package strings

Import Path
	strings (on go.dev)

Dependency Relation
	imports 7 packages, and imported by 41 packages

Involved Source Files

	    builder.go
	    clone.go
	    compare.go
	    reader.go
	    replace.go
	    search.go
	  d strings.go
		Package strings implements simple functions to manipulate UTF-8 encoded strings.
		
		For information about UTF-8 strings in Go, see https://blog.golang.org/strings.
Code Examples

	Builder
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			var b strings.Builder
			for i := 3; i >= 1; i-- {
				fmt.Fprintf(&b, "%d...", i)
			}
			b.WriteString("ignition")
			fmt.Println(b.String())
		
		}

	Clone
		package main
		
		import (
			"fmt"
			"strings"
			"unsafe"
		)
		
		func main() {
			s := "abc"
			clone := strings.Clone(s)
			fmt.Println(s == clone)
			fmt.Println(unsafe.StringData(s) == unsafe.StringData(clone))
		}

	Compare
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.Compare("a", "b"))
			fmt.Println(strings.Compare("a", "a"))
			fmt.Println(strings.Compare("b", "a"))
		}

	Contains
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.Contains("seafood", "foo"))
			fmt.Println(strings.Contains("seafood", "bar"))
			fmt.Println(strings.Contains("seafood", ""))
			fmt.Println(strings.Contains("", ""))
		}

	ContainsAny
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.ContainsAny("team", "i"))
			fmt.Println(strings.ContainsAny("fail", "ui"))
			fmt.Println(strings.ContainsAny("ure", "ui"))
			fmt.Println(strings.ContainsAny("failure", "ui"))
			fmt.Println(strings.ContainsAny("foo", ""))
			fmt.Println(strings.ContainsAny("", ""))
		}

	ContainsRune
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			// Finds whether a string contains a particular Unicode code point.
			// The code point for the lowercase letter "a", for example, is 97.
			fmt.Println(strings.ContainsRune("aardvark", 97))
			fmt.Println(strings.ContainsRune("timeout", 97))
		}

	Count
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.Count("cheese", "e"))
			fmt.Println(strings.Count("five", "")) // before & after each rune
		}

	Cut
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			show := func(s, sep string) {
				before, after, found := strings.Cut(s, sep)
				fmt.Printf("Cut(%q, %q) = %q, %q, %v\n", s, sep, before, after, found)
			}
			show("Gopher", "Go")
			show("Gopher", "ph")
			show("Gopher", "er")
			show("Gopher", "Badger")
		}

	CutPrefix
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			show := func(s, sep string) {
				after, found := strings.CutPrefix(s, sep)
				fmt.Printf("CutPrefix(%q, %q) = %q, %v\n", s, sep, after, found)
			}
			show("Gopher", "Go")
			show("Gopher", "ph")
		}

	CutSuffix
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			show := func(s, sep string) {
				before, found := strings.CutSuffix(s, sep)
				fmt.Printf("CutSuffix(%q, %q) = %q, %v\n", s, sep, before, found)
			}
			show("Gopher", "Go")
			show("Gopher", "er")
		}

	EqualFold
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.EqualFold("Go", "go"))
			fmt.Println(strings.EqualFold("AB", "ab")) // true because comparison uses simple case-folding
			fmt.Println(strings.EqualFold("ß", "ss"))  // false because comparison does not use full case-folding
		}

	Fields
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Printf("Fields are: %q", strings.Fields("  foo bar  baz   "))
		}

	FieldsFunc
		package main
		
		import (
			"fmt"
			"strings"
			"unicode"
		)
		
		func main() {
			f := func(c rune) bool {
				return !unicode.IsLetter(c) && !unicode.IsNumber(c)
			}
			fmt.Printf("Fields are: %q", strings.FieldsFunc("  foo1;bar2,baz3...", f))
		}

	HasPrefix
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.HasPrefix("Gopher", "Go"))
			fmt.Println(strings.HasPrefix("Gopher", "C"))
			fmt.Println(strings.HasPrefix("Gopher", ""))
		}

	HasSuffix
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.HasSuffix("Amigo", "go"))
			fmt.Println(strings.HasSuffix("Amigo", "O"))
			fmt.Println(strings.HasSuffix("Amigo", "Ami"))
			fmt.Println(strings.HasSuffix("Amigo", ""))
		}

	Index
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.Index("chicken", "ken"))
			fmt.Println(strings.Index("chicken", "dmr"))
		}

	IndexAny
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.IndexAny("chicken", "aeiouy"))
			fmt.Println(strings.IndexAny("crwth", "aeiouy"))
		}

	IndexByte
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.IndexByte("golang", 'g'))
			fmt.Println(strings.IndexByte("gophers", 'h'))
			fmt.Println(strings.IndexByte("golang", 'x'))
		}

	IndexFunc
		package main
		
		import (
			"fmt"
			"strings"
			"unicode"
		)
		
		func main() {
			f := func(c rune) bool {
				return unicode.Is(unicode.Han, c)
			}
			fmt.Println(strings.IndexFunc("Hello, 世界", f))
			fmt.Println(strings.IndexFunc("Hello, world", f))
		}

	IndexRune
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.IndexRune("chicken", 'k'))
			fmt.Println(strings.IndexRune("chicken", 'd'))
		}

	Join
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			s := []string{"foo", "bar", "baz"}
			fmt.Println(strings.Join(s, ", "))
		}

