android/util.go - SHIFTPHONES/android_build_soong - Gitiles

 // Copyright 2015 Google Inc. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package android

 import (
 	"fmt"
 	"path/filepath"
 	"reflect"
 	"regexp"
 	"runtime"
 	"sort"
 	"strings"
 )

 // CopyOf returns a new slice that has the same contents as s.
 func CopyOf(s []string) []string {
 	return append([]string(nil), s...)
 }

 // JoinWithPrefix prepends the prefix to each string in the list and
 // returns them joined together with " " as separator.
 func JoinWithPrefix(strs []string, prefix string) string {
 	if len(strs) == 0 {
 		return ""
 	}

 	var buf strings.Builder
 	buf.WriteString(prefix)
 	buf.WriteString(strs[0])
 	for i := 1; i < len(strs); i++ {
 		buf.WriteString(" ")
 		buf.WriteString(prefix)
 		buf.WriteString(strs[i])
 	}
 	return buf.String()
 }

 // JoinWithSuffix appends the suffix to each string in the list and
 // returns them joined together with given separator.
 func JoinWithSuffix(strs []string, suffix string, separator string) string {
 	if len(strs) == 0 {
 		return ""
 	}

 	var buf strings.Builder
 	buf.WriteString(strs[0])
 	buf.WriteString(suffix)
 	for i := 1; i < len(strs); i++ {
 		buf.WriteString(separator)
 		buf.WriteString(strs[i])
 		buf.WriteString(suffix)
 	}
 	return buf.String()
 }

 // SortedIntKeys returns the keys of the given integer-keyed map in the ascending order
 // TODO(asmundak): once Go has generics, combine this with SortedStringKeys below.
 func SortedIntKeys(m interface{}) []int {
 	v := reflect.ValueOf(m)
 	if v.Kind() != reflect.Map {
 		panic(fmt.Sprintf("%#v is not a map", m))
 	}
 	keys := v.MapKeys()
 	s := make([]int, 0, len(keys))
 	for _, key := range keys {
 		s = append(s, int(key.Int()))
 	}
 	sort.Ints(s)
 	return s
 }

 // SorterStringKeys returns the keys of the given string-keyed map in the ascending order
 func SortedStringKeys(m interface{}) []string {
 	v := reflect.ValueOf(m)
 	if v.Kind() != reflect.Map {
 		panic(fmt.Sprintf("%#v is not a map", m))
 	}
 	keys := v.MapKeys()
 	s := make([]string, 0, len(keys))
 	for _, key := range keys {
 		s = append(s, key.String())
 	}
 	sort.Strings(s)
 	return s
 }

 // SortedStringMapValues returns the values of the string-values map in the ascending order
 func SortedStringMapValues(m interface{}) []string {
 	v := reflect.ValueOf(m)
 	if v.Kind() != reflect.Map {
 		panic(fmt.Sprintf("%#v is not a map", m))
 	}
 	keys := v.MapKeys()
 	s := make([]string, 0, len(keys))
 	for _, key := range keys {
 		s = append(s, v.MapIndex(key).String())
 	}
 	sort.Strings(s)
 	return s
 }

 // IndexList returns the index of the first occurrence of the given string in the list or -1
 func IndexList(s string, list []string) int {
 	for i, l := range list {
 		if l == s {
 			return i
 		}
 	}

 	return -1
 }

 // InList checks if the string belongs to the list
 func InList(s string, list []string) bool {
 	return IndexList(s, list) != -1
 }

 // Returns true if the given string s is prefixed with any string in the given prefix list.
 func HasAnyPrefix(s string, prefixList []string) bool {
 	for _, prefix := range prefixList {
 		if strings.HasPrefix(s, prefix) {
 			return true
 		}
 	}
 	return false
 }

 // Returns true if any string in the given list has the given prefix.
 func PrefixInList(list []string, prefix string) bool {
 	for _, s := range list {
 		if strings.HasPrefix(s, prefix) {
 			return true
 		}
 	}
 	return false
 }

 // Returns true if any string in the given list has the given suffix.
 func SuffixInList(list []string, suffix string) bool {
 	for _, s := range list {
 		if strings.HasSuffix(s, suffix) {
 			return true
 		}
 	}
 	return false
 }

