106 lines
2.6 KiB
Go
106 lines
2.6 KiB
Go
package format
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import (
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"strings"
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"unsafe"
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)
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const (
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// SingleTermLine: beyond a certain length of string, all of the
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// extra checks to handle quoting/not-quoting add a significant
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// amount of extra processing time. Quoting in this manner only really
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// effects readability on a single line, so a max string length that
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// encompasses the maximum number of columns on *most* terminals was
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// selected. This was chosen using the metric that 1080p is one of the
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// most common display resolutions, and that a relatively small font size
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// of 7 requires 223 columns. So 256 should be >= $COLUMNS (fullscreen)
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// in 99% of usecases (these figures all pulled out of my ass).
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SingleTermLine = 256
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)
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// IsSafeASCII checks whether string is printable (i.e. non-control char) ASCII text.
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func IsSafeASCII(str string) bool {
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for _, r := range str {
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if (r < ' ' && r != '\t') ||
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r >= 0x7f {
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return false
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}
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}
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return true
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}
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// ContainsSpaceOrTab checks if "s" contains space or tabs. EXPECTS ASCII.
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func ContainsSpaceOrTab(s string) bool {
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if i := strings.IndexByte(s, ' '); i >= 0 {
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return true // note using indexbyte as it is ASM.
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} else if i := strings.IndexByte(s, '\t'); i >= 0 {
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return true
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}
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return false
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}
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// ContainsDoubleQuote checks if "s" contains a double quote. EXPECTS ASCII.
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func ContainsDoubleQuote(s string) bool {
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return (strings.IndexByte(s, '"') >= 0)
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}
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// AppendEscape will append 's' to 'dst' and escape any double quotes. EXPECTS ASCII.
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func AppendEscape(dst []byte, str string) []byte {
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for i := range str {
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switch str[i] {
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case '\\':
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// Append delimited '\'
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dst = append(dst, '\\', '\\')
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case '"':
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// Append delimited '"'
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dst = append(dst, '\\', '"')
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default:
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// Append char as-is
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dst = append(dst, str[i])
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}
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}
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return dst
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}
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// Byte2Str returns 'c' as a string, escaping if necessary.
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func Byte2Str(c byte) string {
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switch c {
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case '\a':
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return `\a`
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case '\b':
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return `\b`
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case '\f':
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return `\f`
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case '\n':
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return `\n`
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case '\r':
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return `\r`
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case '\t':
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return `\t`
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case '\v':
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return `\v`
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case '\\':
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return `\\`
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default:
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if c < ' ' {
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const hex = "0123456789abcdef"
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return `\x` +
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string(hex[c>>4]) +
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string(hex[c&0xF])
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}
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return string(c)
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}
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}
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// isNil will safely check if 'v' is nil without dealing with weird Go interface nil bullshit.
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func isNil(i interface{}) bool {
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type eface struct{ _type, data unsafe.Pointer } //nolint
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return (*(*eface)(unsafe.Pointer(&i))).data == nil //nolint
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}
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// b2s converts a byteslice to string without allocation.
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func b2s(b []byte) string {
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return *(*string)(unsafe.Pointer(&b))
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}
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