Replace Jaro-Winkler algorithm usage with an internal function

go.mod

@@ -2,10 +2,7 @@ module github.com/urfave/cli/v3
 
 go 1.18
 
-require (
-	github.com/stretchr/testify v1.8.4
-	github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673
-)
+require github.com/stretchr/testify v1.8.4
 
 require (
 	github.com/BurntSushi/toml v1.3.2 // indirect

go.sum

@@ -8,8 +8,6 @@ github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcU
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/urfave/cli-altsrc/v3 v3.0.0-alpha2 h1:j4SaBpPB8++L0c0KuTnz/Yus3UQoWJ54hQjhIMW8rCM=
 github.com/urfave/cli-altsrc/v3 v3.0.0-alpha2/go.mod h1:Q79oyIY/z4jtzIrKEK6MUeWC7/szGr46x4QdOaOAIWc=
-github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673 h1:bAn7/zixMGCfxrRTfdpNzjtPYqr8smhKouy9mxVdGPU=
-github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673/go.mod h1:N3UwUGtsrSj3ccvlPHLoLsHnpR27oXr4ZE984MbSER8=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

suggestions.go

@@ -1,7 +1,7 @@
 package cli
 
 import (
-	"github.com/xrash/smetrics"
+	"math"
 )
 
 const suggestDidYouMeanTemplate = "Did you mean %q?"
@@ -16,13 +16,90 @@ 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 {
-	// magic values are from https://github.com/xrash/smetrics/blob/039620a656736e6ad994090895784a7af15e0b80/jaro-winkler.go#L8
 	const (
 		boostThreshold = 0.7
 		prefixSize     = 4
 	)
-	return smetrics.JaroWinkler(a, b, boostThreshold, prefixSize)
+	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 {

suggestions_test.go

@@ -8,6 +8,33 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func TestJaroWinkler(t *testing.T) {
+	// Given
+	for _, testCase := range []struct {
+		a, b     string
+		expected float64
+	}{
+		{"", "", 1},
+		{"a", "", 0},
+		{"", "a", 0},
+		{"a", "a", 1},
+		{"a", "b", 0},
+		{"aa", "aa", 1},
+		{"aa", "bb", 0},
+		{"aaa", "aaa", 1},
+		{"aa", "ab", 0.6666666666666666},
+		{"aa", "ba", 0.6666666666666666},
+		{"ba", "aa", 0.6666666666666666},
+		{"ab", "aa", 0.6666666666666666},
+	} {
+		// When
+		res := jaroWinkler(testCase.a, testCase.b)
+
+		// Then
+		assert.Equal(t, testCase.expected, res)
+	}
+}
+
 func TestSuggestFlag(t *testing.T) {
 	// Given
 	app := buildExtendedTestCommand()