refactor: Split SegmentOptimizer#_compute_costs into three methods

Author: OUDON

src/rmqrcode/segments.py

@@ -107,36 +107,63 @@ def _compute_costs(self, data):
                         if not encoders[new_mode].is_valid_characters(data[n]):
                             continue
 
-                        encoder_class = encoders[new_mode]
-                        character_count_indicator_length = self.qr_version["character_count_indicator_length"][
-                            encoder_class
-                        ]
                         if new_mode == mode:
-                            # Keep the mode
-                            if encoder_class == encoder.NumericEncoder:
-                                new_length = (unfilled_length + 1) % 3
-                                cost = 4 if unfilled_length == 0 else 3
-                            elif encoder_class == encoder.AlphanumericEncoder:
-                                new_length = (unfilled_length + 1) % 2
-                                cost = 6 if unfilled_length == 0 else 5
-                            elif encoder_class == encoder.ByteEncoder:
-                                new_length = 0
-                                cost = 8 * len(data[n].encode("utf-8"))
-                            elif encoder_class == encoder.KanjiEncoder:
-                                new_length = 0
-                                cost = 13
+                            cost, new_length = self._compute_new_state_without_mode_changing(data[n], new_mode, unfilled_length)
                         else:
-                            # Change the mode
-                            if encoder_class in [encoder.NumericEncoder, encoder.AlphanumericEncoder]:
-                                new_length = 1
-                            elif encoder_class in [encoder.ByteEncoder, encoder.KanjiEncoder]:
-                                new_length = 0
-                            cost = encoders[new_mode].length(data[n], character_count_indicator_length)
+                            cost, new_length = self._compute_new_state_with_mode_changing(data[n], new_mode, unfilled_length)
 
                         if self.dp[n][mode][unfilled_length] + cost < self.dp[n + 1][new_mode][new_length]:
                             self.dp[n + 1][new_mode][new_length] = self.dp[n][mode][unfilled_length] + cost
                             self.parents[n + 1][new_mode][new_length] = (n, mode, unfilled_length)
 
+    def _compute_new_state_without_mode_changing(self, character, new_mode, unfilled_length):
+        """Computes the new state without mode changing.
+
+        Args:
+            character (str): The current character. Assume this as one length string.
+            new_mode (int): The state of the new mode.
+            unfilled_length (int): The state of the current unfilled_length.
+
+        Returns:
+            tuple: (cost, new_length).
+
+        """
+        encoder_class = encoders[new_mode]
+        if encoder_class == encoder.NumericEncoder:
+            new_length = (unfilled_length + 1) % 3
+            cost = 4 if unfilled_length == 0 else 3
+        elif encoder_class == encoder.AlphanumericEncoder:
+            new_length = (unfilled_length + 1) % 2
+            cost = 6 if unfilled_length == 0 else 5
+        elif encoder_class == encoder.ByteEncoder:
+            new_length = 0
+            cost = 8 * len(character.encode("utf-8"))
+        elif encoder_class == encoder.KanjiEncoder:
+            new_length = 0
+            cost = 13
+        return (cost, new_length)
+
+    def _compute_new_state_with_mode_changing(self, character, new_mode, unfilled_length):
+        """Computes the new state with mode changing.
+
+        Args:
+            character (str): The current character. Assume this as one length string.
+            new_mode (int): The state of the new mode.
+            unfilled_length (int): The state of the current unfilled_length.
+
+        Returns:
+            tuple: (cost, new_length).
+
+        """
+        encoder_class = encoders[new_mode]
+        character_count_indicator_length = self.qr_version["character_count_indicator_length"][encoder_class]
+        if encoder_class in [encoder.NumericEncoder, encoder.AlphanumericEncoder]:
+            new_length = 1
+        elif encoder_class in [encoder.ByteEncoder, encoder.KanjiEncoder]:
+            new_length = 0
+        cost = encoder_class.length(character, character_count_indicator_length)
+        return (cost, new_length)
+
     def _find_best(self, data):
         """Find the index which has the minimum costs.