mirror of
https://codeberg.org/forgejo/forgejo.git
synced 2024-11-29 09:31:11 -05:00
85 lines
2.2 KiB
Go
85 lines
2.2 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
|
|
|
|
// Automaton represents the general contract of a byte-based finite automaton
|
|
type Automaton interface {
|
|
|
|
// Start returns the start state
|
|
Start() int
|
|
|
|
// IsMatch returns true if and only if the state is a match
|
|
IsMatch(int) bool
|
|
|
|
// CanMatch returns true if and only if it is possible to reach a match
|
|
// in zero or more steps
|
|
CanMatch(int) bool
|
|
|
|
// WillAlwaysMatch returns true if and only if the current state matches
|
|
// and will always match no matter what steps are taken
|
|
WillAlwaysMatch(int) bool
|
|
|
|
// Accept returns the next state given the input to the specified state
|
|
Accept(int, byte) int
|
|
}
|
|
|
|
// AutomatonContains implements an generic Contains() method which works
|
|
// on any implementation of Automaton
|
|
func AutomatonContains(a Automaton, k []byte) bool {
|
|
i := 0
|
|
curr := a.Start()
|
|
for a.CanMatch(curr) && i < len(k) {
|
|
curr = a.Accept(curr, k[i])
|
|
if curr == noneAddr {
|
|
break
|
|
}
|
|
i++
|
|
}
|
|
if i != len(k) {
|
|
return false
|
|
}
|
|
return a.IsMatch(curr)
|
|
}
|
|
|
|
// AlwaysMatch is an Automaton implementation which always matches
|
|
type AlwaysMatch struct{}
|
|
|
|
// Start returns the AlwaysMatch start state
|
|
func (m *AlwaysMatch) Start() int {
|
|
return 0
|
|
}
|
|
|
|
// IsMatch always returns true
|
|
func (m *AlwaysMatch) IsMatch(int) bool {
|
|
return true
|
|
}
|
|
|
|
// CanMatch always returns true
|
|
func (m *AlwaysMatch) CanMatch(int) bool {
|
|
return true
|
|
}
|
|
|
|
// WillAlwaysMatch always returns true
|
|
func (m *AlwaysMatch) WillAlwaysMatch(int) bool {
|
|
return true
|
|
}
|
|
|
|
// Accept returns the next AlwaysMatch state
|
|
func (m *AlwaysMatch) Accept(int, byte) int {
|
|
return 0
|
|
}
|
|
|
|
// creating an alwaysMatchAutomaton to avoid unnecesary repeated allocations.
|
|
var alwaysMatchAutomaton = &AlwaysMatch{}
|