	LastIndex
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.Index("go gopher", "go"))
			fmt.Println(strings.LastIndex("go gopher", "go"))
			fmt.Println(strings.LastIndex("go gopher", "rodent"))
		}

	LastIndexAny
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.LastIndexAny("go gopher", "go"))
			fmt.Println(strings.LastIndexAny("go gopher", "rodent"))
			fmt.Println(strings.LastIndexAny("go gopher", "fail"))
		}

	LastIndexByte
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.LastIndexByte("Hello, world", 'l'))
			fmt.Println(strings.LastIndexByte("Hello, world", 'o'))
			fmt.Println(strings.LastIndexByte("Hello, world", 'x'))
		}

	LastIndexFunc
		package main
		
		import (
			"fmt"
			"strings"
			"unicode"
		)
		
		func main() {
			fmt.Println(strings.LastIndexFunc("go 123", unicode.IsNumber))
			fmt.Println(strings.LastIndexFunc("123 go", unicode.IsNumber))
			fmt.Println(strings.LastIndexFunc("go", unicode.IsNumber))
		}

	Map
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			rot13 := func(r rune) rune {
				switch {
				case r >= 'A' && r <= 'Z':
					return 'A' + (r-'A'+13)%26
				case r >= 'a' && r <= 'z':
					return 'a' + (r-'a'+13)%26
				}
				return r
			}
			fmt.Println(strings.Map(rot13, "'Twas brillig and the slithy gopher..."))
		}

	NewReplacer
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			r := strings.NewReplacer("<", "&lt;", ">", "&gt;")
			fmt.Println(r.Replace("This is <b>HTML</b>!"))
		}

	Repeat
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println("ba" + strings.Repeat("na", 2))
		}

	Replace
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.Replace("oink oink oink", "k", "ky", 2))
			fmt.Println(strings.Replace("oink oink oink", "oink", "moo", -1))
		}

	ReplaceAll
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.ReplaceAll("oink oink oink", "oink", "moo"))
		}

	Split
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Printf("%q\n", strings.Split("a,b,c", ","))
			fmt.Printf("%q\n", strings.Split("a man a plan a canal panama", "a "))
			fmt.Printf("%q\n", strings.Split(" xyz ", ""))
			fmt.Printf("%q\n", strings.Split("", "Bernardo O'Higgins"))
		}

	SplitAfter
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Printf("%q\n", strings.SplitAfter("a,b,c", ","))
		}

	SplitAfterN
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Printf("%q\n", strings.SplitAfterN("a,b,c", ",", 2))
		}

	SplitN
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Printf("%q\n", strings.SplitN("a,b,c", ",", 2))
			z := strings.SplitN("a,b,c", ",", 0)
			fmt.Printf("%q (nil = %v)\n", z, z == nil)
		}

	Title
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			// Compare this example to the ToTitle example.
			fmt.Println(strings.Title("her royal highness"))
			fmt.Println(strings.Title("loud noises"))
			fmt.Println(strings.Title("хлеб"))
		}

	ToLower
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.ToLower("Gopher"))
		}

	ToLowerSpecial
		package main
		
		import (
			"fmt"
			"strings"
			"unicode"
		)
		
		func main() {
			fmt.Println(strings.ToLowerSpecial(unicode.TurkishCase, "Önnek İş"))
		}

	ToTitle
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			// Compare this example to the Title example.
			fmt.Println(strings.ToTitle("her royal highness"))
			fmt.Println(strings.ToTitle("loud noises"))
			fmt.Println(strings.ToTitle("хлеб"))
		}

	ToTitleSpecial
		package main
		
		import (
			"fmt"
			"strings"
			"unicode"
		)
		
		func main() {
			fmt.Println(strings.ToTitleSpecial(unicode.TurkishCase, "dünyanın ilk borsa yapısı Aizonai kabul edilir"))
		}

	ToUpper
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.ToUpper("Gopher"))
		}

	ToUpperSpecial
		package main
		
		import (
			"fmt"
			"strings"
			"unicode"
		)
		
		func main() {
			fmt.Println(strings.ToUpperSpecial(unicode.TurkishCase, "örnek iş"))
		}

	ToValidUTF8
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Printf("%s\n", strings.ToValidUTF8("abc", "\uFFFD"))
			fmt.Printf("%s\n", strings.ToValidUTF8("a\xffb\xC0\xAFc\xff", ""))
			fmt.Printf("%s\n", strings.ToValidUTF8("\xed\xa0\x80", "abc"))
		}

	Trim
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Print(strings.Trim("¡¡¡Hello, Gophers!!!", "!¡"))
		}

	TrimFunc
		package main
		
		import (
			"fmt"
			"strings"
			"unicode"
		)
		
		func main() {
			fmt.Print(strings.TrimFunc("¡¡¡Hello, Gophers!!!", func(r rune) bool {
				return !unicode.IsLetter(r) && !unicode.IsNumber(r)
			}))
		}

	TrimLeft
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Print(strings.TrimLeft("¡¡¡Hello, Gophers!!!", "!¡"))
		}

	TrimLeftFunc
		package main
		
		import (
			"fmt"
			"strings"
			"unicode"
		)
		
		func main() {
			fmt.Print(strings.TrimLeftFunc("¡¡¡Hello, Gophers!!!", func(r rune) bool {
				return !unicode.IsLetter(r) && !unicode.IsNumber(r)
			}))
		}

	TrimPrefix
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			var s = "¡¡¡Hello, Gophers!!!"
			s = strings.TrimPrefix(s, "¡¡¡Hello, ")
			s = strings.TrimPrefix(s, "¡¡¡Howdy, ")
			fmt.Print(s)
		}

	TrimRight
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Print(strings.TrimRight("¡¡¡Hello, Gophers!!!", "!¡"))
		}

	TrimRightFunc
		package main
		
		import (
			"fmt"
			"strings"
			"unicode"
		)
		
		func main() {
			fmt.Print(strings.TrimRightFunc("¡¡¡Hello, Gophers!!!", func(r rune) bool {
				return !unicode.IsLetter(r) && !unicode.IsNumber(r)
			}))
		}

	TrimSpace
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			fmt.Println(strings.TrimSpace(" \t\n Hello, Gophers \n\t\r\n"))
		}

	TrimSuffix
		package main
		
		import (
			"fmt"
			"strings"
		)
		
		func main() {
			var s = "¡¡¡Hello, Gophers!!!"
			s = strings.TrimSuffix(s, ", Gophers!!!")
			s = strings.TrimSuffix(s, ", Marmots!!!")
			fmt.Print(s)
		}


Package-Level Type Names (total 13, in which 3 are exported)

	/* sort exporteds by: alphabet | popularity */
	 type Builder (struct)
		A Builder is used to efficiently build a string using Write methods.
		It minimizes memory copying. The zero value is ready to use.
		Do not copy a non-zero Builder.

		Fields (total 2, neither is exported)
			/* 2 unexporteds ... *//* 2 unexporteds: */
			addr *Builder
				// of receiver, to detect copies by value

			buf []byte
		Methods (total 11, in which 9 are exported)
			(*Builder) Cap() int
				Cap returns the capacity of the builder's underlying byte slice. It is the
				total space allocated for the string being built and includes any bytes
				already written.

			(*Builder) Grow(n int)
				Grow grows b's capacity, if necessary, to guarantee space for
				another n bytes. After Grow(n), at least n bytes can be written to b
				without another allocation. If n is negative, Grow panics.

			(*Builder) Len() int
				Len returns the number of accumulated bytes; b.Len() == len(b.String()).

			(*Builder) Reset()
				Reset resets the Builder to be empty.

			(*Builder) String() string
				String returns the accumulated string.

			(*Builder) Write(p []byte) (int, error)
				Write appends the contents of p to b's buffer.
				Write always returns len(p), nil.

			(*Builder) WriteByte(c byte) error
				WriteByte appends the byte c to b's buffer.
				The returned error is always nil.

			(*Builder) WriteRune(r rune) (int, error)
				WriteRune appends the UTF-8 encoding of Unicode code point r to b's buffer.
				It returns the length of r and a nil error.

			(*Builder) WriteString(s string) (int, error)
				WriteString appends the contents of s to b's buffer.
				It returns the length of s and a nil error.

			/* 2 unexporteds ... *//* 2 unexporteds: */
			(*Builder) copyCheck()
			(*Builder) grow(n int)
				grow copies the buffer to a new, larger buffer so that there are at least n
				bytes of capacity beyond len(b.buf).

		Implements (at least 9, in which 5 are exported)
			*Builder : fmt.Stringer
			*Builder : internal/bisect.Writer
			*Builder : io.ByteWriter
			*Builder : io.StringWriter
			*Builder : io.Writer
			/* 4+ unexporteds ... *//* 4+ unexporteds: */
			*Builder : context.stringer
			*Builder : crypto/tls.transcriptHash
			*Builder : net/http.http2stringWriter
			*Builder : runtime.stringer
		As Inputs Of (at least 14, none are exported)
			/* 14+ unexporteds ... *//* 14+ unexporteds: */
			func github.com/gotd/td/tdp.format(b *Builder, prefix string, opt tdp.options, obj tdp.Object)
			func github.com/gotd/td/tdp.formatValue(b *Builder, prefix, fieldName string, opt tdp.options, v reflect.Value)
			func mime.closeWord(buf *Builder)
			func mime.writeQString(buf *Builder, s string)
			func mime.(*WordDecoder).convert(buf *Builder, charset string, content []byte) error
			func mime.WordEncoder.bEncode(buf *Builder, charset, s string)
			func mime.WordEncoder.openWord(buf *Builder, charset string)
			func mime.WordEncoder.qEncode(buf *Builder, charset, s string)
			func mime.WordEncoder.splitWord(buf *Builder, charset string)
			func regexp/syntax.bw(b *Builder, args ...string)
			func regexp/syntax.dumpInst(b *Builder, i *syntax.Inst)
			func regexp/syntax.dumpProg(b *Builder, p *syntax.Prog)
			func regexp/syntax.escape(b *Builder, r rune, force bool)
			func regexp/syntax.writeRegexp(b *Builder, re *syntax.Regexp)

	 type Reader (struct)
		A Reader implements the io.Reader, io.ReaderAt, io.ByteReader, io.ByteScanner,
		io.RuneReader, io.RuneScanner, io.Seeker, and io.WriterTo interfaces by reading
		from a string.
		The zero value for Reader operates like a Reader of an empty string.

		Fields (total 3, none are exported)
			/* 3 unexporteds ... *//* 3 unexporteds: */
			i int64
				// current reading index

			prevRune int
				// index of previous rune; or < 0

			s string
		Methods (total 11, all are exported)
			(*Reader) Len() int
				Len returns the number of bytes of the unread portion of the
				string.

