Add support for legacy string tag option behavior (#63)

In v1, the `string` tag option would stringify bools and strings. Add an option to support this behavior in v2.
go-json-experiment · Nov 24, 2024 · 7696f99 · 7696f99
1 parent b5f849c
commit 7696f99
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Showing 4 changed files with 378 additions and 7 deletions.
diff --git a/arshal_default.go b/arshal_default.go
@@ -126,7 +126,7 @@ func makeBoolArshaler(t reflect.Type) *arshaler {
 		}
 
 		// Optimize for marshaling without preceding whitespace.
-		if optimizeCommon && !xe.Flags.Get(jsonflags.AnyWhitespace) && !xe.Tokens.Last.NeedObjectName() {
+		if optimizeCommon && !xe.Flags.Get(jsonflags.AnyWhitespace) && !mo.Flags.Get(jsonflags.StringifyBoolsAndStrings) && !xe.Tokens.Last.NeedObjectName() {
 			xe.Buf = strconv.AppendBool(xe.Tokens.MayAppendDelim(xe.Buf, 't'), va.Bool())
 			xe.Tokens.Last.Increment()
 			if xe.NeedFlush() {
@@ -135,6 +135,13 @@ func makeBoolArshaler(t reflect.Type) *arshaler {
 			return nil
 		}
 
+		if mo.Flags.Get(jsonflags.StringifyBoolsAndStrings) {
+			if va.Bool() {
+				return enc.WriteToken(jsontext.String("true"))
+			} else {
+				return enc.WriteToken(jsontext.String("false"))
+			}
+		}
 		return enc.WriteToken(jsontext.Bool(va.Bool()))
 	}
 	fncs.unmarshal = func(dec *jsontext.Decoder, va addressableValue, uo *jsonopts.Struct) error {
@@ -152,8 +159,22 @@ func makeBoolArshaler(t reflect.Type) *arshaler {
 			va.SetBool(false)
 			return nil
 		case 't', 'f':
-			va.SetBool(tok.Bool())
-			return nil
+			if !uo.Flags.Get(jsonflags.StringifyBoolsAndStrings) {
+				va.SetBool(tok.Bool())
+				return nil
+			}
+		case '"':
+			if uo.Flags.Get(jsonflags.StringifyBoolsAndStrings) {
+				switch tok.String() {
+				case "true":
+					va.SetBool(true)
+				case "false":
+					va.SetBool(false)
+				default:
+					return &SemanticError{action: "unmarshal", JSONKind: k, GoType: t, Err: fmt.Errorf("cannot parse %q as bool", tok.String())}
+				}
+				return nil
+			}
 		}
 		return &SemanticError{action: "unmarshal", JSONKind: k, GoType: t}
 	}
@@ -170,7 +191,7 @@ func makeStringArshaler(t reflect.Type) *arshaler {
 
 		// Optimize for marshaling without preceding whitespace or string escaping.
 		s := va.String()
-		if optimizeCommon && !xe.Flags.Get(jsonflags.AnyWhitespace) && !xe.Tokens.Last.NeedObjectName() && !jsonwire.NeedEscape(s) {
+		if optimizeCommon && !xe.Flags.Get(jsonflags.AnyWhitespace) && !mo.Flags.Get(jsonflags.StringifyBoolsAndStrings) && !xe.Tokens.Last.NeedObjectName() && !jsonwire.NeedEscape(s) {
 			b := xe.Buf
 			b = xe.Tokens.MayAppendDelim(b, '"')
 			b = append(b, '"')
@@ -184,6 +205,14 @@ func makeStringArshaler(t reflect.Type) *arshaler {
 			return nil
 		}
 
