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bytes, strings: add LastIndexByte

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Currently the packages have the following index functions:

func Index(s, sep []byte) int
func IndexAny(s []byte, chars string) int
func IndexByte(s []byte, c byte) int
func IndexFunc(s []byte, f func(r rune) bool) int
func IndexRune(s []byte, r rune) int

func LastIndex(s, sep []byte) int
func LastIndexAny(s []byte, chars string) int
func LastIndexFunc(s []byte, f func(r rune) bool) int

Searching for the last occurrence of a byte is quite common
for string parsing algorithms (e.g. find the last paren on a line).
Also addition of LastIndexByte makes the set more orthogonal.

Change-Id: Ida168849acacf8e78dd70c1354bef9eac5effafe
Reviewed-on: https://go-review.googlesource.com/9500
Reviewed-by: Rob Pike <r@golang.org>
This commit is contained in:
Dmitry Vyukov 2015-04-29 20:45:55 +03:00
parent 89454b1c39
commit 0fb5475bdf
4 changed files with 54 additions and 0 deletions
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17
src/strings/strings_test.go
View file

@ -120,6 +120,23 @@ func TestLastIndex(t *testing.T) { runIndexTests(t, LastIndex, "LastIndex", l
func TestIndexAny(t *testing.T) { runIndexTests(t, IndexAny, "IndexAny", indexAnyTests) }
func TestLastIndexAny(t *testing.T) { runIndexTests(t, LastIndexAny, "LastIndexAny", lastIndexAnyTests) }
func TestLastIndexByte(t *testing.T) {
testCases := []IndexTest{
{"", "q", -1},
{"abcdef", "q", -1},
{"abcdefabcdef", "a", len("abcdef")}, // something in the middle
{"abcdefabcdef", "f", len("abcdefabcde")}, // last byte
{"zabcdefabcdef", "z", 0}, // first byte
{"a☺b☻c☹d", "b", len("a☺")}, // non-ascii
}
for _, test := range testCases {
actual := LastIndexByte(test.s, test.sep[0])
if actual != test.out {
t.Errorf("LastIndexByte(%q,%c) = %v; want %v", test.s, test.sep[0], actual, test.out)
}
}
}
var indexRuneTests = []struct {
s string
rune rune