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Signed-off-by: Saswata Mukherjee <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,65 @@ | ||
| // Copyright (c) Bartłomiej Płotka @bwplotka | ||
| // Licensed under the Apache License 2.0. | ||
|
|
||
| // Taken from Thanos project. | ||
| // | ||
| // Copyright (c) The Thanos Authors. | ||
| // Licensed under the Apache License 2.0. | ||
|
|
||
| package yamlgen | ||
|
|
||
| import ( | ||
| "io" | ||
| "reflect" | ||
|
|
||
| "github.com/fatih/structtag" | ||
| "github.com/pkg/errors" | ||
| "gopkg.in/yaml.v3" | ||
| ) | ||
|
|
||
| func Generate(obj interface{}, w io.Writer) error { | ||
| // We forbid omitempty option. This is for simplification for doc generation. | ||
| if err := checkForOmitEmptyTagOption(obj); err != nil { | ||
| return errors.Wrap(err, "invalid type") | ||
| } | ||
| return yaml.NewEncoder(w).Encode(obj) | ||
| } | ||
|
|
||
| func checkForOmitEmptyTagOption(obj interface{}) error { | ||
| return checkForOmitEmptyTagOptionRec(reflect.ValueOf(obj)) | ||
| } | ||
|
|
||
| func checkForOmitEmptyTagOptionRec(v reflect.Value) error { | ||
| switch v.Kind() { | ||
| case reflect.Struct: | ||
| for i := 0; i < v.NumField(); i++ { | ||
| tags, err := structtag.Parse(string(v.Type().Field(i).Tag)) | ||
| if err != nil { | ||
| return errors.Wrapf(err, "%s: failed to parse tag %q", v.Type().Field(i).Name, v.Type().Field(i).Tag) | ||
| } | ||
|
|
||
| tag, err := tags.Get("yaml") | ||
| if err != nil { | ||
| return errors.Wrapf(err, "%s: failed to get tag %q", v.Type().Field(i).Name, v.Type().Field(i).Tag) | ||
| } | ||
|
|
||
| for _, opts := range tag.Options { | ||
| if opts == "omitempty" { | ||
| return errors.Errorf("omitempty is forbidden for config, but spotted on field '%s'", v.Type().Field(i).Name) | ||
| } | ||
| } | ||
|
|
||
| if err := checkForOmitEmptyTagOptionRec(v.Field(i)); err != nil { | ||
| return errors.Wrapf(err, "%s", v.Type().Field(i).Name) | ||
| } | ||
| } | ||
|
|
||
| case reflect.Ptr: | ||
| return errors.New("nil pointers are not allowed in configuration") | ||
|
|
||
| case reflect.Interface: | ||
| return checkForOmitEmptyTagOptionRec(v.Elem()) | ||
| } | ||
|
|
||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,221 @@ | ||
| // Copyright (c) Bartłomiej Płotka @bwplotka | ||
| // Licensed under the Apache License 2.0. | ||
|
|
||
| package yamlgen | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "context" | ||
| "fmt" | ||
| "go/ast" | ||
| "go/parser" | ||
| "go/token" | ||
| "io/ioutil" | ||
| "os" | ||
| "os/exec" | ||
| "path/filepath" | ||
|
|
||
| "github.com/dave/jennifer/jen" | ||
| "github.com/pkg/errors" | ||
| ) | ||
|
|
||
| // TODO(saswatamcode): Add tests. | ||
| // TODO(saswatamcode): Check jennifer code for some safety. | ||
| // TODO(saswatamcode): Add mechanism for caching output from generated code. | ||
| // TODO(saswatamcode): Currently takes file names, need to make it module based(something such as https://golang.org/pkg/cmd/go/internal/list/). | ||
|
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| // GenGoCode generates Go code for yaml gen from structs in src file. | ||
| func GenGoCode(src []byte) (string, error) { | ||
| // Create new main file. | ||
| fset := token.NewFileSet() | ||
| generatedCode := jen.NewFile("main") | ||
|
|
||
| // Parse source file. | ||
