mirror of
https://github.com/go-gitea/gitea.git
synced 2024-12-25 01:33:58 +03:00
114 lines
3.2 KiB
Go
114 lines
3.2 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 regexp
|
|
|
|
import (
|
|
"fmt"
|
|
"regexp/syntax"
|
|
)
|
|
|
|
// ErrNoEmpty returned when "zero width assertions" are used
|
|
var ErrNoEmpty = fmt.Errorf("zero width assertions not allowed")
|
|
|
|
// ErrNoWordBoundary returned when word boundaries are used
|
|
var ErrNoWordBoundary = fmt.Errorf("word boundaries are not allowed")
|
|
|
|
// ErrNoBytes returned when byte literals are used
|
|
var ErrNoBytes = fmt.Errorf("byte literals are not allowed")
|
|
|
|
// ErrNoLazy returned when lazy quantifiers are used
|
|
var ErrNoLazy = fmt.Errorf("lazy quantifiers are not allowed")
|
|
|
|
// ErrCompiledTooBig returned when regular expression parses into
|
|
// too many instructions
|
|
var ErrCompiledTooBig = fmt.Errorf("too many instructions")
|
|
|
|
// Regexp implements the vellum.Automaton interface for matcing a user
|
|
// specified regular expression.
|
|
type Regexp struct {
|
|
orig string
|
|
dfa *dfa
|
|
}
|
|
|
|
// NewRegexp creates a new Regular Expression automaton with the specified
|
|
// expression. By default it is limited to approximately 10MB for the
|
|
// compiled finite state automaton. If this size is exceeded,
|
|
// ErrCompiledTooBig will be returned.
|
|
func New(expr string) (*Regexp, error) {
|
|
return NewWithLimit(expr, 10*(1<<20))
|
|
}
|
|
|
|
// NewRegexpWithLimit creates a new Regular Expression automaton with
|
|
// the specified expression. The size of the compiled finite state
|
|
// automaton exceeds the user specified size, ErrCompiledTooBig will be
|
|
// returned.
|
|
func NewWithLimit(expr string, size uint) (*Regexp, error) {
|
|
parsed, err := syntax.Parse(expr, syntax.Perl)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
compiler := newCompiler(size)
|
|
insts, err := compiler.compile(parsed)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
dfaBuilder := newDfaBuilder(insts)
|
|
dfa, err := dfaBuilder.build()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return &Regexp{
|
|
orig: expr,
|
|
dfa: dfa,
|
|
}, nil
|
|
}
|
|
|
|
// Start returns the start state of this automaton.
|
|
func (r *Regexp) Start() int {
|
|
return 1
|
|
}
|
|
|
|
// IsMatch returns if the specified state is a matching state.
|
|
func (r *Regexp) IsMatch(s int) bool {
|
|
if s < len(r.dfa.states) {
|
|
return r.dfa.states[s].match
|
|
}
|
|
return false
|
|
}
|
|
|
|
// CanMatch returns if the specified state can ever transition to a matching
|
|
// state.
|
|
func (r *Regexp) CanMatch(s int) bool {
|
|
if s < len(r.dfa.states) && s > 0 {
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
// WillAlwaysMatch returns if the specified state will always end in a
|
|
// matching state.
|
|
func (r *Regexp) WillAlwaysMatch(int) bool {
|
|
return false
|
|
}
|
|
|
|
// Accept returns the new state, resulting from the transite byte b
|
|
// when currently in the state s.
|
|
func (r *Regexp) Accept(s int, b byte) int {
|
|
if s < len(r.dfa.states) {
|
|
return r.dfa.states[s].next[b]
|
|
}
|
|
return 0
|
|
}
|