forked from tinylib/msgp
/
getast.go
585 lines (528 loc) · 12.1 KB
/
getast.go
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package parse
import (
"fmt"
"go/ast"
"go/parser"
"go/token"
"os"
"reflect"
"sort"
"strings"
"github.com/tinylib/msgp/gen"
"github.com/ttacon/chalk"
)
// A FileSet is the in-memory representation of a
// parsed file.
type FileSet struct {
Package string // package name
Specs map[string]ast.Expr // type specs in file
Identities map[string]gen.Elem // processed from specs
Directives []string // raw preprocessor directives
}
// File parses a file at the relative path
// provided and produces a new *FileSet.
// If you pass in a path to a directory, the entire
// directory will be parsed.
// If unexport is false, only exported identifiers are included in the FileSet.
// If the resulting FileSet would be empty, an error is returned.
func File(name string, unexported bool) (*FileSet, error) {
pushstate(name)
defer popstate()
fs := &FileSet{
Specs: make(map[string]ast.Expr),
Identities: make(map[string]gen.Elem),
}
fset := token.NewFileSet()
finfo, err := os.Stat(name)
if err != nil {
return nil, err
}
if finfo.IsDir() {
pkgs, err := parser.ParseDir(fset, name, nil, parser.ParseComments)
if err != nil {
return nil, err
}
if len(pkgs) != 1 {
return nil, fmt.Errorf("multiple packages in directory: %s", name)
}
var one *ast.Package
for _, nm := range pkgs {
one = nm
break
}
fs.Package = one.Name
for _, fl := range one.Files {
pushstate(fl.Name.Name)
fs.Directives = append(fs.Directives, yieldComments(fl.Comments)...)
if !unexported {
ast.FileExports(fl)
}
fs.getTypeSpecs(fl)
popstate()
}
} else {
f, err := parser.ParseFile(fset, name, nil, parser.ParseComments)
if err != nil {
return nil, err
}
fs.Package = f.Name.Name
fs.Directives = yieldComments(f.Comments)
if !unexported {
ast.FileExports(f)
}
fs.getTypeSpecs(f)
}
if len(fs.Specs) == 0 {
return nil, fmt.Errorf("no definitions in %s", name)
}
fs.process()
fs.applyDirectives()
fs.propInline()
return fs, nil
}
// applyDirectives applies all of the directives that
// are known to the parser. additional method-specific
// directives remain in f.Directives
func (f *FileSet) applyDirectives() {
newdirs := make([]string, 0, len(f.Directives))
for _, d := range f.Directives {
chunks := strings.Split(d, " ")
if len(chunks) > 0 {
if fn, ok := directives[chunks[0]]; ok {
pushstate(chunks[0])
err := fn(chunks, f)
if err != nil {
warnln(err.Error())
}
popstate()
} else {
newdirs = append(newdirs, d)
}
}
}
f.Directives = newdirs
}
// A linkset is a graph of unresolved
// identities.
//
// Since gen.Ident can only represent
// one level of type indirection (e.g. Foo -> uint8),
// type declarations like `type Foo Bar`
// aren't resolve-able until we've processed
// everything else.
//
// The goal of this dependency resolution
// is to distill the type declaration
// into just one level of indirection.
// In other words, if we have:
//
// type A uint64
// type B A
// type C B
// type D C
//
// ... then we want to end up
// figuring out that D is just a uint64.
type linkset map[string]*gen.BaseElem
func (f *FileSet) resolve(ls linkset) {
progress := true
for progress && len(ls) > 0 {
progress = false
for name, elem := range ls {
real, ok := f.Identities[elem.TypeName()]
if ok {
// copy the old type descriptor,
// alias it to the new value,
// and insert it into the resolved
// identities list
progress = true
nt := real.Copy()
nt.Alias(name)
f.Identities[name] = nt
delete(ls, name)
}
}
}
// what's left can't be resolved
for name, elem := range ls {
warnf("couldn't resolve type %s (%s)\n", name, elem.TypeName())
}
}
// process takes the contents of f.Specs and
// uses them to populate f.Identities
func (f *FileSet) process() {
deferred := make(linkset)
parse:
for name, def := range f.Specs {
pushstate(name)
el := f.parseExpr(def)
if el == nil {
warnln("failed to parse")
popstate()
continue parse
}
// push unresolved identities into
// the graph of links and resolve after
// we've handled every possible named type.
