* Add get_valid method

spacy/syntax/arc_eager.pyx

@@ -120,6 +120,20 @@ cdef class ArcEager(TransitionSystem):
             if state.sent[i].head == 0 and state.sent[i].dep == 0:
                 state.sent[i].dep = root_label
 
+    cdef bint* get_valid(self, const State* s) except NULL:
+        cdef bint[N_MOVES] is_valid
+        is_valid[SHIFT] = _can_shift(s)
+        is_valid[REDUCE] = _can_reduce(s)
+        is_valid[LEFT] = _can_left(s)
+        is_valid[RIGHT] = _can_right(s)
+        is_valid[BREAK] = _can_break(s)
+        is_valid[CONSTITUENT] = _can_constituent(s)
+        is_valid[ADJUST] = _can_adjust(s)
+        cdef int i
+        for i in range(self.n_moves):
+            self._is_valid[i] = is_valid[self.c[i].move]
+        return self._is_valid
+
     cdef Transition best_valid(self, const weight_t* scores, const State* s) except *:
         cdef bint[N_MOVES] is_valid
         is_valid[SHIFT] = _can_shift(s)
@@ -451,4 +465,3 @@ cdef inline bint _can_adjust(const State* s) nogil:
     #    return False
     #elif b0 >= b1:
     #    return False
-    return True

spacy/syntax/ner.pyx

@@ -140,6 +140,13 @@ cdef class BiluoPushDown(TransitionSystem):
         t.score = score
         return t
 
+    cdef bint* get_valid(self, const State* s) except NULL:
+        cdef int i
+        for i in range(self.n_moves):
+            m = &self.c[i]
+            self._is_valid[i] = _is_valid(m.move, m.label, s)
+        return self._is_valid
+
 
 cdef int _get_cost(const Transition* self, const State* s, GoldParse gold) except -1:
     if not _is_valid(self.move, self.label, s):

spacy/syntax/transition_system.pxd

@@ -28,6 +28,7 @@ cdef class TransitionSystem:
     cdef Pool mem
     cdef StringStore strings
     cdef const Transition* c
+    cdef bint* _is_valid
     cdef readonly int n_moves
 
     cdef int initialize_state(self, State* state) except -1
@@ -39,6 +40,8 @@ cdef class TransitionSystem:
 
     cdef Transition init_transition(self, int clas, int move, int label) except *
 
+    cdef bint* get_valid(self, const State* state) except NULL
+
     cdef Transition best_valid(self, const weight_t* scores, const State* state) except *
 
     cdef Transition best_gold(self, const weight_t* scores, const State* state,

spacy/syntax/transition_system.pyx

@@ -15,6 +15,7 @@ cdef class TransitionSystem:
     def __init__(self, StringStore string_table, dict labels_by_action):
         self.mem = Pool()
         self.n_moves = sum(len(labels) for labels in labels_by_action.values())
+        self._is_valid = <bint*>self.mem.alloc(self.n_moves, sizeof(bint))
         moves = <Transition*>self.mem.alloc(self.n_moves, sizeof(Transition))
         cdef int i = 0
         cdef int label_id
@@ -43,6 +44,9 @@ cdef class TransitionSystem:
 
     cdef Transition best_valid(self, const weight_t* scores, const State* s) except *:
         raise NotImplementedError
+    
+    cdef bint* get_valid(self, const State* state) except NULL:
+        raise NotImplementedError
 
     cdef Transition best_gold(self, const weight_t* scores, const State* s,
                               GoldParse gold) except *: