Package strings

According to static analysis, spaces, dashes, zeros, equals, and tabs are the most commonly repeated string literal, often used for display on fixed-width terminal windows. Pre-declare constants for these for O(1) repetition in the common-case.

const (
    repeatedSpaces = "" +
        "                                                                " +
        "                                                                "
    repeatedDashes = "" +
        "----------------------------------------------------------------" +
        "----------------------------------------------------------------"
    repeatedZeroes = "" +
        "0000000000000000000000000000000000000000000000000000000000000000"
    repeatedEquals = "" +
        "================================================================" +
        "================================================================"
    repeatedTabs = "" +
        "\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t" +
        "\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t"
)

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 countCutOff = 8

const maxInt = int(^uint(0) >> 1)

Variables

var asciiSpace = [256]uint8{'\t': 1, '\n': 1, '\v': 1, '\f': 1, '\r': 1, ' ': 1}

func Clone ¶ 1.18

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.

▸ Example

▾ Example

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))
}

true
false

func Compare ¶ 1.5

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.

Use Compare when you need to perform a three-way comparison (with slices.SortFunc, for example). It is usually clearer and always faster to use the built-in string comparison operators ==, <, >, and so on.

▸ Example

▾ Example

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"))
}

-1
0
1

func Contains ¶

func Contains(s, substr string) bool

Contains reports whether substr is within s.

▸ Example

▾ Example

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("", ""))
}

true
false
true
true

func ContainsAny ¶

func ContainsAny(s, chars string) bool

ContainsAny reports whether any Unicode code points in chars are within s.

▸ Example

▾ Example

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("", ""))
}

false
true
true
true
false
false

func ContainsFunc ¶ 1.21

func ContainsFunc(s string, f func(rune) bool) bool

ContainsFunc reports whether any Unicode code points r within s satisfy f(r).

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

func main() {
	f := func(r rune) bool {
		return r == 'a' || r == 'e' || r == 'i' || r == 'o' || r == 'u'
	}
	fmt.Println(strings.ContainsFunc("hello", f))
	fmt.Println(strings.ContainsFunc("rhythms", f))
}

true
false

func ContainsRune ¶

func ContainsRune(s string, r rune) bool

ContainsRune reports whether the Unicode code point r is within s.

▸ Example

▾ Example

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))
}

true
false

func Count ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

3
5

func Cut ¶ 1.18

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.

▸ Example

▾ Example

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")
}

Cut("Gopher", "Go") = "", "pher", true
Cut("Gopher", "ph") = "Go", "er", true
Cut("Gopher", "er") = "Goph", "", true
Cut("Gopher", "Badger") = "Gopher", "", false

func CutPrefix ¶ 1.20

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.

▸ Example

▾ Example

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")
}

CutPrefix("Gopher", "Go") = "pher", true
CutPrefix("Gopher", "ph") = "Gopher", false

func CutSuffix ¶ 1.20

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.

▸ Example

▾ Example

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")
}

CutSuffix("Gopher", "Go") = "Gopher", false
CutSuffix("Gopher", "er") = "Goph", true

func EqualFold ¶

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.

▸ Example

▾ Example

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
}

true
true
false

func Fields ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

Fields are: ["foo" "bar" "baz"]

func FieldsFunc ¶

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.

▸ Example

▾ Example

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))
}

Fields are: ["foo1" "bar2" "baz3"]

func FieldsFuncSeq ¶ 1.24

func FieldsFuncSeq(s string, f func(rune) bool) iter.Seq[string]

FieldsFuncSeq returns an iterator over substrings of s split around runs of Unicode code points satisfying f(c). The iterator yields the same strings that would be returned by FieldsFunc(s), but without constructing the slice.

func FieldsSeq ¶ 1.24

func FieldsSeq(s string) iter.Seq[string]

FieldsSeq returns an iterator over substrings of s split around runs of whitespace characters, as defined by unicode.IsSpace. The iterator yields the same strings that would be returned by Fields(s), but without constructing the slice.

func HasPrefix ¶

func HasPrefix(s, prefix string) bool

HasPrefix reports whether the string s begins with prefix.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

true
false
true

func HasSuffix ¶

func HasSuffix(s, suffix string) bool

HasSuffix reports whether the string s ends with suffix.

