Update to last common bleve (#3986)

vendor/github.com/couchbase/vellum/transducer.go

@@ -0,0 +1,55 @@
+//  Copyright (c) 2017 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package vellum
+
+// Transducer represents the general contract of a byte-based finite transducer
+type Transducer interface {
+
+	// all transducers are also automatons
+	Automaton
+
+	// IsMatchWithValue returns true if and only if the state is a match
+	// additionally it returns a states final value (if any)
+	IsMatchWithVal(int) (bool, uint64)
+
+	// Accept returns the next state given the input to the specified state
+	// additionally it returns the value associated with the transition
+	AcceptWithVal(int, byte) (int, uint64)
+}
+
+// TransducerGet implements an generic Get() method which works
+// on any implementation of Transducer
+// The caller MUST check the boolean return value for a match.
+// Zero is a valid value regardless of match status,
+// and if it is NOT a match, the value collected so far is returned.
+func TransducerGet(t Transducer, k []byte) (bool, uint64) {
+	var total uint64
+	i := 0
+	curr := t.Start()
+	for t.CanMatch(curr) && i < len(k) {
+		var transVal uint64
+		curr, transVal = t.AcceptWithVal(curr, k[i])
+		if curr == noneAddr {
+			break
+		}
+		total += transVal
+		i++
+	}
+	if i != len(k) {
+		return false, total
+	}
+	match, finalVal := t.IsMatchWithVal(curr)
+	return match, total + finalVal
+}