build: move package sources from src/pkg to src

Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.

3 files changed, 779 insertions, 0 deletions

diff --git a/src/index/suffixarray/qsufsort.go b/src/index/suffixarray/qsufsort.go
new file mode 100644
index 000000000..9c36a98f8
--- /dev/null
+++ b/src/index/suffixarray/qsufsort.go
@@ -0,0 +1,168 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This algorithm is based on "Faster Suffix Sorting"
+//   by N. Jesper Larsson and Kunihiko Sadakane
+// paper: http://www.larsson.dogma.net/ssrev-tr.pdf
+// code:  http://www.larsson.dogma.net/qsufsort.c
+
+// This algorithm computes the suffix array sa by computing its inverse.
+// Consecutive groups of suffixes in sa are labeled as sorted groups or
+// unsorted groups. For a given pass of the sorter, all suffixes are ordered
+// up to their first h characters, and sa is h-ordered. Suffixes in their
+// final positions and unambiguously sorted in h-order are in a sorted group.
+// Consecutive groups of suffixes with identical first h characters are an
+// unsorted group. In each pass of the algorithm, unsorted groups are sorted
+// according to the group number of their following suffix.
+
+// In the implementation, if sa[i] is negative, it indicates that i is
+// the first element of a sorted group of length -sa[i], and can be skipped.
+// An unsorted group sa[i:k] is given the group number of the index of its
+// last element, k-1. The group numbers are stored in the inverse slice (inv),
+// and when all groups are sorted, this slice is the inverse suffix array.
+
+package suffixarray
+
+import "sort"
+
+func qsufsort(data []byte) []int {
+	// initial sorting by first byte of suffix
+	sa := sortedByFirstByte(data)
+	if len(sa) < 2 {
+		return sa
+	}
+	// initialize the group lookup table
+	// this becomes the inverse of the suffix array when all groups are sorted
+	inv := initGroups(sa, data)
+
+	// the index starts 1-ordered
+	sufSortable := &suffixSortable{sa: sa, inv: inv, h: 1}
+
+	for sa[0] > -len(sa) { // until all suffixes are one big sorted group
+		// The suffixes are h-ordered, make them 2*h-ordered
+		pi := 0 // pi is first position of first group
+		sl := 0 // sl is negated length of sorted groups
+		for pi < len(sa) {
+			if s := sa[pi]; s < 0 { // if pi starts sorted group
+				pi -= s // skip over sorted group
+				sl += s // add negated length to sl
+			} else { // if pi starts unsorted group
+				if sl != 0 {
+					sa[pi+sl] = sl // combine sorted groups before pi
+					sl = 0
+				}
+				pk := inv[s] + 1 // pk-1 is last position of unsorted group
+				sufSortable.sa = sa[pi:pk]
+				sort.Sort(sufSortable)
+				sufSortable.updateGroups(pi)
+				pi = pk // next group
+			}
+		}
+		if sl != 0 { // if the array ends with a sorted group
+			sa[pi+sl] = sl // combine sorted groups at end of sa
+		}
+
+		sufSortable.h *= 2 // double sorted depth
+	}
+
+	for i := range sa { // reconstruct suffix array from inverse
+		sa[inv[i]] = i
+	}
+	return sa
+}
+
+func sortedByFirstByte(data []byte) []int {
+	// total byte counts
+	var count [256]int
+	for _, b := range data {
+		count[b]++
+	}
+	// make count[b] equal index of first occurrence of b in sorted array
+	sum := 0
+	for b := range count {
+		count[b], sum = sum, count[b]+sum
+	}
+	// iterate through bytes, placing index into the correct spot in sa
+	sa := make([]int, len(data))
+	for i, b := range data {
+		sa[count[b]] = i
+		count[b]++
+	}
+	return sa
+}
+
+func initGroups(sa []int, data []byte) []int {
+	// label contiguous same-letter groups with the same group number
+	inv := make([]int, len(data))
+	prevGroup := len(sa) - 1
+	groupByte := data[sa[prevGroup]]
+	for i := len(sa) - 1; i >= 0; i-- {
+		if b := data[sa[i]]; b < groupByte {
+			if prevGroup == i+1 {
+				sa[i+1] = -1
+			}
+			groupByte = b
+			prevGroup = i
+		}
+		inv[sa[i]] = prevGroup
+		if prevGroup == 0 {
+			sa[0] = -1
+		}
+	}
+	// Separate out the final suffix to the start of its group.
