/
tokenizer.go
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/
tokenizer.go
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// Copyright (c) 2016 Tigera, Inc. 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 tokenizer
import (
"errors"
"regexp"
"strings"
log "github.com/sirupsen/logrus"
)
type tokenKind uint8
const (
TokLabel tokenKind = iota + 1
TokStringLiteral
TokLBrace
TokRBrace
TokComma
TokEq
TokNe
TokIn
TokNot
TokNotIn
TokAll
TokHas
TokLParen
TokRParen
TokAnd
TokOr
TokEOF
)
const tokenizerDebug = false
var whitespace = " \t"
// Token has a kind and a value
type Token struct {
Kind tokenKind
Value interface{}
}
const (
// LabelKeyMatcher is the base regex for a valid label key.
LabelKeyMatcher = `[a-zA-Z0-9_./-]{1,512}`
hasExpr = `has\(\s*(` + LabelKeyMatcher + `)\s*\)`
allExpr = `all\(\s*\)`
notInExpr = `not\s*in\b`
inExpr = `in\b`
)
var (
identifierRegex = regexp.MustCompile("^" + LabelKeyMatcher)
hasRegex = regexp.MustCompile("^" + hasExpr)
allRegex = regexp.MustCompile("^" + allExpr)
notInRegex = regexp.MustCompile("^" + notInExpr)
inRegex = regexp.MustCompile("^" + inExpr)
)
// Tokenize transforms string to token slice
func Tokenize(input string) (tokens []Token, err error) {
for {
if tokenizerDebug {
log.Debug("Remaining input: ", input)
}
startLen := len(input)
input = strings.TrimLeft(input, whitespace)
if len(input) == 0 {
tokens = append(tokens, Token{TokEOF, nil})
return
}
switch input[0] {
case '(':
tokens = append(tokens, Token{TokLParen, nil})
input = input[1:]
case ')':
tokens = append(tokens, Token{TokRParen, nil})
input = input[1:]
case '"':
input = input[1:]
index := strings.Index(input, `"`)
if index == -1 {
return nil, errors.New("unterminated string")
}
value := input[0:index]
tokens = append(tokens, Token{TokStringLiteral, value})
input = input[index+1:]
case '\'':
input = input[1:]
index := strings.Index(input, `'`)
if index == -1 {
return nil, errors.New("unterminated string")
}
value := input[0:index]
tokens = append(tokens, Token{TokStringLiteral, value})
input = input[index+1:]
case '{':
tokens = append(tokens, Token{TokLBrace, nil})
input = input[1:]
case '}':
tokens = append(tokens, Token{TokRBrace, nil})
input = input[1:]
case ',':
tokens = append(tokens, Token{TokComma, nil})
input = input[1:]
case '=':
if len(input) > 1 && input[1] == '=' {
tokens = append(tokens, Token{TokEq, nil})
input = input[2:]
} else {
return nil, errors.New("expected ==")
}
case '!':
if len(input) > 1 && input[1] == '=' {
tokens = append(tokens, Token{TokNe, nil})
input = input[2:]
} else {
tokens = append(tokens, Token{TokNot, nil})
input = input[1:]
}
case '&':
if len(input) > 1 && input[1] == '&' {
tokens = append(tokens, Token{TokAnd, nil})
input = input[2:]
} else {
return nil, errors.New("expected &&")
}
case '|':
if len(input) > 1 && input[1] == '|' {
tokens = append(tokens, Token{TokOr, nil})
input = input[2:]
} else {
return nil, errors.New("expected ||")
}
default:
// Handle less-simple cases with regex matches. We've
// already stripped any whitespace.
if idxs := hasRegex.FindStringSubmatchIndex(input); idxs != nil {
// Found "has(label)"
wholeMatchEnd := idxs[1]
labelNameMatchStart := idxs[2]
labelNameMatchEnd := idxs[3]
labelName := input[labelNameMatchStart:labelNameMatchEnd]
tokens = append(tokens, Token{TokHas, labelName})
input = input[wholeMatchEnd:]
} else if idxs := notInRegex.FindStringIndex(input); idxs != nil {
// Found "not in"
tokens = append(tokens, Token{TokNotIn, nil})
input = input[idxs[1]:]
} else if idxs := inRegex.FindStringIndex(input); idxs != nil {
// Found "in"
tokens = append(tokens, Token{TokIn, nil})
input = input[idxs[1]:]
} else if idxs := allRegex.FindStringIndex(input); idxs != nil {
// Found "all"
tokens = append(tokens, Token{TokAll, nil})
input = input[idxs[1]:]
} else if idxs := identifierRegex.FindStringIndex(input); idxs != nil {
// Found "label"
endIndex := idxs[1]
identifier := input[:endIndex]
log.Debug("Identifier ", identifier)
tokens = append(tokens, Token{TokLabel, identifier})
input = input[endIndex:]
} else {
err = errors.New("unexpected characters")
return
}
}
if len(input) >= startLen {
err = errors.New("infinite loop detected in tokenizer")
return
}
}
}