util: Reduce boundery check in escape functions. (#1316)

utils.go

@@ -652,32 +652,32 @@ func escapeBytesBackslash(buf, v []byte) []byte {
 	for _, c := range v {
 		switch c {
 		case '\x00':
-			buf[pos] = '\\'
 			buf[pos+1] = '0'
+			buf[pos] = '\\'
 			pos += 2
 		case '\n':
-			buf[pos] = '\\'
 			buf[pos+1] = 'n'
+			buf[pos] = '\\'
 			pos += 2
 		case '\r':
-			buf[pos] = '\\'
 			buf[pos+1] = 'r'
+			buf[pos] = '\\'
 			pos += 2
 		case '\x1a':
-			buf[pos] = '\\'
 			buf[pos+1] = 'Z'
+			buf[pos] = '\\'
 			pos += 2
 		case '\'':
-			buf[pos] = '\\'
 			buf[pos+1] = '\''
+			buf[pos] = '\\'
 			pos += 2
 		case '"':
-			buf[pos] = '\\'
 			buf[pos+1] = '"'
+			buf[pos] = '\\'
 			pos += 2
 		case '\\':
-			buf[pos] = '\\'
 			buf[pos+1] = '\\'
+			buf[pos] = '\\'
 			pos += 2
 		default:
 			buf[pos] = c
@@ -697,32 +697,32 @@ func escapeStringBackslash(buf []byte, v string) []byte {
 		c := v[i]
 		switch c {
 		case '\x00':
-			buf[pos] = '\\'
 			buf[pos+1] = '0'
+			buf[pos] = '\\'
 			pos += 2
 		case '\n':
-			buf[pos] = '\\'
 			buf[pos+1] = 'n'
+			buf[pos] = '\\'
 			pos += 2
 		case '\r':
-			buf[pos] = '\\'
 			buf[pos+1] = 'r'
+			buf[pos] = '\\'
 			pos += 2
 		case '\x1a':
-			buf[pos] = '\\'
 			buf[pos+1] = 'Z'
+			buf[pos] = '\\'
 			pos += 2
 		case '\'':
-			buf[pos] = '\\'
 			buf[pos+1] = '\''
+			buf[pos] = '\\'
 			pos += 2
 		case '"':
-			buf[pos] = '\\'
 			buf[pos+1] = '"'
+			buf[pos] = '\\'
 			pos += 2
 		case '\\':
-			buf[pos] = '\\'
 			buf[pos+1] = '\\'
+			buf[pos] = '\\'
 			pos += 2
 		default:
 			buf[pos] = c
@@ -744,8 +744,8 @@ func escapeBytesQuotes(buf, v []byte) []byte {
 
 	for _, c := range v {
 		if c == '\'' {
-			buf[pos] = '\''
 			buf[pos+1] = '\''
+			buf[pos] = '\''
 			pos += 2
 		} else {
 			buf[pos] = c
@@ -764,8 +764,8 @@ func escapeStringQuotes(buf []byte, v string) []byte {
 	for i := 0; i < len(v); i++ {
 		c := v[i]
 		if c == '\'' {
-			buf[pos] = '\''
 			buf[pos+1] = '\''
+			buf[pos] = '\''
 			pos += 2
 		} else {
 			buf[pos] = c