+	// This is necessary to ensure the suffix "a" is before "aba"
+	// when using a potentially unstable sort.
+	lastByte := data[len(data)-1]
+	s := -1
+	for i := range sa {
+		if sa[i] >= 0 {
+			if data[sa[i]] == lastByte && s == -1 {
+				s = i
+			}
+			if sa[i] == len(sa)-1 {
+				sa[i], sa[s] = sa[s], sa[i]
+				inv[sa[s]] = s
+				sa[s] = -1 // mark it as an isolated sorted group
+				break
+			}
+		}
+	}
+	return inv
+}
+
+type suffixSortable struct {
+	sa  []int
+	inv []int
+	h   int
+	buf []int // common scratch space
+}
+
+func (x *suffixSortable) Len() int           { return len(x.sa) }
+func (x *suffixSortable) Less(i, j int) bool { return x.inv[x.sa[i]+x.h] < x.inv[x.sa[j]+x.h] }
+func (x *suffixSortable) Swap(i, j int)      { x.sa[i], x.sa[j] = x.sa[j], x.sa[i] }
+
+func (x *suffixSortable) updateGroups(offset int) {
+	bounds := x.buf[0:0]
+	group := x.inv[x.sa[0]+x.h]
+	for i := 1; i < len(x.sa); i++ {
+		if g := x.inv[x.sa[i]+x.h]; g > group {
+			bounds = append(bounds, i)
+			group = g
+		}
+	}
+	bounds = append(bounds, len(x.sa))
+	x.buf = bounds
+
+	// update the group numberings after all new groups are determined
+	prev := 0
+	for _, b := range bounds {
+		for i := prev; i < b; i++ {
+			x.inv[x.sa[i]] = offset + b - 1
+		}
+		if b-prev == 1 {
+			x.sa[prev] = -1
+		}
+		prev = b
+	}
+}
diff --git a/src/index/suffixarray/suffixarray.go b/src/index/suffixarray/suffixarray.go
new file mode 100644
index 000000000..c59ae6eef
--- /dev/null
+++ b/src/index/suffixarray/suffixarray.go
@@ -0,0 +1,307 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package suffixarray implements substring search in logarithmic time using
+// an in-memory suffix array.
+//
+// Example use:
+//
+//	// create index for some data
+//	index := suffixarray.New(data)
+//
+//	// lookup byte slice s
+//	offsets1 := index.Lookup(s, -1) // the list of all indices where s occurs in data
+//	offsets2 := index.Lookup(s, 3)  // the list of at most 3 indices where s occurs in data
+//
+package suffixarray
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+	"regexp"
+	"sort"
+)
+
+// Index implements a suffix array for fast substring search.
+type Index struct {
+	data []byte
+	sa   []int // suffix array for data; len(sa) == len(data)
+}
+
+// New creates a new Index for data.
+// Index creation time is O(N*log(N)) for N = len(data).
+func New(data []byte) *Index {
+	return &Index{data, qsufsort(data)}
+}
+
+// writeInt writes an int x to w using buf to buffer the write.
+func writeInt(w io.Writer, buf []byte, x int) error {
+	binary.PutVarint(buf, int64(x))
+	_, err := w.Write(buf[0:binary.MaxVarintLen64])
+	return err
+}
+
+// readInt reads an int x from r using buf to buffer the read and returns x.
+func readInt(r io.Reader, buf []byte) (int, error) {
+	_, err := io.ReadFull(r, buf[0:binary.MaxVarintLen64]) // ok to continue with error
+	x, _ := binary.Varint(buf)
+	return int(x), err
+}
+
+// writeSlice writes data[:n] to w and returns n.
+// It uses buf to buffer the write.
+func writeSlice(w io.Writer, buf []byte, data []int) (n int, err error) {
+	// encode as many elements as fit into buf
+	p := binary.MaxVarintLen64
+	for ; n < len(data) && p+binary.MaxVarintLen64 <= len(buf); n++ {
+		p += binary.PutUvarint(buf[p:], uint64(data[n]))
+	}
+
+	// update buffer size
+	binary.PutVarint(buf, int64(p))
+
+	// write buffer
+	_, err = w.Write(buf[0:p])
+	return
+}
+
+// readSlice reads data[:n] from r and returns n.