▸ Example

▾ Example

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", ""))
}

true
false
false
true

func Index ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

4
-1

func IndexAny ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

2
-1

func IndexByte ¶ 1.2

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.

▸ Example

▾ Example

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'))
}

0
3
-1

func IndexFunc ¶

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.

▸ Example

▾ Example

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))
}

7
-1

func IndexRune ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

4
-1

func Join ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

foo, bar, baz

func LastIndex ¶

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.

▸ Example

▾ Example

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"))
}

0
3
-1

func LastIndexAny ¶

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.

▸ Example

▾ Example

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"))
}

4
8
-1

func LastIndexByte ¶ 1.5

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.

▸ Example

▾ Example

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'))
}

10
8
-1

func LastIndexFunc ¶

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.

▸ Example

▾ Example

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))
}

5
2
-1

func Lines ¶ 1.24

func Lines(s string) iter.Seq[string]

Lines returns an iterator over the newline-terminated lines in the string s. The lines yielded by the iterator include their terminating newlines. If s is empty, the iterator yields no lines at all. If s does not end in a newline, the final yielded line will not end in a newline. It returns a single-use iterator.

func Map ¶

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.

▸ Example

▾ Example

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..."))
}

'Gjnf oevyyvt naq gur fyvgul tbcure...

func Repeat ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

banana

func Replace ¶

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.

▸ Example

▾ Example

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))
}

oinky oinky oink
moo moo moo

func ReplaceAll ¶ 1.12

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

moo moo moo

func Split ¶

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.

▸ Example

▾ Example

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"))
}

["a" "b" "c"]
["" "man " "plan " "canal panama"]
[" " "x" "y" "z" " "]
[""]

func SplitAfter ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

["a," "b," "c"]

func SplitAfterN ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

["a," "b,c"]

func SplitAfterSeq ¶ 1.24

func SplitAfterSeq(s, sep string) iter.Seq[string]

SplitAfterSeq returns an iterator over substrings of s split after each instance of sep. The iterator yields the same strings that would be returned by SplitAfter(s, sep), but without constructing the slice. It returns a single-use iterator.

func SplitN ¶

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.

▸ Example

▾ Example

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)
}

["a" "b,c"]
[] (nil = true)

func SplitSeq ¶ 1.24

func SplitSeq(s, sep string) iter.Seq[string]

SplitSeq returns an iterator over all substrings of s separated by sep. The iterator yields the same strings that would be returned by Split(s, sep), but without constructing the slice. It returns a single-use iterator.

func Title ¶

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.

▸ Example

▾ Example

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("брат"))
}

Her Royal Highness
Loud Noises
Брат

func ToLower ¶

func ToLower(s string) string

ToLower returns s with all Unicode letters mapped to their lower case.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

gopher

func ToLowerSpecial ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
	"unicode"
)

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

örnek iş

func ToTitle ¶

func ToTitle(s string) string

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

▸ Example

▾ Example

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("брат"))
}

HER ROYAL HIGHNESS
LOUD NOISES
БРАТ

func ToTitleSpecial ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
	"unicode"
)

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

DÜNYANIN İLK BORSA YAPISI AİZONAİ KABUL EDİLİR

func ToUpper ¶

func ToUpper(s string) string

ToUpper returns s with all Unicode letters mapped to their upper case.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

GOPHER

func ToUpperSpecial ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
	"unicode"
)

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

ÖRNEK İŞ

func ToValidUTF8 ¶ 1.13

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.

▸ Example

▾ Example

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"))
}

abc
abc
abc

func Trim ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

Hello, Gophers

func TrimFunc ¶

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.

▸ Example

▾ Example

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)
	}))
}

Hello, Gophers

func TrimLeft ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

Hello, Gophers!!!

func TrimLeftFunc ¶

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.

▸ Example

▾ Example

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)
	}))
}

Hello, Gophers!!!

func TrimPrefix ¶ 1.1

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

Gophers!!!

func TrimRight ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

¡¡¡Hello, Gophers

func TrimRightFunc ¶

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.

