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add s3 region filters for cloudfront

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Signed-off-by: tifayuki <tifayuki@gmail.com>
This commit is contained in:
tifayuki 2017-11-14 17:21:36 -08:00
parent 3800056b88
commit e8ecc6dc55
11 changed files with 716 additions and 1548 deletions
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68
vendor/golang.org/x/net/idna/idna.go generated vendored
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@ -1,68 +0,0 @@
// Copyright 2012 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 idna implements IDNA2008 (Internationalized Domain Names for
// Applications), defined in RFC 5890, RFC 5891, RFC 5892, RFC 5893 and
// RFC 5894.
package idna // import "golang.org/x/net/idna"
import (
"strings"
"unicode/utf8"
)
// TODO(nigeltao): specify when errors occur. For example, is ToASCII(".") or
// ToASCII("foo\x00") an error? See also http://www.unicode.org/faq/idn.html#11
// acePrefix is the ASCII Compatible Encoding prefix.
const acePrefix = "xn--"
// ToASCII converts a domain or domain label to its ASCII form. For example,
// ToASCII("bücher.example.com") is "xn--bcher-kva.example.com", and
// ToASCII("golang") is "golang".
func ToASCII(s string) (string, error) {
if ascii(s) {
return s, nil
}
labels := strings.Split(s, ".")
for i, label := range labels {
if !ascii(label) {
a, err := encode(acePrefix, label)
if err != nil {
return "", err
}
labels[i] = a
}
}
return strings.Join(labels, "."), nil
}
// ToUnicode converts a domain or domain label to its Unicode form. For example,
// ToUnicode("xn--bcher-kva.example.com") is "bücher.example.com", and
// ToUnicode("golang") is "golang".
func ToUnicode(s string) (string, error) {
if !strings.Contains(s, acePrefix) {
return s, nil
}
labels := strings.Split(s, ".")
for i, label := range labels {
if strings.HasPrefix(label, acePrefix) {
u, err := decode(label[len(acePrefix):])
if err != nil {
return "", err
}
labels[i] = u
}
}
return strings.Join(labels, "."), nil
}
func ascii(s string) bool {
for i := 0; i < len(s); i++ {
if s[i] >= utf8.RuneSelf {
return false
}
}
return true
}

200
vendor/golang.org/x/net/idna/punycode.go generated vendored
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@ -1,200 +0,0 @@
// Copyright 2012 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 idna
// This file implements the Punycode algorithm from RFC 3492.
import (
"fmt"
"math"
"strings"
"unicode/utf8"
)
// These parameter values are specified in section 5.
//
// All computation is done with int32s, so that overflow behavior is identical
// regardless of whether int is 32-bit or 64-bit.
const (
base int32 = 36
damp int32 = 700
initialBias int32 = 72
initialN int32 = 128
skew int32 = 38
tmax int32 = 26
tmin int32 = 1
)
// decode decodes a string as specified in section 6.2.
func decode(encoded string) (string, error) {
if encoded == "" {
return "", nil
}
pos := 1 + strings.LastIndex(encoded, "-")
if pos == 1 {
return "", fmt.Errorf("idna: invalid label %q", encoded)
}
if pos == len(encoded) {
return encoded[:len(encoded)-1], nil
}
output := make([]rune, 0, len(encoded))
if pos != 0 {
for _, r := range encoded[:pos-1] {
output = append(output, r)
}
}
i, n, bias := int32(0), initialN, initialBias
for pos < len(encoded) {
oldI, w := i, int32(1)
for k := base; ; k += base {
if pos == len(encoded) {
return "", fmt.Errorf("idna: invalid label %q", encoded)
}
digit, ok := decodeDigit(encoded[pos])
if !ok {
return "", fmt.Errorf("idna: invalid label %q", encoded)
}
pos++
i += digit * w
if i < 0 {
return "", fmt.Errorf("idna: invalid label %q", encoded)
}
t := k - bias
if t < tmin {
t = tmin
} else if t > tmax {
t = tmax
}
if digit < t {
break
}
w *= base - t
if w >= math.MaxInt32/base {
return "", fmt.Errorf("idna: invalid label %q", encoded)
}
}
x := int32(len(output) + 1)
bias = adapt(i-oldI, x, oldI == 0)
n += i / x
i %= x
if n > utf8.MaxRune || len(output) >= 1024 {
return "", fmt.Errorf("idna: invalid label %q", encoded)
}
output = append(output, 0)
copy(output[i+1:], output[i:])
output[i] = n
i++
}
return string(output), nil
}
// encode encodes a string as specified in section 6.3 and prepends prefix to
// the result.