+// It uses buf to buffer the read.
+func readSlice(r io.Reader, buf []byte, data []int) (n int, err error) {
+	// read buffer size
+	var size int
+	size, err = readInt(r, buf)
+	if err != nil {
+		return
+	}
+
+	// read buffer w/o the size
+	if _, err = io.ReadFull(r, buf[binary.MaxVarintLen64:size]); err != nil {
+		return
+	}
+
+	// decode as many elements as present in buf
+	for p := binary.MaxVarintLen64; p < size; n++ {
+		x, w := binary.Uvarint(buf[p:])
+		data[n] = int(x)
+		p += w
+	}
+
+	return
+}
+
+const bufSize = 16 << 10 // reasonable for BenchmarkSaveRestore
+
+// Read reads the index from r into x; x must not be nil.
+func (x *Index) Read(r io.Reader) error {
+	// buffer for all reads
+	buf := make([]byte, bufSize)
+
+	// read length
+	n, err := readInt(r, buf)
+	if err != nil {
+		return err
+	}
+
+	// allocate space
+	if 2*n < cap(x.data) || cap(x.data) < n {
+		// new data is significantly smaller or larger then
+		// existing buffers - allocate new ones
+		x.data = make([]byte, n)
+		x.sa = make([]int, n)
+	} else {
+		// re-use existing buffers
+		x.data = x.data[0:n]
+		x.sa = x.sa[0:n]
+	}
+
+	// read data
+	if _, err := io.ReadFull(r, x.data); err != nil {
+		return err
+	}
+
+	// read index
+	for sa := x.sa; len(sa) > 0; {
+		n, err := readSlice(r, buf, sa)
+		if err != nil {
+			return err
+		}
+		sa = sa[n:]
+	}
+	return nil
+}
+
+// Write writes the index x to w.
+func (x *Index) Write(w io.Writer) error {
+	// buffer for all writes
+	buf := make([]byte, bufSize)
+
+	// write length
+	if err := writeInt(w, buf, len(x.data)); err != nil {
+		return err
+	}
+
+	// write data
+	if _, err := w.Write(x.data); err != nil {
+		return err
+	}
+
+	// write index
+	for sa := x.sa; len(sa) > 0; {
+		n, err := writeSlice(w, buf, sa)
+		if err != nil {
+			return err
+		}
+		sa = sa[n:]
+	}
+	return nil
+}
+
+// Bytes returns the data over which the index was created.
+// It must not be modified.
+//
+func (x *Index) Bytes() []byte {
+	return x.data
+}
+
+func (x *Index) at(i int) []byte {
+	return x.data[x.sa[i]:]
+}
+
+// lookupAll returns a slice into the matching region of the index.
+// The runtime is O(log(N)*len(s)).
+func (x *Index) lookupAll(s []byte) []int {
+	// find matching suffix index range [i:j]
+	// find the first index where s would be the prefix
+	i := sort.Search(len(x.sa), func(i int) bool { return bytes.Compare(x.at(i), s) >= 0 })
+	// starting at i, find the first index at which s is not a prefix
+	j := i + sort.Search(len(x.sa)-i, func(j int) bool { return !bytes.HasPrefix(x.at(j+i), s) })
+	return x.sa[i:j]
+}
+
+// Lookup returns an unsorted list of at most n indices where the byte string s
+// occurs in the indexed data. If n < 0, all occurrences are returned.
+// The result is nil if s is empty, s is not found, or n == 0.
+// Lookup time is O(log(N)*len(s) + len(result)) where N is the
+// size of the indexed data.
+//
+func (x *Index) Lookup(s []byte, n int) (result []int) {
+	if len(s) > 0 && n != 0 {
+		matches := x.lookupAll(s)
+		if n < 0 || len(matches) < n {
+			n = len(matches)
+		}
+		// 0 <= n <= len(matches)
+		if n > 0 {
+			result = make([]int, n)
+			copy(result, matches)
+		}
+	}
+	return
+}
+
+// FindAllIndex returns a sorted list of non-overlapping matches of the
+// regular expression r, where a match is a pair of indices specifying
+// the matched slice of x.Bytes(). If n < 0, all matches are returned
+// in successive order. Otherwise, at most n matches are returned and
+// they may not be successive. The result is nil if there are no matches,
+// or if n == 0.