▸ Example

▾ Example

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)
	}))
}

¡¡¡Hello, Gophers

func TrimSpace ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

Hello, Gophers

func TrimSuffix ¶ 1.1

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

¡¡¡Hello

func explode ¶

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 explodeSeq ¶

func explodeSeq(s string) iter.Seq[string]

explodeSeq returns an iterator over the runes in s.

func genSplit ¶

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 ¶

func getStringWriter(w io.Writer) io.StringWriter

func indexFunc ¶

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 ¶

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 ¶

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 ¶

func longestCommonSuffix(a, b string) (i int)

func splitSeq ¶

func splitSeq(s, sep string, sepSave int) iter.Seq[string]

splitSeq is SplitSeq or SplitAfterSeq, configured by how many bytes of sep to include in the results (none or all).

func trimLeftASCII ¶

func trimLeftASCII(s string, as *asciiSet) string

func trimLeftByte ¶

func trimLeftByte(s string, c byte) string

func trimLeftUnicode ¶

func trimLeftUnicode(s, cutset string) string

func trimRightASCII ¶

func trimRightASCII(s string, as *asciiSet) string

func trimRightByte ¶

func trimRightByte(s string, c byte) string

func trimRightUnicode ¶

func trimRightUnicode(s, cutset string) string

type Builder ¶ 1.10

A Builder is used to efficiently build a string using Builder.Write methods. It minimizes memory copying. The zero value is ready to use. Do not copy a non-zero Builder.

type Builder struct {
    addr *Builder // of receiver, to detect copies by value

    // External users should never get direct access to this buffer, since
    // the slice at some point will be converted to a string using unsafe, also
    // data between len(buf) and cap(buf) might be uninitialized.
    buf []byte
}

▸ Example

▾ Example

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())

}

3...2...1...ignition

func (*Builder) Cap ¶ 1.12

func (b *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.

func (*Builder) Grow ¶ 1.10

func (b *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.

func (*Builder) Len ¶ 1.10

func (b *Builder) Len() int

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

func (*Builder) Reset ¶ 1.10

func (b *Builder) Reset()

Reset resets the Builder to be empty.

func (*Builder) String ¶ 1.10

func (b *Builder) String() string

String returns the accumulated string.

func (*Builder) Write ¶ 1.10

func (b *Builder) Write(p []byte) (int, error)

Write appends the contents of p to b's buffer. Write always returns len(p), nil.

func (*Builder) WriteByte ¶ 1.10

func (b *Builder) WriteByte(c byte) error

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

func (*Builder) WriteRune ¶ 1.10

func (b *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.

func (*Builder) WriteString ¶ 1.10

func (b *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.

func (*Builder) copyCheck ¶

func (b *Builder) copyCheck()

func (*Builder) grow ¶

func (b *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).

type Reader ¶

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.

type Reader struct {
    s        string
    i        int64 // current reading index
    prevRune int   // index of previous rune; or < 0
}

func NewReader ¶

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 (*Reader) Len ¶

func (r *Reader) Len() int

Len returns the number of bytes of the unread portion of the string.

func (*Reader) Read ¶

func (r *Reader) Read(b []byte) (n int, err error)

Read implements the io.Reader interface.

func (*Reader) ReadAt ¶

func (r *Reader) ReadAt(b []byte, off int64) (n int, err error)

ReadAt implements the io.ReaderAt interface.

func (*Reader) ReadByte ¶

func (r *Reader) ReadByte() (byte, error)

ReadByte implements the io.ByteReader interface.

func (*Reader) ReadRune ¶

func (r *Reader) ReadRune() (ch rune, size int, err error)

ReadRune implements the io.RuneReader interface.

func (*Reader) Reset ¶ 1.7

func (r *Reader) Reset(s string)

Reset resets the Reader to be reading from s.

func (*Reader) Seek ¶

func (r *Reader) Seek(offset int64, whence int) (int64, error)

Seek implements the io.Seeker interface.

func (*Reader) Size ¶ 1.5

func (r *Reader) Size() int64

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

func (*Reader) UnreadByte ¶

func (r *Reader) UnreadByte() error

UnreadByte implements the io.ByteScanner interface.

func (*Reader) UnreadRune ¶

func (r *Reader) UnreadRune() error

UnreadRune implements the io.RuneScanner interface.

func (*Reader) WriteTo ¶ 1.1

func (r *Reader) WriteTo(w io.Writer) (n int64, err error)

WriteTo implements the io.WriterTo interface.

type Replacer ¶

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

type Replacer struct {
    once   sync.Once // guards buildOnce method
    r      replacer
    oldnew []string
}

func NewReplacer ¶

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.

