bytes

package
v0.1.0 Latest Latest
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 Go to latest Published: May 5, 2026 License: BSD-3-Clause Imports: 9 Imported by: 0

Documentation

Overview

Package bytes implements functions for the manipulation of byte slices. It is analogous to the facilities of the strings package.

Based on the bytes package, with fewer features.

Index

Examples

Constants

View Source 
const MinRead = 512

MinRead is the minimum slice size passed to a Buffer.Read call by Buffer.ReadFrom. As long as the Buffer has at least MinRead bytes beyond what is required to hold the contents of r, Buffer.ReadFrom will not grow the underlying buffer.

Variables

View Source 
var ErrNegativeGrow = errors.New("bytes: negative grow")

ErrNegativeGrow means that a Buffer.Grow call was given a negative count.

Functions

func Clone 

func Clone(a mem.Allocator, b []byte) []byte

Clone returns a copy of b[:len(b)]. If the allocator is nil, uses the system allocator. The returned slice is allocated; the caller owns it.

Example 
package main

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

func main() {
	b := []byte("abc")
	clone := bytes.Clone(nil, b)
	fmt.Printf("%s\n", clone)
	clone[0] = 'd'
	fmt.Printf("%s\n", b)
	fmt.Printf("%s\n", clone)
}

Output:
abc
abc
dbc

func Compare 

func Compare(a, b []byte) int

Compare returns an integer comparing two byte slices lexicographically. The result will be 0 if a == b, -1 if a < b, and +1 if a > b. A nil argument is equivalent to an empty slice.

Example 
package main

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

func main() {
	// Interpret Compare's result by comparing it to zero.
	var a, b []byte
	if bytes.Compare(a, b) < 0 {
		// a less b
	}
	if bytes.Compare(a, b) <= 0 {
		// a less or equal b
	}
	if bytes.Compare(a, b) > 0 {
		// a greater b
	}
	if bytes.Compare(a, b) >= 0 {
		// a greater or equal b
	}

	// Prefer Equal to Compare for equality comparisons.
	if bytes.Equal(a, b) {
		// a equal b
	}
	if !bytes.Equal(a, b) {
		// a not equal b
	}
}

func Contains 

func Contains(b, subslice []byte) bool

Contains reports whether subslice is within b.

Example 
package main

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

func main() {
	fmt.Printf("%t\n", bytes.Contains([]byte("seafood"), []byte("foo")))
	fmt.Printf("%t\n", bytes.Contains([]byte("seafood"), []byte("bar")))
	fmt.Printf("%t\n", bytes.Contains([]byte("seafood"), []byte("")))
	fmt.Printf("%t\n", bytes.Contains([]byte(""), []byte("")))
}

Output:
true
false
true
true

func Count 

func Count(s, sep []byte) int

Count counts the number of non-overlapping instances of sep in s. If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.

Example 
package main

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

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

Output:
3
5

func Equal 

func Equal(a, b []byte) bool

Equal reports whether a and b are the same length and contain the same bytes. A nil argument is equivalent to an empty slice.

Example 
package main

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

func main() {
	fmt.Printf("%t\n", bytes.Equal([]byte("Go"), []byte("Go")))
	fmt.Printf("%t\n", bytes.Equal([]byte("Go"), []byte("C++")))
}

Output:
true
false

func HasPrefix 

func HasPrefix(s, prefix []byte) bool

HasPrefix reports whether the byte slice s begins with prefix.

Example 
package main

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

func main() {
	fmt.Printf("%t\n", bytes.HasPrefix([]byte("Gopher"), []byte("Go")))
	fmt.Printf("%t\n", bytes.HasPrefix([]byte("Gopher"), []byte("C")))
	fmt.Printf("%t\n", bytes.HasPrefix([]byte("Gopher"), []byte("")))
}

Output:
true
false
true

func HasSuffix 

func HasSuffix(s, suffix []byte) bool

HasSuffix reports whether the byte slice s ends with suffix.

