format.go

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package fs
     6  
     7  import (
     8  	"time"
     9  )
    10  
    11  // FormatFileInfo returns a formatted version of info for human readability.
    12  // Implementations of [FileInfo] can call this from a String method.
    13  // The output for a file named "hello.go", 100 bytes, mode 0o644, created
    14  // January 1, 1970 at noon is
    15  //
    16  //	-rw-r--r-- 100 1970-01-01 12:00:00 hello.go
    17  func FormatFileInfo(info FileInfo) string {
    18  	name := info.Name()
    19  	b := make([]byte, 0, 40+len(name))
    20  	b = append(b, info.Mode().String()...)
    21  	b = append(b, ' ')
    22  
    23  	size := info.Size()
    24  	var usize uint64
    25  	if size >= 0 {
    26  		usize = uint64(size)
    27  	} else {
    28  		b = append(b, '-')
    29  		usize = uint64(-size)
    30  	}
    31  	var buf [20]byte
    32  	i := len(buf) - 1
    33  	for usize >= 10 {
    34  		q := usize / 10
    35  		buf[i] = byte('0' + usize - q*10)
    36  		i--
    37  		usize = q
    38  	}
    39  	buf[i] = byte('0' + usize)
    40  	b = append(b, buf[i:]...)
    41  	b = append(b, ' ')
    42  
    43  	b = append(b, info.ModTime().Format(time.DateTime)...)
    44  	b = append(b, ' ')
    45  
    46  	b = append(b, name...)
    47  	if info.IsDir() {
    48  		b = append(b, '/')
    49  	}
    50  
    51  	return string(b)
    52  }
    53  
    54  // FormatDirEntry returns a formatted version of dir for human readability.
    55  // Implementations of [DirEntry] can call this from a String method.
    56  // The outputs for a directory named subdir and a file named hello.go are:
    57  //
    58  //	d subdir/
    59  //	- hello.go
    60  func FormatDirEntry(dir DirEntry) string {
    61  	name := dir.Name()
    62  	b := make([]byte, 0, 5+len(name))
    63  
    64  	// The Type method does not return any permission bits,
    65  	// so strip them from the string.
    66  	mode := dir.Type().String()
    67  	mode = mode[:len(mode)-9]
    68  
    69  	b = append(b, mode...)
    70  	b = append(b, ' ')
    71  	b = append(b, name...)
    72  	if dir.IsDir() {
    73  		b = append(b, '/')
    74  	}
    75  	return string(b)
    76  }
    77
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