//
// The "while h < length(input)" line in the specification becomes "for
// remaining != 0" in the Go code, because len(s) in Go is in bytes, not runes.
func encode(prefix, s string) (string, error) {
output := make([]byte, len(prefix), len(prefix)+1+2*len(s))
copy(output, prefix)
delta, n, bias := int32(0), initialN, initialBias
b, remaining := int32(0), int32(0)
for _, r := range s {
if r < 0x80 {
b++
output = append(output, byte(r))
} else {
remaining++
}
}
h := b
if b > 0 {
output = append(output, '-')
}
for remaining != 0 {
m := int32(0x7fffffff)
for _, r := range s {
if m > r && r >= n {
m = r
}
}
delta += (m - n) * (h + 1)
if delta < 0 {
return "", fmt.Errorf("idna: invalid label %q", s)
}
n = m
for _, r := range s {
if r < n {
delta++
if delta < 0 {
return "", fmt.Errorf("idna: invalid label %q", s)
}
continue
}
if r > n {
continue
}
q := delta
for k := base; ; k += base {
t := k - bias
if t < tmin {
t = tmin
} else if t > tmax {
t = tmax
}
if q < t {
break
}
output = append(output, encodeDigit(t+(q-t)%(base-t)))
q = (q - t) / (base - t)
}
output = append(output, encodeDigit(q))
bias = adapt(delta, h+1, h == b)
delta = 0
h++
remaining--
}
delta++
n++
}
return string(output), nil
}
func decodeDigit(x byte) (digit int32, ok bool) {
switch {
case '0' <= x && x <= '9':
return int32(x - ('0' - 26)), true
case 'A' <= x && x <= 'Z':
return int32(x - 'A'), true
case 'a' <= x && x <= 'z':
return int32(x - 'a'), true
}
return 0, false
}
func encodeDigit(digit int32) byte {
switch {
case 0 <= digit && digit < 26:
return byte(digit + 'a')
case 26 <= digit && digit < 36:
return byte(digit + ('0' - 26))
}
panic("idna: internal error in punycode encoding")
}
// adapt is the bias adaptation function specified in section 6.1.
func adapt(delta, numPoints int32, firstTime bool) int32 {
if firstTime {
delta /= damp
} else {
delta /= 2
}
delta += delta / numPoints
k := int32(0)
for delta > ((base-tmin)*tmax)/2 {
delta /= base - tmin
k += base
}
return k + (base-tmin+1)*delta/(delta+skew)
}

663
vendor/golang.org/x/net/publicsuffix/gen.go generated vendored
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@ -1,663 +0,0 @@
// Copyright 2012 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.
// +build ignore
package main
// This program generates table.go and table_test.go.
// Invoke as:
//
// go run gen.go -version "xxx" >table.go
// go run gen.go -version "xxx" -test >table_test.go
//
// Pass -v to print verbose progress information.
//
// The version is derived from information found at
// https://github.com/publicsuffix/list/commits/master/public_suffix_list.dat
//
// To fetch a particular git revision, such as 5c70ccd250, pass
// -url "https://raw.githubusercontent.com/publicsuffix/list/5c70ccd250/public_suffix_list.dat"
import (
"bufio"
"bytes"
"flag"
"fmt"
"go/format"
"io"
"net/http"
"os"
"regexp"
"sort"
"strings"
"golang.org/x/net/idna"
)
const (
// These sum of these four values must be no greater than 32.
nodesBitsChildren = 9
nodesBitsICANN = 1
nodesBitsTextOffset = 15
nodesBitsTextLength = 6
// These sum of these four values must be no greater than 32.