| f, err := parser.ParseFile(fset, "", src, parser.AllErrors) | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
|
|
||
| // Add imports if needed(will not be used if not required in code). | ||
| for _, s := range f.Imports { | ||
| generatedCode.ImportName(s.Path.Value[1:len(s.Path.Value)-1], "") | ||
| } | ||
|
|
||
| // Init statements for structs. | ||
| var init []jen.Code | ||
| // Declare config map, i.e, `configs := map[string]interface{}{}`. | ||
| init = append(init, jen.Id("configs").Op(":=").Map(jen.String()).Interface().Values()) | ||
|
|
||
| // Loop through declarations in file. | ||
| for _, decl := range f.Decls { | ||
| // Cast to generic declaration node. | ||
| if genericDecl, ok := decl.(*ast.GenDecl); ok { | ||
| // Check if declaration spec is `type`. | ||
| if typeDecl, ok := genericDecl.Specs[0].(*ast.TypeSpec); ok { | ||
| var structFields []jen.Code | ||
| // Cast to `type struct`. | ||
| structDecl := typeDecl.Type.(*ast.StructType) | ||
| fields := structDecl.Fields.List | ||
| // Loop and generate fields for each field. | ||
| for _, field := range fields { | ||
| // Each field might have multiple names. | ||
| names := field.Names | ||
| for _, n := range names { | ||
| pos := n.Obj.Decl.(*ast.Field) | ||
| structFields = append(structFields, jen.Id(n.Name).Id(string(src[pos.Type.Pos()-1:pos.Type.End()-1])).Id(string(src[pos.Tag.Pos()-1:pos.Tag.End()-1]))) | ||
| } | ||
| } | ||
|
|
||
| // Add initialize statements for struct. | ||
| init = append(init, jen.Id("configs").Index(jen.Lit(typeDecl.Name.Name)).Op("=").Id(typeDecl.Name.Name+"{}")) | ||
| // Finally put struct inside generated code. | ||
| generatedCode.Type().Id(typeDecl.Name.Name).Struct(structFields...) | ||
| } | ||
| } | ||
| } | ||
|
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| // Add for loop to iterate through map and return config YAML. | ||
| init = append(init, jen.For( | ||
| jen.List(jen.Id("k"), jen.Id("config")).Op(":=").Range().Id("configs"), | ||
| ).Block( | ||
| // We import the cfggen Generate method directly to generate output. | ||
| jen.Qual("fmt", "Println").Call(jen.Lit("---")), | ||
| jen.Qual("fmt", "Println").Call(jen.Id("k")), | ||
| // TODO(saswatamcode): Replace with import from mdox itself once merged. | ||
| // jen.Qual("github.com/bwplotka/mdox/yamlgen", "Generate").Call(jen.Id("config"), jen.Qual("os", "Stderr")), | ||
| jen.Qual("structgen/cfggen", "Generate").Call(jen.Id("config"), jen.Qual("os", "Stderr")), | ||
| )) | ||
|
|
||
| // Generate main function in new module. | ||
| generatedCode.Func().Id("main").Params().Block( | ||
| init..., | ||
| ) | ||
| return fmt.Sprintf("%#v", generatedCode), nil | ||
| } | ||
|
|
||
| // execGoCode executes and returns output from generated Go code. | ||
| func ExecGoCode(ctx context.Context, mainGo string) ([]byte, error) { | ||
| tmpDir, err := ioutil.TempDir("", "structgen") | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| defer os.RemoveAll(tmpDir) | ||
|
|
||
| // TODO(saswatamcode): Remove once merged. | ||
| // This is weird but need it for getting Generate function inside tmpDir in PR. | ||
| // Once merged this can be removed and can be replaced with just an import in tmpDir/main.go. | ||
| err = os.Mkdir(filepath.Join(tmpDir, "cfggen"), 0700) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| code, err := os.Create(filepath.Join(tmpDir, "cfggen/cfggen.go")) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| defer code.Close() | ||
