* Add base class to do transitions

spacy/_transitions.pxd

@@ -0,0 +1,25 @@
+cdef struct Transition:
+    int clas
+    int move
+    int label
+
+    weight_t score
+    int cost
+
+    int (*get_cost)(const Transition* self, const State* state, const TokenC* gold) except -1
+
+    int (*is_valid)(const Transition* self, const State* state) except -1
+    
+    int (*do)(const Transition* self, State* state) except -1
+
+
+cdef class TransitionSystem:
+    cdef readonly dict label_ids
+    cdef Pool mem
+    cdef const Transition* c
+
+    cdef const Transition best_valid(self, const weight_t*, const State*) except *
+
+    cdef const Transition best_gold(self, const weight_t*, const State*,
+                                    const TokenC*) except *
+

spacy/_transitions.pyx

@@ -0,0 +1,44 @@
+from cymem.cymem cimport Pool
+from ._state cimport State
+from ..structs cimport TokenC
+from thinc.typedefs cimport weight_t
+
+
+cdef weight_t MIN_SCORE = -90000
+
+cdef class TransitionSystem:
+    cdef Pool mem
+    cdef const Transition* c
+
+    def __init__(self, dict move_types):
+        entries = []
+        for move, labels in move_types.items():
+            entries.extend((move, label) for label in labels)
+        entries.sort()
+        moves = <Transition*>self.mem.alloc(len(entries), sizeof(Transition))
+        for i, (move, label_str) in enumerate(entries):
+            moves[i].move = move
+            moves[i].label = self.label_ids.setdefault(label_str, len(self.label_ids))
+            moves[i].clas
+    
+    cdef const Transition best_valid(self, const weight_t* scores,
+                                     const State* s) except *:
+        cdef int best = -1
+        cdef weight_t score = MIN_SCORE
+        cdef int i
+        for i in range(self.n_moves):
+            if scores[i] > score and self.c[i].is_valid(&self.c[i], s):
+                best = i
+                score = scores[i]
+        return self.c[best]
+
+    cdef const Transition best_gold(self, const weight_t* scores, const State* s,
+                                    const TokenC* gold) except *:
+        cdef int best = -1
+        cdef weight_t score = MIN_SCORE
+        cdef int i
+        for i in range(self.n_moves):
+            if scores[i] > score and self.c[i].get_cost(&self.c[i], s, gold) == 0:
+                best = i
+                score = scores[i]
+        return self.c[best]