▸ Example

▾ Example

package main

import (
	"fmt"
	"strings"
)

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

This is &lt;b&gt;HTML&lt;/b&gt;!

func (*Replacer) Replace ¶

func (r *Replacer) Replace(s string) string

Replace returns a copy of s with all replacements performed.

func (*Replacer) WriteString ¶

func (r *Replacer) WriteString(w io.Writer, s string) (n int, err error)

WriteString writes s to w with all replacements performed.

func (*Replacer) build ¶

func (b *Replacer) build() replacer

func (*Replacer) buildOnce ¶

func (r *Replacer) buildOnce()

type appendSliceWriter ¶

type appendSliceWriter []byte

func (*appendSliceWriter) Write ¶

func (w *appendSliceWriter) Write(p []byte) (int, error)

Write writes to the buffer to satisfy io.Writer.

func (*appendSliceWriter) WriteString ¶

func (w *appendSliceWriter) WriteString(s string) (int, error)

WriteString writes to the buffer without string->[]byte->string allocations.

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.

type asciiSet [8]uint32

func makeASCIISet ¶

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 (*asciiSet) contains ¶

func (as *asciiSet) contains(c byte) bool

contains reports whether c is inside the set.

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.

type byteReplacer [256]byte

func (*byteReplacer) Replace ¶

func (r *byteReplacer) Replace(s string) string

func (*byteReplacer) WriteString ¶

func (r *byteReplacer) WriteString(w io.Writer, s string) (n int, err error)

type byteStringReplacer ¶

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

type byteStringReplacer struct {
    // replacements contains replacement byte slices indexed by old byte.
    // A nil []byte means that the old byte should not be replaced.
    replacements [256][]byte
    // 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.
    toReplace []string
}

func (*byteStringReplacer) Replace ¶

func (r *byteStringReplacer) Replace(s string) string

func (*byteStringReplacer) WriteString ¶

func (r *byteStringReplacer) WriteString(w io.Writer, s string) (n int, err error)

type genericReplacer ¶

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

type genericReplacer struct {
    root trieNode
    // tableSize is the size of a trie node's lookup table. It is the number
    // of unique key bytes.
    tableSize int
    // mapping maps from key bytes to a dense index for trieNode.table.
    mapping [256]byte
}

func makeGenericReplacer ¶

func makeGenericReplacer(oldnew []string) *genericReplacer

func (*genericReplacer) Replace ¶

func (r *genericReplacer) Replace(s string) string

func (*genericReplacer) WriteString ¶

func (r *genericReplacer) WriteString(w io.Writer, s string) (n int, err error)

func (*genericReplacer) lookup ¶

func (r *genericReplacer) lookup(s string, ignoreRoot bool) (val string, keylen int, found bool)

type replacer ¶

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

type replacer interface {
    Replace(s string) string
    WriteString(w io.Writer, s string) (n int, err error)
}

type singleStringReplacer ¶

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

type singleStringReplacer struct {
    finder *stringFinder
    // value is the new string that replaces that pattern when it's found.
    value string
}

func makeSingleStringReplacer ¶

func makeSingleStringReplacer(pattern string, value string) *singleStringReplacer

func (*singleStringReplacer) Replace ¶

func (r *singleStringReplacer) Replace(s string) string

func (*singleStringReplacer) WriteString ¶

func (r *singleStringReplacer) WriteString(w io.Writer, s string) (n int, err error)

type stringFinder ¶

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)

type stringFinder struct {
    // pattern is the string that we are searching for in the text.
    pattern string

    // 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.
    badCharSkip [256]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.
    goodSuffixSkip []int
}

func makeStringFinder ¶

func makeStringFinder(pattern string) *stringFinder

func (*stringFinder) next ¶

func (f *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.

type stringWriter ¶

type stringWriter struct {
    w io.Writer
}

func (stringWriter) WriteString ¶

func (w stringWriter) WriteString(s string) (int, error)

type trieNode ¶

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.

type trieNode struct {
    // value is the value of the trie node's key/value pair. It is empty if
    // this node is not a complete key.
    value string
    // 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 "-".
    priority int

    // 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.
    prefix string
    next   *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'.
    table []*trieNode
}

func (*trieNode) add ¶

func (t *trieNode) add(key, val string, priority int, r *genericReplacer)