4 files changed, 95 insertions, 12 deletions
diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
index 8a4409cb6b..305c85d9f4 100644
--- a/src/bytes/bytes.go
+++ b/src/bytes/bytes.go
@@ -83,6 +83,16 @@ func Contains(b, subslice []byte) bool {
 	return Index(b, subslice) != -1
 }
 
+// ContainsAny reports whether any of the UTF-8-encoded Unicode code points in chars are within b.
+func ContainsAny(b []byte, chars string) bool {
+	return IndexAny(b, chars) >= 0
+}
+
+// ContainsRune reports whether the Unicode code point r is within b.
+func ContainsRune(b []byte, r rune) bool {
+	return IndexRune(b, r) >= 0
+}
+
 // Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
 func Index(s, sep []byte) int {
 	n := len(sep)
diff --git a/src/bytes/bytes_test.go b/src/bytes/bytes_test.go
index 1be29d6cc6..620cfd1bce 100644
--- a/src/bytes/bytes_test.go
+++ b/src/bytes/bytes_test.go
@@ -1218,6 +1218,57 @@ func TestContains(t *testing.T) {
 	}
 }
 
+var ContainsAnyTests = []struct {
+	b        []byte
+	substr   string
+	expected bool
+}{
+	{[]byte(""), "", false},
+	{[]byte(""), "a", false},
+	{[]byte(""), "abc", false},
+	{[]byte("a"), "", false},
+	{[]byte("a"), "a", true},
+	{[]byte("aaa"), "a", true},
+	{[]byte("abc"), "xyz", false},
+	{[]byte("abc"), "xcz", true},
+	{[]byte("a☺b☻c☹d"), "uvw☻xyz", true},
+	{[]byte("aRegExp*"), ".(|)*+?^$[]", true},
+	{[]byte(dots + dots + dots), " ", false},
+}
+
+func TestContainsAny(t *testing.T) {
+	for _, ct := range ContainsAnyTests {
+		if ContainsAny(ct.b, ct.substr) != ct.expected {
+			t.Errorf("ContainsAny(%s, %s) = %v, want %v",
+				ct.b, ct.substr, !ct.expected, ct.expected)
+		}
+	}
+}
+
+var ContainsRuneTests = []struct {
+	b        []byte
+	r        rune
+	expected bool
+}{
+	{[]byte(""), 'a', false},
+	{[]byte("a"), 'a', true},
+	{[]byte("aaa"), 'a', true},
+	{[]byte("abc"), 'y', false},
+	{[]byte("abc"), 'c', true},
+	{[]byte("a☺b☻c☹d"), 'x', false},
+	{[]byte("a☺b☻c☹d"), '☻', true},
+	{[]byte("aRegExp*"), '*', true},
+}
+
+func TestContainsRune(t *testing.T) {
+	for _, ct := range ContainsRuneTests {
+		if ContainsRune(ct.b, ct.r) != ct.expected {
+			t.Errorf("ContainsRune(%q, %q) = %v, want %v",
+				ct.b, ct.r, !ct.expected, ct.expected)
+		}
+	}
+}
+
 var makeFieldsInput = func() []byte {
 	x := make([]byte, 1<<20)
 	// Input is ~10% space, ~10% 2-byte UTF-8, rest ASCII non-space.
diff --git a/src/bytes/reader.go b/src/bytes/reader.go
index 5941ebdab4..aa39890f3b 100644
--- a/src/bytes/reader.go
+++ b/src/bytes/reader.go
@@ -114,7 +114,7 @@ func (r *Reader) Seek(offset int64, whence int) (int64, error) {
 	case 0:
 		abs = offset
 	case 1:
-		abs = int64(r.i) + offset
+		abs = r.i + offset
 	case 2:
 		abs = int64(len(r.s)) + offset
 	default:
@@ -146,5 +146,8 @@ func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
 	return
 }
 
+// Reset resets the Reader to be reading from b.
+func (r *Reader) Reset(b []byte) { *r = Reader{b, 0, -1} }
+
 // NewReader returns a new Reader reading from b.
 func NewReader(b []byte) *Reader { return &Reader{b, 0, -1} }
diff --git a/src/bytes/reader_test.go b/src/bytes/reader_test.go
index b929a28260..9341cd5b45 100644
--- a/src/bytes/reader_test.go
+++ b/src/bytes/reader_test.go
@@ -9,7 +9,6 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
-	"os"
 	"sync"
 	"testing"
 )
@@ -24,15 +23,15 @@ func TestReader(t *testing.T) {
 		wantpos int64
 		seekerr string
 	}{
-		{seek: os.SEEK_SET, off: 0, n: 20, want: "0123456789"},
-		{seek: os.SEEK_SET, off: 1, n: 1, want: "1"},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 3, n: 2, want: "34"},
-		{seek: os.SEEK_SET, off: -1, seekerr: "bytes.Reader.Seek: negative position"},
-		{seek: os.SEEK_SET, off: 1 << 33, wantpos: 1 << 33},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 1<<33 + 1},
-		{seek: os.SEEK_SET, n: 5, want: "01234"},
-		{seek: os.SEEK_CUR, n: 5, want: "56789"},
-		{seek: os.SEEK_END, off: -1, n: 1, wantpos: 9, want: "9"},
+		{seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
+		{seek: io.SeekStart, off: 1, n: 1, want: "1"},
+		{seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
+		{seek: io.SeekStart, off: -1, seekerr: "bytes.Reader.Seek: negative position"},
+		{seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33},
+		{seek: io.SeekCurrent, off: 1, wantpos: 1<<33 + 1},
+		{seek: io.SeekStart, n: 5, want: "01234"},
+		{seek: io.SeekCurrent, n: 5, want: "56789"},
+		{seek: io.SeekEnd, off: -1, n: 1, wantpos: 9, want: "9"},
 	}
 
 	for i, tt := range tests {
@@ -63,7 +62,7 @@ func TestReader(t *testing.T) {
 
 func TestReadAfterBigSeek(t *testing.T) {
 	r := NewReader([]byte("0123456789"))
-	if _, err := r.Seek(1<<31+5, os.SEEK_SET); err != nil {
+	if _, err := r.Seek(1<<31+5, io.SeekStart); err != nil {
 		t.Fatal(err)
 	}
 	if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {
@@ -256,3 +255,23 @@ func TestReaderLenSize(t *testing.T) {
 		t.Errorf("Size = %d; want 3", r.Size())
 	}
 }
+
+func TestReaderReset(t *testing.T) {
+	r := NewReader([]byte("世界"))
+	if _, _, err := r.ReadRune(); err != nil {
+		t.Errorf("ReadRune: unexpected error: %v", err)
+	}
+
+	const want = "abcdef"
+	r.Reset([]byte(want))
+	if err := r.UnreadRune(); err == nil {
+		t.Errorf("UnreadRune: expected error, got nil")
+	}
+	buf, err := ioutil.ReadAll(r)
+	if err != nil {
+		t.Errorf("ReadAll: unexpected error: %v", err)
+	}
+	if got := string(buf); got != want {
+		t.Errorf("ReadAll: got %q, want %q", got, want)
+	}
+}