childrenBitsWildcard = 1
childrenBitsNodeType = 2
childrenBitsHi = 14
childrenBitsLo = 14
)
var (
maxChildren int
maxTextOffset int
maxTextLength int
maxHi uint32
maxLo uint32
)
func max(a, b int) int {
if a < b {
return b
}
return a
}
func u32max(a, b uint32) uint32 {
if a < b {
return b
}
return a
}
const (
nodeTypeNormal = 0
nodeTypeException = 1
nodeTypeParentOnly = 2
numNodeType = 3
)
func nodeTypeStr(n int) string {
switch n {
case nodeTypeNormal:
return "+"
case nodeTypeException:
return "!"
case nodeTypeParentOnly:
return "o"
}
panic("unreachable")
}
var (
labelEncoding = map[string]uint32{}
labelsList = []string{}
labelsMap = map[string]bool{}
rules = []string{}
// validSuffix is used to check that the entries in the public suffix list
// are in canonical form (after Punycode encoding). Specifically, capital
// letters are not allowed.
validSuffix = regexp.MustCompile(`^[a-z0-9_\!\*\-\.]+$`)
subset = flag.Bool("subset", false, "generate only a subset of the full table, for debugging")
url = flag.String("url",
"https://publicsuffix.org/list/effective_tld_names.dat",
"URL of the publicsuffix.org list. If empty, stdin is read instead")
v = flag.Bool("v", false, "verbose output (to stderr)")
version = flag.String("version", "", "the effective_tld_names.dat version")
test = flag.Bool("test", false, "generate table_test.go")
)
func main() {
if err := main1(); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}
func main1() error {
flag.Parse()
if nodesBitsTextLength+nodesBitsTextOffset+nodesBitsICANN+nodesBitsChildren > 32 {
return fmt.Errorf("not enough bits to encode the nodes table")
}
if childrenBitsLo+childrenBitsHi+childrenBitsNodeType+childrenBitsWildcard > 32 {
return fmt.Errorf("not enough bits to encode the children table")
}
if *version == "" {
return fmt.Errorf("-version was not specified")
}
var r io.Reader = os.Stdin
if *url != "" {
res, err := http.Get(*url)
if err != nil {
return err
}
if res.StatusCode != http.StatusOK {
return fmt.Errorf("bad GET status for %s: %d", *url, res.Status)
}
r = res.Body
defer res.Body.Close()
}
var root node
icann := false
buf := new(bytes.Buffer)
br := bufio.NewReader(r)
for {
s, err := br.ReadString('\n')
if err != nil {
if err == io.EOF {
break
}
return err
}
s = strings.TrimSpace(s)
if strings.Contains(s, "BEGIN ICANN DOMAINS") {
icann = true
continue
}
if strings.Contains(s, "END ICANN DOMAINS") {
icann = false
continue
}
if s == "" || strings.HasPrefix(s, "//") {
continue
}
s, err = idna.ToASCII(s)
if err != nil {
return err
}
if !validSuffix.MatchString(s) {
return fmt.Errorf("bad publicsuffix.org list data: %q", s)
}
if *subset {
switch {
case s == "ac.jp" || strings.HasSuffix(s, ".ac.jp"):
case s == "ak.us" || strings.HasSuffix(s, ".ak.us"):
case s == "ao" || strings.HasSuffix(s, ".ao"):
case s == "ar" || strings.HasSuffix(s, ".ar"):
case s == "arpa" || strings.HasSuffix(s, ".arpa"):
case s == "cy" || strings.HasSuffix(s, ".cy"):
case s == "dyndns.org" || strings.HasSuffix(s, ".dyndns.org"):
case s == "jp":
case s == "kobe.jp" || strings.HasSuffix(s, ".kobe.jp"):
case s == "kyoto.jp" || strings.HasSuffix(s, ".kyoto.jp"):
case s == "om" || strings.HasSuffix(s, ".om"):
case s == "uk" || strings.HasSuffix(s, ".uk"):
case s == "uk.com" || strings.HasSuffix(s, ".uk.com"):
case s == "tw" || strings.HasSuffix(s, ".tw"):
case s == "zw" || strings.HasSuffix(s, ".zw"):
case s == "xn--p1ai" || strings.HasSuffix(s, ".xn--p1ai"):
// xn--p1ai is Russian-Cyrillic "рф".
