feat: escape backticks (#42)

* feat: escape backticks

* perf: improve quote performance

* style: update benchmark

Co-authored-by: humodi <humodi@bytedance.com>

mysql.go

@@ -203,32 +203,55 @@ func (dialector Dialector) BindVarTo(writer clause.Writer, stmt *gorm.Statement,
 }
 
 func (dialector Dialector) QuoteTo(writer clause.Writer, str string) {
-	if str == "*" {
-		writer.WriteString(str)
-		return
-	}
-
-	writer.WriteByte('`')
-	if strings.Contains(str, ".") {
-		for idx, str := range strings.Split(str, ".") {
-			if str == "*" {
-				if idx > 0 {
-					writer.WriteString(".")
+	var (
+		unfinishedBacktick int
+		continuousBacktick int
+		shiftDelimiter     int
+		selfQuoted         = 0
+	)
+
+	for _, v := range []byte(str) {
+		switch v {
+		case '`':
+			continuousBacktick++
+			if continuousBacktick == 2 {
+				writer.WriteString("``")
+				continuousBacktick = 0
+			}
+		case '.':
+			shiftDelimiter = 0
+			if continuousBacktick > 0 || selfQuoted == 0 {
+				unfinishedBacktick = 0
+				continuousBacktick = 0
+				writer.WriteString("`")
+			}
+			writer.WriteByte(v)
+			continue
+		default:
+			if shiftDelimiter-continuousBacktick <= 0 && unfinishedBacktick == 0 {
+				writer.WriteByte('`')
+				unfinishedBacktick = 1
+				if continuousBacktick > 0 {
+					continuousBacktick -= 1
+					selfQuoted = 1
+				} else {
+					selfQuoted = 0
 				}
-				writer.WriteString(str)
-				continue
 			}
 
-			if idx > 0 {
-				writer.WriteString(".`")
+			for ; continuousBacktick > 0; continuousBacktick -= 1 {
+				writer.WriteString("``")
 			}
-			writer.WriteString(str)
-			writer.WriteByte('`')
+
+			writer.WriteByte(v)
 		}
-	} else {
-		writer.WriteString(str)
-		writer.WriteByte('`')
+		shiftDelimiter++
+	}
+
+	for ; continuousBacktick > selfQuoted; continuousBacktick -= 2 {
+		writer.WriteString("``")
 	}
+	writer.WriteString("`")
 }
 
 func (dialector Dialector) Explain(sql string, vars ...interface{}) string {

mysql_test.go

@@ -0,0 +1,60 @@
+package mysql
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestDialector_QuoteTo(t *testing.T) {
+	testdatas := []struct {
+		raw    string
+		expect string
+	}{
+		{"datadase.tableUser", "`datadase`.`tableUser`"},
+		{"datadase.table`User", "`datadase`.`table``User`"},
+		{"`a`.`b`", "`a`.`b`"},
+		{"`a`.b`", "`a`.`b```"},
+		{"a.`b`", "`a`.`b`"},
+		{"`a`.b`c", "`a`.`b``c`"},
+		{"`a`.`b`c`", "`a`.`b``c`"},
+		{"`a`.b", "`a`.`b`"},
+		{"`ab`", "`ab`"},
+		{"`a``b`", "`a``b`"},
+		{"`a```b`", "`a````b`"},
+		{"a`b", "`a``b`"},
+		{"ab", "`ab`"},
+		{"`a.b`", "`a.b`"},
+		{"a.b", "`a`.`b`"},
+	}
+
+	dailor := Open("")
+	for _, item := range testdatas {
+		buf := &bytes.Buffer{}
+		dailor.QuoteTo(buf, item.raw)
+		if buf.String() != item.expect {
+			t.Errorf("quote %q fail, got %q, expect %q", item.raw, buf.String(), item.expect)
+		}
+	}
+}
+
+// BenchmarkDialector_QuoteTo
+// Result:
+// goos: darwin
+// goarch: amd64
+// pkg: gorm.io/driver/mysql
+// cpu: Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz
+// BenchmarkDialector_QuoteTo               9184232               113.2 ns/op
+// BenchmarkDialector_QuoteTo-2             9782818               112.3 ns/op
+// BenchmarkDialector_QuoteTo-4            10726722               109.0 ns/op
+// BenchmarkDialector_QuoteTo-8             9656778               113.1 ns/op
+// BenchmarkDialector_QuoteTo-12           10729615               112.7 ns/op
+func BenchmarkDialector_QuoteTo(b *testing.B) {
+	dailor := Open("")
+	buf := &bytes.Buffer{}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		dailor.QuoteTo(buf, "datadase.table`User")
+		buf.Reset()
+	}
+}