* Add base TransitionSystem class. Still need to rethink how non-monotonic labelling will work for best_valid

spacy/syntax/transition_system.pxd

@@ -0,0 +1,42 @@
+from cymem.cymem cimport Pool
+from thinc.typedefs cimport weight_t
+
+from ..structs cimport TokenC
+from ._state cimport State
+
+
+
+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
+
+
+ctypedef int (*get_cost_func_t)(const Transition* self, const State* state,
+              const TokenC* gold) except -1
+
+ctypedef int (*is_valid_func_t)(const Transition* self, const State* state) except -1
+    
+ctypedef int (*do_func_t)(const Transition* self, State* state) except -1
+
+
+cdef class TransitionSystem:
+    cdef readonly dict label_ids
+    cdef Pool mem
+    cdef const Transition* c
+
+    cdef Transition init_transition(self, int clas, int move, int label) except *
+
+    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/syntax/transition_system.pyx

@@ -0,0 +1,54 @@
+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:
+    def __init__(self, dict labels_by_action):
+        self.mem = Pool()
+        self.n_moves = sum(len(labels) for labels in labels_by_action.items())
+        moves = <Transition*>self.mem.alloc(self.n_moves, sizeof(Transition))
+        cdef int i = 0
+        self.label_ids = {}
+        for action, label_strs in sorted(labels_by_action.items()):
+            label_str = unicode(label_str)
+            label_id = self.label_ids.setdefault(label_str, len(self.label_ids))
+            moves[i] = self.init_transition(i, action, label_id)
+            i += 1
+        self.c = moves
+
+    cdef Transition init_transition(self, int clas, int move, int label) except *:
+        raise NotImplementedError
+
+    cdef Transition best_valid(self, const weight_t* scores, const State* s) except *:
+        cdef Transition best
+        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 = self.c[i]
+                score = scores[i]
+        # Label Shift moves with the best Right-Arc label, for non-monotonic
+        # actions
+        #if best.move == SHIFT:
+        #    score = MIN_SCORE
+        #    for i in range(self.n_moves):
+        #        if self.c[i].move == RIGHT and scores[i] > score:
+        #            best.label = self.c[i].label
+        #            score = scores[i]
+        return best
+
+    cdef Transition best_gold(self, const weight_t* scores, const State* s,
+                              const TokenC* gold) except *:
+        cdef Transition best
+        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 = self.c[i]
+                score = scores[i]
+        return best