github.com/v2pro/plz@v0.0.0-20221028024117-e5f9aec5b631/msgfmt/formatter_bytes.go (about)

     1  package msgfmt
     2  
     3  import "unicode/utf8"
     4  
     5  type bytesFormatter int
     6  
     7  func (formatter bytesFormatter) Format(space []byte, properties []interface{}) []byte {
     8  	return writeBytes(space, properties[formatter].([]byte))
     9  }
    10  
    11  // safeSet holds the value true if the ASCII character with the given array
    12  // position can be represented inside a JSON string without any further
    13  // escaping.
    14  //
    15  // All values are true except for the ASCII control characters (0-31), the
    16  // double quote ("), and the backslash character ("\").
    17  var safeSet = [utf8.RuneSelf]bool{
    18  	' ':      true,
    19  	'!':      true,
    20  	'"':      true,
    21  	'#':      true,
    22  	'$':      true,
    23  	'%':      true,
    24  	'&':      true,
    25  	'\'':     true,
    26  	'(':      true,
    27  	')':      true,
    28  	'*':      true,
    29  	'+':      true,
    30  	',':      true,
    31  	'-':      true,
    32  	'.':      true,
    33  	'/':      true,
    34  	'0':      true,
    35  	'1':      true,
    36  	'2':      true,
    37  	'3':      true,
    38  	'4':      true,
    39  	'5':      true,
    40  	'6':      true,
    41  	'7':      true,
    42  	'8':      true,
    43  	'9':      true,
    44  	':':      true,
    45  	';':      true,
    46  	'<':      true,
    47  	'=':      true,
    48  	'>':      true,
    49  	'?':      true,
    50  	'@':      true,
    51  	'A':      true,
    52  	'B':      true,
    53  	'C':      true,
    54  	'D':      true,
    55  	'E':      true,
    56  	'F':      true,
    57  	'G':      true,
    58  	'H':      true,
    59  	'I':      true,
    60  	'J':      true,
    61  	'K':      true,
    62  	'L':      true,
    63  	'M':      true,
    64  	'N':      true,
    65  	'O':      true,
    66  	'P':      true,
    67  	'Q':      true,
    68  	'R':      true,
    69  	'S':      true,
    70  	'T':      true,
    71  	'U':      true,
    72  	'V':      true,
    73  	'W':      true,
    74  	'X':      true,
    75  	'Y':      true,
    76  	'Z':      true,
    77  	'[':      true,
    78  	'\\':     false,
    79  	']':      true,
    80  	'^':      true,
    81  	'_':      true,
    82  	'`':      true,
    83  	'a':      true,
    84  	'b':      true,
    85  	'c':      true,
    86  	'd':      true,
    87  	'e':      true,
    88  	'f':      true,
    89  	'g':      true,
    90  	'h':      true,
    91  	'i':      true,
    92  	'j':      true,
    93  	'k':      true,
    94  	'l':      true,
    95  	'm':      true,
    96  	'n':      true,
    97  	'o':      true,
    98  	'p':      true,
    99  	'q':      true,
   100  	'r':      true,
   101  	's':      true,
   102  	't':      true,
   103  	'u':      true,
   104  	'v':      true,
   105  	'w':      true,
   106  	'x':      true,
   107  	'y':      true,
   108  	'z':      true,
   109  	'{':      true,
   110  	'|':      false,
   111  	'}':      true,
   112  	'~':      true,
   113  	'\u007f': true,
   114  }
   115  
   116  var hex = "0123456789abcdef"
   117  
   118  func writeBytes(space []byte, s []byte) []byte {
   119  	// write string, the fast path, without utf8 and escape support
   120  	var i int
   121  	var c byte
   122  	for i, c = range s {
   123  		if c < utf8.RuneSelf && safeSet[c] {
   124  			space = append(space, c)
   125  		} else {
   126  			break
   127  		}
   128  	}
   129  	if i == len(s)-1 {
   130  		return space
   131  	}
   132  	return writeBytesSlowPath(space, s[i:])
   133  }
   134  
   135  func writeBytesSlowPath(space []byte, s []byte) []byte {
   136  	start := 0
   137  	// for the remaining parts, we process them char by char
   138  	var i int
   139  	var b byte
   140  	for i, b = range s {
   141  		if b >= utf8.RuneSelf {
   142  			space = append(space, '\\', 'x', hex[b>>4], hex[b&0xF])
   143  			start = i + 1
   144  			continue
   145  		}
   146  		if safeSet[b] {
   147  			continue
   148  		}
   149  		if start < i {
   150  			space = append(space, s[start:i]...)
   151  		}
   152  		switch b {
   153  		case '\\', '"':
   154  			space = append(space, '\\', b)
   155  		case '\n':
   156  			space = append(space, '\\', 'n')
   157  		case '\r':
   158  			space = append(space, '\\', 'r')
   159  		case '\t':
   160  			space = append(space, '\\', 't')
   161  		default:
   162  			// This encodes bytes < 0x20 except for \t, \n and \r.
   163  			space = append(space, '\\', 'x', hex[b>>4], hex[b&0xF])
   164  		}
   165  		start = i + 1
   166  	}
   167  	if start < len(s) {
   168  		space = append(space, s[start:]...)
   169  	}
   170  	return space
   171  }