Example 
package main

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

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

Output:
true
false
false
true

func Index 

func Index(s, sep []byte) int

Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.

Example 
package main

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

func main() {
	fmt.Printf("%d\n", bytes.Index([]byte("chicken"), []byte("ken")))
	fmt.Printf("%d\n", bytes.Index([]byte("chicken"), []byte("dmr")))
}

Output:
4
-1

func IndexByte 

func IndexByte(b []byte, c byte) int

IndexByte returns the index of the first instance of c in b, or -1 if c is not present in b.

Example 
package main

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

func main() {
	fmt.Printf("%d\n", bytes.IndexByte([]byte("chicken"), byte('k')))
	fmt.Printf("%d\n", bytes.IndexByte([]byte("chicken"), byte('g')))
}

Output:
4
-1

func Join 

func Join(a mem.Allocator, s [][]byte, sep []byte) []byte

Join concatenates the elements of s to create a new byte slice. The separator sep is placed between elements in the resulting slice. Panics if the result is too large to allocate.

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

Example 
package main

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

func main() {
	s := [][]byte{[]byte("foo"), []byte("bar"), []byte("baz")}
	fmt.Printf("%s", bytes.Join(nil, s, []byte(", ")))
}

Output:
foo, bar, baz

func Map 

func Map(a mem.Allocator, mapping RuneFunc, s []byte) []byte

Map returns a copy of the byte slice s with all its characters modified according to the mapping function. If mapping returns a negative value, the character is dropped from the byte slice with no replacement. The characters in s and the output are interpreted as UTF-8-encoded code points.

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

Example 
package main

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

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.Printf("%s\n", bytes.Map(nil, rot13, []byte("'Twas brillig and the slithy gopher...")))
}

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

func Repeat 

func Repeat(a mem.Allocator, b []byte, count int) []byte

Repeat returns a new byte slice consisting of count copies of b. It panics if count is negative or if the result of (len(b) * count) overflows.

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

func Replace 

func Replace(a mem.Allocator, s, old, new []byte, n int) []byte

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

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

Example 
package main

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

func main() {
	old := []byte("oink oink oink")
	fmt.Printf("%s\n", bytes.Replace(nil, old, []byte("k"), []byte("ky"), 2))
	fmt.Printf("%s\n", bytes.Replace(nil, old, []byte("oink"), []byte("moo"), -1))
}

Output:
oinky oinky oink
moo moo moo

func Runes 

func Runes(a mem.Allocator, s []byte) []rune

Runes interprets s as a sequence of UTF-8-encoded code points. It returns a slice of runes (Unicode code points) equivalent to s.

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

Example 
package main

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

func main() {
	rs := bytes.Runes(nil, []byte("go gopher"))
	for _, r := range rs {
		fmt.Printf("%#U\n", r)
	}
}

Output:
U+0067 'g'
U+006F 'o'
U+0020 ' '
U+0067 'g'
U+006F 'o'
U+0070 'p'
U+0068 'h'
U+0065 'e'
U+0072 'r'

func Split 

func Split(a mem.Allocator, s, sep []byte) [][]byte

Split slices s into all subslices separated by sep and returns a slice of the subslices between those separators. If sep is empty, Split splits after each UTF-8 sequence. 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 subslices in the returned slice are views into the original slice s.

Example 
package main

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

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

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

func SplitN 

func SplitN(a mem.Allocator, s, sep []byte, n int) [][]byte

SplitN slices s into subslices separated by sep and returns a slice of the subslices between those separators. If sep is empty, SplitN splits after each UTF-8 sequence. The count determines the number of subslices to return:

  • n > 0: at most n subslices; the last subslice will be the unsplit remainder;
  • n == 0: the result is nil (zero subslices);
  • n < 0: all subslices.

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 subslices in the returned slice are views into the original slice s.