 // IndexListPred returns the index of the element which in the given `list` satisfying the predicate, or -1 if there is no such element.
 func IndexListPred(pred func(s string) bool, list []string) int {
 	for i, l := range list {
 		if pred(l) {
 			return i
 		}
 	}

 	return -1
 }

 // FilterList divides the string list into two lists: one with the strings belonging
 // to the given filter list, and the other with the remaining ones
 func FilterList(list []string, filter []string) (remainder []string, filtered []string) {
 	// InList is O(n). May be worth using more efficient lookup for longer lists.
 	for _, l := range list {
 		if InList(l, filter) {
 			filtered = append(filtered, l)
 		} else {
 			remainder = append(remainder, l)
 		}
 	}

 	return
 }

 // RemoveListFromList removes the strings belonging to the filter list from the
 // given list and returns the result
 func RemoveListFromList(list []string, filter_out []string) (result []string) {
 	result = make([]string, 0, len(list))
 	for _, l := range list {
 		if !InList(l, filter_out) {
 			result = append(result, l)
 		}
 	}
 	return
 }

 // RemoveFromList removes given string from the string list.
 func RemoveFromList(s string, list []string) (bool, []string) {
 	result := make([]string, 0, len(list))
 	var removed bool
 	for _, item := range list {
 		if item != s {
 			result = append(result, item)
 		} else {
 			removed = true
 		}
 	}
 	return removed, result
 }

 // FirstUniqueStrings returns all unique elements of a slice of strings, keeping the first copy of
 // each.  It modifies the slice contents in place, and returns a subslice of the original slice.
 func FirstUniqueStrings(list []string) []string {
 	// 128 was chosen based on BenchmarkFirstUniqueStrings results.
 	if len(list) > 128 {
 		return firstUniqueStringsMap(list)
 	}
 	return firstUniqueStringsList(list)
 }

 func firstUniqueStringsList(list []string) []string {
 	k := 0
 outer:
 	for i := 0; i < len(list); i++ {
 		for j := 0; j < k; j++ {
 			if list[i] == list[j] {
 				continue outer
 			}
 		}
 		list[k] = list[i]
 		k++
 	}
 	return list[:k]
 }

 func firstUniqueStringsMap(list []string) []string {
 	k := 0
 	seen := make(map[string]bool, len(list))
 	for i := 0; i < len(list); i++ {
 		if seen[list[i]] {
 			continue
 		}
 		seen[list[i]] = true
 		list[k] = list[i]
 		k++
 	}
 	return list[:k]
 }

 // LastUniqueStrings returns all unique elements of a slice of strings, keeping the last copy of
 // each.  It modifies the slice contents in place, and returns a subslice of the original slice.
 func LastUniqueStrings(list []string) []string {
 	totalSkip := 0
 	for i := len(list) - 1; i >= totalSkip; i-- {
 		skip := 0
 		for j := i - 1; j >= totalSkip; j-- {
 			if list[i] == list[j] {
 				skip++
 			} else {
 				list[j+skip] = list[j]
 			}
 		}
 		totalSkip += skip
 	}
 	return list[totalSkip:]
 }

 // SortedUniqueStrings returns what the name says
 func SortedUniqueStrings(list []string) []string {
 	unique := FirstUniqueStrings(list)
 	sort.Strings(unique)
 	return unique
 }

 // checkCalledFromInit panics if a Go package's init function is not on the
 // call stack.
 func checkCalledFromInit() {
 	for skip := 3; ; skip++ {
 		_, funcName, ok := callerName(skip)
 		if !ok {
 			panic("not called from an init func")
 		}

 		if funcName == "init" || strings.HasPrefix(funcName, "init·") ||
 			strings.HasPrefix(funcName, "init.") {
 			return
 		}
 	}
 }

 // A regex to find a package path within a function name. It finds the shortest string that is
 // followed by '.' and doesn't have any '/'s left.
 var pkgPathRe = regexp.MustCompile(`^(.*?)\.([^/]+)$`)

