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Package runes

import "golang.org/x/text/runes"
Overview
Index
Examples

Overview ▾

Package runes provide transforms for UTF-8 encoded text.

type Set

type Set interface {
    // Contains returns true if r is contained in the set.
    Contains(r rune) bool
}

A Set is a collection of runes.

func In

func In(rt *unicode.RangeTable) Set

In creates a Set with a Contains method that returns true for all runes in the given RangeTable.

▾ Example

Code:

// Convert Latin characters to their canonical form, while keeping other
// width distinctions.
t := runes.If(runes.In(unicode.Latin), width.Fold, nil)
s, _, _ := transform.String(t, "ｱﾙｱﾉﾘｳ tech / アルアノリウ ｔｅｃｈ")
fmt.Println(s)

Output:

ｱﾙｱﾉﾘｳ tech / アルアノリウ tech

func NotIn

func NotIn(rt *unicode.RangeTable) Set

In creates a Set with a Contains method that returns true for all runes not in the given RangeTable.

func Predicate

func Predicate(f func(rune) bool) Set

Predicate creates a Set with a Contains method that returns f(r).

type Transformer

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

Transformer implements the transform.Transformer interface.

func If

func If(s Set, tIn, tNotIn transform.Transformer) Transformer

If returns a transformer that applies tIn to consecutive runes for which s.Contains(r) and tNotIn to consecutive runes for which !s.Contains(r). Reset is called on tIn and tNotIn at the start of each run. A Nop transformer will substitute a nil value passed to tIn or tNotIn. Invalid UTF-8 is translated to RuneError to determine which transformer to apply, but is passed as is to the respective transformer.

▾ Example

Code:

// Widen everything but ASCII.
isASCII := func(r rune) bool { return r <= unicode.MaxASCII }
t := runes.If(runes.Predicate(isASCII), nil, width.Widen)
s, _, _ := transform.String(t, "ｱﾙｱﾉﾘｳ tech / 中國 / 5₩")
fmt.Println(s)

Output:

アルアノリウ tech / 中國 / 5￦

func Map

func Map(mapping func(rune) rune) Transformer

Map returns a Transformer that maps the runes in the input using the given mapping. Illegal bytes in the input are converted to utf8.RuneError before being passed to the mapping func.

▾ Example

Code:

replaceHyphens := runes.Map(func(r rune) rune {
    if unicode.Is(unicode.Hyphen, r) {
        return '|'
    }
    return r
})
s, _, _ := transform.String(replaceHyphens, "a-b‐c⸗d﹣e")
fmt.Println(s)

Output:

a|b|c|d|e

func Remove

func Remove(s Set) Transformer

Remove returns a Transformer that removes runes r for which s.Contains(r). Illegal input bytes are replaced by RuneError before being passed to f.

▾ Example

Code:

t := transform.Chain(norm.NFD, runes.Remove(runes.In(unicode.Mn)), norm.NFC)
s, _, _ := transform.String(t, "résumé")
fmt.Println(s)

Output:

resume

func ReplaceIllFormed

func ReplaceIllFormed() Transformer

ReplaceIllFormed returns a transformer that replaces all input bytes that are not part of a well-formed UTF-8 code sequence with utf8.RuneError.

func (Transformer) Bytes

func (t Transformer) Bytes(b []byte) []byte

Bytes returns a new byte slice with the result of converting b using t. It calls Reset on t. It returns nil if any error was found. This can only happen if an error-producing Transformer is passed to If.

func (Transformer) Reset

func (t Transformer) Reset()

func (Transformer) Span

func (t Transformer) Span(b []byte, atEOF bool) (n int, err error)

func (Transformer) String

func (t Transformer) String(s string) string

String returns a string with the result of converting s using t. It calls Reset on t. It returns the empty string if any error was found. This can only happen if an error-producing Transformer is passed to If.

func (Transformer) Transform

func (t Transformer) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error)