vendor/go.opencensus.io/internal/sanitize.go

   1 // Copyright 2017, OpenCensus Authors
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 package internal
  16
  17 import (
  18         "strings"
  19         "unicode"
  20 )
  21
  22 const labelKeySizeLimit = 100
  23
  24 // Sanitize returns a string that is trunacated to 100 characters if it's too
  25 // long, and replaces non-alphanumeric characters to underscores.
  26 func Sanitize(s string) string {
  27         if len(s) == 0 {
  28                 return s
  29         }
  30         if len(s) > labelKeySizeLimit {
  31                 s = s[:labelKeySizeLimit]
  32         }
  33         s = strings.Map(sanitizeRune, s)
  34         if unicode.IsDigit(rune(s[0])) {
  35                 s = "key_" + s
  36         }
  37         if s[0] == '_' {
  38                 s = "key" + s
  39         }
  40         return s
  41 }
  42
  43 // converts anything that is not a letter or digit to an underscore
  44 func sanitizeRune(r rune) rune {
  45         if unicode.IsLetter(r) || unicode.IsDigit(r) {
  46                 return r
  47         }
  48         // Everything else turns into an underscore
  49         return '_'
  50 }