Example 
package main

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

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

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

func String 

func String(a mem.Allocator, s []byte) string

String creates a string from a byte slice. If the allocator is nil, uses the system allocator. The returned string is allocated; the caller owns it.

func ToLower 

func ToLower(a mem.Allocator, s []byte) []byte

ToLower returns a copy of the byte slice s with all Unicode letters mapped to their lower case.

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

Example 
package main

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

func main() {
	fmt.Printf("%s", bytes.ToLower(nil, []byte("Gopher")))
}

Output:
gopher

func ToUpper 

func ToUpper(a mem.Allocator, s []byte) []byte

ToUpper returns a copy of the byte slice s with all Unicode letters mapped to their upper case.

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

Example 
package main

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

func main() {
	fmt.Printf("%s", bytes.ToUpper(nil, []byte("Gopher")))
}

Output:
GOPHER

func Trim 

func Trim(s []byte, cutset string) []byte

Trim returns a subslice of s by slicing off all leading and trailing UTF-8-encoded code points contained in cutset.

Example 
package main

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

func main() {
	fmt.Printf("[%q]", bytes.Trim([]byte(" !!! Achtung! Achtung! !!! "), "! "))
}

Output:
["Achtung! Achtung"]

func TrimFunc 

func TrimFunc(s []byte, f RunePredicate) []byte

TrimFunc returns a subslice of s by slicing off all leading and trailing UTF-8-encoded code points c that satisfy f(c).

Example 
package main

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

func main() {
	fmt.Println(string(bytes.TrimFunc([]byte("go-gopher!"), unicode.IsLetter)))
	fmt.Println(string(bytes.TrimFunc([]byte("\"go-gopher!\""), unicode.IsLetter)))
	fmt.Println(string(bytes.TrimFunc([]byte("1234go-gopher!567"), unicode.IsDigit)))
}

Output:
-gopher!
"go-gopher!"
go-gopher!

func TrimLeft 

func TrimLeft(s []byte, cutset string) []byte

TrimLeft returns a subslice of s by slicing off all leading UTF-8-encoded code points contained in cutset.

Example 
package main

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

func main() {
	fmt.Print(string(bytes.TrimLeft([]byte("453gopher8257"), "0123456789")))
}

Output:
gopher8257

func TrimPrefix 

func TrimPrefix(s, prefix []byte) []byte

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

func main() {
	var b = []byte("Goodbye,, world!")
	b = bytes.TrimPrefix(b, []byte("Goodbye,"))
	b = bytes.TrimPrefix(b, []byte("See ya,"))
	fmt.Printf("Hello%s", b)
}

Output:
Hello, world!

func TrimRight 

func TrimRight(s []byte, cutset string) []byte

TrimRight returns a subslice of s by slicing off all trailing UTF-8-encoded code points that are contained in cutset.

Example 
package main

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

func main() {
	fmt.Print(string(bytes.TrimRight([]byte("453gopher8257"), "0123456789")))
}

Output:
453gopher

func TrimSpace 

func TrimSpace(s []byte) []byte

TrimSpace returns a subslice of s by slicing off all leading and trailing white space, as defined by Unicode.

Example 
package main

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

func main() {
	fmt.Printf("%s", bytes.TrimSpace([]byte(" \t\n a lone gopher \n\t\r\n")))
}

Output:
a lone gopher

func TrimSuffix 

func TrimSuffix(s, suffix []byte) []byte

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

Example 
package main

import (
	"os"

	"solod.dev/so/bytes"
)

func main() {
	var b = []byte("Hello, goodbye, etc!")
	b = bytes.TrimSuffix(b, []byte("goodbye, etc!"))
	b = bytes.TrimSuffix(b, []byte("gopher"))
	b = append(b, bytes.TrimSuffix([]byte("world!"), []byte("x!"))...)
	os.Stdout.Write(b)
}

Output:
Hello, world!

Types

type Buffer 

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

A Buffer is a variable-sized buffer of bytes with Buffer.Read and Buffer.Write methods. The zero value for Buffer is an empty buffer ready to use (with default allocator). A Buffer grows as needed when writing data, using the provided allocator. The caller is responsible for freeing the buffer's resources with Buffer.Free when done using it.

