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// Copyright (c) 2014 Dataence, LLC. All rights reserved.
//
// 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 sequence
import "strings"
type timeNode struct {
ntype int
value rune
final TokenType
subtype int
children []*timeNode
}
const (
timeNodeRoot = iota
timeNodeLeaf
timeNodeDigit
timeNodeLetter
timeNodeLiteral
timeNodeSpace
timeNodeDigitOrSpace
timeNodePlusOrMinus
)
var (
timeFsmRoot *timeNode
minTimeLength int = 1000
)
func buildTimeFSM(fmts []string) *timeNode {
root := &timeNode{ntype: timeNodeRoot}
for i, f := range fmts {
f = strings.ToLower(f)
if len(f) < minTimeLength {
minTimeLength = len(f)
}
parent := root
for _, r := range f {
t := tnType(r)
hasChild := false
var child *timeNode
for _, child = range parent.children {
if (child.ntype == t && (t != timeNodeLiteral || (t == timeNodeLiteral && child.value == r))) ||
(child.ntype == timeNodeDigitOrSpace && (t == timeNodeDigit || t == timeNodeSpace)) {
hasChild = true
break
} else if child.ntype == timeNodeDigit && t == timeNodeDigitOrSpace {
child.ntype = timeNodeDigitOrSpace
hasChild = true
break
}
}
if !hasChild {
child = &timeNode{ntype: t, value: r}
parent.children = append(parent.children, child)
}
parent = child
}
parent.final = TokenTime
parent.subtype = i
}
return root
}
func tnType(r rune) int {
switch {
case r >= '0' && r <= '9':
return timeNodeDigit
case r >= 'a' && r <= 'y' || r >= 'A' && r <= 'Y':
return timeNodeLetter
case r == ' ':
return timeNodeSpace
case r == '_':
return timeNodeDigitOrSpace
case r == '+' || r == '-' || r == 'z' || r == 'Z':
return timeNodePlusOrMinus
}
return timeNodeLiteral
}
func timeStep(r rune, cur *timeNode) *timeNode {
if cur == nil {
return nil
}
t := tnType(r)
for _, n := range cur.children {
if (n.ntype == timeNodeDigitOrSpace && (t == timeNodeDigit || t == timeNodeSpace)) ||
(n.ntype == t && (t != timeNodeLiteral || (t == timeNodeLiteral && n.value == r))) {
return n
}
}
return nil
}