Major refactor and feature enhancements for enum generator

.gitignore

@@ -1,3 +1,7 @@
 *.prof
 .idea
-mise.toml
+coverage.out
+coverage.html
+coverage_*.out
+coverage_*.html
+*.coverprofile

README.md

@@ -10,7 +10,10 @@
 - Case-sensitive or case-insensitive string representations
 - Panic-free parsing with error handling
 - Must-style parsing variants for convenience
-- Easy value enumeration with Values() and Names() functions
+- Declaration order preservation (enums maintain source code order, not alphabetical)
+- Type fidelity preservation (generated code uses the same underlying type as your enum)
+- Optimized parsing with O(1) map-based lookups
+- Smart SQL null handling (uses zero value when available, errors otherwise)
 - Generated code is fully tested and documented
 - No external runtime dependencies
 - Supports Go 1.23's range-over-func iteration
@@ -109,10 +112,12 @@ The generator creates a new type with the following features:
 
 - String representation (implements `fmt.Stringer`)
 - Text marshaling (implements `encoding.TextMarshaler` and `encoding.TextUnmarshaler`)
-- Parse function with error handling (`ParseStatus`)
+- SQL support (implements `database/sql/driver.Valuer` and `sql.Scanner`)
+- Parse function with error handling (`ParseStatus`) - uses efficient O(1) map lookup
 - Must-style parse function that panics on error (`MustStatus`)
-- All possible values slice (`StatusValues`)
-- All possible names slice (`StatusNames`)
+- All possible values as package variable (`StatusValues`) - preserves declaration order
+- All possible names as package variable (`StatusNames`) - preserves declaration order
+- Index method to get underlying integer value (`Status.Index()`)
 - Go 1.23 iterator support (`StatusIter()`) for range-over-func syntax
 - Public constants for each value (`StatusActive`, `StatusInactive`, etc.) - note that these are capitalized versions of your original constants
 
