56 lines
1.8 KiB
Go
56 lines
1.8 KiB
Go
// 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
|
|
}
|