gopkg.in/tools/godep.v67@v67.0.0-20160513230433-2d182dfe781d/Godeps/_workspace/src/github.com/kr/text/indent.go (about)

     1  package text
     2  
     3  import (
     4  	"io"
     5  )
     6  
     7  // Indent inserts prefix at the beginning of each non-empty line of s. The
     8  // end-of-line marker is NL.
     9  func Indent(s, prefix string) string {
    10  	return string(IndentBytes([]byte(s), []byte(prefix)))
    11  }
    12  
    13  // IndentBytes inserts prefix at the beginning of each non-empty line of b.
    14  // The end-of-line marker is NL.
    15  func IndentBytes(b, prefix []byte) []byte {
    16  	var res []byte
    17  	bol := true
    18  	for _, c := range b {
    19  		if bol && c != '\n' {
    20  			res = append(res, prefix...)
    21  		}
    22  		res = append(res, c)
    23  		bol = c == '\n'
    24  	}
    25  	return res
    26  }
    27  
    28  // Writer indents each line of its input.
    29  type indentWriter struct {
    30  	w   io.Writer
    31  	bol bool
    32  	pre [][]byte
    33  	sel int
    34  	off int
    35  }
    36  
    37  // NewIndentWriter makes a new write filter that indents the input
    38  // lines. Each line is prefixed in order with the corresponding
    39  // element of pre. If there are more lines than elements, the last
    40  // element of pre is repeated for each subsequent line.
    41  func NewIndentWriter(w io.Writer, pre ...[]byte) io.Writer {
    42  	return &indentWriter{
    43  		w:   w,
    44  		pre: pre,
    45  		bol: true,
    46  	}
    47  }
    48  
    49  // The only errors returned are from the underlying indentWriter.
    50  func (w *indentWriter) Write(p []byte) (n int, err error) {
    51  	for _, c := range p {
    52  		if w.bol {
    53  			var i int
    54  			i, err = w.w.Write(w.pre[w.sel][w.off:])
    55  			w.off += i
    56  			if err != nil {
    57  				return n, err
    58  			}
    59  		}
    60  		_, err = w.w.Write([]byte{c})
    61  		if err != nil {
    62  			return n, err
    63  		}
    64  		n++
    65  		w.bol = c == '\n'
    66  		if w.bol {
    67  			w.off = 0
    68  			if w.sel < len(w.pre)-1 {
    69  				w.sel++
    70  			}
    71  		}
    72  	}
    73  	return n, nil
    74  }