refactor: modernize go codebase per golangci-lint recommendations

Apply Go 1.18+ improvements and performance optimizations:
- replace interface{} with any for modern Go syntax
- use strings.Builder instead of += in loops for better performance
- replace reflect.TypeOf with reflect.TypeFor for type safety
- use strings.CutPrefix instead of HasPrefix + TrimPrefix
- simplify conditionals using max() builtin
- replace manual loops with slices.Contains

These changes improve code readability, performance, and align with current Go best practices.

Author: albertodvp

main.go

@@ -239,13 +239,13 @@ func allKeys(in ...map[string]string) []string {
 	return result
 }
 
-func logf(format string, args ...interface{}) {
+func logf(format string, args ...any) {
 	fmt.Fprint(os.Stderr, "go-jsonschema: ")
 	fmt.Fprintf(os.Stderr, format, args...)
 	fmt.Fprint(os.Stderr, "\n")
 }
 
-func verboseLogf(format string, args ...interface{}) {
+func verboseLogf(format string, args ...any) {
 	if verbose {
 		logf(format, args...)
 	}

pkg/codegen/emitter.go

@@ -39,10 +39,7 @@ func (e *Emitter) Indent(n int32) {
 
 func (e *Emitter) Comment(s string) {
 	if s != "" {
-		limit := e.maxLineLength - e.indent
-		if limit < 0 {
-			limit = 0
-		}
+		limit := max(e.maxLineLength-e.indent, 0)
 
 		//nolint:gosec // limit is guarded against negative values
 		lines := strings.Split(wordwrap.WrapString(s, uint(limit)), "\n")
@@ -53,13 +50,10 @@ func (e *Emitter) Comment(s string) {
 	}
 }
 
-func (e *Emitter) Commentf(s string, args ...interface{}) {
+func (e *Emitter) Commentf(s string, args ...any) {
 	s = fmt.Sprintf(s, args...)
 	if s != "" {
-		limit := e.maxLineLength - e.indent
-		if limit < 0 {
-			limit = 0
-		}
+		limit := max(e.maxLineLength-e.indent, 0)
 
 		//nolint:gosec // limit is guarded against negative values
 		lines := strings.Split(wordwrap.WrapString(s, uint(limit)), "\n")
@@ -70,13 +64,13 @@ func (e *Emitter) Commentf(s string, args ...interface{}) {
 	}
 }
 
-func (e *Emitter) Printf(format string, args ...interface{}) {
+func (e *Emitter) Printf(format string, args ...any) {
 	e.checkIndent()
 	fmt.Fprintf(&e.sb, format, args...)
 	e.start = false
 }
 
-func (e *Emitter) Printlnf(format string, args ...interface{}) {
+func (e *Emitter) Printlnf(format string, args ...any) {
 	e.Printf(format, args...)
 	e.Newline()
 }

pkg/codegen/model.go

@@ -146,7 +146,7 @@ func (p *Package) Generate(out *Emitter) error {
 type Var struct {
 	Type  Type
 	Name  string
-	Value interface{}
+	Value any
 }
 
 func (v *Var) GetName() string {
@@ -171,7 +171,7 @@ func (v *Var) Generate(out *Emitter) error {
 type Constant struct {
 	Type  Type
 	Name  string
-	Value interface{}
+	Value any
 }
 
 func (c *Constant) GetName() string {
@@ -427,7 +427,7 @@ func (NullType) Generate(out *Emitter) error {
 type StructType struct {
 	Fields             []StructField
 	RequiredJSONFields []string
-	DefaultValue       interface{}
+	DefaultValue       any
 }
 
 func (*StructType) IsNillable() bool { return false }
@@ -468,7 +468,7 @@ type StructField struct {
 	Comment      string
 	Tags         string
 	JSONName     string
-	DefaultValue interface{}
+	DefaultValue any
 	SchemaType   *schemas.Type
 }
 

pkg/generator/schema_generator.go

@@ -3,6 +3,7 @@ package generator
 import (
 	"errors"
 	"fmt"
+	"slices"
 	"strings"
 
