github.com/sohaha/zlsgo@v1.7.13-0.20240501141223-10dd1a906f76/zstring/expand.go (about)

     1  package zstring
     2  
     3  func Expand(s string, process func(key string) string) string {
     4  	var buf []byte
     5  	i := 0
     6  	for j := 0; j < len(s); j++ {
     7  		if s[j] == '$' && j+1 < len(s) {
     8  			if buf == nil {
     9  				buf = make([]byte, 0, 2*len(s))
    10  			}
    11  			buf = append(buf, s[i:j]...)
    12  			name, w := getShellName(s[j+1:])
    13  			if name != "" {
    14  				buf = append(buf, process(name)...)
    15  			} else if w == 0 {
    16  				buf = append(buf, s[j])
    17  			}
    18  			j += w
    19  			i = j + 1
    20  		}
    21  	}
    22  
    23  	if buf == nil {
    24  		return s
    25  	}
    26  
    27  	return Bytes2String(buf) + s[i:]
    28  }
    29  
    30  func getShellName(s string) (string, int) {
    31  	switch {
    32  	case s[0] == '{':
    33  		if len(s) > 2 && isShellSpecialVar(s[1]) && s[2] == '}' {
    34  			return s[1:2], 3
    35  		}
    36  		for i := 1; i < len(s); i++ {
    37  			if s[i] == '}' {
    38  				if i == 1 {
    39  					return "", 2
    40  				}
    41  				return s[1:i], i + 1
    42  			}
    43  		}
    44  		return "", 1
    45  	case isShellSpecialVar(s[0]):
    46  		return s[0:1], 1
    47  	}
    48  	var i int
    49  	for i = 0; i < len(s) && isAlphaNum(s[i]); i++ {
    50  	}
    51  	return s[:i], i
    52  }
    53  
    54  func isShellSpecialVar(c uint8) bool {
    55  	switch c {
    56  	case '*', '#', '$', '@', '!', '?', '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
    57  		return true
    58  	}
    59  	return false
    60  }
    61  
    62  func isAlphaNum(c uint8) bool {
    63  	return c == '_' || '0' <= c && c <= '9' || 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z'
    64  }