internal/index/nixattr/states.go (view raw)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 | // Copyright (c) 2016 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 nixattr
import (
"unicode"
)
// States codify the classes that the parser recognizes.
type State interface {
// is _sym_ the start character
StartSym(sym rune) bool
// is _sym_ a member of a class.
// peek, the next sym on the tape, can also be used to determine a class.
Member(sym rune, peek *rune) bool
}
func IsNonSplittingSymbolCase(sym rune) bool {
return unicode.IsPunct(sym) && sym != '.'
}
type LowerCaseState struct{}
func (s *LowerCaseState) Member(sym rune, _ *rune) bool {
return unicode.IsLower(sym) || IsNonSplittingSymbolCase(sym) || unicode.IsNumber(sym)
}
func (s *LowerCaseState) StartSym(sym rune) bool {
return s.Member(sym, nil)
}
type UpperCaseState struct {
startedCollecting bool // denotes that the start character has been read
collectingUpper bool // denotes if this is a class of all upper case letters
}
func (s *UpperCaseState) Member(sym rune, peek *rune) bool {
if !unicode.IsLower(sym) && !unicode.IsUpper(sym) {
return false
}
if peek != nil && unicode.IsUpper(sym) && unicode.IsLower(*peek) {
return false
}
if !s.startedCollecting {
// now we have to determine if upper-case letters are collected.
s.startedCollecting = true
s.collectingUpper = unicode.IsUpper(sym)
return true
}
return s.collectingUpper == unicode.IsUpper(sym)
}
func (s *UpperCaseState) StartSym(sym rune) bool {
return unicode.IsUpper(sym)
}
type NumberCaseState struct{}
func (s *NumberCaseState) Member(sym rune, _ *rune) bool {
return unicode.IsNumber(sym) || IsNonSplittingSymbolCase(sym) || unicode.IsLower(sym)
}
func (s *NumberCaseState) StartSym(sym rune) bool {
return s.Member(sym, nil)
}
type NonAlphaNumericCaseState struct{}
func (s *NonAlphaNumericCaseState) Member(sym rune, _ *rune) bool {
return !unicode.IsLower(sym) && !unicode.IsUpper(sym) && !unicode.IsNumber(sym) &&
!IsNonSplittingSymbolCase(sym)
}
func (s *NonAlphaNumericCaseState) StartSym(sym rune) bool {
return s.Member(sym, nil)
}
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