if be, ok := el.(*gen.BaseElem); ok && be.Value == gen.IDENT {
deferred[name] = be
popstate()
continue parse
}
el.Alias(name)
f.Identities[name] = el
popstate()
}
if len(deferred) > 0 {
f.resolve(deferred)
}
}
func strToMethod(s string) gen.Method {
switch s {
case "encode":
return gen.Encode
case "decode":
return gen.Decode
case "test":
return gen.Test
case "size":
return gen.Size
case "marshal":
return gen.Marshal
case "unmarshal":
return gen.Unmarshal
default:
return 0
}
}
func (f *FileSet) applyDirs(p *gen.Printer) {
// apply directives of the form
//
// //msgp:encode ignore {{TypeName}}
//
loop:
for _, d := range f.Directives {
chunks := strings.Split(d, " ")
if len(chunks) > 1 {
for i := range chunks {
chunks[i] = strings.TrimSpace(chunks[i])
}
m := strToMethod(chunks[0])
if m == 0 {
warnf("unknown pass name: %q\n", chunks[0])
continue loop
}
if fn, ok := passDirectives[chunks[1]]; ok {
pushstate(chunks[1])
err := fn(m, chunks[2:], p)
if err != nil {
warnf("error applying directive: %s\n", err)
}
popstate()
} else {
warnf("unrecognized directive %q\n", chunks[1])
}
} else {
warnf("empty directive: %q\n", d)
}
}
}
func (f *FileSet) PrintTo(p *gen.Printer) error {
f.applyDirs(p)
names := make([]string, 0, len(f.Identities))
for name := range f.Identities {
names = append(names, name)
}
sort.Strings(names)
for _, name := range names {
el := f.Identities[name]
el.SetVarname("z")
pushstate(el.TypeName())
err := p.Print(el)
popstate()
if err != nil {
return err
}
}
return nil
}
// getTypeSpecs extracts all of the *ast.TypeSpecs in the file
// into fs.Identities, but does not set the actual element
func (fs *FileSet) getTypeSpecs(f *ast.File) {
// check all declarations...
for i := range f.Decls {
// for GenDecls...
if g, ok := f.Decls[i].(*ast.GenDecl); ok {
// and check the specs...
for _, s := range g.Specs {
// for ast.TypeSpecs....
if ts, ok := s.(*ast.TypeSpec); ok {
switch ts.Type.(type) {
// this is the list of parse-able
// type specs
case *ast.StructType,
*ast.ArrayType,
*ast.StarExpr,
*ast.MapType,
*ast.Ident:
fs.Specs[ts.Name.Name] = ts.Type
}
}
}
}
}
}
func fieldName(f *ast.Field) string {
switch len(f.Names) {
case 0:
return stringify(f.Type)
case 1:
return f.Names[0].Name
default:
return f.Names[0].Name + " (and others)"
}
}
func (fs *FileSet) parseFieldList(fl *ast.FieldList) []gen.StructField {
if fl == nil || fl.NumFields() == 0 {
return nil
}
out := make([]gen.StructField, 0, fl.NumFields())
for _, field := range fl.List {
pushstate(fieldName(field))
fds := fs.getField(field)
if len(fds) > 0 {
out = append(out, fds...)
} else {
warnln("ignored.")
}
popstate()
}
return out
}
// translate *ast.Field into []gen.StructField
func (fs *FileSet) getField(f *ast.Field) []gen.StructField {
sf := make([]gen.StructField, 1)
var extension bool
// parse tag; otherwise field name is field tag
if f.Tag != nil {
body := reflect.StructTag(strings.Trim(f.Tag.Value, "`")).Get("msg")
tags := strings.Split(body, ",")
if len(tags) == 2 && tags[1] == "extension" {
extension = true
}
// ignore "-" fields
if tags[0] == "-" {
return nil
}
sf[0].FieldTag = tags[0]
}
ex := fs.parseExpr(f.Type)
if ex == nil {
return nil
}
// parse field name
switch len(f.Names) {
case 0:
sf[0].FieldName = embedded(f.Type)
case 1:
sf[0].FieldName = f.Names[0].Name
default:
// this is for a multiple in-line declaration,
// e.g. type A struct { One, Two int }
sf = sf[0:0]
for _, nm := range f.Names {
sf = append(sf, gen.StructField{
FieldTag: nm.Name,
FieldName: nm.Name,
FieldElem: ex.Copy(),
})
}
return sf
}
sf[0].FieldElem = ex
if sf[0].FieldTag == "" {
sf[0].FieldTag = sf[0].FieldName
}
// validate extension
if extension {
switch ex := ex.(type) {
case *gen.Ptr:
if b, ok := ex.Value.(*gen.BaseElem); ok {
b.Value = gen.Ext
} else {
warnln("couldn't cast to extension.")
return nil
}
case *gen.BaseElem:
ex.Value = gen.Ext
default:
warnln("couldn't cast to extension.")
return nil
}
}
return sf
}
// extract embedded field name
//
// so, for a struct like
//
// type A struct {
// io.Writer
// }
//
// we want "Writer"
func embedded(f ast.Expr) string {
switch f := f.(type) {
case *ast.Ident:
return f.Name
case *ast.StarExpr:
return embedded(f.X)
case *ast.SelectorExpr:
return f.Sel.Name
default:
// other possibilities are disallowed
return ""
}
}
// stringify a field type name
func stringify(e ast.Expr) string {
switch e := e.(type) {
case *ast.Ident:
return e.Name
case *ast.StarExpr:
return "*" + stringify(e.X)
case *ast.SelectorExpr:
return stringify(e.X) + "." + e.Sel.Name
case *ast.ArrayType:
if e.Len == nil {
return "[]" + stringify(e.Elt)
}
return fmt.Sprintf("[%s]%s", stringify(e.Len), stringify(e.Elt))
case *ast.InterfaceType:
if e.Methods == nil || e.Methods.NumFields() == 0 {
return "interface{}"
}
}
return "<BAD>"
}
// recursively translate ast.Expr to gen.Elem; nil means type not supported
// expected input types:
// - *ast.MapType (map[T]J)
// - *ast.Ident (name)
// - *ast.ArrayType ([(sz)]T)
// - *ast.StarExpr (*T)
// - *ast.StructType (struct {})
// - *ast.SelectorExpr (a.B)
// - *ast.InterfaceType (interface {})
func (fs *FileSet) parseExpr(e ast.Expr) gen.Elem {
switch e := e.(type) {
case *ast.MapType:
if k, ok := e.Key.(*ast.Ident); ok && k.Name == "string" {
if in := fs.parseExpr(e.Value); in != nil {
return &gen.Map{Value: in}
}
}
return nil
case *ast.Ident:
b := gen.Ident(e.Name)
// work to resove this expression
// can be done later, once we've resolved
// everything else.
if b.Value == gen.IDENT {
if _, ok := fs.Specs[e.Name]; !ok {
warnf("non-local identifier: %s\n", e.Name)
}
}
return b
case *ast.ArrayType:
// special case for []byte
if e.Len == nil {
if i, ok := e.Elt.(*ast.Ident); ok && i.Name == "byte" {
return &gen.BaseElem{Value: gen.Bytes}
}
}
// return early if we don't know
// what the slice element type is
els := fs.parseExpr(e.Elt)
if els == nil {
return nil
}
// array and not a slice
if e.Len != nil {
switch s := e.Len.(type) {
case *ast.BasicLit:
return &gen.Array{
Size: s.Value,
Els: els,
}
case *ast.Ident:
return &gen.Array{
Size: s.String(),
Els: els,
}
case *ast.SelectorExpr:
return &gen.Array{
Size: stringify(s),
Els: els,
}
default:
return nil
}
}
return &gen.Slice{Els: els}
case *ast.StarExpr:
if v := fs.parseExpr(e.X); v != nil {
return &gen.Ptr{Value: v}
}
return nil
case *ast.StructType:
if fields := fs.parseFieldList(e.Fields); len(fields) > 0 {
return &gen.Struct{Fields: fields}
}
return nil
case *ast.SelectorExpr:
return gen.Ident(stringify(e))
case *ast.InterfaceType:
// support `interface{}`
if len(e.Methods.List) == 0 {
return &gen.BaseElem{Value: gen.Intf}
}
return nil
default: // other types not supported
return nil
}
}
func infof(s string, v ...interface{}) {
pushstate(s)
fmt.Printf(chalk.Green.Color(strings.Join(logctx, ": ")), v...)
popstate()
}
func infoln(s string) {
pushstate(s)
fmt.Println(chalk.Green.Color(strings.Join(logctx, ": ")))
popstate()
}
func warnf(s string, v ...interface{}) {
pushstate(s)
fmt.Printf(chalk.Yellow.Color(strings.Join(logctx, ": ")), v...)
popstate()
}
func warnln(s string) {
pushstate(s)
fmt.Println(chalk.Yellow.Color(strings.Join(logctx, ": ")))
popstate()
}
func fatalf(s string, v ...interface{}) {
pushstate(s)
fmt.Printf(chalk.Red.Color(strings.Join(logctx, ": ")), v...)
popstate()
}
var logctx []string
// push logging state
func pushstate(s string) {
logctx = append(logctx, s)
}
// pop logging state
func popstate() {
logctx = logctx[:len(logctx)-1]
}