Example 
package main

import (
	"os"

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

func main() {
	var b bytes.Buffer // A Buffer needs no initialization.
	b.Write([]byte("Hello "))
	fmt.Fprintf(&b, "world!")
	b.WriteTo(os.Stdout)
}

Output:
Hello world!
Example (Reader) 
package main

import (
	"encoding/base64"
	"os"

	"solod.dev/so/bytes"
	"solod.dev/so/io"
)

func main() {
	// A Buffer can turn a string or a []byte into an io.Reader.
	buf := bytes.NewBufferString(nil, "R29waGVycyBydWxlIQ==")
	dec := base64.NewDecoder(base64.StdEncoding, &buf)
	io.Copy(os.Stdout, dec)
}

Output:
Gophers rule!

func NewBuffer 

func NewBuffer(a mem.Allocator, buf []byte) Buffer

NewBuffer creates and initializes a new Buffer using buf as its initial contents. The new Buffer takes ownership of buf, and the caller should not use buf after this call. NewBuffer is intended to prepare a Buffer to read existing data. It can also be used to set the initial size of the internal buffer for writing. To do that, buf should have the desired capacity but a length of zero.

If buf was allocated with an allocator, the same allocator must be passed to NewBuffer so that Buffer.Free can release it correctly. Do not call Buffer.Free if buf was not heap-allocated.

Do not provide a stack-allocated buf if you intend to write to the buffer, as the buffer may need to grow and reallocate, which would cause free() on a stack pointer. Only use heap-allocated slices in this case.

If the allocator is nil, uses the system allocator.

func NewBufferString 

func NewBufferString(a mem.Allocator, s string) Buffer

NewBufferString creates and initializes a new Buffer using string s as its initial contents. It is intended to prepare a buffer to read an existing string.

If s was allocated with an allocator, the same allocator must be passed to NewBuffer so that Buffer.Free can release it correctly. Do not call Buffer.Free if s was not heap-allocated.

Do not provide a stack-allocated s if you intend to write to the buffer, as the buffer may need to grow and reallocate, which would cause free() on a stack pointer. Only use heap-allocated strings in this case.

If the allocator is nil, uses the system allocator.

func (*Buffer) Available 

func (b *Buffer) Available() int

Available returns how many bytes are unused in the buffer.

func (*Buffer) Bytes 

func (b *Buffer) Bytes() []byte

Bytes returns a slice of length b.Len() holding the unread portion of the buffer. The slice is valid for use only until the next buffer modification (that is, only until the next call to a method like Buffer.Read, Buffer.Write, Buffer.Reset. The slice aliases the buffer content at least until the next buffer modification, so immediate changes to the slice will affect the result of future reads.

Example 
package main

import (
	"os"

	"solod.dev/so/bytes"
)

func main() {
	buf := bytes.Buffer{}
	buf.Write([]byte{'h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd'})
	os.Stdout.Write(buf.Bytes())
}

Output:
hello world

func (*Buffer) Cap 

func (b *Buffer) Cap() int

Cap returns the capacity of the buffer's underlying byte slice, that is, the total space allocated for the buffer's data.

Example 
package main

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

func main() {
	buf1 := bytes.NewBuffer(nil, make([]byte, 10))
	buf2 := bytes.NewBuffer(nil, make([]byte, 0, 10))
	fmt.Printf("%d\n", buf1.Cap())
	fmt.Printf("%d\n", buf2.Cap())
}

Output:
10
10

func (*Buffer) Free 

func (b *Buffer) Free()

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

func (*Buffer) Grow 

func (b *Buffer) Grow(n int)

Grow grows the buffer's capacity, if necessary, to guarantee space for another n bytes. After Grow(n), at least n bytes can be written to the buffer without another allocation. Panics if n is negative or if the buffer cannot grow.

