Add web binding Tokenizer.tokenToId()

src/sentencepiece_tokenizer.cc

@@ -37,7 +37,13 @@ class SentencePieceTokenizer : public Tokenizer {
 
   std::string IdToToken(int32_t id) final { return sentence_piece_.IdToPiece(id); }
 
-  int32_t TokenToId(const std::string& token) final { return sentence_piece_.PieceToId(token); }
+  int32_t TokenToId(const std::string& token) final {
+    int32_t id = sentence_piece_.PieceToId(token);
+    if (id == sentence_piece_.unk_id()) {
+      return -1;
+    }
+    return id;
+  }
 
  private:
   // the tokenizer

web/src/tokenizers.ts

@@ -75,6 +75,17 @@ export class Tokenizer {
     return res;
   }
 
+  /**
+   * Convert the given token to its corresponding id if it exists. If not, return -1.
+   *
+   * @param token the input token string.
+   * @returns The encoded token id.
+   */
+  tokenToId(token: string): number {
+    const id = this.handle.TokenToId(token.slice());
+    return id;
+  }
+
   /**
    * Create a tokenizer from jsonArrayBuffer
    *

web/src/tokenizers_binding.cc

@@ -23,5 +23,6 @@ EMSCRIPTEN_BINDINGS(tokenizers) {
       .function("Encode", &tokenizers::Tokenizer::Encode)
       .function("Decode", &tokenizers::Tokenizer::Decode)
       .function("GetVocabSize", &tokenizers::Tokenizer::GetVocabSize)
-      .function("IdToToken", &tokenizers::Tokenizer::IdToToken);
+      .function("IdToToken", &tokenizers::Tokenizer::IdToToken)
+      .function("TokenToId", &tokenizers::Tokenizer::TokenToId);
 }

web/tests/src/index.ts

@@ -27,6 +27,18 @@ async function testJSONTokenizer() {
   if (tok49407 !== "<|endoftext|>") {
     throw Error("Expect token 49407 to be <|endoftext|>");
   }
+
+  const id0 = tok.tokenToId("!");
+  console.log("id0=" + id0);
+  if (id0 !== 0) {
+    throw Error("Expect token 0 to be !");
+  }
+
+  const id49407 = tok.tokenToId("<|endoftext|>");
+  console.log("id49407=" + id49407);
+  if (id49407 !== 49407) {
+    throw Error("Expect token 49407 to be <|endoftext|>");
+  }
 }
 
 async function testLlamaTokenizer() {