default:
continue
}
}
rules = append(rules, s)
nt, wildcard := nodeTypeNormal, false
switch {
case strings.HasPrefix(s, "*."):
s, nt = s[2:], nodeTypeParentOnly
wildcard = true
case strings.HasPrefix(s, "!"):
s, nt = s[1:], nodeTypeException
}
labels := strings.Split(s, ".")
for n, i := &root, len(labels)-1; i >= 0; i-- {
label := labels[i]
n = n.child(label)
if i == 0 {
if nt != nodeTypeParentOnly && n.nodeType == nodeTypeParentOnly {
n.nodeType = nt
}
n.icann = n.icann && icann
n.wildcard = n.wildcard || wildcard
}
labelsMap[label] = true
}
}
labelsList = make([]string, 0, len(labelsMap))
for label := range labelsMap {
labelsList = append(labelsList, label)
}
sort.Strings(labelsList)
p := printReal
if *test {
p = printTest
}
if err := p(buf, &root); err != nil {
return err
}
b, err := format.Source(buf.Bytes())
if err != nil {
return err
}
_, err = os.Stdout.Write(b)
return err
}
func printTest(w io.Writer, n *node) error {
fmt.Fprintf(w, "// generated by go run gen.go; DO NOT EDIT\n\n")
fmt.Fprintf(w, "package publicsuffix\n\nvar rules = [...]string{\n")
for _, rule := range rules {
fmt.Fprintf(w, "%q,\n", rule)
}
fmt.Fprintf(w, "}\n\nvar nodeLabels = [...]string{\n")
if err := n.walk(w, printNodeLabel); err != nil {
return err
}
fmt.Fprintf(w, "}\n")
return nil
}
func printReal(w io.Writer, n *node) error {
const header = `// generated by go run gen.go; DO NOT EDIT
package publicsuffix
const version = %q
const (
nodesBitsChildren = %d
nodesBitsICANN = %d
nodesBitsTextOffset = %d
nodesBitsTextLength = %d
childrenBitsWildcard = %d
childrenBitsNodeType = %d
childrenBitsHi = %d
childrenBitsLo = %d
)
const (
nodeTypeNormal = %d
nodeTypeException = %d
nodeTypeParentOnly = %d
)
// numTLD is the number of top level domains.
const numTLD = %d
`
fmt.Fprintf(w, header, *version,
nodesBitsChildren, nodesBitsICANN, nodesBitsTextOffset, nodesBitsTextLength,
childrenBitsWildcard, childrenBitsNodeType, childrenBitsHi, childrenBitsLo,
nodeTypeNormal, nodeTypeException, nodeTypeParentOnly, len(n.children))
text := combineText(labelsList)
if text == "" {
return fmt.Errorf("internal error: makeText returned no text")
}
for _, label := range labelsList {
offset, length := strings.Index(text, label), len(label)
if offset < 0 {
return fmt.Errorf("internal error: could not find %q in text %q", label, text)
}
maxTextOffset, maxTextLength = max(maxTextOffset, offset), max(maxTextLength, length)
if offset >= 1<<nodesBitsTextOffset {
return fmt.Errorf("text offset %d is too large, or nodeBitsTextOffset is too small", offset)
}
if length >= 1<<nodesBitsTextLength {
return fmt.Errorf("text length %d is too large, or nodeBitsTextLength is too small", length)
}
labelEncoding[label] = uint32(offset)<<nodesBitsTextLength | uint32(length)
}
fmt.Fprintf(w, "// Text is the combined text of all labels.\nconst text = ")
for len(text) > 0 {
n, plus := len(text), ""
if n > 64 {
n, plus = 64, " +"
}
fmt.Fprintf(w, "%q%s\n", text[:n], plus)
text = text[n:]
}
if err := n.walk(w, assignIndexes); err != nil {
return err
}
fmt.Fprintf(w, `
// nodes is the list of nodes. Each node is represented as a uint32, which
// encodes the node's children, wildcard bit and node type (as an index into
// the children array), ICANN bit and text.
