65 lines
1.5 KiB
Go
65 lines
1.5 KiB
Go
package jsh
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import (
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"math"
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"os"
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"os/exec"
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"unicode"
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)
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// FieldsN slices s into substrings after each instance of a whitespace
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// character (according to unicode.IsSpace) and returns a slice of those
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// substrings. The slice's length is guaranteed to be at most maxN, and
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// all leftover fields are put into the last substring.
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func FieldsN(s string, maxN int) []string {
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// First count the fields.
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n := 0
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inField := false
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for _, rune := range s {
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wasInField := inField
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inField = !unicode.IsSpace(rune)
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if inField && !wasInField {
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n++
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}
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}
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n = int(math.Min(float64(n), float64(maxN)))
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// Now create them.
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a := make([]string, n)
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na := 0
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fieldStart := -1 // Set to -1 when looking for start of field.
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for i, rune := range s {
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if unicode.IsSpace(rune) && na+1 < maxN {
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if fieldStart >= 0 {
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a[na] = s[fieldStart:i]
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na++
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fieldStart = -1
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}
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} else if fieldStart == -1 {
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fieldStart = i
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}
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}
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if fieldStart >= 0 { // Last field might end at EOF.
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a[na] = s[fieldStart:]
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}
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return a
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}
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// Falls back to procps-ng passing the space-separated arguments in the given
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// args slice. If args is nil, we default to the arguments passed to the command
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// line using os.Args
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func FallbackWithArgs(program string, args []string) *[]byte {
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if args == nil {
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args = os.Args[1:]
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}
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out, err := exec.Command(program, args...).Output()
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if err != nil {
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panic(err)
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}
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return &out
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}
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func Fallback(program string) *[]byte {
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return FallbackWithArgs(program, nil)
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}
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