@@ -151,6 +156,30 @@ if err != nil {
 status := MustStatus("active") // panics if invalid
 ```
 
+### SQL Database Support
+
+The generated enums implement `database/sql/driver.Valuer` and `sql.Scanner` interfaces for seamless database integration:
+
+```go
+// Scanning from database
+var s Status
+err := db.QueryRow("SELECT status FROM users WHERE id = ?", userID).Scan(&s)
+
+// Writing to database
+_, err = db.Exec("UPDATE users SET status = ? WHERE id = ?", StatusActive, userID)
+
+// Handling NULL values
+// If the enum has a zero value (value = 0), NULL will scan to that value
+// Otherwise, scanning NULL returns an error
+```
+
+### Performance Characteristics
+
+- **Parsing**: O(1) constant time using map lookup (previously O(n) with switch statement)
+- **Values/Names access**: Zero allocation - returns pre-computed package variables
+- **Memory efficient**: Single shared instance for each enum value
+- **Declaration order**: Preserved from source code, not alphabetically sorted
+
 ## Contributing
 
 Contributions are welcome! Please feel free to submit a Pull Request.

go.mod

@@ -4,7 +4,7 @@ go 1.24
 
 require (
 	github.com/stretchr/testify v1.10.0
-	golang.org/x/text v0.23.0
+	golang.org/x/text v0.28.0
 )
 
 require (

go.sum

@@ -4,8 +4,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-golang.org/x/text v0.23.0 h1:D71I7dUrlY+VX0gQShAThNGHFxZ13dGLBHQLVl1mJlY=
-golang.org/x/text v0.23.0/go.mod h1:/BLNzu4aZCJ1+kcD0DNRotWKage4q2rGVAg4o22unh4=
+golang.org/x/text v0.28.0 h1:rhazDwis8INMIwQ4tpjLDzUhx6RlXqZNPEM0huQojng=
+golang.org/x/text v0.28.0/go.mod h1:U8nCwOR8jO/marOQ0QbDiOngZVEBB7MAiitBuMjXiNU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

go.work.sum

@@ -10,18 +10,24 @@ github.com/yuin/goldmark v1.4.13 h1:fVcFKWvrslecOb/tg+Cc05dkeYx540o0FuFt3nUVDoE=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/mod v0.17.0 h1:zY54UmvipHiNd+pm+m0x9KhZ9hl1/7QNMyxXbc6ICqA=
 golang.org/x/mod v0.17.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/mod v0.26.0 h1:EGMPT//Ezu+ylkCijjPc+f4Aih7sZvaAr+O3EHBxvZg=
+golang.org/x/mod v0.26.0/go.mod h1:/j6NAhSk8iQ723BGAUyoAcn7SlD7s15Dp9Nd/SfeaFQ=
 golang.org/x/net v0.35.0 h1:T5GQRQb2y08kTAByq9L4/bz8cipCdA8FbRTXewonqY8=
 golang.org/x/net v0.35.0/go.mod h1:EglIi67kWsHKlRzzVMUD93VMSWGFOMSZgxFjparz1Qk=
 golang.org/x/sync v0.11.0 h1:GGz8+XQP4FvTTrjZPzNKTMFtSXH80RAzG+5ghFPgK9w=
 golang.org/x/sync v0.11.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sync v0.12.0 h1:MHc5BpPuC30uJk597Ri8TV3CNZcTLu6B6z4lJy+g6Jw=
 golang.org/x/sync v0.12.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
+golang.org/x/sync v0.16.0 h1:ycBJEhp9p4vXvUZNszeOq0kGTPghopOL8q0fq3vstxw=
+golang.org/x/sync v0.16.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
 golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
 golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/telemetry v0.0.0-20240521205824-bda55230c457 h1:zf5N6UOrA487eEFacMePxjXAJctxKmyjKUsjA11Uzuk=
 golang.org/x/telemetry v0.0.0-20240521205824-bda55230c457/go.mod h1:pRgIJT+bRLFKnoM1ldnzKoxTIn14Yxz928LQRYYgIN0=
 golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d h1:vU5i/LfpvrRCpgM/VPfJLg5KjxD3E+hfT1SH+d9zLwg=
 golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d/go.mod h1:aiJjzUbINMkxbQROHiO6hDPo2LHcIPhhQsa9DLh0yGk=
+golang.org/x/tools v0.35.0 h1:mBffYraMEf7aa0sB+NuKnuCy8qI/9Bughn8dC2Gu5r0=
+golang.org/x/tools v0.35.0/go.mod h1:NKdj5HkL/73byiZSJjqJgKn3ep7KjFkBOkR/Hps3VPw=
 lukechampine.com/uint128 v1.2.0 h1:mBi/5l91vocEN8otkC5bDLhi2KdCticRiwbdB0O+rjI=
 lukechampine.com/uint128 v1.2.0/go.mod h1:c4eWIwlEGaxC/+H1VguhU4PHXNWDCDMUlWdIWl2j1gk=
 modernc.org/cc/v3 v3.41.0 h1:QoR1Sn3YWlmA1T4vLaKZfawdVtSiGx8H+cEojbC7v1Q=

internal/generator/enum.go.tmpl

@@ -13,11 +13,14 @@ import (
 // {{.Type | title}} is the exported type for the enum
 type {{.Type | title}} struct {
 	name  string
-	value int
+	value {{if .UnderlyingType}}{{.UnderlyingType}}{{else}}int{{end}}
 }
 
 func (e {{.Type | title}}) String() string { return e.name }
 