//
// In the //-comment after each node's data, the nodes indexes of the children
// are formatted as (n0x1234-n0x1256), with * denoting the wildcard bit. The
// nodeType is printed as + for normal, ! for exception, and o for parent-only
// nodes that have children but don't match a domain label in their own right.
// An I denotes an ICANN domain.
//
// The layout within the uint32, from MSB to LSB, is:
// [%2d bits] unused
// [%2d bits] children index
// [%2d bits] ICANN bit
// [%2d bits] text index
// [%2d bits] text length
var nodes = [...]uint32{
`,
32-nodesBitsChildren-nodesBitsICANN-nodesBitsTextOffset-nodesBitsTextLength,
nodesBitsChildren, nodesBitsICANN, nodesBitsTextOffset, nodesBitsTextLength)
if err := n.walk(w, printNode); err != nil {
return err
}
fmt.Fprintf(w, `}
// children is the list of nodes' children, the parent's wildcard bit and the
// parent's node type. If a node has no children then their children index
// will be in the range [0, 6), depending on the wildcard bit and node type.
//
// The layout within the uint32, from MSB to LSB, is:
// [%2d bits] unused
// [%2d bits] wildcard bit
// [%2d bits] node type
// [%2d bits] high nodes index (exclusive) of children
// [%2d bits] low nodes index (inclusive) of children
var children=[...]uint32{
`,
32-childrenBitsWildcard-childrenBitsNodeType-childrenBitsHi-childrenBitsLo,
childrenBitsWildcard, childrenBitsNodeType, childrenBitsHi, childrenBitsLo)
for i, c := range childrenEncoding {
s := "---------------"
lo := c & (1<<childrenBitsLo - 1)
hi := (c >> childrenBitsLo) & (1<<childrenBitsHi - 1)
if lo != hi {
s = fmt.Sprintf("n0x%04x-n0x%04x", lo, hi)
}
nodeType := int(c>>(childrenBitsLo+childrenBitsHi)) & (1<<childrenBitsNodeType - 1)
wildcard := c>>(childrenBitsLo+childrenBitsHi+childrenBitsNodeType) != 0
fmt.Fprintf(w, "0x%08x, // c0x%04x (%s)%s %s\n",
c, i, s, wildcardStr(wildcard), nodeTypeStr(nodeType))
}
fmt.Fprintf(w, "}\n\n")
fmt.Fprintf(w, "// max children %d (capacity %d)\n", maxChildren, 1<<nodesBitsChildren-1)
fmt.Fprintf(w, "// max text offset %d (capacity %d)\n", maxTextOffset, 1<<nodesBitsTextOffset-1)
fmt.Fprintf(w, "// max text length %d (capacity %d)\n", maxTextLength, 1<<nodesBitsTextLength-1)
fmt.Fprintf(w, "// max hi %d (capacity %d)\n", maxHi, 1<<childrenBitsHi-1)
fmt.Fprintf(w, "// max lo %d (capacity %d)\n", maxLo, 1<<childrenBitsLo-1)
return nil
}
type node struct {
label string
nodeType int
icann bool
wildcard bool
// nodesIndex and childrenIndex are the index of this node in the nodes
// and the index of its children offset/length in the children arrays.
nodesIndex, childrenIndex int
// firstChild is the index of this node's first child, or zero if this
// node has no children.
firstChild int
// children are the node's children, in strictly increasing node label order.
children []*node
}
func (n *node) walk(w io.Writer, f func(w1 io.Writer, n1 *node) error) error {
if err := f(w, n); err != nil {
return err
}
for _, c := range n.children {
if err := c.walk(w, f); err != nil {
return err
}
}
return nil
}
// child returns the child of n with the given label. The child is created if
// it did not exist beforehand.
func (n *node) child(label string) *node {
for _, c := range n.children {
if c.label == label {
return c
}
}
c := &node{
label: label,
nodeType: nodeTypeParentOnly,
icann: true,
}
n.children = append(n.children, c)
sort.Sort(byLabel(n.children))
return c
}
type byLabel []*node
func (b byLabel) Len() int { return len(b) }
func (b byLabel) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
func (b byLabel) Less(i, j int) bool { return b[i].label < b[j].label }
var nextNodesIndex int
// childrenEncoding are the encoded entries in the generated children array.
