最低限のドキュメントを追加

README.md

@@ -1 +1,55 @@
-# dynamodb-repo
+# DynamoDB Repo
+
+## Quick Start
+
+Go言語の環境が整っていることを前提とします。
+
+`dynamodb-repo` を導入します。
+```bash
+$ go get github.com/go-generalize/dynamodb-repo
+```
+
+`package` と `struct` を適宜定義したファイルを作ります。
+
+<details>
+<summary>クリックしてファイル例を表示</summary>
+
+```golang
+package model
+
+import dda "github.com/aws/aws-sdk-go/service/dynamodb/dynamodbattribute"
+
+//go:generate dynamodb-repo -disable-meta Name
+//NOTE: go generateの最後の引数は生成したい struct 名を指定する
+
+type CustomStruct struct {
+	Value int
+	Str   string
+}
+
+// Name RangeKeyあり
+type Name struct {
+	ID        int64           `dynamo:"id,hash" auto:""`
+	Count     int             `dynamo:"count,range"`
+	Created   dda.UnixTime    `dynamo:"created"`
+	Desc      string          `dynamo:"description"`
+	Desc2     string          `dynamo:"description2"`
+	Done      bool            `dynamo:"done"`
+	PriceList []int           `dynamo:"priceList"`
+	Array     []*CustomStruct `dynamo:"customs"`
+}
+```
+
+</details>
+
+最後に `go generate` をすると、適宜ファイルが生成されます。
+```bash
+$ go generate
+```
+
+ファイルが生成されたことを確認します。
+
+```
+$ ls
+constant.go  misc.go  name.go  name_gen.go
+```

generator.go

@@ -107,6 +107,7 @@ func (g *generator) setting() {
 	g.RepositoryStructName = strcase.ToLowerCamel(g.RepositoryInterfaceName)
 }
 
+// generates "(.*)_gen.go"
 func (g *generator) generate(writer io.Writer) {
 	g.setting()
 	funcMap := g.setFuncMap()
@@ -119,6 +120,7 @@ func (g *generator) generate(writer io.Writer) {
 	}
 }
 
+// generates "constant.go"
 func (g *generator) generateConstant(writer io.Writer) {
 	contents := getFileContents("constant")
 
@@ -129,6 +131,7 @@ func (g *generator) generateConstant(writer io.Writer) {
 	}
 }
 
+// generates "misc.go"
 func (g *generator) generateMisc(writer io.Writer) {
 	contents := getFileContents("misc")
 
@@ -139,6 +142,7 @@ func (g *generator) generateMisc(writer io.Writer) {
 	}
 }
 
+// define functions in template files
 func (g *generator) setFuncMap() template.FuncMap {
 	return template.FuncMap{
 		"Parse": func(fieldType string) string {

main.go

@@ -22,6 +22,7 @@ var (
 	isShowVersion = flag.Bool("v", false, "print version")
 )
 
+// Entry Point
 func main() {
 	flag.Parse()
 
@@ -42,6 +43,7 @@ func main() {
 	}
 }
 
+// Entry point of generating process
 func run(structName, prefix string, isDisableMeta bool) error {
 	disableMeta = &isDisableMeta
 	fs := token.NewFileSet()
@@ -51,6 +53,7 @@ func run(structName, prefix string, isDisableMeta bool) error {
 		panic(err)
 	}
 
+	// traverse for each package whose name doesn't have suffix "_test"
 	for name, v := range pkgs {
 		if strings.HasSuffix(name, "_test") {
 			continue
@@ -62,12 +65,14 @@ func run(structName, prefix string, isDisableMeta bool) error {
 	return nil
 }
 
+// main routine for generating process
 func traverse(pkg *ast.Package, fs *token.FileSet, structName, prefix string) error {
 	gen := &generator{PackageName: pkg.Name}
 	for name, file := range pkg.Files {
 		gen.FileName = strings.TrimSuffix(filepath.Base(name), ".go")
 		gen.GeneratedFileName = gen.FileName + "_gen"
 
+		// process for each type declaration
 		for _, decl := range file.Decls {
 			genDecl, ok := decl.(*ast.GenDecl)
 			if !ok {
@@ -83,6 +88,7 @@ func traverse(pkg *ast.Package, fs *token.FileSet, structName, prefix string) er
 				if !ok {
 					continue
 				}
+
 				name := typeSpec.Name.Name
 
 				if name != structName {
@@ -105,6 +111,7 @@ func traverse(pkg *ast.Package, fs *token.FileSet, structName, prefix string) er
 	return xerrors.Errorf("no such struct: %s", structName)
 }
 
+// process for types whose name is `structName`
 func generate(gen *generator, fs *token.FileSet, structType *ast.StructType) error {
 	var metaList map[string]*field.Field
 	if !*disableMeta {
@@ -189,6 +196,7 @@ func generate(gen *generator, fs *token.FileSet, structType *ast.StructType) err
 				gen.FieldInfos = append(gen.FieldInfos, fieldInfo)
 				continue
 			}
+			// turn `dynamo:"id,hash"` into string{"id", "hash"} as `sp`
 			sp := strings.Split(dynamoTag.Value(), ",")
 			fieldInfo.Tags = &FieldParsedTags{
 				Raw: sp,
@@ -254,6 +262,7 @@ func generate(gen *generator, fs *token.FileSet, structType *ast.StructType) err
 		gen.UniqueFields = nil
 	}
 
+	// precondition: `gen` (is a Generate) is ready to generate files
 	if gen.EnableCreateTime || gen.EnableUpdateTime {
 		if !(gen.EnableCreateTime && gen.EnableUpdateTime) {
 			return xerrors.New("requires both CreatedAt and UpdatedAt")
@@ -319,6 +328,7 @@ func parseTags(tags []string) *FieldParsedTags {
 	return p
 }
 
+// handles field metadata such as `dynamo:"id,hash"`
 func keyFieldHandle(gen *generator, label string, keyKind KeyKind, name, typeName, pos string) error {
 	switch keyKind {
 	case KeyKindHash:

misc.go

@@ -17,6 +17,7 @@ var (
 	UpdateTime = "UpdateTime"
 )
 
+// content of the template file as string
 func getFileContents(name string) string {
 	fp, err := statikFS.Open("/" + name + ".go.tmpl")
 	if err != nil {
@@ -30,6 +31,7 @@ func getFileContents(name string) string {
 	return string(contents)
 }
 
+// convert input AST node to go-style declaration string
 func getTypeName(typ ast.Expr) string {
 	switch v := typ.(type) {
 	case *ast.SelectorExpr:
@@ -49,6 +51,7 @@ func getTypeName(typ ast.Expr) string {
 	}
 }
 
+// check if input name is valid as identifier
 func dynamoTagCheck(pos string, label string) error {
 	if label == "" {
 		return nil