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package cli
import (
"math"
)
const suggestDidYouMeanTemplate = "Did you mean %q?"
var (
SuggestFlag SuggestFlagFunc = suggestFlag
SuggestCommand SuggestCommandFunc = suggestCommand
SuggestDidYouMeanTemplate string = suggestDidYouMeanTemplate
)
type SuggestFlagFunc func(flags []Flag, provided string, hideHelp bool) string
type SuggestCommandFunc func(commands []*Command, provided string) string
// jaroDistance is the measure of similarity between two strings. It returns a
// value between 0 and 1, where 1 indicates identical strings and 0 indicates
// completely different strings.
//
// Adapted from https://github.com/xrash/smetrics/blob/5f08fbb34913bc8ab95bb4f2a89a0637ca922666/jaro.go.
func jaroDistance(a, b string) float64 {
if len(a) == 0 && len(b) == 0 {
return 1
}
if len(a) == 0 || len(b) == 0 {
return 0
}
lenA := float64(len(a))
lenB := float64(len(b))
hashA := make([]bool, len(a))
hashB := make([]bool, len(b))
maxDistance := int(math.Max(0, math.Floor(math.Max(lenA, lenB)/2.0)-1))
var matches float64
for i := 0; i < len(a); i++ {
start := int(math.Max(0, float64(i-maxDistance)))
end := int(math.Min(lenB-1, float64(i+maxDistance)))
for j := start; j <= end; j++ {
if hashB[j] {
continue
}
if a[i] == b[j] {
hashA[i] = true
hashB[j] = true
matches++
break
}
}
}
if matches == 0 {
return 0
}
var transpositions float64
var j int
for i := 0; i < len(a); i++ {
if !hashA[i] {
continue
}
for !hashB[j] {
j++
}
if a[i] != b[j] {
transpositions++
}
j++
}
transpositions /= 2
return ((matches / lenA) + (matches / lenB) + ((matches - transpositions) / matches)) / 3.0
}
// jaroWinkler is more accurate when strings have a common prefix up to a
// defined maximum length.
//
// Adapted from https://github.com/xrash/smetrics/blob/5f08fbb34913bc8ab95bb4f2a89a0637ca922666/jaro-winkler.go.
func jaroWinkler(a, b string) float64 {
const (
boostThreshold = 0.7
prefixSize = 4
)
jaroDist := jaroDistance(a, b)
if jaroDist <= boostThreshold {
return jaroDist
}
prefix := int(math.Min(float64(len(a)), math.Min(float64(prefixSize), float64(len(b)))))
var prefixMatch float64
for i := 0; i < prefix; i++ {
if a[i] == b[i] {
prefixMatch++
} else {
break
}
}
return jaroDist + 0.1*prefixMatch*(1.0-jaroDist)
}
func suggestFlag(flags []Flag, provided string, hideHelp bool) string {
distance := 0.0
suggestion := ""
for _, flag := range flags {
flagNames := flag.Names()
if !hideHelp && HelpFlag != nil {
flagNames = append(flagNames, HelpFlag.Names()...)
}
for _, name := range flagNames {
newDistance := jaroWinkler(name, provided)
if newDistance > distance {
distance = newDistance
suggestion = name
}
}
}
if len(suggestion) == 1 {
suggestion = "-" + suggestion
} else if len(suggestion) > 1 {
suggestion = "--" + suggestion
}
return suggestion
}
// suggestCommand takes a list of commands and a provided string to suggest a
// command name
func suggestCommand(commands []*Command, provided string) (suggestion string) {
distance := 0.0
for _, command := range commands {
for _, name := range append(command.Names(), helpName, helpAlias) {
newDistance := jaroWinkler(name, provided)
if newDistance > distance {
distance = newDistance
suggestion = name
}
}
}
return suggestion
}
|
