strings

package
v0.1.0 Latest Latest
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 Go to latest Published: May 5, 2026 License: BSD-3-Clause Imports: 8 Imported by: 0

Documentation

Overview

Package strings implements simple functions to manipulate UTF-8 encoded strings.

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func Clone 

func Clone(a mem.Allocator, 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.

If the allocator is nil, uses the system allocator. The returned string is allocated; the caller owns it.

Example 
package main

import (
	"unsafe"

	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	s := "abc"
	clone := strings.Clone(nil, s)
	fmt.Printf("%t\n", s == clone)
	fmt.Printf("%t\n", unsafe.StringData(s) == unsafe.StringData(clone))
}

Output:
true
false

func Compare 

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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%d\n", strings.Compare("a", "b"))
	fmt.Printf("%d\n", strings.Compare("a", "a"))
	fmt.Printf("%d\n", strings.Compare("b", "a"))
}

Output:
-1
0
1

func Contains 

func Contains(s, substr string) bool

Contains reports whether substr is within s.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%t\n", strings.Contains("seafood", "foo"))
	fmt.Printf("%t\n", strings.Contains("seafood", "bar"))
	fmt.Printf("%t\n", strings.Contains("seafood", ""))
	fmt.Printf("%t\n", strings.Contains("", ""))
}

Output:
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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%t\n", strings.ContainsAny("team", "i"))
	fmt.Printf("%t\n", strings.ContainsAny("fail", "ui"))
	fmt.Printf("%t\n", strings.ContainsAny("ure", "ui"))
	fmt.Printf("%t\n", strings.ContainsAny("failure", "ui"))
	fmt.Printf("%t\n", strings.ContainsAny("foo", ""))
	fmt.Printf("%t\n", strings.ContainsAny("", ""))
}

Output:
false
true
true
true
false
false

func ContainsFunc 

func ContainsFunc(s string, f RunePredicate) bool

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

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	f := func(r rune) bool {
		return r == 'a' || r == 'e' || r == 'i' || r == 'o' || r == 'u'
	}
	fmt.Printf("%t\n", strings.ContainsFunc("hello", f))
	fmt.Printf("%t\n", strings.ContainsFunc("rhythms", f))
}

Output:
true
false

func ContainsRune 

func ContainsRune(s string, r rune) bool

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

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/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.Printf("%t\n", strings.ContainsRune("aardvark", 97))
	fmt.Printf("%t\n", strings.ContainsRune("timeout", 97))
}

Output:
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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%d\n", strings.Count("cheese", "e"))
	fmt.Printf("%d\n", strings.Count("five", "")) // before & after each rune
}

Output:
3
5

func Cut 

func Cut(s, sep string) (string, string)

Cut slices s around the first instance of sep, returning the text before and after sep. If sep does not appear in s, cut returns s, "".

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
Cut("Gopher", "Go") = "", "pher"
Cut("Gopher", "ph") = "Go", "er"
Cut("Gopher", "er") = "Goph", ""
Cut("Gopher", "Badger") = "Gopher", ""

func CutPrefix 

func CutPrefix(s, prefix string) (string, 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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

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

func CutSuffix 

func CutSuffix(s, suffix string) (string, 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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

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

func Fields 

func Fields(a mem.Allocator, 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. Every element of the returned slice is non-empty. Unlike Split, leading and trailing runs of white space characters are discarded.

If the allocator is nil, uses the system allocator. The returned slice is allocated; the caller owns it. The substrings in the slice are references to the original string s.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

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

func FieldsFunc 

func FieldsFunc(a mem.Allocator, s string, f RunePredicate) []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. Every element of the returned slice is non-empty. Unlike Split, leading and trailing runs of code points satisfying f(c) are discarded.

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.

If the allocator is nil, uses the system allocator. The returned slice is allocated; the caller owns it. The substrings in the slice are references to the original string s.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
	"solod.dev/so/unicode"
)

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

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

func HasPrefix 

func HasPrefix(s, prefix string) bool

HasPrefix reports whether the string s begins with prefix.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%t\n", strings.HasPrefix("Gopher", "Go"))
	fmt.Printf("%t\n", strings.HasPrefix("Gopher", "C"))
	fmt.Printf("%t\n", strings.HasPrefix("Gopher", ""))
}

Output:
true
false
true

func HasSuffix 

func HasSuffix(s, suffix string) bool

HasSuffix reports whether the string s ends with suffix.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%t\n", strings.HasSuffix("Amigo", "go"))
	fmt.Printf("%t\n", strings.HasSuffix("Amigo", "O"))
	fmt.Printf("%t\n", strings.HasSuffix("Amigo", "Ami"))
	fmt.Printf("%t\n", strings.HasSuffix("Amigo", ""))
}

Output:
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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%d\n", strings.Index("chicken", "ken"))
	fmt.Printf("%d\n", strings.Index("chicken", "dmr"))
}

Output:
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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%d\n", strings.IndexAny("chicken", "aeiouy"))
	fmt.Printf("%d\n", strings.IndexAny("crwth", "aeiouy"))
}

Output:
2
-1

func IndexByte 

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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%d\n", strings.IndexByte("golang", 'g'))
	fmt.Printf("%d\n", strings.IndexByte("gophers", 'h'))
	fmt.Printf("%d\n", strings.IndexByte("golang", 'x'))
}

Output:
0
3
-1

func IndexFunc 

func IndexFunc(s string, f RunePredicate) int

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

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
	"solod.dev/so/unicode"
)

func main() {
	f := func(c rune) bool {
		return unicode.Is(unicode.White_Space, c)
	}
	fmt.Printf("%d\n", strings.IndexFunc("Hello, 世界", f))
	fmt.Printf("%d\n", strings.IndexFunc("Helloworld", f))
}

Output:
6
-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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%d\n", strings.IndexRune("chicken", 'k'))
	fmt.Printf("%d\n", strings.IndexRune("chicken", 'd'))
}

Output:
4
-1

func Join 

func Join(a mem.Allocator, 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. Panics if the result is too large to fit in a string.