			(*Reader) Read(b []byte) (n int, err error)
				Read implements the io.Reader interface.

			(*Reader) ReadAt(b []byte, off int64) (n int, err error)
				ReadAt implements the io.ReaderAt interface.

			(*Reader) ReadByte() (byte, error)
				ReadByte implements the io.ByteReader interface.

			(*Reader) ReadRune() (ch rune, size int, err error)
				ReadRune implements the io.RuneReader interface.

			(*Reader) Reset(s string)
				Reset resets the Reader to be reading from s.

			(*Reader) Seek(offset int64, whence int) (int64, error)
				Seek implements the io.Seeker interface.

			(*Reader) Size() int64
				Size returns the original length of the underlying string.
				Size is the number of bytes available for reading via ReadAt.
				The returned value is always the same and is not affected by calls
				to any other method.

			(*Reader) UnreadByte() error
				UnreadByte implements the io.ByteScanner interface.

			(*Reader) UnreadRune() error
				UnreadRune implements the io.RuneScanner interface.

			(*Reader) WriteTo(w io.Writer) (n int64, err error)
				WriteTo implements the io.WriterTo interface.

		Implements (at least 11, all are exported)
			*Reader : compress/flate.Reader
			*Reader : github.com/klauspost/compress/flate.Reader
			*Reader : io.ByteReader
			*Reader : io.ByteScanner
			*Reader : io.Reader
			*Reader : io.ReaderAt
			*Reader : io.ReadSeeker
			*Reader : io.RuneReader
			*Reader : io.RuneScanner
			*Reader : io.Seeker
			*Reader : io.WriterTo
		As Outputs Of (at least one exported)
			func NewReader(s string) *Reader

	 type Replacer (struct)
		Replacer replaces a list of strings with replacements.
		It is safe for concurrent use by multiple goroutines.

		Fields (total 3, none are exported)
			/* 3 unexporteds ... *//* 3 unexporteds: */
			oldnew []string
			once sync.Once
				// guards buildOnce method

			r replacer
		Methods (total 4, in which 2 are exported)
			(*Replacer) Replace(s string) string
				Replace returns a copy of s with all replacements performed.

			(*Replacer) WriteString(w io.Writer, s string) (n int, err error)
				WriteString writes s to w with all replacements performed.

			/* 2 unexporteds ... *//* 2 unexporteds: */
			(*Replacer) build() replacer
			(*Replacer) buildOnce()
		Implements (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			*Replacer : replacer
		As Outputs Of (at least one exported)
			func NewReplacer(oldnew ...string) *Replacer
		As Types Of (total 4, none are exported)
			/* 4 unexporteds ... *//* 4 unexporteds: */
			  var mime/multipart.quoteEscaper *Replacer
			  var net/http.cookieNameSanitizer *Replacer
			  var net/http.headerNewlineToSpace *Replacer
			  var net/http.htmlReplacer *Replacer

	/* 10 unexporteds ... *//* 10 unexporteds: */
	 type appendSliceWriter ([])

		Methods (total 2, both are exported)
			(*appendSliceWriter) Write(p []byte) (int, error)
				Write writes to the buffer to satisfy io.Writer.

			(*appendSliceWriter) WriteString(s string) (int, error)
				WriteString writes to the buffer without string->[]byte->string allocations.

		Implements (at least 5, in which 3 are exported)
			*appendSliceWriter : internal/bisect.Writer
			*appendSliceWriter : io.StringWriter
			*appendSliceWriter : io.Writer
			/* 2+ unexporteds ... *//* 2+ unexporteds: */
			*appendSliceWriter : crypto/tls.transcriptHash
			*appendSliceWriter : net/http.http2stringWriter

	 type asciiSet ([...])
		asciiSet is a 32-byte value, where each bit represents the presence of a
		given ASCII character in the set. The 128-bits of the lower 16 bytes,
		starting with the least-significant bit of the lowest word to the
		most-significant bit of the highest word, map to the full range of all
		128 ASCII characters. The 128-bits of the upper 16 bytes will be zeroed,
		ensuring that any non-ASCII character will be reported as not in the set.
		This allocates a total of 32 bytes even though the upper half
		is unused to avoid bounds checks in asciiSet.contains.

		Methods (only one, which is unexported)
			/* one unexported ... *//* one unexported: */
			(*asciiSet) contains(c byte) bool
				contains reports whether c is inside the set.

		As Outputs Of (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			func makeASCIISet(chars string) (as asciiSet, ok bool)
		As Inputs Of (at least 2, neither is exported)
			/* 2+ unexporteds ... *//* 2+ unexporteds: */
			func trimLeftASCII(s string, as *asciiSet) string
			func trimRightASCII(s string, as *asciiSet) string

	 type byteReplacer ([...])
		byteReplacer is the implementation that's used when all the "old"
		and "new" values are single ASCII bytes.
		The array contains replacement bytes indexed by old byte.

		Methods (total 2, both are exported)
			(*byteReplacer) Replace(s string) string
			(*byteReplacer) WriteString(w io.Writer, s string) (n int, err error)
		Implements (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			*byteReplacer : replacer

	 type byteStringReplacer (struct)
		byteStringReplacer is the implementation that's used when all the
		"old" values are single ASCII bytes but the "new" values vary in size.