 	"github.com/google/go-cmp/cmp"
@@ -812,19 +813,19 @@ func (g *schemaGenerator) addStructField(
 		SchemaType: prop,
 	}
 
-	tags := ""
+	var tags strings.Builder
 
 	if isRequired || g.DisableOmitempty() {
 		for _, tag := range g.config.Tags {
-			tags += fmt.Sprintf(`%s:"%s" `, tag, name)
+			tags.WriteString(fmt.Sprintf(`%s:"%s" `, tag, name))
 		}
 	} else {
 		for _, tag := range g.config.Tags {
-			tags += fmt.Sprintf(`%s:"%s,omitempty" `, tag, name)
+			tags.WriteString(fmt.Sprintf(`%s:"%s,omitempty" `, tag, name))
 		}
 	}
 
-	structField.Tags = strings.TrimSpace(tags)
+	structField.Tags = strings.TrimSpace(tags.String())
 
 	if structField.Comment == "" {
 		structField.Comment = fmt.Sprintf("%s corresponds to the JSON schema field %q.",
@@ -1350,10 +1351,8 @@ func (g *schemaGenerator) isTypeNullable(t *schemas.Type) (int, bool) {
 		return 0, true
 	}
 
-	for _, tt := range t.Type {
-		if tt == schemas.TypeNameNull {
-			return -1, true
-		}
+	if slices.Contains(t.Type, schemas.TypeNameNull) {
+		return -1, true
 	}
 
 	return -1, false

pkg/generator/validator.go

@@ -153,7 +153,7 @@ type defaultValidator struct {
 	jsonName         string
 	fieldName        string
 	defaultValueType codegen.Type
-	defaultValue     interface{}
+	defaultValue     any
 }
 
 func (v *defaultValidator) generate(out *codegen.Emitter, format string) error {
@@ -176,14 +176,14 @@ func (v *defaultValidator) dumpDefaultValueAssignment(out *codegen.Emitter) (any
 		if nt, ok := v.defaultValueType.(*codegen.NamedType); ok {
 			dvm, ok := v.defaultValue.(map[string]any)
 			if ok {
-				namedFields := ""
+				var namedFields strings.Builder
 				for _, k := range sortedKeys(dvm) {
-					namedFields += fmt.Sprintf("\n%s: %s,", upperFirst(k), litter.Sdump(dvm[k]))
+					namedFields.WriteString(fmt.Sprintf("\n%s: %s,", upperFirst(k), litter.Sdump(dvm[k])))
 				}
 
-				namedFields += "\n"
+				namedFields.WriteString("\n")
 
-				defaultValue := fmt.Sprintf(`%s{%s}`, nt.Decl.GetName(), namedFields)
+				defaultValue := fmt.Sprintf(`%s{%s}`, nt.Decl.GetName(), namedFields.String())
 
 				return fmt.Sprintf(`%s = %s`, getPlainName(v.fieldName), defaultValue), nil
 			}
@@ -246,7 +246,7 @@ func (v *defaultValidator) tryDumpDefaultSlice(maxLineLen int32) (string, error)
 	kind := reflect.ValueOf(v.defaultValue).Kind()
 
 	if kind == reflect.Slice {
-		df, ok := v.defaultValue.([]interface{})
+		df, ok := v.defaultValue.([]any)
 		if !ok {
 			return "", ErrInvalidDefaultValue
 		}