 // callerName returns the package path and function name of the calling
 // function.  The skip argument has the same meaning as the skip argument of
 // runtime.Callers.
 func callerName(skip int) (pkgPath, funcName string, ok bool) {
 	var pc [1]uintptr
 	n := runtime.Callers(skip+1, pc[:])
 	if n != 1 {
 		return "", "", false
 	}

 	f := runtime.FuncForPC(pc[0]).Name()
 	s := pkgPathRe.FindStringSubmatch(f)
 	if len(s) < 3 {
 		panic(fmt.Errorf("failed to extract package path and function name from %q", f))
 	}

 	return s[1], s[2], true
 }

 // GetNumericSdkVersion removes the first occurrence of system_ in a string,
 // which is assumed to be something like "system_1.2.3"
 func GetNumericSdkVersion(v string) string {
 	return strings.Replace(v, "system_", "", 1)
 }

 // copied from build/kati/strutil.go
 func substPattern(pat, repl, str string) string {
 	ps := strings.SplitN(pat, "%", 2)
 	if len(ps) != 2 {
 		if str == pat {
 			return repl
 		}
 		return str
 	}
 	in := str
 	trimmed := str
 	if ps[0] != "" {
 		trimmed = strings.TrimPrefix(in, ps[0])
 		if trimmed == in {
 			return str
 		}
 	}
 	in = trimmed
 	if ps[1] != "" {
 		trimmed = strings.TrimSuffix(in, ps[1])
 		if trimmed == in {
 			return str
 		}
 	}

 	rs := strings.SplitN(repl, "%", 2)
 	if len(rs) != 2 {
 		return repl
 	}
 	return rs[0] + trimmed + rs[1]
 }

 // copied from build/kati/strutil.go
 func matchPattern(pat, str string) bool {
 	i := strings.IndexByte(pat, '%')
 	if i < 0 {
 		return pat == str
 	}
 	return strings.HasPrefix(str, pat[:i]) && strings.HasSuffix(str, pat[i+1:])
 }

 var shlibVersionPattern = regexp.MustCompile("(?:\\.\\d+(?:svn)?)+")

 // splitFileExt splits a file name into root, suffix and ext. root stands for the file name without
 // the file extension and the version number (e.g. "libexample"). suffix stands for the
 // concatenation of the file extension and the version number (e.g. ".so.1.0"). ext stands for the
 // file extension after the version numbers are trimmed (e.g. ".so").
 func SplitFileExt(name string) (string, string, string) {
 	// Extract and trim the shared lib version number if the file name ends with dot digits.
 	suffix := ""
 	matches := shlibVersionPattern.FindAllStringIndex(name, -1)
 	if len(matches) > 0 {
 		lastMatch := matches[len(matches)-1]
 		if lastMatch[1] == len(name) {
 			suffix = name[lastMatch[0]:lastMatch[1]]
 			name = name[0:lastMatch[0]]
 		}
 	}

 	// Extract the file name root and the file extension.
 	ext := filepath.Ext(name)
 	root := strings.TrimSuffix(name, ext)
 	suffix = ext + suffix

 	return root, suffix, ext
 }

 // ShardPaths takes a Paths, and returns a slice of Paths where each one has at most shardSize paths.
 func ShardPaths(paths Paths, shardSize int) []Paths {
 	if len(paths) == 0 {
 		return nil
 	}
 	ret := make([]Paths, 0, (len(paths)+shardSize-1)/shardSize)
 	for len(paths) > shardSize {
 		ret = append(ret, paths[0:shardSize])
 		paths = paths[shardSize:]
 	}
 	if len(paths) > 0 {
 		ret = append(ret, paths)
 	}
 	return ret
 }

 // ShardString takes a string and returns a slice of strings where the length of each one is
 // at most shardSize.
 func ShardString(s string, shardSize int) []string {
 	if len(s) == 0 {
 		return nil
 	}
 	ret := make([]string, 0, (len(s)+shardSize-1)/shardSize)
 	for len(s) > shardSize {
 		ret = append(ret, s[0:shardSize])
 		s = s[shardSize:]
 	}
 	if len(s) > 0 {
 		ret = append(ret, s)
 	}
 	return ret
 }

 // ShardStrings takes a slice of strings, and returns a slice of slices of strings where each one has at most shardSize
 // elements.
 func ShardStrings(s []string, shardSize int) [][]string {
 	if len(s) == 0 {
 		return nil
 	}
 	ret := make([][]string, 0, (len(s)+shardSize-1)/shardSize)
 	for len(s) > shardSize {
 		ret = append(ret, s[0:shardSize])
 		s = s[shardSize:]
 	}
 	if len(s) > 0 {
 		ret = append(ret, s)
 	}
 	return ret
 }

