fix updating of SymbolTable multiple times for new words, so that the…

…re is only one instance for a single model

kaldi_active_grammar/compiler.py

@@ -338,7 +338,7 @@ def add_word(self, word, phones=None, lazy_compilation=False, allow_online_pronu
     def prepare_for_compilation(self):
         if self._lexicon_files_stale:
             self.model.generate_lexicon_files()
-            self.model.load_words()
+            self.model.load_words()  # FIXME: This re-loading from the words.txt file may be unnecessary now that we have/use NativeWFST + SymbolTable, but it's not clear if it's safe to remove it.
             self.decoder.load_lexicon()
             if self._agf_compiler:
                 # TODO: Just update the necessary files in the config

kaldi_active_grammar/model.py

@@ -252,13 +252,14 @@ def __init__(self, model_dir=None, tmp_dir=None, tmp_dir_needed=False):
         if self.fst_cache.cache_is_new or files_are_not_current(necessary_files + non_lazy_files):
             self.generate_lexicon_files()
 
+        self.words_table = SymbolTable()
         self.load_words()
 
     def load_words(self, words_file=None):
         if words_file is None: words_file = self.files_dict['words.txt']
         _log.debug("loading words from %r", words_file)
         invalid_words = "<eps> !SIL <UNK> #0 <s> </s>".lower().split()
-        self.words_table = SymbolTable(words_file)
+        self.words_table.load_text_file(words_file)
         self.longest_word = max(self.words_table.word_to_id_map.keys(), key=len)
         return self.words_table
 
@@ -281,7 +282,7 @@ def add_word(self, word, phones=None, lazy_compilation=False, allow_online_pronu
         word = word.strip().lower()
 
         if phones is None:
-            # Generate pronunciations, then call ourselves recursively
+            # Not given pronunciation(s), so generate pronunciation(s), then call ourselves recursively for each individual pronunciation
             pronunciations = Lexicon.generate_pronunciations(word, model_dir=self.model_dir, allow_online_pronunciations=allow_online_pronunciations)
             pronunciations = sum([
                 self.add_word(word, phones, lazy_compilation=True)

kaldi_active_grammar/wfst.py

@@ -356,11 +356,20 @@ def compile_text(cls, fst_text, isymbols_filename, osymbols_filename):
 
 class SymbolTable(object):
 
-    def __init__(self, filename):
+    def __init__(self, filename=None):
+        self.word_to_id_map = dict()
+        self.id_to_word_map = dict()
+        self.max_term_word_id = -1
+        if filename is not None:
+            self.load_text_file(filename)
+
+    def load_text_file(self, filename):
         with open(filename, 'r', encoding='utf-8') as file:
             word_id_pairs = [line.strip().split() for line in file]
-        self.word_to_id_map = { word: int(id) for (word, id) in word_id_pairs }
-        self.id_to_word_map = { id: word for (word, id) in self.word_to_id_map.items() }
+        self.word_to_id_map.clear()
+        self.id_to_word_map.clear()
+        self.word_to_id_map.update({ word: int(id) for (word, id) in word_id_pairs })
+        self.id_to_word_map.update({ id: word for (word, id) in self.word_to_id_map.items() })
         self.max_term_word_id = max(id for (word, id) in self.word_to_id_map.items() if not word.startswith('#nonterm'))
 
     def add_word(self, word, id=None):