Allow go2idl to generate non-Go file types

Remove some indentation from file generation for specific languages,
allow SnippetWriter's io.Writer to be accessed, and add Path to
types.Name for languages where Package and Path can be disjoint.

cmd/libs/go2idl/generator/execute.go

@@ -44,17 +44,9 @@ func (c *Context) ExecutePackages(outDir string, packages Packages) error {
 	return nil
 }
 
-type file struct {
-	name        string
-	packageName string
-	header      []byte
-	imports     map[string]struct{}
-	vars        bytes.Buffer
-	consts      bytes.Buffer
-	body        bytes.Buffer
-}
+type golangFileType struct{}
 
-func (f *file) assembleToFile(pathname string) error {
+func (ft golangFileType) AssembleFile(f *File, pathname string) error {
 	log.Printf("Assembling file %q", pathname)
 	destFile, err := os.Create(pathname)
 	if err != nil {
@@ -64,7 +56,7 @@ func (f *file) assembleToFile(pathname string) error {
 
 	b := &bytes.Buffer{}
 	et := NewErrorTracker(b)
-	f.assemble(et)
+	ft.assemble(et, f)
 	if et.Error() != nil {
 		return et.Error()
 	}
@@ -78,14 +70,14 @@ func (f *file) assembleToFile(pathname string) error {
 	}
 }
 
-func (f *file) assemble(w io.Writer) {
-	w.Write(f.header)
-	fmt.Fprintf(w, "package %v\n\n", f.packageName)
+func (ft golangFileType) assemble(w io.Writer, f *File) {
+	w.Write(f.Header)
+	fmt.Fprintf(w, "package %v\n\n", f.PackageName)
 
-	if len(f.imports) > 0 {
+	if len(f.Imports) > 0 {
 		fmt.Fprint(w, "import (\n")
 		// TODO: sort imports like goimports does.
-		for i := range f.imports {
+		for i := range f.Imports {
 			if strings.Contains(i, "\"") {
 				// they included quotes, or are using the
 				// `name "path/to/pkg"` format.
@@ -97,27 +89,27 @@ func (f *file) assemble(w io.Writer) {
 		fmt.Fprint(w, ")\n\n")
 	}
 
-	if f.vars.Len() > 0 {
+	if f.Vars.Len() > 0 {
 		fmt.Fprint(w, "var (\n")
-		w.Write(f.vars.Bytes())
+		w.Write(f.Vars.Bytes())
 		fmt.Fprint(w, ")\n\n")
 	}
 
-	if f.consts.Len() > 0 {
+	if f.Consts.Len() > 0 {
 		fmt.Fprint(w, "const (\n")
-		w.Write(f.consts.Bytes())
+		w.Write(f.Consts.Bytes())
 		fmt.Fprint(w, ")\n\n")
 	}
 
-	w.Write(f.body.Bytes())
+	w.Write(f.Body.Bytes())
 }
 
 // format should be one line only, and not end with \n.
 func addIndentHeaderComment(b *bytes.Buffer, format string, args ...interface{}) {
 	if b.Len() > 0 {
-		fmt.Fprintf(b, "\n\t// "+format+"\n", args...)
+		fmt.Fprintf(b, "\n// "+format+"\n", args...)
 	} else {
-		fmt.Fprintf(b, "\t// "+format+"\n", args...)
+		fmt.Fprintf(b, "// "+format+"\n", args...)
 	}
 }
 
@@ -161,52 +153,66 @@ func (c *Context) ExecutePackage(outDir string, p Package) error {
 	// Filter out any types the *package* doesn't care about.
 	packageContext := c.filteredBy(p.Filter)
 	os.MkdirAll(path, 0755)
-	files := map[string]*file{}
+	files := map[string]*File{}
 	for _, g := range p.Generators(packageContext) {
 		// Filter out types the *generator* doesn't care about.
 		genContext := packageContext.filteredBy(g.Filter)
 		// Now add any extra name systems defined by this generator
 		genContext = genContext.addNameSystems(g.Namers(genContext))
 
+		fileType := g.FileType()
+		if len(fileType) == 0 {
+			return fmt.Errorf("generator %q must specify a file type", g.Name())
+		}
 		f := files[g.Filename()]
 		if f == nil {
 			// This is the first generator to reference this file, so start it.
-			f = &file{
-				name:        g.Filename(),
-				packageName: p.Name(),
-				header:      p.Header(g.Filename()),
-				imports:     map[string]struct{}{},
+			f = &File{
+				Name:        g.Filename(),
+				FileType:    fileType,
+				PackageName: p.Name(),
+				Header:      p.Header(g.Filename()),
+				Imports:     map[string]struct{}{},
+			}
+			files[f.Name] = f
+		} else {
+			if f.FileType != g.FileType() {
+				return fmt.Errorf("file %q already has type %q, but generator %q wants to use type %q", f.Name, f.FileType, g.Name(), g.FileType())
 			}
-			files[f.name] = f
 		}
+
 		if vars := g.PackageVars(genContext); len(vars) > 0 {
-			addIndentHeaderComment(&f.vars, "Package-wide variables from generator %q.", g.Name())
+			addIndentHeaderComment(&f.Vars, "Package-wide variables from generator %q.", g.Name())
 			for _, v := range vars {
-				if _, err := fmt.Fprintf(&f.vars, "\t%s\n", v); err != nil {
+				if _, err := fmt.Fprintf(&f.Vars, "%s\n", v); err != nil {
 					return err
 				}
 			}
 		}
 		if consts := g.PackageVars(genContext); len(consts) > 0 {
-			addIndentHeaderComment(&f.consts, "Package-wide consts from generator %q.", g.Name())
+			addIndentHeaderComment(&f.Consts, "Package-wide consts from generator %q.", g.Name())
 			for _, v := range consts {
-				if _, err := fmt.Fprintf(&f.consts, "\t%s\n", v); err != nil {
+				if _, err := fmt.Fprintf(&f.Consts, "%s\n", v); err != nil {
 					return err
 				}
 			}
 		}
-		if err := genContext.executeBody(&f.body, g); err != nil {
+		if err := genContext.executeBody(&f.Body, g); err != nil {
 			return err
 		}
 		if imports := g.Imports(genContext); len(imports) > 0 {
 			for _, i := range imports {
-				f.imports[i] = struct{}{}
+				f.Imports[i] = struct{}{}
 			}
 		}
 	}
 
 	for _, f := range files {
-		if err := f.assembleToFile(filepath.Join(path, f.name)); err != nil {
+		assembler, ok := c.FileTypes[f.FileType]
+		if !ok {
+			return fmt.Errorf("the file type %q registered for file %q does not exist in the context", f.FileType, f.Name)
+		}
+		if err := assembler.AssembleFile(f, filepath.Join(path, f.Name)); err != nil {
 			return err
 		}
 	}