Make Alphabet init fallible and check it in model creation

native_client/alphabet.h

@@ -15,15 +15,15 @@
  */
 class Alphabet {
 public:
-  Alphabet() {
-  }
+  Alphabet() = default;
+  Alphabet(const Alphabet&) = default;
+  Alphabet& operator=(const Alphabet&) = default;
 
-  Alphabet(const char *config_file) {
-    init(config_file);
-  }
-
-  void init(const char *config_file) {
+  int init(const char *config_file) {
     std::ifstream in(config_file, std::ios::in);
+    if (!in) {
+      return 1;
+    }
     unsigned int label = 0;
     space_label_ = -2;
     for (std::string line; std::getline(in, line);) {
@@ -42,6 +42,7 @@ public:
     }
     size_ = label;
     in.close();
+    return 0;
   }
 
   const std::string& StringFromLabel(unsigned int label) const {

native_client/ctcdecode/swigwrapper.i

@@ -19,42 +19,44 @@ import_array();
 %apply (double* IN_ARRAY3, int DIM1, int DIM2, int DIM3) {(const double *probs, int batch_dim, int time_dim, int class_dim)};
 %apply (int* IN_ARRAY1, int DIM1) {(const int *seq_lengths, int seq_lengths_size)};
 
-// Convert char* to Alphabet
-%rename (ctc_beam_search_decoder) mod_decoder;
+// Add overloads converting char* to Alphabet
 %inline %{
 std::vector<Output>
-mod_decoder(const double *probs,
-            int time_dim,
-            int class_dim,
-            char* alphabet_config_path,
-            size_t beam_size,
-            double cutoff_prob,
-            size_t cutoff_top_n,
-            Scorer *ext_scorer)
+ctc_beam_search_decoder(const double *probs,
+                        int time_dim,
+                        int class_dim,
+                        char* alphabet_config_path,
+                        size_t beam_size,
+                        double cutoff_prob,
+                        size_t cutoff_top_n,
+                        Scorer *ext_scorer)
 {
-    Alphabet a(alphabet_config_path);
+    Alphabet a;
+    if (a.init(alphabet_config_path)) {
+      std::cerr << "Error initializing alphabet from file: \"" << alphabet_config_path << "\"\n";
+    }
     return ctc_beam_search_decoder(probs, time_dim, class_dim, a, beam_size,
                                    cutoff_prob, cutoff_top_n, ext_scorer);
 }
-%}
 
-%rename (ctc_beam_search_decoder_batch) mod_decoder_batch;
-%inline %{
 std::vector<std::vector<Output>>
-mod_decoder_batch(const double *probs,
-                  int batch_dim,
-                  int time_dim,
-                  int class_dim,
-                  const int *seq_lengths,
-                  int seq_lengths_size,
-                  char* alphabet_config_path,
-                  size_t beam_size,
-                  size_t num_processes,
-                  double cutoff_prob,
-                  size_t cutoff_top_n,
-                  Scorer *ext_scorer)
+ctc_beam_search_decoder_batch(const double *probs,
+                              int batch_dim,
+                              int time_dim,
+                              int class_dim,
+                              const int *seq_lengths,
+                              int seq_lengths_size,
+                              char* alphabet_config_path,
+                              size_t beam_size,
+                              size_t num_processes,
+                              double cutoff_prob,
+                              size_t cutoff_top_n,
+                              Scorer *ext_scorer)
 {
-    Alphabet a(alphabet_config_path);
+    Alphabet a;
+    if (a.init(alphabet_config_path)) {
+      std::cerr << "Error initializing alphabet from file: \"" << alphabet_config_path << "\"\n";
+    }
     return ctc_beam_search_decoder_batch(probs, batch_dim, time_dim, class_dim,
                                          seq_lengths, seq_lengths_size, a, beam_size,
                                          num_processes, cutoff_prob, cutoff_top_n,

native_client/generate_trie.cpp

@@ -8,7 +8,10 @@
 using namespace std;
 
 int generate_trie(const char* alphabet_path, const char* kenlm_path, const char* trie_path) {
-  Alphabet alphabet(alphabet_path);
+  Alphabet alphabet;
+  if (int err = alphabet.init(alphabet_path)) {
+    return err;
+  }
   Scorer scorer(0.0, 0.0, kenlm_path, "", alphabet);
   scorer.save_dictionary(trie_path);
   return 0;

native_client/modelstate.cc

@@ -32,7 +32,9 @@ ModelState::init(const char* model_path,
 {
   n_features_ = n_features;
   n_context_ = n_context;
-  alphabet_.init(alphabet_path);
+  if (alphabet_.init(alphabet_path)) {
+    return DS_ERR_INVALID_ALPHABET;
+  }
   beam_width_ = beam_width;
   return DS_ERR_OK;
 }

native_client/trie_load.cc

@@ -16,7 +16,10 @@ int main(int argc, char** argv)
 
   printf("Loading trie(%s) and alphabet(%s)\n", trie_path, alphabet_path);
 
-  Alphabet alphabet(alphabet_path);
+  Alphabet alphabet;
+  if (int err = alphabet.init(alphabet_path)) {
+    return err;
+  }
   Scorer scorer(0.0, 0.0, kenlm_path, trie_path, alphabet);
 
   return 0;