		Fields (total 2, neither is exported)
			/* 2 unexporteds ... *//* 2 unexporteds: */
			replacements [256][]byte
				replacements contains replacement byte slices indexed by old byte.
				A nil []byte means that the old byte should not be replaced.

			toReplace []string
				toReplace keeps a list of bytes to replace. Depending on length of toReplace
				and length of target string it may be faster to use Count, or a plain loop.
				We store single byte as a string, because Count takes a string.

		Methods (total 2, both are exported)
			(*byteStringReplacer) Replace(s string) string
			(*byteStringReplacer) WriteString(w io.Writer, s string) (n int, err error)
		Implements (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			*byteStringReplacer : replacer

	 type genericReplacer (struct)
		genericReplacer is the fully generic algorithm.
		It's used as a fallback when nothing faster can be used.

		Fields (total 3, none are exported)
			/* 3 unexporteds ... *//* 3 unexporteds: */
			mapping [256]byte
				mapping maps from key bytes to a dense index for trieNode.table.

			root trieNode
			tableSize int
				tableSize is the size of a trie node's lookup table. It is the number
				of unique key bytes.

		Methods (total 3, in which 2 are exported)
			(*genericReplacer) Replace(s string) string
			(*genericReplacer) WriteString(w io.Writer, s string) (n int, err error)
			/* one unexported ... *//* one unexported: */
			(*genericReplacer) lookup(s string, ignoreRoot bool) (val string, keylen int, found bool)
		Implements (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			*genericReplacer : replacer
		As Outputs Of (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			func makeGenericReplacer(oldnew []string) *genericReplacer

	 type replacer (interface)
		replacer is the interface that a replacement algorithm needs to implement.

		Methods (total 2, both are exported)
			( replacer) Replace(s string) string
			( replacer) WriteString(w io.Writer, s string) (n int, err error)
		Implemented By (at least 5, in which 1 is exported)
			*Replacer
			/* 4+ unexporteds ... *//* 4+ unexporteds: */
			*byteReplacer
			*byteStringReplacer
			*genericReplacer
			*singleStringReplacer
		As Outputs Of (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			func (*Replacer).build() replacer

	 type singleStringReplacer (struct)
		singleStringReplacer is the implementation that's used when there is only
		one string to replace (and that string has more than one byte).

		Fields (total 2, neither is exported)
			/* 2 unexporteds ... *//* 2 unexporteds: */
			finder *stringFinder
			value string
				value is the new string that replaces that pattern when it's found.

		Methods (total 2, both are exported)
			(*singleStringReplacer) Replace(s string) string
			(*singleStringReplacer) WriteString(w io.Writer, s string) (n int, err error)
		Implements (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			*singleStringReplacer : replacer
		As Outputs Of (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			func makeSingleStringReplacer(pattern string, value string) *singleStringReplacer

	 type stringFinder (struct)
		stringFinder efficiently finds strings in a source text. It's implemented
		using the Boyer-Moore string search algorithm:
		https://en.wikipedia.org/wiki/Boyer-Moore_string_search_algorithm
		https://www.cs.utexas.edu/~moore/publications/fstrpos.pdf (note: this aged
		document uses 1-based indexing)

		Fields (total 3, none are exported)
			/* 3 unexporteds ... *//* 3 unexporteds: */
			badCharSkip [256]int
				badCharSkip[b] contains the distance between the last byte of pattern
				and the rightmost occurrence of b in pattern. If b is not in pattern,
				badCharSkip[b] is len(pattern).
				
				Whenever a mismatch is found with byte b in the text, we can safely
				shift the matching frame at least badCharSkip[b] until the next time
				the matching char could be in alignment.

			goodSuffixSkip []int
				goodSuffixSkip[i] defines how far we can shift the matching frame given
				that the suffix pattern[i+1:] matches, but the byte pattern[i] does
				not. There are two cases to consider:
				
				1. The matched suffix occurs elsewhere in pattern (with a different
				byte preceding it that we might possibly match). In this case, we can
				shift the matching frame to align with the next suffix chunk. For
				example, the pattern "mississi" has the suffix "issi" next occurring
				(in right-to-left order) at index 1, so goodSuffixSkip[3] ==
				shift+len(suffix) == 3+4 == 7.
				
				2. If the matched suffix does not occur elsewhere in pattern, then the
				matching frame may share part of its prefix with the end of the
				matching suffix. In this case, goodSuffixSkip[i] will contain how far
				to shift the frame to align this portion of the prefix to the
				suffix. For example, in the pattern "abcxxxabc", when the first
				mismatch from the back is found to be in position 3, the matching
				suffix "xxabc" is not found elsewhere in the pattern. However, its
				rightmost "abc" (at position 6) is a prefix of the whole pattern, so
				goodSuffixSkip[3] == shift+len(suffix) == 6+5 == 11.

			pattern string
				pattern is the string that we are searching for in the text.

		Methods (only one, which is unexported)
			/* one unexported ... *//* one unexported: */
			(*stringFinder) next(text string) int
				next returns the index in text of the first occurrence of the pattern. If
				the pattern is not found, it returns -1.

		As Outputs Of (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			func makeStringFinder(pattern string) *stringFinder

	 type stringWriter (struct)

		Fields (only one, which is unexported)
			/* one unexported ... *//* one unexported: */
			w io.Writer
		Methods (only one, which is exported)
			( stringWriter) WriteString(s string) (int, error)
		Implements (at least 2, in which 1 is exported)
			 stringWriter : io.StringWriter
			/* at least one unexported ... *//* at least one unexported: */
			 stringWriter : net/http.http2stringWriter

	 type trieNode (struct)
		trieNode is a node in a lookup trie for prioritized key/value pairs. Keys
		and values may be empty. For example, the trie containing keys "ax", "ay",
		"bcbc", "x" and "xy" could have eight nodes:
		
			n0  -
			n1  a-
			n2  .x+
			n3  .y+
			n4  b-
			n5  .cbc+
			n6  x+
			n7  .y+
		
		n0 is the root node, and its children are n1, n4 and n6; n1's children are
		n2 and n3; n4's child is n5; n6's child is n7. Nodes n0, n1 and n4 (marked
		with a trailing "-") are partial keys, and nodes n2, n3, n5, n6 and n7
		(marked with a trailing "+") are complete keys.

		Fields (total 5, none are exported)
			/* 5 unexporteds ... *//* 5 unexporteds: */
			next *trieNode
			prefix string
				prefix is the difference in keys between this trie node and the next.
				In the example above, node n4 has prefix "cbc" and n4's next node is n5.
				Node n5 has no children and so has zero prefix, next and table fields.

			priority int
				priority is the priority (higher is more important) of the trie node's
				key/value pair; keys are not necessarily matched shortest- or longest-
				first. Priority is positive if this node is a complete key, and zero
				otherwise. In the example above, positive/zero priorities are marked
				with a trailing "+" or "-".

			table []*trieNode
				table is a lookup table indexed by the next byte in the key, after
				remapping that byte through genericReplacer.mapping to create a dense
				index. In the example above, the keys only use 'a', 'b', 'c', 'x' and
				'y', which remap to 0, 1, 2, 3 and 4. All other bytes remap to 5, and
				genericReplacer.tableSize will be 5. Node n0's table will be
				[]*trieNode{ 0:n1, 1:n4, 3:n6 }, where the 0, 1 and 3 are the remapped
				'a', 'b' and 'x'.

			value string
				value is the value of the trie node's key/value pair. It is empty if
				this node is not a complete key.

		Methods (only one, which is unexported)
			/* one unexported ... *//* one unexported: */
			(*trieNode) add(key, val string, priority int, r *genericReplacer)


Package-Level Functions (total 71, in which 52 are exported)

	 func Clone(s string) string
		Clone returns a fresh copy of s.
		It guarantees to make a copy of s into a new allocation,
		which can be important when retaining only a small substring
		of a much larger string. Using Clone can help such programs
		use less memory. Of course, since using Clone makes a copy,
		overuse of Clone can make programs use more memory.
		Clone should typically be used only rarely, and only when
		profiling indicates that it is needed.
		For strings of length zero the string "" will be returned
		and no allocation is made.

	 func Compare(a, b string) int
		Compare returns an integer comparing two strings lexicographically.
		The result will be 0 if a == b, -1 if a < b, and +1 if a > b.
		
		Compare is included only for symmetry with package bytes.
		It is usually clearer and always faster to use the built-in
		string comparison operators ==, <, >, and so on.

	 func Contains(s, substr string) bool
		Contains reports whether substr is within s.

	 func ContainsAny(s, chars string) bool
		ContainsAny reports whether any Unicode code points in chars are within s.

	 func ContainsFunc(s string, f func(rune) bool) bool
		ContainsFunc reports whether any Unicode code points r within s satisfy f(r).

	 func ContainsRune(s string, r rune) bool
		ContainsRune reports whether the Unicode code point r is within s.

	 func Count(s, substr string) int
		Count counts the number of non-overlapping instances of substr in s.
		If substr is an empty string, Count returns 1 + the number of Unicode code points in s.

	 func Cut(s, sep string) (before, after string, found bool)
		Cut slices s around the first instance of sep,
		returning the text before and after sep.
		The found result reports whether sep appears in s.
		If sep does not appear in s, cut returns s, "", false.

	 func CutPrefix(s, prefix string) (after string, found bool)
		CutPrefix returns s without the provided leading prefix string
		and reports whether it found the prefix.
		If s doesn't start with prefix, CutPrefix returns s, false.
		If prefix is the empty string, CutPrefix returns s, true.

	 func CutSuffix(s, suffix string) (before string, found bool)
		CutSuffix returns s without the provided ending suffix string
		and reports whether it found the suffix.
		If s doesn't end with suffix, CutSuffix returns s, false.
		If suffix is the empty string, CutSuffix returns s, true.

	 func EqualFold(s, t string) bool
		EqualFold reports whether s and t, interpreted as UTF-8 strings,
		are equal under simple Unicode case-folding, which is a more general
		form of case-insensitivity.

	 func Fields(s string) []string
		Fields splits the string s around each instance of one or more consecutive white space
		characters, as defined by unicode.IsSpace, returning a slice of substrings of s or an
		empty slice if s contains only white space.

	 func FieldsFunc(s string, f func(rune) bool) []string
		FieldsFunc splits the string s at each run of Unicode code points c satisfying f(c)
		and returns an array of slices of s. If all code points in s satisfy f(c) or the
		string is empty, an empty slice is returned.
		
		FieldsFunc makes no guarantees about the order in which it calls f(c)
		and assumes that f always returns the same value for a given c.

	 func HasPrefix(s, prefix string) bool
		HasPrefix tests whether the string s begins with prefix.

	 func HasSuffix(s, suffix string) bool
		HasSuffix tests whether the string s ends with suffix.

	 func Index(s, substr string) int
		Index returns the index of the first instance of substr in s, or -1 if substr is not present in s.

	 func IndexAny(s, chars string) int
		IndexAny returns the index of the first instance of any Unicode code point
		from chars in s, or -1 if no Unicode code point from chars is present in s.

	 func IndexByte(s string, c byte) int
		IndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.

	 func IndexFunc(s string, f func(rune) bool) int
		IndexFunc returns the index into s of the first Unicode
		code point satisfying f(c), or -1 if none do.

	 func IndexRune(s string, r rune) int
		IndexRune returns the index of the first instance of the Unicode code point
		r, or -1 if rune is not present in s.
		If r is utf8.RuneError, it returns the first instance of any
		invalid UTF-8 byte sequence.

	 func Join(elems []string, sep string) string
		Join concatenates the elements of its first argument to create a single string. The separator
		string sep is placed between elements in the resulting string.

	 func LastIndex(s, substr string) int
		LastIndex returns the index of the last instance of substr in s, or -1 if substr is not present in s.

	 func LastIndexAny(s, chars string) int
		LastIndexAny returns the index of the last instance of any Unicode code
		point from chars in s, or -1 if no Unicode code point from chars is
		present in s.

	 func LastIndexByte(s string, c byte) int
		LastIndexByte returns the index of the last instance of c in s, or -1 if c is not present in s.

	 func LastIndexFunc(s string, f func(rune) bool) int
		LastIndexFunc returns the index into s of the last
		Unicode code point satisfying f(c), or -1 if none do.

	 func Map(mapping func(rune) rune, s string) string
		Map returns a copy of the string s with all its characters modified
		according to the mapping function. If mapping returns a negative value, the character is
		dropped from the string with no replacement.

	 func NewReader(s string) *Reader
		NewReader returns a new Reader reading from s.
		It is similar to bytes.NewBufferString but more efficient and non-writable.

	 func NewReplacer(oldnew ...string) *Replacer
		NewReplacer returns a new Replacer from a list of old, new string
		pairs. Replacements are performed in the order they appear in the
		target string, without overlapping matches. The old string
		comparisons are done in argument order.
		
		NewReplacer panics if given an odd number of arguments.

	 func Repeat(s string, count int) string
		Repeat returns a new string consisting of count copies of the string s.
		
		It panics if count is negative or if the result of (len(s) * count)
		overflows.

	 func Replace(s, old, new string, n int) string
		Replace returns a copy of the string s with the first n
		non-overlapping instances of old replaced by new.
		If old is empty, it matches at the beginning of the string
		and after each UTF-8 sequence, yielding up to k+1 replacements
		for a k-rune string.
		If n < 0, there is no limit on the number of replacements.

	 func ReplaceAll(s, old, new string) string
		ReplaceAll returns a copy of the string s with all
		non-overlapping instances of old replaced by new.
		If old is empty, it matches at the beginning of the string
		and after each UTF-8 sequence, yielding up to k+1 replacements
		for a k-rune string.

	 func Split(s, sep string) []string
		Split slices s into all substrings separated by sep and returns a slice of
		the substrings between those separators.
		
		If s does not contain sep and sep is not empty, Split returns a
		slice of length 1 whose only element is s.
		
		If sep is empty, Split splits after each UTF-8 sequence. If both s
		and sep are empty, Split returns an empty slice.
		
		It is equivalent to SplitN with a count of -1.
		
		To split around the first instance of a separator, see Cut.

	 func SplitAfter(s, sep string) []string
		SplitAfter slices s into all substrings after each instance of sep and
		returns a slice of those substrings.
		
		If s does not contain sep and sep is not empty, SplitAfter returns
		a slice of length 1 whose only element is s.
		
		If sep is empty, SplitAfter splits after each UTF-8 sequence. If
		both s and sep are empty, SplitAfter returns an empty slice.
		
		It is equivalent to SplitAfterN with a count of -1.

	 func SplitAfterN(s, sep string, n int) []string
		SplitAfterN slices s into substrings after each instance of sep and
		returns a slice of those substrings.
		
		The count determines the number of substrings to return:
		
			n > 0: at most n substrings; the last substring will be the unsplit remainder.
			n == 0: the result is nil (zero substrings)
			n < 0: all substrings
		
		Edge cases for s and sep (for example, empty strings) are handled
		as described in the documentation for SplitAfter.

	 func SplitN(s, sep string, n int) []string
		SplitN slices s into substrings separated by sep and returns a slice of
		the substrings between those separators.
		
		The count determines the number of substrings to return:
		
			n > 0: at most n substrings; the last substring will be the unsplit remainder.
			n == 0: the result is nil (zero substrings)
			n < 0: all substrings
		
		Edge cases for s and sep (for example, empty strings) are handled
		as described in the documentation for Split.
		
		To split around the first instance of a separator, see Cut.

	 func Title(s string) string
		Title returns a copy of the string s with all Unicode letters that begin words
		mapped to their Unicode title case.
		
		Deprecated: The rule Title uses for word boundaries does not handle Unicode
		punctuation properly. Use golang.org/x/text/cases instead.

	 func ToLower(s string) string
		ToLower returns s with all Unicode letters mapped to their lower case.

	 func ToLowerSpecial(c unicode.SpecialCase, s string) string
		ToLowerSpecial returns a copy of the string s with all Unicode letters mapped to their
		lower case using the case mapping specified by c.

	 func ToTitle(s string) string
		ToTitle returns a copy of the string s with all Unicode letters mapped to
		their Unicode title case.

	 func ToTitleSpecial(c unicode.SpecialCase, s string) string
		ToTitleSpecial returns a copy of the string s with all Unicode letters mapped to their
		Unicode title case, giving priority to the special casing rules.

	 func ToUpper(s string) string
		ToUpper returns s with all Unicode letters mapped to their upper case.

	 func ToUpperSpecial(c unicode.SpecialCase, s string) string
		ToUpperSpecial returns a copy of the string s with all Unicode letters mapped to their
		upper case using the case mapping specified by c.

	 func ToValidUTF8(s, replacement string) string
		ToValidUTF8 returns a copy of the string s with each run of invalid UTF-8 byte sequences
		replaced by the replacement string, which may be empty.

	 func Trim(s, cutset string) string
		Trim returns a slice of the string s with all leading and
		trailing Unicode code points contained in cutset removed.

	 func TrimFunc(s string, f func(rune) bool) string
		TrimFunc returns a slice of the string s with all leading
		and trailing Unicode code points c satisfying f(c) removed.

	 func TrimLeft(s, cutset string) string
		TrimLeft returns a slice of the string s with all leading
		Unicode code points contained in cutset removed.
		
		To remove a prefix, use TrimPrefix instead.

	 func TrimLeftFunc(s string, f func(rune) bool) string
		TrimLeftFunc returns a slice of the string s with all leading
		Unicode code points c satisfying f(c) removed.

	 func TrimPrefix(s, prefix string) string
		TrimPrefix returns s without the provided leading prefix string.
		If s doesn't start with prefix, s is returned unchanged.

	 func TrimRight(s, cutset string) string
		TrimRight returns a slice of the string s, with all trailing
		Unicode code points contained in cutset removed.
		
		To remove a suffix, use TrimSuffix instead.

	 func TrimRightFunc(s string, f func(rune) bool) string
		TrimRightFunc returns a slice of the string s with all trailing
		Unicode code points c satisfying f(c) removed.

	 func TrimSpace(s string) string
		TrimSpace returns a slice of the string s, with all leading
		and trailing white space removed, as defined by Unicode.

	 func TrimSuffix(s, suffix string) string
		TrimSuffix returns s without the provided trailing suffix string.
		If s doesn't end with suffix, s is returned unchanged.

	/* 19 unexporteds ... *//* 19 unexporteds: */
	 func explode(s string, n int) []string
		explode splits s into a slice of UTF-8 strings,
		one string per Unicode character up to a maximum of n (n < 0 means no limit).
		Invalid UTF-8 bytes are sliced individually.

	 func genSplit(s, sep string, sepSave, n int) []string
		Generic split: splits after each instance of sep,
		including sepSave bytes of sep in the subarrays.

	 func getStringWriter(w io.Writer) io.StringWriter
	 func indexFunc(s string, f func(rune) bool, truth bool) int
		indexFunc is the same as IndexFunc except that if
		truth==false, the sense of the predicate function is
		inverted.

	 func isSeparator(r rune) bool
		isSeparator reports whether the rune could mark a word boundary.
		TODO: update when package unicode captures more of the properties.

	 func lastIndexFunc(s string, f func(rune) bool, truth bool) int
		lastIndexFunc is the same as LastIndexFunc except that if
		truth==false, the sense of the predicate function is
		inverted.

	 func longestCommonSuffix(a, b string) (i int)
	 func makeASCIISet(chars string) (as asciiSet, ok bool)
		makeASCIISet creates a set of ASCII characters and reports whether all
		characters in chars are ASCII.

	 func makeGenericReplacer(oldnew []string) *genericReplacer
	 func makeSingleStringReplacer(pattern string, value string) *singleStringReplacer
	 func makeStringFinder(pattern string) *stringFinder
	 func max(a, b int) int
	 func noescape(p unsafe.Pointer) unsafe.Pointer
		noescape hides a pointer from escape analysis. It is the identity function
		but escape analysis doesn't think the output depends on the input.
		noescape is inlined and currently compiles down to zero instructions.
		USE CAREFULLY!
		This was copied from the runtime; see issues 23382 and 7921.

	 func trimLeftASCII(s string, as *asciiSet) string
	 func trimLeftByte(s string, c byte) string
	 func trimLeftUnicode(s, cutset string) string
	 func trimRightASCII(s string, as *asciiSet) string
	 func trimRightByte(s string, c byte) string
	 func trimRightUnicode(s, cutset string) string
Package-Level Variables (only one, which is unexported)

	/* one unexported ... *//* one unexported: */
	  var asciiSpace [256]uint8
Package-Level Constants (total 2, neither is exported)

	/* 2 unexporteds ... *//* 2 unexporteds: */
	const countCutOff = 8
		countCutOff controls the ratio of a string length to a number of replacements
		at which (*byteStringReplacer).Replace switches algorithms.
		For strings with higher ration of length to replacements than that value,
		we call Count, for each replacement from toReplace.
		For strings, with a lower ratio we use simple loop, because of Count overhead.
		countCutOff is an empirically determined overhead multiplier.
		TODO(tocarip) revisit once we have register-based abi/mid-stack inlining.

	const maxInt int = 9223372036854775807

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Golds is a Go 101 project developed by Tapir Liu.
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