fallback to shorter error if there are no enough parts

typetrainer/generator.py

@@ -84,6 +84,9 @@ def make_choicer(self):
 
         return ch
 
+    def count(self, part):
+        return sum(1 if part in p else 0 for p in self.parts)
+
     def choice(self, rnd):
         if not self.choicer:
             self.choicer = self.make_choicer()

typetrainer/tutors/common.py

@@ -72,4 +72,16 @@ def strip_non_word_chars(self, string):
             if c in self.word_chars:
                 result += c
 
-        return result
+        return result
+
+    def get_available_parts_for(self, key):
+        result = total = 0
+        for p in self.other.values():
+            result += p.count(key)
+            total += len(p.parts)
+
+        for p in self.first.values():
+            result += p.count(key)
+            total += len(p.parts)
+
+        return result / float(total)

typetrainer/ui/main.py

@@ -112,9 +112,14 @@ def on_type_entry_activate(self, *args):
                     errors += 1
 
             err = self.get_error(self.typed_chars)
-            if err:
-                self.filler.change_distribution(err, 0.8, True)
-                self.retype_lb.set_text(err)
+            while err:
+                volume = self.filler.get_available_parts_for(err)
+                if volume > 0.005:
+                    self.filler.change_distribution(err, 0.8, True)
+                    self.retype_lb.set_text(err)
+                    break
+
+                err = err[1:]
             else:
                 self.filler.reset_distribution()
                 self.retype_lb.set_text('')