json: encode \b and \f like the Go 1.22 stdlib does (#145)

* go.mod: upgrade to 1.23 (oldest supported by Go project)

* json: encode `\b` and `\f` like the Go 1.22 stdlib does

https://go-review.googlesource.com/c/go/+/521675

Author: extemporalgenome

.github/workflows/benchmark.yml

@@ -18,7 +18,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v2
         with:
-          go-version: "1.21"
+          go-version: "1.24"
 
       - name: Checkout
         uses: actions/checkout@v2
@@ -43,7 +43,7 @@ jobs:
       - name: Steup Go
         uses: actions/setup-go@v2
         with:
-          go-version: "1.21"
+          go-version: "1.24"
 
       - name: Setup Benchstat
         run: go install golang.org/x/perf/cmd/benchstat@latest

.github/workflows/test.yml

@@ -9,8 +9,8 @@ jobs:
     strategy:
       matrix:
         go:
-          - "1.20"
-          - "1.21"
+          - "1.23"
+          - "1.24"
 
     runs-on: ubuntu-latest
 

go.mod

@@ -1,6 +1,6 @@
 module github.com/segmentio/encoding
 
-go 1.18
+go 1.23
 
 require github.com/segmentio/asm v1.1.3
 

json/encode.go

@@ -158,30 +158,9 @@ func (e encoder) encodeString(b []byte, p unsafe.Pointer) ([]byte, error) {
 		}
 
 		switch c {
-		case '\\', '"':
+		case '\\', '"', '\b', '\f', '\n', '\r', '\t':
 			b = append(b, s[i:j]...)
-			b = append(b, '\\', c)
-			i = j + 1
-			j = j + 1
-			continue
-
-		case '\n':
-			b = append(b, s[i:j]...)
-			b = append(b, '\\', 'n')
-			i = j + 1
-			j = j + 1
-			continue
-
-		case '\r':
-			b = append(b, s[i:j]...)
-			b = append(b, '\\', 'r')
-			i = j + 1
-			j = j + 1
-			continue
-
-		case '\t':
-			b = append(b, s[i:j]...)
-			b = append(b, '\\', 't')
+			b = append(b, '\\', escapeByteRepr(c))
 			i = j + 1
 			j = j + 1
 			continue

json/golang_encode_test.go

@@ -685,11 +685,11 @@ var encodeStringTests = []struct {
 	{"\x05", `"\u0005"`},
 	{"\x06", `"\u0006"`},
 	{"\x07", `"\u0007"`},
-	{"\x08", `"\u0008"`},
+	{"\x08", `"\b"`},
 	{"\x09", `"\t"`},
 	{"\x0a", `"\n"`},
 	{"\x0b", `"\u000b"`},
-	{"\x0c", `"\u000c"`},
+	{"\x0c", `"\f"`},
 	{"\x0d", `"\r"`},
 	{"\x0e", `"\u000e"`},
 	{"\x0f", `"\u000f"`},

json/string.go

@@ -40,6 +40,25 @@ func escapeIndex(s string, escapeHTML bool) int {
 	return -1
 }
 
+func escapeByteRepr(b byte) byte {
+	switch b {
+	case '\\', '"':
+		return b
+	case '\b':
+		return 'b'
+	case '\f':
+		return 'f'
+	case '\n':
+		return 'n'
+	case '\r':
+		return 'r'
+	case '\t':
+		return 't'
+	}
+
+	return 0
+}
+
 // below return a mask that can be used to determine if any of the bytes
 // in `n` are below `b`. If a byte's MSB is set in the mask then that byte was
 // below `b`. The result is only valid if `b`, and each byte in `n`, is below