Example 
package main

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

func main() {
	var b bytes.Buffer
	b.Grow(64)
	bb := b.Bytes()
	b.Write([]byte("64 bytes or fewer"))
	fmt.Printf("%q", bb[:b.Len()])
}

Output:
"64 bytes or fewer"

func (*Buffer) Len 

func (b *Buffer) Len() int

Len returns the number of bytes of the unread portion of the buffer; b.Len() == len(b.Bytes()).

Example 
package main

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

func main() {
	var b bytes.Buffer
	b.Grow(64)
	b.Write([]byte("abcde"))
	fmt.Printf("%d", b.Len())
}

Output:
5

func (*Buffer) Next 

func (b *Buffer) Next(n int) []byte

Next returns a slice containing the next n bytes from the buffer, advancing the buffer as if the bytes had been returned by Buffer.Read. If there are fewer than n bytes in the buffer, Next returns the entire buffer. The slice is only valid until the next call to a read or write method.

Example 
package main

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

func main() {
	var b bytes.Buffer
	b.Grow(64)
	b.Write([]byte("abcde"))
	fmt.Printf("%s\n", b.Next(2))
	fmt.Printf("%s\n", b.Next(2))
	fmt.Printf("%s", b.Next(2))
}

Output:
ab
cd
e

func (*Buffer) Peek 

func (b *Buffer) Peek(n int) ([]byte, error)

Peek returns the next n bytes without advancing the buffer. If Peek returns fewer than n bytes, it also returns io.EOF. The slice is only valid until the next call to a read or write method. The slice aliases the buffer content at least until the next buffer modification, so immediate changes to the slice will affect the result of future reads.

func (*Buffer) Read 

func (b *Buffer) Read(p []byte) (int, error)

Read reads the next len(p) bytes from the buffer or until the buffer is drained. The return value n is the number of bytes read. If the buffer has no data to return, err is io.EOF (unless len(p) is zero); otherwise it is nil.

Example 
package main

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

func main() {
	var b bytes.Buffer
	b.Grow(64)
	b.Write([]byte("abcde"))
	rdbuf := make([]byte, 1)
	n, err := b.Read(rdbuf)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%d\n", n)
	fmt.Println(b.String())
	fmt.Println(string(rdbuf))
}

Output:
1
bcde
a

func (*Buffer) ReadByte 

func (b *Buffer) ReadByte() (byte, error)

ReadByte reads and returns the next byte from the buffer. If no byte is available, it returns error io.EOF.

Example 
package main

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

func main() {
	var b bytes.Buffer
	b.Grow(64)
	b.Write([]byte("abcde"))
	c, err := b.ReadByte()
	if err != nil {
		panic(err)
	}
	fmt.Printf("%d\n", c)
	fmt.Println(b.String())
}

Output:
97
bcde

func (*Buffer) ReadBytes 

func (b *Buffer) ReadBytes(delim byte) ([]byte, error)

ReadBytes reads until the first occurrence of delim in the input, returning a slice containing the data up to and including the delimiter. If ReadBytes encounters an error before finding a delimiter, it returns the data read before the error and the error itself (often io.EOF). ReadBytes returns err != nil if and only if the returned data does not end in delim.

The returned slice is allocated; the caller owns it.

func (*Buffer) ReadFrom 

func (b *Buffer) ReadFrom(r io.Reader) (int64, error)

ReadFrom reads data from r until EOF and appends it to the buffer, growing the buffer as needed. The return value n is the number of bytes read. Any error except io.EOF encountered during the read is also returned. Panics if the buffer becomes too large.

func (*Buffer) ReadRune 

func (b *Buffer) ReadRune() io.RuneSizeResult

ReadRune reads and returns the next UTF-8-encoded Unicode code point from the buffer. If no bytes are available, the error returned is io.EOF. If the bytes are an erroneous UTF-8 encoding, it consumes one byte and returns U+FFFD, 1.

func (*Buffer) ReadString 

func (b *Buffer) ReadString(delim byte) (string, error)

ReadString reads until the first occurrence of delim in the input, returning a string containing the data up to and including the delimiter. If ReadString encounters an error before finding a delimiter, it returns the data read before the error and the error itself (often io.EOF). ReadString returns err != nil if and only if the returned data does not end in delim.

