From 87f0a371b1c0c903f2cae54039753196bf70cce4 Mon Sep 17 00:00:00 2001
From: Reuben Morais <reuben.morais@gmail.com>
Date: Mon, 23 Aug 2021 16:02:13 +0200
Subject: [PATCH] Serialize alphabet alongside checkpoint

---
 native_client/alphabet.cc            | 18 ++++++++++++++++++
 native_client/alphabet.h             |  3 +++
 training/coqui_stt_training/train.py |  5 +++++
 3 files changed, 26 insertions(+)

diff --git a/native_client/alphabet.cc b/native_client/alphabet.cc
index 9abc65a5..bd231a45 100644
--- a/native_client/alphabet.cc
+++ b/native_client/alphabet.cc
@@ -69,6 +69,24 @@ Alphabet::init(const char *config_file)
   return 0;
 }
 
+std::string
+Alphabet::SerializeText()
+{
+  std::stringstream out;
+
+  out << "# Each line in this file represents the Unicode codepoint (UTF-8 encoded)\n"
+      << "# associated with a numeric label.\n"
+      << "# A line that starts with # is a comment. You can escape it with \\# if you wish\n"
+      << "# to use '#' as a label.\n";
+
+  for (int label = 0; label < size_; ++label) {
+    out << label_to_str_[label] << "\n";
+  }
+
+  out << "# The last (non-comment) line needs to end with a newline.\n";
+  return out.str();
+}
+
 std::string
 Alphabet::Serialize()
 {
diff --git a/native_client/alphabet.h b/native_client/alphabet.h
index f402cc0d..3eb26790 100644
--- a/native_client/alphabet.h
+++ b/native_client/alphabet.h
@@ -22,6 +22,9 @@ public:
   // Serialize alphabet into a binary buffer.
   std::string Serialize();
 
+  // Serialize alphabet into a text representation (ie. config file read by `init`)
+  std::string SerializeText();
+
   // Deserialize alphabet from a binary buffer.
   int Deserialize(const char* buffer, const int buffer_size);
 
diff --git a/training/coqui_stt_training/train.py b/training/coqui_stt_training/train.py
index 6032184c..67079474 100644
--- a/training/coqui_stt_training/train.py
+++ b/training/coqui_stt_training/train.py
@@ -429,6 +429,11 @@ def train():
     with open_remote(flags_file, "w") as fout:
         json.dump(Config.serialize(), fout, indent=2)
 
+    # Serialize alphabet alongside checkpoint
+    preserved_alphabet_file = os.path.join(Config.save_checkpoint_dir, "alphabet.txt")
+    with open_remote(preserved_alphabet_file, "wb") as fout:
+        fout.write(Config.alphabet.SerializeText())
+
     with tfv1.Session(config=Config.session_config) as session:
         log_debug("Session opened.")