 // CheckDuplicate checks if there are duplicates in given string list.
 // If there are, it returns first such duplicate and true.
 func CheckDuplicate(values []string) (duplicate string, found bool) {
 	seen := make(map[string]string)
 	for _, v := range values {
 		if duplicate, found = seen[v]; found {
 			return duplicate, true
 		}
 		seen[v] = v
 	}
 	return "", false
 }
	// Copyright 2015 Google Inc. All rights reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package android

	import (
	"fmt"
	"path/filepath"
	"reflect"
	"regexp"
	"runtime"
	"sort"
	"strings"
	)

	// CopyOf returns a new slice that has the same contents as s.
	func CopyOf(s []string) []string {
	return append([]string(nil), s...)
	}

	// JoinWithPrefix prepends the prefix to each string in the list and
	// returns them joined together with " " as separator.
	func JoinWithPrefix(strs []string, prefix string) string {
	if len(strs) == 0 {
	return ""
	}

	var buf strings.Builder
	buf.WriteString(prefix)
	buf.WriteString(strs[0])
	for i := 1; i < len(strs); i++ {
	buf.WriteString(" ")
	buf.WriteString(prefix)
	buf.WriteString(strs[i])
	}
	return buf.String()
	}

	// JoinWithSuffix appends the suffix to each string in the list and
	// returns them joined together with given separator.
	func JoinWithSuffix(strs []string, suffix string, separator string) string {
	if len(strs) == 0 {
	return ""
	}

	var buf strings.Builder
	buf.WriteString(strs[0])
	buf.WriteString(suffix)
	for i := 1; i < len(strs); i++ {
	buf.WriteString(separator)
	buf.WriteString(strs[i])
	buf.WriteString(suffix)
	}
	return buf.String()
	}

	// SortedIntKeys returns the keys of the given integer-keyed map in the ascending order
	// TODO(asmundak): once Go has generics, combine this with SortedStringKeys below.
	func SortedIntKeys(m interface{}) []int {
	v := reflect.ValueOf(m)
	if v.Kind() != reflect.Map {
	panic(fmt.Sprintf("%#v is not a map", m))
	}
	keys := v.MapKeys()
	s := make([]int, 0, len(keys))
	for _, key := range keys {
	s = append(s, int(key.Int()))
	}
	sort.Ints(s)
	return s
	}

	// SorterStringKeys returns the keys of the given string-keyed map in the ascending order
	func SortedStringKeys(m interface{}) []string {
	v := reflect.ValueOf(m)
	if v.Kind() != reflect.Map {
	panic(fmt.Sprintf("%#v is not a map", m))
	}
	keys := v.MapKeys()
	s := make([]string, 0, len(keys))
	for _, key := range keys {
	s = append(s, key.String())
	}
	sort.Strings(s)
	return s
	}

	// SortedStringMapValues returns the values of the string-values map in the ascending order
	func SortedStringMapValues(m interface{}) []string {
	v := reflect.ValueOf(m)
	if v.Kind() != reflect.Map {
	panic(fmt.Sprintf("%#v is not a map", m))
	}
	keys := v.MapKeys()
	s := make([]string, 0, len(keys))
	for _, key := range keys {
	s = append(s, v.MapIndex(key).String())
	}
	sort.Strings(s)
	return s
	}

	// IndexList returns the index of the first occurrence of the given string in the list or -1
	func IndexList(s string, list []string) int {
	for i, l := range list {
	if l == s {
	return i
	}
	}

	return -1
	}

	// InList checks if the string belongs to the list
	func InList(s string, list []string) bool {
	return IndexList(s, list) != -1
	}

	// Returns true if the given string s is prefixed with any string in the given prefix list.
	func HasAnyPrefix(s string, prefixList []string) bool {
	for _, prefix := range prefixList {
	if strings.HasPrefix(s, prefix) {
	return true
	}
	}
	return false
	}

	// Returns true if any string in the given list has the given prefix.
	func PrefixInList(list []string, prefix string) bool {
	for _, s := range list {
	if strings.HasPrefix(s, prefix) {
	return true
	}
	}
	return false
	}

	// Returns true if any string in the given list has the given suffix.
	func SuffixInList(list []string, suffix string) bool {
	for _, s := range list {
	if strings.HasSuffix(s, suffix) {
	return true
	}
	}
	return false
	}