| _, err = code.Write([]byte(cfggenFile)) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| // Copy generated code to main.go. | ||
| main, err := os.Create(filepath.Join(tmpDir, "main.go")) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| defer main.Close() | ||
|
|
||
| _, err = main.Write([]byte(mainGo)) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| // Create go.mod in temp dir. | ||
| cmd := exec.CommandContext(ctx, "go", "mod", "init", "structgen") | ||
| cmd.Dir = tmpDir | ||
| if err := cmd.Run(); err != nil { | ||
| return nil, errors.Wrapf(err, "run %v", cmd) | ||
| } | ||
|
|
||
| // Import required packages(generate go.sum). | ||
| cmd = exec.CommandContext(ctx, "go", "mod", "tidy") | ||
| cmd.Dir = tmpDir | ||
| if err := cmd.Run(); err != nil { | ||
| return nil, errors.Wrapf(err, "run %v", cmd) | ||
| } | ||
|
|
||
| // Execute generate code and return output. | ||
| b := bytes.Buffer{} | ||
| cmd = exec.CommandContext(ctx, "go", "run", "main.go") | ||
| cmd.Dir = tmpDir | ||
| cmd.Stderr = &b | ||
| cmd.Stdout = &b | ||
| if err := cmd.Run(); err != nil { | ||
| return nil, errors.Wrapf(err, "run %v out %v", cmd, b.String()) | ||
| } | ||
|
|
||
| return b.Bytes(), nil | ||
| } | ||
|
|
||
| // TODO(saswatamcode): Remove once merged. | ||
| // This is weird but need it for getting Generate function inside tmpDir in PR. | ||
| // Could also do with commit hash and go.mod, but it would change on each commit in PR). | ||
| // Once merged this can be removed and can be replaced with just an import in tmpDir/main.go. | ||
| const cfggenFile = `package cfggen | ||
| import ( | ||
| "io" | ||
| "reflect" | ||
| "github.com/fatih/structtag" | ||
| "github.com/pkg/errors" | ||
| "gopkg.in/yaml.v3" | ||
| ) | ||
| func Generate(obj interface{}, w io.Writer) error { | ||
| // We forbid omitempty option. This is for simplification for doc generation. | ||
| if err := checkForOmitEmptyTagOption(obj); err != nil { | ||
| return errors.Wrap(err, "invalid type") | ||
| } | ||
| return yaml.NewEncoder(w).Encode(obj) | ||
| } | ||
| func checkForOmitEmptyTagOption(obj interface{}) error { | ||
| return checkForOmitEmptyTagOptionRec(reflect.ValueOf(obj)) | ||
| } | ||
| func checkForOmitEmptyTagOptionRec(v reflect.Value) error { | ||
| switch v.Kind() { | ||
| case reflect.Struct: | ||
| for i := 0; i < v.NumField(); i++ { | ||
| tags, err := structtag.Parse(string(v.Type().Field(i).Tag)) | ||
| if err != nil { | ||
| return errors.Wrapf(err, "%s: failed to parse tag %q", v.Type().Field(i).Name, v.Type().Field(i).Tag) | ||
| } | ||
| tag, err := tags.Get("yaml") | ||
| if err != nil { | ||
| return errors.Wrapf(err, "%s: failed to get tag %q", v.Type().Field(i).Name, v.Type().Field(i).Tag) | ||
| } | ||
| for _, opts := range tag.Options { | ||
| if opts == "omitempty" { | ||
| return errors.Errorf("omitempty is forbidden for config, but spotted on field '%s'", v.Type().Field(i).Name) | ||
| } | ||
| } | ||
| if err := checkForOmitEmptyTagOptionRec(v.Field(i)); err != nil { | ||
| return errors.Wrapf(err, "%s", v.Type().Field(i).Name) | ||
| } | ||
| } | ||
| case reflect.Ptr: | ||
| return errors.New("nil pointers are not allowed in configuration") | ||
| case reflect.Interface: | ||
| return checkForOmitEmptyTagOptionRec(v.Elem()) | ||
| } | ||
| return nil | ||
| } | ||
| ` |