Created
July 3, 2019 03:00
-
-
Save packrat386/16feafb69f85da25e6fbdc34372ef323 to your computer and use it in GitHub Desktop.
Dumb impl of `bytes.Index`
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
package index | |
func Index(s, sep []byte) int { | |
pos := 0 | |
for { | |
if pos+len(sep) > len(s) { | |
return -1 | |
} | |
if eql(s[pos:pos+len(sep)], sep) { | |
return pos | |
} | |
pos++ | |
} | |
} | |
func eql(a, b []byte) bool { | |
for i, v := range a { | |
if v != b[i] { | |
return false | |
} | |
} | |
return true | |
} |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
package index | |
import ( | |
"bytes" | |
"testing" | |
) | |
type BinOpTest struct { | |
a string | |
b string | |
i int | |
} | |
var indexTests = []BinOpTest{ | |
{"", "", 0}, | |
{"", "a", -1}, | |
{"", "foo", -1}, | |
{"fo", "foo", -1}, | |
{"foo", "baz", -1}, | |
{"foo", "foo", 0}, | |
{"oofofoofooo", "f", 2}, | |
{"oofofoofooo", "foo", 4}, | |
{"barfoobarfoo", "foo", 3}, | |
{"foo", "", 0}, | |
{"foo", "o", 1}, | |
{"abcABCabc", "A", 3}, | |
// cases with one byte strings - test IndexByte and special case in Index() | |
{"", "a", -1}, | |
{"x", "a", -1}, | |
{"x", "x", 0}, | |
{"abc", "a", 0}, | |
{"abc", "b", 1}, | |
{"abc", "c", 2}, | |
{"abc", "x", -1}, | |
{"barfoobarfooyyyzzzyyyzzzyyyzzzyyyxxxzzzyyy", "x", 33}, | |
{"foofyfoobarfoobar", "y", 4}, | |
{"oooooooooooooooooooooo", "r", -1}, | |
// test fallback to Rabin-Karp. | |
{"oxoxoxoxoxoxoxoxoxoxoxoy", "oy", 22}, | |
{"oxoxoxoxoxoxoxoxoxoxoxox", "oy", -1}, | |
} | |
func TestIndex(t *testing.T) { | |
for _, tt := range indexTests { | |
a := []byte(tt.a) | |
b := []byte(tt.b) | |
pos := Index(a, b) | |
if pos != tt.i { | |
t.Errorf(`Index(%q, %q) = %v`, tt.a, tt.b, pos) | |
} | |
} | |
} | |
func TestIndexStdlib(t *testing.T) { | |
for _, tt := range indexTests { | |
a := []byte(tt.a) | |
b := []byte(tt.b) | |
pos := bytes.Index(a, b) | |
if pos != tt.i { | |
t.Errorf(`Index(%q, %q) = %v`, tt.a, tt.b, pos) | |
} | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment