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moby--moby/pkg/plugins/pluginrpc-gen/parser.go

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package main
import (
"errors"
"fmt"
"go/ast"
"go/parser"
"go/token"
"path"
"reflect"
"strings"
)
var errBadReturn = errors.New("found return arg with no name: all args must be named")
type errUnexpectedType struct {
expected string
actual interface{}
}
func (e errUnexpectedType) Error() string {
return fmt.Sprintf("got wrong type expecting %s, got: %v", e.expected, reflect.TypeOf(e.actual))
}
// ParsedPkg holds information about a package that has been parsed,
// its name and the list of functions.
type ParsedPkg struct {
Name string
Functions []function
Imports []importSpec
}
type function struct {
Name string
Args []arg
Returns []arg
Doc string
}
type arg struct {
Name string
ArgType string
PackageSelector string
}
func (a *arg) String() string {
return a.Name + " " + a.ArgType
}
type importSpec struct {
Name string
Path string
}
func (s *importSpec) String() string {
var ss string
if len(s.Name) != 0 {
ss += s.Name
}
ss += s.Path
return ss
}
// Parse parses the given file for an interface definition with the given name.
func Parse(filePath string, objName string) (*ParsedPkg, error) {
fs := token.NewFileSet()
pkg, err := parser.ParseFile(fs, filePath, nil, parser.AllErrors)
if err != nil {
return nil, err
}
p := &ParsedPkg{}
p.Name = pkg.Name.Name
obj, exists := pkg.Scope.Objects[objName]
if !exists {
return nil, fmt.Errorf("could not find object %s in %s", objName, filePath)
}
if obj.Kind != ast.Typ {
return nil, fmt.Errorf("exected type, got %s", obj.Kind)
}
spec, ok := obj.Decl.(*ast.TypeSpec)
if !ok {
return nil, errUnexpectedType{"*ast.TypeSpec", obj.Decl}
}
iface, ok := spec.Type.(*ast.InterfaceType)
if !ok {
return nil, errUnexpectedType{"*ast.InterfaceType", spec.Type}
}
p.Functions, err = parseInterface(iface)
if err != nil {
return nil, err
}
// figure out what imports will be needed
imports := make(map[string]importSpec)
for _, f := range p.Functions {
args := append(f.Args, f.Returns...)
for _, arg := range args {
if len(arg.PackageSelector) == 0 {
continue
}
for _, i := range pkg.Imports {
if i.Name != nil {
if i.Name.Name != arg.PackageSelector {
continue
}
imports[i.Path.Value] = importSpec{Name: arg.PackageSelector, Path: i.Path.Value}
break
}
_, name := path.Split(i.Path.Value)
splitName := strings.Split(name, "-")
if len(splitName) > 1 {
name = splitName[len(splitName)-1]
}
// import paths have quotes already added in, so need to remove them for name comparison
name = strings.TrimPrefix(name, `"`)
name = strings.TrimSuffix(name, `"`)
if name == arg.PackageSelector {
imports[i.Path.Value] = importSpec{Path: i.Path.Value}
break
}
}
}
}
for _, spec := range imports {
p.Imports = append(p.Imports, spec)
}
return p, nil
}
func parseInterface(iface *ast.InterfaceType) ([]function, error) {
var functions []function
for _, field := range iface.Methods.List {
switch f := field.Type.(type) {
case *ast.FuncType:
method, err := parseFunc(field)
if err != nil {
return nil, err
}
if method == nil {
continue
}
functions = append(functions, *method)
case *ast.Ident:
spec, ok := f.Obj.Decl.(*ast.TypeSpec)
if !ok {
return nil, errUnexpectedType{"*ast.TypeSpec", f.Obj.Decl}
}
iface, ok := spec.Type.(*ast.InterfaceType)
if !ok {
return nil, errUnexpectedType{"*ast.TypeSpec", spec.Type}
}
funcs, err := parseInterface(iface)
if err != nil {
fmt.Println(err)
continue
}
functions = append(functions, funcs...)
default:
return nil, errUnexpectedType{"*astFuncType or *ast.Ident", f}
}
}
return functions, nil
}
func parseFunc(field *ast.Field) (*function, error) {
f := field.Type.(*ast.FuncType)
method := &function{Name: field.Names[0].Name}
if _, exists := skipFuncs[method.Name]; exists {
fmt.Println("skipping:", method.Name)
return nil, nil
}
if f.Params != nil {
args, err := parseArgs(f.Params.List)
if err != nil {
return nil, err
}
method.Args = args
}
if f.Results != nil {
returns, err := parseArgs(f.Results.List)
if err != nil {
return nil, fmt.Errorf("error parsing function returns for %q: %v", method.Name, err)
}
method.Returns = returns
}
return method, nil
}
func parseArgs(fields []*ast.Field) ([]arg, error) {
var args []arg
for _, f := range fields {
if len(f.Names) == 0 {
return nil, errBadReturn
}
for _, name := range f.Names {
p, err := parseExpr(f.Type)
if err != nil {
return nil, err
}
args = append(args, arg{name.Name, p.value, p.pkg})
}
}
return args, nil
}
type parsedExpr struct {
value string
pkg string
}
func parseExpr(e ast.Expr) (parsedExpr, error) {
var parsed parsedExpr
switch i := e.(type) {
case *ast.Ident:
parsed.value += i.Name
case *ast.StarExpr:
p, err := parseExpr(i.X)
if err != nil {
return parsed, err
}
parsed.value += "*"
parsed.value += p.value
parsed.pkg = p.pkg
case *ast.SelectorExpr:
p, err := parseExpr(i.X)
if err != nil {
return parsed, err
}
parsed.pkg = p.value
parsed.value += p.value + "."
parsed.value += i.Sel.Name
case *ast.MapType:
parsed.value += "map["
p, err := parseExpr(i.Key)
if err != nil {
return parsed, err
}
parsed.value += p.value
parsed.value += "]"
p, err = parseExpr(i.Value)
if err != nil {
return parsed, err
}
parsed.value += p.value
parsed.pkg = p.pkg
case *ast.ArrayType:
parsed.value += "[]"
p, err := parseExpr(i.Elt)
if err != nil {
return parsed, err
}
parsed.value += p.value
parsed.pkg = p.pkg
default:
return parsed, errUnexpectedType{"*ast.Ident or *ast.StarExpr", i}
}
return parsed, nil
}