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go-mtree/vis.go
Vincent Batts 08b1000418
vis: adding a pure golang Vis()
The current Vis() and Unvis() are using the C implementation from
MTREE(8).

But that means that cgo is used, which is not always desired.

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>
2016-12-07 16:12:28 -05:00

89 lines
2.6 KiB
Go

package mtree
import "unicode"
// Vis is a wrapper of the C implementation of the function vis, which encodes
// a character with a particular format/style.
// For most use-cases use DefaultVisFlags.
func Vis(src string, flags VisFlag) (string, error) {
return vis(src, flags)
}
// DefaultVisFlags are the typical flags used for encoding strings in mtree
// manifests.
var DefaultVisFlags = VisWhite | VisOctal | VisGlob
// VisFlag sets the extent of charactures to be encoded
type VisFlag int
// flags for encoding
const (
// to select alternate encoding format
VisOctal VisFlag = 0x01 // use octal \ddd format
VisCstyle VisFlag = 0x02 // use \[nrft0..] where appropriate
// to alter set of characters encoded (default is to encode all non-graphic
// except space, tab, and newline).
VisSp VisFlag = 0x04 // also encode space
VisTab VisFlag = 0x08 // also encode tab
VisNl VisFlag = 0x10 // also encode newline
VisWhite VisFlag = (VisSp | VisTab | VisNl)
VisSafe VisFlag = 0x20 // only encode "unsafe" characters
// other
VisNoSlash VisFlag = 0x40 // inhibit printing '\'
VisHttpstyle VisFlag = 0x80 // http-style escape % HEX HEX
VisGlob VisFlag = 0x100 // encode glob(3) magics
)
// errors used in the tokenized decoding strings
const (
// unvis return codes
unvisValid unvisErr = 1 // character valid
unvisValidPush unvisErr = 2 // character valid, push back passed char
unvisNochar unvisErr = 3 // valid sequence, no character produced
unvisErrSynbad unvisErr = -1 // unrecognized escape sequence
unvisErrUnrecoverable unvisErr = -2 // decoder in unknown state (unrecoverable)
unvisNone unvisErr = 0
// unvisEnd means there are no more characters
unvisEnd VisFlag = 1 // no more characters
)
// unvisErr are the return conditions for Unvis
type unvisErr int
func (ue unvisErr) Error() string {
switch ue {
case unvisValid:
return "character valid"
case unvisValidPush:
return "character valid, push back passed char"
case unvisNochar:
return "valid sequence, no character produced"
case unvisErrSynbad:
return "unrecognized escape sequence"
case unvisErrUnrecoverable:
return "decoder in unknown state (unrecoverable)"
}
return "Unknown Error"
}
func ishex(r rune) bool {
lr := unicode.ToLower(r)
return (lr >= '0' && lr <= '9') || (lr >= 'a' && lr <= 'f')
}
func isoctal(r rune) bool {
return r <= '7' && r >= '0'
}
// the ctype isgraph is "any printable character except space"
func isgraph(r rune) bool {
return unicode.IsPrint(r) && !unicode.IsSpace(r)
}
func isalnum(r rune) bool {
return unicode.IsNumber(r) || unicode.IsLetter(r)
}