+//
+func (x *Index) FindAllIndex(r *regexp.Regexp, n int) (result [][]int) {
+	// a non-empty literal prefix is used to determine possible
+	// match start indices with Lookup
+	prefix, complete := r.LiteralPrefix()
+	lit := []byte(prefix)
+
+	// worst-case scenario: no literal prefix
+	if prefix == "" {
+		return r.FindAllIndex(x.data, n)
+	}
+
+	// if regexp is a literal just use Lookup and convert its
+	// result into match pairs
+	if complete {
+		// Lookup returns indices that may belong to overlapping matches.
+		// After eliminating them, we may end up with fewer than n matches.
+		// If we don't have enough at the end, redo the search with an
+		// increased value n1, but only if Lookup returned all the requested
+		// indices in the first place (if it returned fewer than that then
+		// there cannot be more).
+		for n1 := n; ; n1 += 2 * (n - len(result)) /* overflow ok */ {
+			indices := x.Lookup(lit, n1)
+			if len(indices) == 0 {
+				return
+			}
+			sort.Ints(indices)
+			pairs := make([]int, 2*len(indices))
+			result = make([][]int, len(indices))
+			count := 0
+			prev := 0
+			for _, i := range indices {
+				if count == n {
+					break
+				}
+				// ignore indices leading to overlapping matches
+				if prev <= i {
+					j := 2 * count
+					pairs[j+0] = i
+					pairs[j+1] = i + len(lit)
+					result[count] = pairs[j : j+2]
+					count++
+					prev = i + len(lit)
+				}
+			}
+			result = result[0:count]
+			if len(result) >= n || len(indices) != n1 {
+				// found all matches or there's no chance to find more
+				// (n and n1 can be negative)
+				break
+			}
+		}
+		if len(result) == 0 {
+			result = nil
+		}
+		return
+	}
+
+	// regexp has a non-empty literal prefix; Lookup(lit) computes
+	// the indices of possible complete matches; use these as starting
+	// points for anchored searches
+	// (regexp "^" matches beginning of input, not beginning of line)
+	r = regexp.MustCompile("^" + r.String()) // compiles because r compiled
+
+	// same comment about Lookup applies here as in the loop above
+	for n1 := n; ; n1 += 2 * (n - len(result)) /* overflow ok */ {
+		indices := x.Lookup(lit, n1)
+		if len(indices) == 0 {
+			return
+		}
+		sort.Ints(indices)
+		result = result[0:0]
+		prev := 0
+		for _, i := range indices {
+			if len(result) == n {
+				break
+			}
+			m := r.FindIndex(x.data[i:]) // anchored search - will not run off
+			// ignore indices leading to overlapping matches
+			if m != nil && prev <= i {
+				m[0] = i // correct m
+				m[1] += i
+				result = append(result, m)
+				prev = m[1]
+			}
+		}
+		if len(result) >= n || len(indices) != n1 {
+			// found all matches or there's no chance to find more
+			// (n and n1 can be negative)
+			break
+		}
+	}
+	if len(result) == 0 {
+		result = nil
+	}
+	return
+}
diff --git a/src/index/suffixarray/suffixarray_test.go b/src/index/suffixarray/suffixarray_test.go
new file mode 100644
index 000000000..644f00c75
--- /dev/null
+++ b/src/index/suffixarray/suffixarray_test.go
@@ -0,0 +1,304 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package suffixarray
+
+import (
+	"bytes"
+	"math/rand"
+	"regexp"
+	"sort"
+	"strings"
+	"testing"
+)
+
+type testCase struct {
+	name     string   // name of test case
+	source   string   // source to index
+	patterns []string // patterns to lookup
+}
+
+var testCases = []testCase{
+	{
+		"empty string",
+		"",
+		[]string{
+			"",
+			"foo",
+			"(foo)",
+			".*",
+			"a*",
+		},
+	},
+
+	{
+		"all a's",
+		"aaaaaaaaaa", // 10 a's