If the allocator is nil, uses the system allocator. The returned string is allocated; the caller owns it.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%d\n", strings.Index("go gopher", "go"))
	fmt.Printf("%d\n", strings.LastIndex("go gopher", "go"))
	fmt.Printf("%d\n", strings.LastIndex("go gopher", "rodent"))
}

Output:
0
3
-1

func LastIndexByte 

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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

func main() {
	fmt.Printf("%d\n", strings.LastIndexByte("Hello, world", 'l'))
	fmt.Printf("%d\n", strings.LastIndexByte("Hello, world", 'o'))
	fmt.Printf("%d\n", strings.LastIndexByte("Hello, world", 'x'))
}

Output:
10
8
-1

func Map 

func Map(a mem.Allocator, mapping RuneFunc, 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.

If the allocator is nil, uses the system allocator. The returned string is allocated; the caller owns it.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
'Gjnf oevyyvt naq gur fyvgul tbcure...

func Repeat 

func Repeat(a mem.Allocator, 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.

If the allocator is nil, uses the system allocator. The returned string is allocated; the caller owns it.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
banana

func Replace 

func Replace(a mem.Allocator, 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.

If the allocator is nil, uses the system allocator. The returned string is allocated; the caller owns it.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
oinky oinky oink
moo moo moo

func ReplaceAll 

func ReplaceAll(a mem.Allocator, 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.

If the allocator is nil, uses the system allocator. The returned string is allocated; the caller owns it.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
moo moo moo

func Split 

func Split(a mem.Allocator, 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.

If the allocator is nil, uses the system allocator. The returned slice is allocated; the caller owns it. The substrings in the slice are references to the original string s.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

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

func SplitAfter 

func SplitAfter(a mem.Allocator, 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.

If the allocator is nil, uses the system allocator. The returned slice is allocated; the caller owns it. The substrings in the slice are references to the original string s.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
["a," "b," "c"]

func SplitN 

func SplitN(a mem.Allocator, 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.

If the allocator is nil, uses the system allocator. The returned slice is allocated; the caller owns it. The substrings in the slice are references to the original string s.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

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

func ToLower 

func ToLower(a mem.Allocator, s string) string

ToLower returns s with all Unicode letters mapped to their lower case. If the allocator is nil, uses the system allocator. The returned string is allocated; the caller owns it.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
gopher

func ToUpper 

func ToUpper(a mem.Allocator, s string) string

ToUpper returns s with all Unicode letters mapped to their upper case. If the allocator is nil, uses the system allocator. The returned string is allocated; the caller owns it.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
GOPHER

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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
Hello, Gophers

func TrimFunc 

func TrimFunc(s string, f RunePredicate) string

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

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
	"solod.dev/so/unicode"
)

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

Output:
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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
Hello, Gophers!!!

func TrimPrefix 

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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
¡¡¡Hello, Gophers

func TrimSpace 

func TrimSpace(s string) string

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

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
Hello, Gophers

func TrimSuffix 

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 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/strings"
)

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

Output:
¡¡¡Hello

Types

type Builder 

type Builder struct {
	// contains filtered or unexported fields
}

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

The caller is responsible for freeing the builder's resources with Builder.Free when done using it.

Example 
package main

import (
	"solod.dev/so/fmt"
	"solod.dev/so/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())

}

Output:
3...2...1...ignition

func FixedBuilder 

func FixedBuilder(buf []byte) Builder

FixedBuilder returns a new Builder that uses the provided buffer as its internal buffer. The builder doesn't take ownership of the buffer and doesn't free it (Free is a no-op). The builder doesn't allocate additional memory, so writes that exceed the buffer's capacity will panic.

func NewBuilder 

func NewBuilder(a mem.Allocator) Builder

NewBuilder returns a new Builder that uses the provided allocator.

func (*Builder) Cap 

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) Free 

func (b *Builder) Free()

Free frees the internal buffer and resets the builder. After Free, the builder can be reused with new writes.

func (*Builder) Grow 

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 

func (b *Builder) Len() int

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

func (*Builder) Reset 

func (b *Builder) Reset()

Reset resets the builder to be empty without freeing the underlying buffer.

func (*Builder) String 

func (b *Builder) String() string

String returns the accumulated string.

func (*Builder) Write 

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 

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 

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 

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.

type Reader 

type Reader struct {
	// contains filtered or unexported fields
}

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.

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) (int, error)

Read implements the io.Reader interface.

func (*Reader) ReadAt 

func (r *Reader) ReadAt(b []byte, off int64) (int, 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() io.RuneSizeResult

ReadRune implements the io.RuneReader interface.

func (*Reader) Reset 

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 

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 

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

WriteTo implements the io.WriterTo interface.

type RuneFunc 

type RuneFunc func(rune) rune

RuneFunc maps a rune to another rune. If mapping returns a negative value, the rune is dropped from the result.

type RunePredicate 

type RunePredicate func(rune) bool

RunePredicate reports whether the rune satisfies a condition.

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