+		if mo.Flags.Get(jsonflags.StringifyBoolsAndStrings) {
+			b, err := jsontext.AppendQuote(nil, s) // only fails for invalid UTF-8
+			q, _ := jsontext.AppendQuote(nil, b)   // cannot fail since b is valid UTF-8
+			if err != nil && !xe.Flags.Get(jsonflags.AllowInvalidUTF8) {
+				return err
+			}
+			return enc.WriteValue(q)
+		}
 		return enc.WriteToken(jsontext.String(s))
 	}
 	fncs.unmarshal = func(dec *jsontext.Decoder, va addressableValue, uo *jsonopts.Struct) error {
@@ -203,6 +232,12 @@ func makeStringArshaler(t reflect.Type) *arshaler {
 			return nil
 		case '"':
 			val = jsonwire.UnquoteMayCopy(val, flags.IsVerbatim())
+			if uo.Flags.Get(jsonflags.StringifyBoolsAndStrings) {
+				val, err = jsontext.AppendUnquote(nil, val)
+				if err != nil {
+					return &SemanticError{action: "unmarshal", JSONKind: '"', GoType: va.Type(), Err: err}
+				}
+			}
 			if xd.StringCache == nil {
 				xd.StringCache = new(stringCache)
 			}
@@ -1015,7 +1050,11 @@ func makeStructArshaler(t reflect.Type) *arshaler {
 			// Write the object member value.
 			flagsOriginal := mo.Flags
 			if f.string {
-				mo.Flags.Set(jsonflags.StringifyNumbers | 1)
+				if !mo.Flags.Get(jsonflags.StringifyWithLegacySemantics) {
+					mo.Flags.Set(jsonflags.StringifyNumbers | 1)
+				} else if canLegacyStringify(f.typ) {
+					mo.Flags.Set(jsonflags.StringifyNumbers | jsonflags.StringifyBoolsAndStrings | 1)
+				}
 			}
 			if f.format != "" {
 				mo.FormatDepth = xe.Tokens.Depth()
@@ -1154,7 +1193,11 @@ func makeStructArshaler(t reflect.Type) *arshaler {
 				}
 				flagsOriginal := uo.Flags
 				if f.string {
-					uo.Flags.Set(jsonflags.StringifyNumbers | 1)
+					if !uo.Flags.Get(jsonflags.StringifyWithLegacySemantics) {
+						uo.Flags.Set(jsonflags.StringifyNumbers | 1)
+					} else if canLegacyStringify(f.typ) {
+						uo.Flags.Set(jsonflags.StringifyNumbers | jsonflags.StringifyBoolsAndStrings | 1)
+					}
 				}
 				if f.format != "" {
 					uo.FormatDepth = xd.Tokens.Depth()
@@ -1225,6 +1268,25 @@ func isLegacyEmpty(v addressableValue) bool {
 	return false
 }
 
+// canLegacyStringify reports whether t can be stringified according to v1,
+// where t is a bool, string, or number (or unnamed pointer to such).
+// In v1, the `string` option does not apply recursively to nested types within
+// a composite Go type (e.g., an array, slice, struct, map, or interface).
+func canLegacyStringify(t reflect.Type) bool {
+	// Based on encoding/json.typeFields#[email protected]
+	if t.Name() == "" && t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	switch t.Kind() {
+	case reflect.Bool, reflect.String,
+		reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
+		reflect.Float32, reflect.Float64:
+		return true
+	}
+	return false
+}
+
 func makeSliceArshaler(t reflect.Type) *arshaler {
 	var fncs arshaler
 	var (
@@ -1528,7 +1590,7 @@ func makeInterfaceArshaler(t reflect.Type) *arshaler {
 		}
 		// Optimize for the any type if there are no special options.
 		if optimizeCommon &&
-			t == anyType && !mo.Flags.Get(jsonflags.StringifyNumbers) && mo.Format == "" &&
+			t == anyType && !mo.Flags.Get(jsonflags.StringifyNumbers) && !mo.Flags.Get(jsonflags.StringifyBoolsAndStrings) && mo.Format == "" &&
 			(mo.Marshalers == nil || !mo.Marshalers.(*Marshalers).fromAny) {
 			return marshalValueAny(enc, va.Elem().Interface(), mo)
 		}