iter: Byte and String Iterators

iter provides low overhead (zero allocation where possible) iterators for strings and byte slices, fulfilling both (bytes|strings).Split and (bytes|strings).FieldsFunc functionality and additional helper functions.

Examples

Word count:

s := "My long string..."

func isNotLN(r rune) {
  return !unicode.IsLetter(r) && !unicode.IsNumber(r)
}

// Standard library
func stdCountOccurrences(s, word string) int {
  count := 0
  words := strings.FieldsFunc(s, isNotLN)

  for v := range words {
    if strings.EqualFold(word, v) {
      count++
    }
  }

  return count
}

// iter package
func iterCountOccurrences(s, word string) int {
  count := 0
  iter := iter.NewFuncString(s, isNotLN)

  for iter.Next() {
    if strings.EqualFold(word, iter.Value().String()) {
      count++
    }
  }

  return count
}

Benchmarks

goos: linux
goarch: amd64
pkg: github.com/martingallagher/iter
BenchmarkBytes-8           	  100000	     20882 ns/op	       0 B/op	       0 allocs/op
BenchmarkNewString-8       	2000000000	         1.02 ns/op	       0 B/op	       0 allocs/op
BenchmarkString-8          	  100000	     20865 ns/op	       0 B/op	       0 allocs/op
BenchmarkBytesEmitAll-8    	  100000	     23239 ns/op	       0 B/op	       0 allocs/op
BenchmarkStringEmitAll-8   	   50000	     23047 ns/op	       0 B/op	       0 allocs/op
BenchmarkBytesFunc-8       	  100000	     20914 ns/op	       0 B/op	       0 allocs/op
BenchmarkStringFunc-8      	  100000	     20828 ns/op	       0 B/op	       0 allocs/op
BenchmarkStdStringsMap-8   	   50000	     23242 ns/op	   11264 B/op	       4 allocs/op
PASS
ok  	github.com/martingallagher/iter	16.754s