl_ = std::make_unique<Impl>(tokenizer_path);
+}
+
+// Default suffices, but they must be defined after GemmaTokenizer::Impl.
+GemmaTokenizer::GemmaTokenizer() = default;
+GemmaTokenizer::~GemmaTokenizer() = default;
+GemmaTokenizer::GemmaTokenizer(GemmaTokenizer&& other) = default;
+GemmaTokenizer& GemmaTokenizer::operator=(GemmaTokenizer&& other) = default;
+
+bool GemmaTokenizer::Encode(const std::string& input,
+                            std::vector<std::string>* pieces) const {
+  return impl_->Encode(input, pieces);
+}
+
+bool GemmaTokenizer::Encode(const std::string& input,
+                            std::vector<int>* ids) const {
+  return impl_->Encode(input, ids);
+}
+
+// Given a sequence of ids, decodes it into a detokenized output.
+bool GemmaTokenizer::Decode(const std::vector<int>& ids,
+                            std::string* detokenized) const {
+  return impl_->Decode(ids, detokenized);
+}
+
+}  // namespace gcpp

gemma/tokenizer.h

@@ -0,0 +1,52 @@
+// Copyright 2024 Google LLC
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef THIRD_PARTY_GEMMA_CPP_GEMMA_TOKENIZER_H_
+#define THIRD_PARTY_GEMMA_CPP_GEMMA_TOKENIZER_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "compression/io.h"  // Path
+
+namespace gcpp {
+
+// The tokenizer's end of sentence and beginning of sentence token ids.
+constexpr int EOS_ID = 1;
+constexpr int BOS_ID = 2;
+
+class GemmaTokenizer {
+ public:
+  GemmaTokenizer();
+  explicit GemmaTokenizer(const Path& tokenizer_path);
+
+  // must come after definition of Impl
+  ~GemmaTokenizer();
+  GemmaTokenizer(GemmaTokenizer&& other);
+  GemmaTokenizer& operator=(GemmaTokenizer&& other);
+
+  bool Encode(const std::string& input, std::vector<std::string>* pieces) const;
+  bool Encode(const std::string& input, std::vector<int>* ids) const;
+  bool Decode(const std::vector<int>& ids, std::string* detokenized) const;
+
+ private:
+  class Impl;
+  std::unique_ptr<Impl> impl_;
+};
+
+}  // namespace gcpp
+
+#endif  // THIRD_PARTY_GEMMA_CPP_GEMMA_TOKENIZER_H_