+		[]string{
+			"",
+			"a",
+			"aa",
+			"aaa",
+			"aaaa",
+			"aaaaa",
+			"aaaaaa",
+			"aaaaaaa",
+			"aaaaaaaa",
+			"aaaaaaaaa",
+			"aaaaaaaaaa",
+			"aaaaaaaaaaa", // 11 a's
+			".",
+			".*",
+			"a+",
+			"aa+",
+			"aaaa[b]?",
+			"aaa*",
+		},
+	},
+
+	{
+		"abc",
+		"abc",
+		[]string{
+			"a",
+			"b",
+			"c",
+			"ab",
+			"bc",
+			"abc",
+			"a.c",
+			"a(b|c)",
+			"abc?",
+		},
+	},
+
+	{
+		"barbara*3",
+		"barbarabarbarabarbara",
+		[]string{
+			"a",
+			"bar",
+			"rab",
+			"arab",
+			"barbar",
+			"bara?bar",
+		},
+	},
+
+	{
+		"typing drill",
+		"Now is the time for all good men to come to the aid of their country.",
+		[]string{
+			"Now",
+			"the time",
+			"to come the aid",
+			"is the time for all good men to come to the aid of their",
+			"to (come|the)?",
+		},
+	},
+
+	{
+		"godoc simulation",
+		"package main\n\nimport(\n    \"rand\"\n    ",
+		[]string{},
+	},
+}
+
+// find all occurrences of s in source; report at most n occurrences
+func find(src, s string, n int) []int {
+	var res []int
+	if s != "" && n != 0 {
+		// find at most n occurrences of s in src
+		for i := -1; n < 0 || len(res) < n; {
+			j := strings.Index(src[i+1:], s)
+			if j < 0 {
+				break
+			}
+			i += j + 1
+			res = append(res, i)
+		}
+	}
+	return res
+}
+
+func testLookup(t *testing.T, tc *testCase, x *Index, s string, n int) {
+	res := x.Lookup([]byte(s), n)
+	exp := find(tc.source, s, n)
+
+	// check that the lengths match
+	if len(res) != len(exp) {
+		t.Errorf("test %q, lookup %q (n = %d): expected %d results; got %d", tc.name, s, n, len(exp), len(res))
+	}
+
+	// if n >= 0 the number of results is limited --- unless n >= all results,
+	// we may obtain different positions from the Index and from find (because
+	// Index may not find the results in the same order as find) => in general
+	// we cannot simply check that the res and exp lists are equal
+
+	// check that each result is in fact a correct match and there are no duplicates
+	sort.Ints(res)
+	for i, r := range res {
+		if r < 0 || len(tc.source) <= r {
+			t.Errorf("test %q, lookup %q, result %d (n = %d): index %d out of range [0, %d[", tc.name, s, i, n, r, len(tc.source))
+		} else if !strings.HasPrefix(tc.source[r:], s) {
+			t.Errorf("test %q, lookup %q, result %d (n = %d): index %d not a match", tc.name, s, i, n, r)
+		}
+		if i > 0 && res[i-1] == r {
+			t.Errorf("test %q, lookup %q, result %d (n = %d): found duplicate index %d", tc.name, s, i, n, r)
+		}
+	}
+
+	if n < 0 {
+		// all results computed - sorted res and exp must be equal
+		for i, r := range res {
+			e := exp[i]
+			if r != e {
+				t.Errorf("test %q, lookup %q, result %d: expected index %d; got %d", tc.name, s, i, e, r)
+			}
+		}
+	}
+}
+
+func testFindAllIndex(t *testing.T, tc *testCase, x *Index, rx *regexp.Regexp, n int) {
+	res := x.FindAllIndex(rx, n)
+	exp := rx.FindAllStringIndex(tc.source, n)
+
+	// check that the lengths match
+	if len(res) != len(exp) {
+		t.Errorf("test %q, FindAllIndex %q (n = %d): expected %d results; got %d", tc.name, rx, n, len(exp), len(res))
+	}
+
+	// if n >= 0 the number of results is limited --- unless n >= all results,
+	// we may obtain different positions from the Index and from regexp (because
+	// Index may not find the results in the same order as regexp) => in general
+	// we cannot simply check that the res and exp lists are equal
+
+	// check that each result is in fact a correct match and the result is sorted
+	for i, r := range res {