pkg/schemas/model.go

@@ -175,18 +175,18 @@ type Type struct {
 	Properties           map[string]*Type `json:"properties,omitempty"`           // Section 5.16.
 	PatternProperties    map[string]*Type `json:"patternProperties,omitempty"`    // Section 5.17.
 	AdditionalProperties *Type            `json:"additionalProperties,omitempty"` // Section 5.18.
-	Enum                 []interface{}    `json:"enum,omitempty"`                 // Section 5.20.
+	Enum                 []any            `json:"enum,omitempty"`                 // Section 5.20.
 	Type                 TypeList         `json:"type,omitempty"`                 // Section 5.21.
 	// RFC draft-bhutton-json-schema-01, section 10.
 	AllOf []*Type `json:"allOf,omitempty"` // Section 10.2.1.1.
 	AnyOf []*Type `json:"anyOf,omitempty"` // Section 10.2.1.2.
 	OneOf []*Type `json:"oneOf,omitempty"` // Section 10.2.1.3.
 	Not   *Type   `json:"not,omitempty"`   // Section 10.2.1.4.
 	// RFC draft-wright-json-schema-validation-00, section 6, 7.
-	Title       string      `json:"title,omitempty"`       // Section 6.1.
-	Description string      `json:"description,omitempty"` // Section 6.1.
-	Default     interface{} `json:"default,omitempty"`     // Section 6.2.
-	Format      string      `json:"format,omitempty"`      // Section 7.
+	Title       string `json:"title,omitempty"`       // Section 6.1.
+	Description string `json:"description,omitempty"` // Section 6.1.
+	Default     any    `json:"default,omitempty"`     // Section 6.2.
+	Format      string `json:"format,omitempty"`      // Section 7.
 	// RFC draft-wright-json-schema-hyperschema-00, section 4.
 	Media          *Type  `json:"media,omitempty"`          // Section 4.3.
 	BinaryEncoding string `json:"binaryEncoding,omitempty"` // Section 4.3.
@@ -393,7 +393,7 @@ func updateAllRefsValues(structValue *reflect.Value, refPath string) error {
 type typeListTransformer struct{}
 
 func (t typeListTransformer) Transformer(typ reflect.Type) func(dst, src reflect.Value) error {
-	if typ == reflect.TypeOf(TypeList{}) {
+	if typ == reflect.TypeFor[TypeList]() {
 		return func(dst, src reflect.Value) error {
 			return nil
 		}

pkg/schemas/parse.go

@@ -48,7 +48,7 @@ func FromYAMLFile(fileName string) (*Schema, error) {
 
 func FromYAMLReader(r io.Reader) (*Schema, error) {
 	// Marshal to JSON first because YAML decoder doesn't understand JSON tags.
-	var m map[string]interface{}
+	var m map[string]any
 
 	if err := yaml.NewDecoder(r).Decode(&m); err != nil {
 		return nil, fmt.Errorf("failed to unmarshal YAML: %w", err)

pkg/schemas/types.go

@@ -24,8 +24,8 @@ func IsPrimitiveType(t string) bool {
 }
 
 func CleanNameForSorting(name string) string {
-	if strings.HasPrefix(name, PrefixEnumValue) {
-		return strings.TrimPrefix(name, PrefixEnumValue) + "_enumValues" // Append a string for sorting properly.
+	if after, found := strings.CutPrefix(name, PrefixEnumValue); found {
+		return after + "_enumValues" // Append a string for sorting properly.
 	}
 
 	return name

pkg/yamlutils/yaml.go

@@ -3,24 +3,24 @@ package yamlutils
 import "fmt"
 
 // FixMapKeys fixes non-string keys that occur in nested YAML unmarshalling results.
-func FixMapKeys(m map[string]interface{}) {
+func FixMapKeys(m map[string]any) {
 	for k, v := range m {
 		m[k] = fixMapKeysIn(v)
 	}
 }
 
 // Fix non-string keys that occur in nested YAML unmarshalling results.
-func fixMapKeysIn(value interface{}) interface{} {
+func fixMapKeysIn(value any) any {
 	switch t := value.(type) {
-	case []interface{}:
+	case []any:
 		for i, elem := range t {
 			t[i] = fixMapKeysIn(elem)
 		}
 
 		return t
 
-	case map[interface{}]interface{}:
-		m := map[string]interface{}{}
+	case map[any]any:
+		m := map[string]any{}
 
 		for k, v := range t {
 			ks, ok := k.(string)