feature: support cbor struct tag in struct-tag rule (#1527)

RULES_DESCRIPTIONS.md

@@ -1293,6 +1293,7 @@ The list of [supported tags](https://go.dev/wiki/Well-known-struct-tags):
 | ------------- | ------------------------------------------------------------------------ |
 | `asn1`         | <https://pkg.go.dev/encoding/asn1>                                      |
 | `bson`         | <https://pkg.go.dev/go.mongodb.org/mongo-driver/bson>                   |
+| `cbor`         | <https://pkg.go.dev/github.com/fxamacker/cbor/v2>                   |
 | `datastore`    | <https://pkg.go.dev/cloud.google.com/go/datastore>                      |
 | `default`      | The type of "default" must match the type of the field.                 |
 | `json`         | <https://pkg.go.dev/encoding/json>                                      |

rule/struct_tag.go

@@ -24,6 +24,7 @@ type tagKey string
 const (
 	keyASN1         tagKey = "asn1"
 	keyBSON         tagKey = "bson"
+	keyCbor         tagKey = "cbor"
 	keyCodec        tagKey = "codec"
 	keyDatastore    tagKey = "datastore"
 	keyDefault      tagKey = "default"
@@ -45,6 +46,7 @@ type tagChecker func(checkCtx *checkContext, tag *structtag.Tag, field *ast.Fiel
 var tagCheckers = map[tagKey]tagChecker{
 	keyASN1:         checkASN1Tag,
 	keyBSON:         checkBSONTag,
+	keyCbor:         checkCborTag,
 	keyCodec:        checkCodecTag,
 	keyDatastore:    checkDatastoreTag,
 	keyDefault:      checkDefaultTag,
@@ -385,6 +387,66 @@ func checkBSONTag(checkCtx *checkContext, tag *structtag.Tag, _ *ast.Field) (mes
 	return "", true
 }
 
+func checkCborTag(checkCtx *checkContext, tag *structtag.Tag, _ *ast.Field) (message string, succeeded bool) {
+	hasToArray := false
+	hasOmitEmptyOrZero := false
+	hasKeyAsInt := false
+
+	for _, opt := range tag.Options {
+		switch opt {
+		case "omitempty", "omitzero":
+			hasOmitEmptyOrZero = true
+		case "toarray":
+			if tag.Name != "" {
+				return `tag name for option "toarray" should be empty`, false
+			}
+			hasToArray = true
+		case "keyasint":
+			intKey, err := strconv.Atoi(tag.Name)
+			if err != nil {
+				return `tag name for option "keyasint" should be an integer`, false
+			}
+
+			_, ok := checkCtx.usedTagNbr[intKey]
+			if ok {
+				return fmt.Sprintf("duplicated integer key %d", intKey), false
+			}
+
+			checkCtx.usedTagNbr[intKey] = true
+			hasKeyAsInt = true
+			continue
+
+		default:
+			if !checkCtx.isUserDefined(keyCbor, opt) {
+				return fmt.Sprintf(msgUnknownOption, opt), false
+			}
+		}
+	}
+
+	// Check for duplicated tag names
+	if tag.Name != "" {
+		_, ok := checkCtx.usedTagName[tag.Name]
+		if ok {
+			return fmt.Sprintf("duplicated tag name %s", tag.Name), false
+		}
+		checkCtx.usedTagName[tag.Name] = true
+	}
+
+	// Check for integer tag names without keyasint option
+	if !hasKeyAsInt {
+		_, err := strconv.Atoi(tag.Name)
+		if err == nil {
+			return `integer tag names are only allowed in presence of "keyasint" option`, false
+		}
+	}
+
+	if hasToArray && hasOmitEmptyOrZero {
+		return `options "omitempty" and "omitzero" are ignored in presence of "toarray" option`, false
+	}
+
+	return "", true
+}
+
 const structTagCodecSpecialField = "_struct"
 
 func checkCodecTag(checkCtx *checkContext, tag *structtag.Tag, field *ast.Field) (message string, succeeded bool) {

test/struct_tag_test.go

@@ -23,6 +23,7 @@ func TestStructTagWithUserOptions(t *testing.T) {
 			"toml,unknown",
 			"spanner,mySpannerOption",
 			"codec,myCodecOption",
+			"cbor,myCborOption",
 		},
 	})
 }

testdata/struct_tag.go

@@ -215,3 +215,24 @@ type TestDuplicatedCodecTags struct {
 	B       int      `codec:"field_a"` // MATCH /duplicated tag name "field_a" in codec tag/
 	C       int      `codec:"field_c"`
 }
+
+type Cbor struct {
+	RepeatedStr string `cbor:"errors"`
+	Repeated    string `cbor:"1,keyasint"`
+	Useless     string `cbor:"-,omitempty"`              // MATCH /useless option omitempty for ignored field in cbor tag/
+	Inputs      string `cbor:",keyasint"`                // MATCH /tag name for option "keyasint" should be an integer in cbor tag/
+	Outputs     string `cbor:"inputs,keyasint"`          // MATCH /tag name for option "keyasint" should be an integer in cbor tag/
+	Errors      string `cbor:"errors,optempty,keyasint"` // MATCH /unknown option "optempty" in cbor tag/
+	Inputs2     string `cbor:"-10,omitempty"`            // MATCH /integer tag names are only allowed in presence of "keyasint" option in cbor tag/
+	Outputs2    string `cbor:"-12,toarray"`              // MATCH /tag name for option "toarray" should be empty in cbor tag/
+	RepeatedInt string `cbor:"1,keyasint"`               // MATCH /duplicated integer key 1 in cbor tag/
+	RepeatedStr string `cbor:"errors,omitempty"`         // MATCH /duplicated tag name errors in cbor tag/
+	Useless     string `cbor:",toarray,omitempty"`       // MATCH /options "omitempty" and "omitzero" are ignored in presence of "toarray" option in cbor tag/
+	Useless2    string `cbor:",omitzero,toarray"`        // MATCH /options "omitempty" and "omitzero" are ignored in presence of "toarray" option in cbor tag/
+	// OK
+	InputsOk   string `cbor:"8,keyasint"`
+	OutputsOk  string `cbor:"-100,keyasint"`
+	ErrorsOk   string `cbor:"-1,keyasint"`
+	InputsOk2  string `cbor:"inputs,omitempty"`
+	OutputsOk2 string `cbor:",toarray"`
+}

testdata/struct_tag_user_options.go

@@ -102,3 +102,11 @@ type CodecUserOptions struct {
 	ID   int    `codec:"user_id,myCodecOption"`
 	Name string `codec:"full_name,unknownOption"` // MATCH /unknown option "unknownOption" in codec tag/
 }
+
+type CborUserOptions struct {
+	InputsOk   string `cbor:"8,keyasint,myCborOption"`
+	OutputsOk  string `cbor:"-100,keyasint,unknownOption"` // MATCH /unknown option "unknownOption" in cbor tag/
+	ErrorsOk   string `cbor:"-1,keyasint"`
+	InputsOk2  string `cbor:"inputs,omitempty"`
+	OutputsOk2 string `cbor:",toarray"`
+}