github.com/muesli/reflow

reflow

A collection of ANSI-aware methods and io.Writers helping you to transform blocks of text. This means you can still style your terminal output with ANSI escape sequences without them affecting the reflow operations & algorithms.

Word-Wrapping

The wordwrap package lets you word-wrap strings or entire blocks of text.

import "github.com/muesli/reflow/wordwrap"

s := wordwrap.String("Hello World!", 5)
fmt.Println(s)

Result:

Hello
World!

The word-wrapping Writer is compatible with the io.Writer / io.WriteCloser interfaces:

f := wordwrap.NewWriter(limit)
f.Write(b)
f.Close()

fmt.Println(f.String())

Customize word-wrapping behavior:

f := wordwrap.NewWriter(limit)
f.Breakpoints = []rune{':', ','}
f.Newline = []rune{'\r'}

Unconditional Wrapping

The wrap package lets you unconditionally wrap strings or entire blocks of text.

import "github.com/muesli/reflow/wrap"

s := wrap.String("Hello World!", 7)
fmt.Println(s)

Result:

Hello W
orld!

The unconditional wrapping Writer is compatible with the io.Writer interfaces:

f := wrap.NewWriter(limit)
f.Write(b)

fmt.Println(f.String())

Customize word-wrapping behavior:

f := wrap.NewWriter(limit)
f.Newline = []rune{'\r'}
f.KeepNewlines = false
f.reserveSpace = true
f.TabWidth = 2

Tip: This wrapping method can be used in conjunction with word-wrapping when word-wrapping is preferred but a line limit has to be enforced:

wrapped := wrap.String(wordwrap.String("Just an example", 5), 5)
fmt.Println(wrapped)

Result:

Just
an
examp
le

ANSI Example

s := wordwrap.String("I really \x1B[38;2;249;38;114mlove\x1B[0m Go!", 8)
fmt.Println(s)

Result:

Indentation

The indent package lets you indent strings or entire blocks of text.

import "github.com/muesli/reflow/indent"

s := indent.String("Hello World!", 4)
fmt.Println(s)

Result: Hello World!

There is also an indenting Writer, which is compatible with the io.Writer interface:

// indent uses spaces per default:
f := indent.NewWriter(width, nil)

// but you can also use a custom indentation function:
f = indent.NewWriter(width, func(w io.Writer) {
    w.Write([]byte("."))
})

f.Write(b)
f.Close()

fmt.Println(f.String())

Dedentation

The dedent package lets you dedent strings or entire blocks of text.

import "github.com/muesli/reflow/dedent"

input := `    Hello World!
  Hello World!
`

s := dedent.String(input)
fmt.Println(s)

Result:

  Hello World!
Hello World!

Padding

The padding package lets you pad strings or entire blocks of text.

import "github.com/muesli/reflow/padding"

s := padding.String("Hello", 8)
fmt.Println(s)

Result: Hello___ (the underlined portion represents 3 spaces)

There is also a padding Writer, which is compatible with the io.WriteCloser interface:

// padding uses spaces per default:
f := padding.NewWriter(width, nil)

// but you can also use a custom padding function:
f = padding.NewWriter(width, func(w io.Writer) {
    w.Write([]byte("."))
})

f.Write(b)
f.Close()

fmt.Println(f.String())