Update to last common bleve (#3986)

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

@@ -0,0 +1,113 @@
+//  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
+}