	// IndexListPred returns the index of the element which in the given `list` satisfying the predicate, or -1 if there is no such element.
	func IndexListPred(pred func(s string) bool, list []string) int {
	for i, l := range list {
	if pred(l) {
	return i
	}
	}

	return -1
	}

	// FilterList divides the string list into two lists: one with the strings belonging
	// to the given filter list, and the other with the remaining ones
	func FilterList(list []string, filter []string) (remainder []string, filtered []string) {
	// InList is O(n). May be worth using more efficient lookup for longer lists.
	for _, l := range list {
	if InList(l, filter) {
	filtered = append(filtered, l)
	} else {
	remainder = append(remainder, l)
	}
	}

	return
	}

	// RemoveListFromList removes the strings belonging to the filter list from the
	// given list and returns the result
	func RemoveListFromList(list []string, filter_out []string) (result []string) {
	result = make([]string, 0, len(list))
	for _, l := range list {
	if !InList(l, filter_out) {
	result = append(result, l)
	}
	}
	return
	}

	// RemoveFromList removes given string from the string list.
	func RemoveFromList(s string, list []string) (bool, []string) {
	result := make([]string, 0, len(list))
	var removed bool
	for _, item := range list {
	if item != s {
	result = append(result, item)
	} else {
	removed = true
	}
	}
	return removed, result
	}

	// FirstUniqueStrings returns all unique elements of a slice of strings, keeping the first copy of
	// each. It modifies the slice contents in place, and returns a subslice of the original slice.
	func FirstUniqueStrings(list []string) []string {
	// 128 was chosen based on BenchmarkFirstUniqueStrings results.
	if len(list) > 128 {
	return firstUniqueStringsMap(list)
	}
	return firstUniqueStringsList(list)
	}

	func firstUniqueStringsList(list []string) []string {
	k := 0
	outer:
	for i := 0; i < len(list); i++ {
	for j := 0; j < k; j++ {
	if list[i] == list[j] {
	continue outer
	}
	}
	list[k] = list[i]
	k++
	}
	return list[:k]
	}

	func firstUniqueStringsMap(list []string) []string {
	k := 0
	seen := make(map[string]bool, len(list))
	for i := 0; i < len(list); i++ {
	if seen[list[i]] {
	continue
	}
	seen[list[i]] = true
	list[k] = list[i]
	k++
	}
	return list[:k]
	}

	// LastUniqueStrings returns all unique elements of a slice of strings, keeping the last copy of
	// each. It modifies the slice contents in place, and returns a subslice of the original slice.
	func LastUniqueStrings(list []string) []string {
	totalSkip := 0
	for i := len(list) - 1; i >= totalSkip; i-- {
	skip := 0
	for j := i - 1; j >= totalSkip; j-- {
	if list[i] == list[j] {
	skip++
	} else {
	list[j+skip] = list[j]
	}
	}
	totalSkip += skip
	}
	return list[totalSkip:]
	}

	// SortedUniqueStrings returns what the name says
	func SortedUniqueStrings(list []string) []string {
	unique := FirstUniqueStrings(list)
	sort.Strings(unique)
	return unique
	}

	// checkCalledFromInit panics if a Go package's init function is not on the
	// call stack.
	func checkCalledFromInit() {
	for skip := 3; ; skip++ {
	_, funcName, ok := callerName(skip)
	if !ok {
	panic("not called from an init func")
	}

	if funcName == "init" \|\| strings.HasPrefix(funcName, "init·") \|\|
	strings.HasPrefix(funcName, "init.") {
	return
	}
	}
	}

	// A regex to find a package path within a function name. It finds the shortest string that is
	// followed by '.' and doesn't have any '/'s left.
	var pkgPathRe = regexp.MustCompile(`^(.*?)\.([^/]+)$`)

	// callerName returns the package path and function name of the calling
	// function. The skip argument has the same meaning as the skip argument of
	// runtime.Callers.
	func callerName(skip int) (pkgPath, funcName string, ok bool) {
	var pc [1]uintptr
	n := runtime.Callers(skip+1, pc[:])
	if n != 1 {
	return "", "", false
	}

	f := runtime.FuncForPC(pc[0]).Name()
	s := pkgPathRe.FindStringSubmatch(f)
	if len(s) < 3 {
	panic(fmt.Errorf("failed to extract package path and function name from %q", f))
	}

	return s[1], s[2], true
	}

	// GetNumericSdkVersion removes the first occurrence of system_ in a string,
	// which is assumed to be something like "system_1.2.3"
	func GetNumericSdkVersion(v string) string {
	return strings.Replace(v, "system_", "", 1)
	}

