Improve performance and cleanup code

.github/workflows/ci.yml

@@ -4,16 +4,16 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.19.x, 1.20.x]
+        go-version: [1.22.x, 1.23.x]
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:
     - name: Install Go
-      uses: actions/setup-go@v2
+      uses: actions/setup-go@v5
       with:
         go-version: ${{ matrix.go-version }}
     - name: Checkout code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
     - name: Lint
       run: make lint
     - name: Test

go.mod

@@ -1,8 +1,8 @@
 module github.com/agnivade/levenshtein
 
-go 1.13
+go 1.21
 
 require (
 	github.com/arbovm/levenshtein v0.0.0-20160628152529-48b4e1c0c4d0
-	github.com/dgryski/trifles v0.0.0-20200323201526-dd97f9abfb48
+	github.com/dgryski/trifles v0.0.0-20230903005119-f50d829f2e54
 )

go.sum

@@ -1,4 +1,4 @@
 github.com/arbovm/levenshtein v0.0.0-20160628152529-48b4e1c0c4d0 h1:jfIu9sQUG6Ig+0+Ap1h4unLjW6YQJpKZVmUzxsD4E/Q=
 github.com/arbovm/levenshtein v0.0.0-20160628152529-48b4e1c0c4d0/go.mod h1:t2tdKJDJF9BV14lnkjHmOQgcvEKgtqs5a1N3LNdJhGE=
-github.com/dgryski/trifles v0.0.0-20200323201526-dd97f9abfb48 h1:fRzb/w+pyskVMQ+UbP35JkH8yB7MYb4q/qhBarqZE6g=
-github.com/dgryski/trifles v0.0.0-20200323201526-dd97f9abfb48/go.mod h1:if7Fbed8SFyPtHLHbg49SI7NAdJiC5WIA09pe59rfAA=
+github.com/dgryski/trifles v0.0.0-20230903005119-f50d829f2e54 h1:SG7nF6SRlWhcT7cNTs5R6Hk4V2lcmLz2NsG2VnInyNo=
+github.com/dgryski/trifles v0.0.0-20230903005119-f50d829f2e54/go.mod h1:if7Fbed8SFyPtHLHbg49SI7NAdJiC5WIA09pe59rfAA=

levenshtein.go

@@ -41,6 +41,25 @@ func ComputeDistance(a, b string) int {
 	if len(s1) > len(s2) {
 		s1, s2 = s2, s1
 	}
+
+	// remove trailing identical runes.
+	for i := 0; i < len(s1); i++ {
+		if s1[len(s1)-1-i] != s2[len(s2)-1-i] {
+			s1 = s1[:len(s1)-i]
+			s2 = s2[:len(s2)-i]
+			break
+		}
+	}
+
+	// Remove leading identical runes.
+	for i := 0; i < len(s1); i++ {
+		if s1[i] != s2[i] {
+			s1 = s1[i:]
+			s2 = s2[i:]
+			break
+		}
+	}
+
 	lenS1 := len(s1)
 	lenS2 := len(s2)
 
@@ -71,7 +90,7 @@ func ComputeDistance(a, b string) int {
 		for j := 1; j <= lenS1; j++ {
 			current := x[j-1] // match
 			if s2[i-1] != s1[j-1] {
-				current = min(min(x[j-1]+1, prev+1), x[j]+1)
+				current = min(x[j-1]+1, prev+1, x[j]+1)
 			}
 			x[j-1] = prev
 			prev = current
@@ -80,10 +99,3 @@ func ComputeDistance(a, b string) int {
 	}
 	return int(x[lenS1])
 }
-
-func min(a, b uint16) uint16 {
-	if a < b {
-		return a
-	}
-	return b
-}

levenshtein_test.go

@@ -66,13 +66,35 @@ func BenchmarkSimple(b *testing.B) {
 		name string
 	}{
 		// ASCII
-		{"levenshtein", "frankenstein", "ASCII"},
+		{a: "levenshtein", b: "frankenstein", name: "ASCII"},
 		// Testing acutes and umlauts
-		{"resumé and café", "resumés and cafés", "French"},
-		{"Hafþór Júlíus Björnsson", "Hafþor Julius Bjornsson", "Nordic"},
-		{"a very long string that is meant to exceed", "another very long string that is meant to exceed", "long string"},
+		{a: "resumé and café", b: "resumés and cafés", name: "French"},
+		{a: "Hafþór Júlíus Björnsson", b: "Hafþor Julius Bjornsson", name: "Nordic"},
+
+		// Long strings
+		{
+			a:    "a very long string that is meant to exceed",
+			b:    "another very long string that is meant to exceed",
+			name: "Long lead",
+		},
+		{
+			a:    "a very long string with a word in the middle that is different",
+			b:    "a very long string with some text in the middle that is different",
+			name: "Long middle",
+		},
+		{
+			a:    "a very long string with some text at the end that is not the same",
+			b:    "a very long string with some text at the end that is very different",
+			name: "Long trail",
+		},
+		{
+			a:    "+a very long string with different leading and trailing characters+",
+			b:    "-a very long string with different leading and trailing characters-",
+			name: "Long diff",
+		},
+
 		// Only 2 characters are less in the 2nd string
-		{"།་གམ་འས་པ་་མ།", "།་གམའས་པ་་མ", "Tibetan"},
+		{a: "།་གམ་འས་པ་་མ།", b: "།་གམའས་པ་་མ", name: "Tibetan"},
 	}
 	tmp := 0
 	for _, test := range tests {