// All these pre-defined entries have no children.
var childrenEncoding = []uint32{
0 << (childrenBitsLo + childrenBitsHi), // Without wildcard bit, nodeTypeNormal.
1 << (childrenBitsLo + childrenBitsHi), // Without wildcard bit, nodeTypeException.
2 << (childrenBitsLo + childrenBitsHi), // Without wildcard bit, nodeTypeParentOnly.
4 << (childrenBitsLo + childrenBitsHi), // With wildcard bit, nodeTypeNormal.
5 << (childrenBitsLo + childrenBitsHi), // With wildcard bit, nodeTypeException.
6 << (childrenBitsLo + childrenBitsHi), // With wildcard bit, nodeTypeParentOnly.
}
var firstCallToAssignIndexes = true
func assignIndexes(w io.Writer, n *node) error {
if len(n.children) != 0 {
// Assign nodesIndex.
n.firstChild = nextNodesIndex
for _, c := range n.children {
c.nodesIndex = nextNodesIndex
nextNodesIndex++
}
// The root node's children is implicit.
if firstCallToAssignIndexes {
firstCallToAssignIndexes = false
return nil
}
// Assign childrenIndex.
maxChildren = max(maxChildren, len(childrenEncoding))
if len(childrenEncoding) >= 1<<nodesBitsChildren {
return fmt.Errorf("children table size %d is too large, or nodeBitsChildren is too small", len(childrenEncoding))
}
n.childrenIndex = len(childrenEncoding)
lo := uint32(n.firstChild)
hi := lo + uint32(len(n.children))
maxLo, maxHi = u32max(maxLo, lo), u32max(maxHi, hi)
if lo >= 1<<childrenBitsLo {
return fmt.Errorf("children lo %d is too large, or childrenBitsLo is too small", lo)
}
if hi >= 1<<childrenBitsHi {
return fmt.Errorf("children hi %d is too large, or childrenBitsHi is too small", hi)
}
enc := hi<<childrenBitsLo | lo
enc |= uint32(n.nodeType) << (childrenBitsLo + childrenBitsHi)
if n.wildcard {
enc |= 1 << (childrenBitsLo + childrenBitsHi + childrenBitsNodeType)
}
childrenEncoding = append(childrenEncoding, enc)
} else {
n.childrenIndex = n.nodeType
if n.wildcard {
n.childrenIndex += numNodeType
}
}
return nil
}
func printNode(w io.Writer, n *node) error {
for _, c := range n.children {
s := "---------------"
if len(c.children) != 0 {
s = fmt.Sprintf("n0x%04x-n0x%04x", c.firstChild, c.firstChild+len(c.children))
}
encoding := labelEncoding[c.label]
if c.icann {
encoding |= 1 << (nodesBitsTextLength + nodesBitsTextOffset)
}
encoding |= uint32(c.childrenIndex) << (nodesBitsTextLength + nodesBitsTextOffset + nodesBitsICANN)
fmt.Fprintf(w, "0x%08x, // n0x%04x c0x%04x (%s)%s %s %s %s\n",
encoding, c.nodesIndex, c.childrenIndex, s, wildcardStr(c.wildcard),
nodeTypeStr(c.nodeType), icannStr(c.icann), c.label,
)
}
return nil
}
func printNodeLabel(w io.Writer, n *node) error {
for _, c := range n.children {
fmt.Fprintf(w, "%q,\n", c.label)
}
return nil
}
func icannStr(icann bool) string {
if icann {
return "I"
}
return " "
}
func wildcardStr(wildcard bool) string {
if wildcard {
return "*"
}
return " "
}
// combineText combines all the strings in labelsList to form one giant string.