	// copied from build/kati/strutil.go
	func substPattern(pat, repl, str string) string {
	ps := strings.SplitN(pat, "%", 2)
	if len(ps) != 2 {
	if str == pat {
	return repl
	}
	return str
	}
	in := str
	trimmed := str
	if ps[0] != "" {
	trimmed = strings.TrimPrefix(in, ps[0])
	if trimmed == in {
	return str
	}
	}
	in = trimmed
	if ps[1] != "" {
	trimmed = strings.TrimSuffix(in, ps[1])
	if trimmed == in {
	return str
	}
	}

	rs := strings.SplitN(repl, "%", 2)
	if len(rs) != 2 {
	return repl
	}
	return rs[0] + trimmed + rs[1]
	}

	// copied from build/kati/strutil.go
	func matchPattern(pat, str string) bool {
	i := strings.IndexByte(pat, '%')
	if i < 0 {
	return pat == str
	}
	return strings.HasPrefix(str, pat[:i]) && strings.HasSuffix(str, pat[i+1:])
	}

	var shlibVersionPattern = regexp.MustCompile("(?:\\.\\d+(?:svn)?)+")

	// splitFileExt splits a file name into root, suffix and ext. root stands for the file name without
	// the file extension and the version number (e.g. "libexample"). suffix stands for the
	// concatenation of the file extension and the version number (e.g. ".so.1.0"). ext stands for the
	// file extension after the version numbers are trimmed (e.g. ".so").
	func SplitFileExt(name string) (string, string, string) {
	// Extract and trim the shared lib version number if the file name ends with dot digits.
	suffix := ""
	matches := shlibVersionPattern.FindAllStringIndex(name, -1)
	if len(matches) > 0 {
	lastMatch := matches[len(matches)-1]
	if lastMatch[1] == len(name) {
	suffix = name[lastMatch[0]:lastMatch[1]]
	name = name[0:lastMatch[0]]
	}
	}

	// Extract the file name root and the file extension.
	ext := filepath.Ext(name)
	root := strings.TrimSuffix(name, ext)
	suffix = ext + suffix

	return root, suffix, ext
	}

	// ShardPaths takes a Paths, and returns a slice of Paths where each one has at most shardSize paths.
	func ShardPaths(paths Paths, shardSize int) []Paths {
	if len(paths) == 0 {
	return nil
	}
	ret := make([]Paths, 0, (len(paths)+shardSize-1)/shardSize)
	for len(paths) > shardSize {
	ret = append(ret, paths[0:shardSize])
	paths = paths[shardSize:]
	}
	if len(paths) > 0 {
	ret = append(ret, paths)
	}
	return ret
	}

	// ShardString takes a string and returns a slice of strings where the length of each one is
	// at most shardSize.
	func ShardString(s string, shardSize int) []string {
	if len(s) == 0 {
	return nil
	}
	ret := make([]string, 0, (len(s)+shardSize-1)/shardSize)
	for len(s) > shardSize {
	ret = append(ret, s[0:shardSize])
	s = s[shardSize:]
	}
	if len(s) > 0 {
	ret = append(ret, s)
	}
	return ret
	}

	// ShardStrings takes a slice of strings, and returns a slice of slices of strings where each one has at most shardSize
	// elements.
	func ShardStrings(s []string, shardSize int) [][]string {
	if len(s) == 0 {
	return nil
	}
	ret := make([][]string, 0, (len(s)+shardSize-1)/shardSize)
	for len(s) > shardSize {
	ret = append(ret, s[0:shardSize])
	s = s[shardSize:]
	}
	if len(s) > 0 {
	ret = append(ret, s)
	}
	return ret
	}

	// CheckDuplicate checks if there are duplicates in given string list.
	// If there are, it returns first such duplicate and true.
	func CheckDuplicate(values []string) (duplicate string, found bool) {
	seen := make(map[string]string)
	for _, v := range values {
	if duplicate, found = seen[v]; found {
	return duplicate, true
	}
	seen[v] = v
	}
	return "", false
	}