The returned string is allocated; the caller owns it.

func (*Buffer) Reset 

func (b *Buffer) Reset()

Reset resets the buffer to be empty, but it retains the underlying storage for use by future writes.

func (*Buffer) String 

func (b *Buffer) String() string

String returns the contents of the unread portion of the buffer as a string. If the Buffer is a nil pointer, it returns "<nil>". The string is valid for use only until the next buffer modification.

To build strings more efficiently, see the strings.Builder type.

func (*Buffer) Write 

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

Write appends the contents of p to the buffer, growing the buffer as needed. The return value n is the length of p; err is always nil. Panics if the buffer becomes too large.

func (*Buffer) WriteByte 

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

WriteByte appends the byte c to the buffer, growing the buffer as needed. The returned error is always nil, but is included to match bufio.Writer's WriteByte. Panics if the buffer becomes too large.

func (*Buffer) WriteRune 

func (b *Buffer) WriteRune(r rune) (int, error)

WriteRune appends the UTF-8 encoding of Unicode code point r to the buffer, returning its length and an error, which is always nil but is included to match bufio.Writer's WriteRune. The buffer is grown as needed; if it becomes too large, WriteRune will panic.

func (*Buffer) WriteString 

func (b *Buffer) WriteString(s string) (int, error)

WriteString appends the contents of s to the buffer, growing the buffer as needed. The return value n is the length of s; err is always nil. Panics if the buffer becomes too large.

func (*Buffer) WriteTo 

func (b *Buffer) WriteTo(w io.Writer) (int64, error)

WriteTo writes data to w until the buffer is drained or an error occurs. The return value n is the number of bytes written; it always fits into an int, but it is int64 to match the io.WriterTo interface. Any error encountered during the write is also returned.

type CutResult 

type CutResult struct {
	Before []byte
	After  []byte
	Found  bool
}

CutResult is the result of a Cut operation.

func Cut 

func Cut(s, sep []byte) CutResult

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, nil, false.

Cut returns slices of the original slice s, not copies.

Example 
package main

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

func main() {
	show := func(s, sep string) {
		res := bytes.Cut([]byte(s), []byte(sep))
		fmt.Printf("Cut(%q, %q) = %q, %q, %v\n", s, sep, res.Before, res.After, res.Found)
	}
	show("Gopher", "Go")
	show("Gopher", "ph")
	show("Gopher", "er")
	show("Gopher", "Badger")
}

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

type Reader 

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

A Reader implements the io.Reader, io.ReaderAt, io.WriterTo, io.Seeker, io.ByteScanner, and io.RuneScanner interfaces by reading from a byte slice. Unlike a Buffer, a Reader is read-only and supports seeking. The zero value for Reader operates like a Reader of an empty slice.

func NewReader 

func NewReader(b []byte) Reader

NewReader returns a new Reader reading from b.

func (*Reader) Len 

func (r *Reader) Len() int

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

Example 
package main

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

func main() {
	r1 := bytes.NewReader([]byte("Hi!"))
	fmt.Printf("%d\n", r1.Len())
	r2 := bytes.NewReader([]byte("こんにちは!"))
	fmt.Printf("%d\n", r2.Len())
}

Output:
3
16

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(b []byte)

Reset resets the Reader to be reading from b.

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 byte slice. Size is the number of bytes available for reading via Reader.ReadAt. The result is unaffected by any method calls except Reader.Reset.

func (*Reader) UnreadByte 

func (r *Reader) UnreadByte() error

UnreadByte complements Reader.ReadByte in implementing the io.ByteScanner interface.

func (*Reader) UnreadRune 

func (r *Reader) UnreadRune() error

UnreadRune complements Reader.ReadRune in implementing 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.

Source Files

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