// Overlapping strings will be merged: "arpa" and "parliament" could yield
// "arparliament".
func combineText(labelsList []string) string {
beforeLength := 0
for _, s := range labelsList {
beforeLength += len(s)
}
text := crush(removeSubstrings(labelsList))
if *v {
fmt.Fprintf(os.Stderr, "crushed %d bytes to become %d bytes\n", beforeLength, len(text))
}
return text
}
type byLength []string
func (s byLength) Len() int { return len(s) }
func (s byLength) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s byLength) Less(i, j int) bool { return len(s[i]) < len(s[j]) }
// removeSubstrings returns a copy of its input with any strings removed
// that are substrings of other provided strings.
func removeSubstrings(input []string) []string {
// Make a copy of input.
ss := append(make([]string, 0, len(input)), input...)
sort.Sort(byLength(ss))
for i, shortString := range ss {
// For each string, only consider strings higher than it in sort order, i.e.
// of equal length or greater.
for _, longString := range ss[i+1:] {
if strings.Contains(longString, shortString) {
ss[i] = ""
break
}
}
}
// Remove the empty strings.
sort.Strings(ss)
for len(ss) > 0 && ss[0] == "" {
ss = ss[1:]
}
return ss
}
// crush combines a list of strings, taking advantage of overlaps. It returns a
// single string that contains each input string as a substring.
func crush(ss []string) string {
maxLabelLen := 0
for _, s := range ss {
if maxLabelLen < len(s) {
maxLabelLen = len(s)
}
}
for prefixLen := maxLabelLen; prefixLen > 0; prefixLen-- {
prefixes := makePrefixMap(ss, prefixLen)
for i, s := range ss {
if len(s) <= prefixLen {
continue
}
mergeLabel(ss, i, prefixLen, prefixes)
}
}
return strings.Join(ss, "")
}
// mergeLabel merges the label at ss[i] with the first available matching label
// in prefixMap, where the last "prefixLen" characters in ss[i] match the first
// "prefixLen" characters in the matching label.
// It will merge ss[i] repeatedly until no more matches are available.
// All matching labels merged into ss[i] are replaced by "".
func mergeLabel(ss []string, i, prefixLen int, prefixes prefixMap) {
s := ss[i]
suffix := s[len(s)-prefixLen:]
for _, j := range prefixes[suffix] {
// Empty strings mean "already used." Also avoid merging with self.
if ss[j] == "" || i == j {
continue
}
if *v {
fmt.Fprintf(os.Stderr, "%d-length overlap at (%4d,%4d): %q and %q share %q\n",
prefixLen, i, j, ss[i], ss[j], suffix)
}
ss[i] += ss[j][prefixLen:]
ss[j] = ""
// ss[i] has a new suffix, so merge again if possible.
// Note: we only have to merge again at the same prefix length. Shorter
// prefix lengths will be handled in the next iteration of crush's for loop.
// Can there be matches for longer prefix lengths, introduced by the merge?
// I believe that any such matches would by necessity have been eliminated
// during substring removal or merged at a higher prefix length. For
// instance, in crush("abc", "cde", "bcdef"), combining "abc" and "cde"
// would yield "abcde", which could be merged with "bcdef." However, in
// practice "cde" would already have been elimintated by removeSubstrings.
mergeLabel(ss, i, prefixLen, prefixes)
return
}
}
// prefixMap maps from a prefix to a list of strings containing that prefix. The
// list of strings is represented as indexes into a slice of strings stored
// elsewhere.
type prefixMap map[string][]int
// makePrefixMap constructs a prefixMap from a slice of strings.
func makePrefixMap(ss []string, prefixLen int) prefixMap {
prefixes := make(prefixMap)
for i, s := range ss {
// We use < rather than <= because if a label matches on a prefix equal to
// its full length, that's actually a substring match handled by
// removeSubstrings.
if prefixLen < len(s) {
prefix := s[:prefixLen]
prefixes[prefix] = append(prefixes[prefix], i)
}
}
return prefixes
}