+		if r[0] < 0 || r[0] > r[1] || len(tc.source) < r[1] {
+			t.Errorf("test %q, FindAllIndex %q, result %d (n == %d): illegal match [%d, %d]", tc.name, rx, i, n, r[0], r[1])
+		} else if !rx.MatchString(tc.source[r[0]:r[1]]) {
+			t.Errorf("test %q, FindAllIndex %q, result %d (n = %d): [%d, %d] not a match", tc.name, rx, i, n, r[0], r[1])
+		}
+	}
+
+	if n < 0 {
+		// all results computed - sorted res and exp must be equal
+		for i, r := range res {
+			e := exp[i]
+			if r[0] != e[0] || r[1] != e[1] {
+				t.Errorf("test %q, FindAllIndex %q, result %d: expected match [%d, %d]; got [%d, %d]",
+					tc.name, rx, i, e[0], e[1], r[0], r[1])
+			}
+		}
+	}
+}
+
+func testLookups(t *testing.T, tc *testCase, x *Index, n int) {
+	for _, pat := range tc.patterns {
+		testLookup(t, tc, x, pat, n)
+		if rx, err := regexp.Compile(pat); err == nil {
+			testFindAllIndex(t, tc, x, rx, n)
+		}
+	}
+}
+
+// index is used to hide the sort.Interface
+type index Index
+
+func (x *index) Len() int           { return len(x.sa) }
+func (x *index) Less(i, j int) bool { return bytes.Compare(x.at(i), x.at(j)) < 0 }
+func (x *index) Swap(i, j int)      { x.sa[i], x.sa[j] = x.sa[j], x.sa[i] }
+func (a *index) at(i int) []byte    { return a.data[a.sa[i]:] }
+
+func testConstruction(t *testing.T, tc *testCase, x *Index) {
+	if !sort.IsSorted((*index)(x)) {
+		t.Errorf("failed testConstruction %s", tc.name)
+	}
+}
+
+func equal(x, y *Index) bool {
+	if !bytes.Equal(x.data, y.data) {
+		return false
+	}
+	for i, j := range x.sa {
+		if j != y.sa[i] {
+			return false
+		}
+	}
+	return true
+}
+
+// returns the serialized index size
+func testSaveRestore(t *testing.T, tc *testCase, x *Index) int {
+	var buf bytes.Buffer
+	if err := x.Write(&buf); err != nil {
+		t.Errorf("failed writing index %s (%s)", tc.name, err)
+	}
+	size := buf.Len()
+	var y Index
+	if err := y.Read(&buf); err != nil {
+		t.Errorf("failed reading index %s (%s)", tc.name, err)
+	}
+	if !equal(x, &y) {
+		t.Errorf("restored index doesn't match saved index %s", tc.name)
+	}
+	return size
+}
+
+func TestIndex(t *testing.T) {
+	for _, tc := range testCases {
+		x := New([]byte(tc.source))
+		testConstruction(t, &tc, x)
+		testSaveRestore(t, &tc, x)
+		testLookups(t, &tc, x, 0)
+		testLookups(t, &tc, x, 1)
+		testLookups(t, &tc, x, 10)
+		testLookups(t, &tc, x, 2e9)
+		testLookups(t, &tc, x, -1)
+	}
+}
+
+// Of all possible inputs, the random bytes have the least amount of substring
+// repetition, and the repeated bytes have the most. For most algorithms,
+// the running time of every input will be between these two.
+func benchmarkNew(b *testing.B, random bool) {
+	b.StopTimer()
+	data := make([]byte, 1e6)
+	if random {
+		for i := range data {
+			data[i] = byte(rand.Intn(256))
+		}
+	}
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		New(data)
+	}
+}
+
+func BenchmarkNewIndexRandom(b *testing.B) {
+	benchmarkNew(b, true)
+}
+func BenchmarkNewIndexRepeat(b *testing.B) {
+	benchmarkNew(b, false)
+}
+
+func BenchmarkSaveRestore(b *testing.B) {
+	b.StopTimer()
+	r := rand.New(rand.NewSource(0x5a77a1)) // guarantee always same sequence
+	data := make([]byte, 1<<20)             // 1MB of data to index
+	for i := range data {
+		data[i] = byte(r.Intn(256))
+	}
+	x := New(data)
+	size := testSaveRestore(nil, nil, x)       // verify correctness
+	buf := bytes.NewBuffer(make([]byte, size)) // avoid growing
+	b.SetBytes(int64(size))
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		x.Write(buf)
+		var y Index
+		y.Read(buf)
+	}
+}