+// Index returns the underlying integer value
+func (e {{.Type | title}}) Index() {{if .UnderlyingType}}{{.UnderlyingType}}{{else}}int{{end}} { return e.value }
+
 // MarshalText implements encoding.TextMarshaler
 func (e {{.Type | title}}) MarshalText() ([]byte, error) {
 	return []byte(e.name), nil
@@ -38,8 +41,15 @@ func (e {{.Type | title}}) Value() (driver.Value, error) {
 // Scan implements the sql.Scanner interface
 func (e *{{.Type | title}}) Scan(value interface{}) error {
 	if value == nil {
-		*e = {{.Type | title}}Values()[0]
-		return nil
+		// try to find zero value
+		for _, v := range {{.Type | title}}Values {
+			if v.Index() == 0 {
+				*e = v
+				return nil
+			}
+		}
+		// no zero value found, return error
+		return fmt.Errorf("cannot scan nil into {{.Type | title}}: no zero value defined")
 	}
 
 	str, ok := value.(string)
@@ -60,21 +70,22 @@ func (e *{{.Type | title}}) Scan(value interface{}) error {
 	return nil
 }
 
+// _{{.Type}}ParseMap is used for efficient string to enum conversion
+var _{{.Type}}ParseMap = map[string]{{.Type | title}}{
+{{range .Values -}}
+	"{{.Name | ToLower}}": {{.PublicName}},
+{{end}}
+}
+
 // Parse{{.Type | title}} converts string to {{.Type}} enum value
 func Parse{{.Type | title}}(v string) ({{.Type | title}}, error) {
 {{if .LowerCase}}
-	switch v {
-	{{range .Values -}}
-	case "{{.Name | ToLower}}":
-		return {{.PublicName}}, nil
-	{{end}}
+	if val, ok := _{{.Type}}ParseMap[v]; ok {
+		return val, nil
 	}
 {{else}}
-	switch strings.ToLower(v) {
-	{{range .Values -}}
-	case strings.ToLower("{{.Name}}"):
-		return {{.PublicName}}, nil
-	{{end}}
+	if val, ok := _{{.Type}}ParseMap[strings.ToLower(v)]; ok {
+		return val, nil
 	}
 {{end}}
 	return {{.Type | title}}{}, fmt.Errorf("invalid {{.Type}}: %s", v)
@@ -91,7 +102,7 @@ func Must{{.Type | title}}(v string) {{.Type | title}} {
 
 {{if .GenerateGetter -}}
 // Get{{.Type | title}}ByID gets the correspondent {{.Type}} enum value by its ID (raw integer value)
-func Get{{.Type | title}}ByID(v int) ({{.Type | title}}, error) {
+func Get{{.Type | title}}ByID(v {{if .UnderlyingType}}{{.UnderlyingType}}{{else}}int{{end}}) ({{.Type | title}}, error) {
 	switch v {
 	{{range .Values -}}
 	case {{.Index}}:
@@ -109,22 +120,18 @@ var (
 {{end -}}
 )
 
-// {{.Type | title}}Values returns all possible enum values
-func {{.Type | title}}Values() []{{.Type | title}} {
-	return []{{.Type | title}}{
-	{{range .Values -}}
-		{{.PublicName}},
-	{{end -}}
-	}
+// {{.Type | title}}Values contains all possible enum values
+var {{.Type | title}}Values = []{{.Type | title}}{
+{{range .Values -}}
+	{{.PublicName}},
+{{end -}}
 }
 
-// {{.Type | title}}Names returns all possible enum names
-func {{.Type | title}}Names() []string {
-	return []string{
-	{{range .Values -}}
-		"{{if $.LowerCase}}{{.Name | ToLower}}{{else}}{{.Name}}{{end}}",
-	{{end -}}
-	}
+// {{.Type | title}}Names contains all possible enum names
+var {{.Type | title}}Names = []string{
+{{range .Values -}}
+	"{{if $.LowerCase}}{{.Name | ToLower}}{{else}}{{.Name}}{{end}}",
+{{end -}}
 }
 
 // {{.Type | title}}Iter returns a function compatible with Go 1.23's range-over-func syntax.
@@ -136,7 +143,7 @@ func {{.Type | title}}Names() []string {
 //
 func {{.Type | title}}Iter() func(yield func({{.Type | title}}) bool) {
 	return func(yield func({{.Type | title}}) bool) {
-		for _, v := range {{.Type | title}}Values() {
+		for _, v := range {{.Type | title}}Values {
 			if !yield(v) {
 				break
 			}
@@ -148,7 +155,7 @@ func {{.Type | title}}Iter() func(yield func({{.Type | title}}) bool) {
 // for the original enum constants. They are intentionally placed in a var block
 // that is compiled away by the Go compiler.
 var _ = func() bool {
-	var _ {{.Type}} = 0
+	var _ {{.Type}} = {{if .UnderlyingType}}{{.Type}}(0){{else}}0{{end}}
 	{{range .Values -}}
 	// This avoids "defined but not used" linter error for {{.PrivateName}}
 	var _ {{$.Type}} = {{.PrivateName}}