go ureader 源码
golang ureader 代码
文件路径：/src/cmd/compile/internal/importer/ureader.go
// UNREVIEWED
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package importer
import (
"cmd/compile/internal/base"
"cmd/compile/internal/syntax"
"cmd/compile/internal/types2"
"cmd/internal/src"
"internal/pkgbits"
)
type pkgReader struct {
pkgbits.PkgDecoder
ctxt *types2.Context
imports map[string]*types2.Package
posBases []*syntax.PosBase
pkgs []*types2.Package
typs []types2.Type
}
func ReadPackage(ctxt *types2.Context, imports map[string]*types2.Package, input pkgbits.PkgDecoder) *types2.Package {
pr := pkgReader{
PkgDecoder: input,
ctxt: ctxt,
imports: imports,
posBases: make([]*syntax.PosBase, input.NumElems(pkgbits.RelocPosBase)),
pkgs: make([]*types2.Package, input.NumElems(pkgbits.RelocPkg)),
typs: make([]types2.Type, input.NumElems(pkgbits.RelocType)),
}
r := pr.newReader(pkgbits.RelocMeta, pkgbits.PublicRootIdx, pkgbits.SyncPublic)
pkg := r.pkg()
r.Bool() // has init
for i, n := 0, r.Len(); i < n; i++ {
// As if r.obj(), but avoiding the Scope.Lookup call,
// to avoid eager loading of imports.
r.Sync(pkgbits.SyncObject)
assert(!r.Bool())
r.p.objIdx(r.Reloc(pkgbits.RelocObj))
assert(r.Len() == 0)
}
r.Sync(pkgbits.SyncEOF)
pkg.MarkComplete()
return pkg
}
type reader struct {
pkgbits.Decoder
p *pkgReader
dict *readerDict
}
type readerDict struct {
bounds []typeInfo
tparams []*types2.TypeParam
derived []derivedInfo
derivedTypes []types2.Type
}
type readerTypeBound struct {
derived bool
boundIdx int
}
func (pr *pkgReader) newReader(k pkgbits.RelocKind, idx pkgbits.Index, marker pkgbits.SyncMarker) *reader {
return &reader{
Decoder: pr.NewDecoder(k, idx, marker),
p: pr,
}
}
// @@@ Positions
func (r *reader) pos() syntax.Pos {
r.Sync(pkgbits.SyncPos)
if !r.Bool() {
return syntax.Pos{}
}
// TODO(mdempsky): Delta encoding.
posBase := r.posBase()
line := r.Uint()
col := r.Uint()
return syntax.MakePos(posBase, line, col)
}
func (r *reader) posBase() *syntax.PosBase {
return r.p.posBaseIdx(r.Reloc(pkgbits.RelocPosBase))
}
func (pr *pkgReader) posBaseIdx(idx pkgbits.Index) *syntax.PosBase {
if b := pr.posBases[idx]; b != nil {
return b
}
r := pr.newReader(pkgbits.RelocPosBase, idx, pkgbits.SyncPosBase)
var b *syntax.PosBase
filename := r.String()
if r.Bool() {
b = syntax.NewTrimmedFileBase(filename, true)
} else {
pos := r.pos()
line := r.Uint()
col := r.Uint()
b = syntax.NewLineBase(pos, filename, true, line, col)
}
pr.posBases[idx] = b
return b
}
// @@@ Packages
func (r *reader) pkg() *types2.Package {
r.Sync(pkgbits.SyncPkg)
return r.p.pkgIdx(r.Reloc(pkgbits.RelocPkg))
}
func (pr *pkgReader) pkgIdx(idx pkgbits.Index) *types2.Package {
// TODO(mdempsky): Consider using some non-nil pointer to indicate
// the universe scope, so we don't need to keep re-reading it.
if pkg := pr.pkgs[idx]; pkg != nil {
return pkg
}
pkg := pr.newReader(pkgbits.RelocPkg, idx, pkgbits.SyncPkgDef).doPkg()
pr.pkgs[idx] = pkg
return pkg
}
func (r *reader) doPkg() *types2.Package {
path := r.String()
switch path {
case "":
path = r.p.PkgPath()
case "builtin":
return nil // universe
case "unsafe":
return types2.Unsafe
}
if pkg := r.p.imports[path]; pkg != nil {
return pkg
}
name := r.String()
height := r.Len()
pkg := types2.NewPackageHeight(path, name, height)
r.p.imports[path] = pkg
// TODO(mdempsky): The list of imported packages is important for
// go/types, but we could probably skip populating it for types2.
imports := make([]*types2.Package, r.Len())
for i := range imports {
imports[i] = r.pkg()
}
pkg.SetImports(imports)
return pkg
}
// @@@ Types
func (r *reader) typ() types2.Type {
return r.p.typIdx(r.typInfo(), r.dict)
}
func (r *reader) typInfo() typeInfo {
r.Sync(pkgbits.SyncType)
if r.Bool() {
return typeInfo{idx: pkgbits.Index(r.Len()), derived: true}
}
return typeInfo{idx: r.Reloc(pkgbits.RelocType), derived: false}
}
func (pr *pkgReader) typIdx(info typeInfo, dict *readerDict) types2.Type {
idx := info.idx
var where *types2.Type
if info.derived {
where = &dict.derivedTypes[idx]
idx = dict.derived[idx].idx
} else {
where = &pr.typs[idx]
}
if typ := *where; typ != nil {
return typ
}
r := pr.newReader(pkgbits.RelocType, idx, pkgbits.SyncTypeIdx)
r.dict = dict
typ := r.doTyp()
assert(typ != nil)
// See comment in pkgReader.typIdx explaining how this happens.
if prev := *where; prev != nil {
return prev
}
*where = typ
return typ
}
func (r *reader) doTyp() (res types2.Type) {
switch tag := pkgbits.CodeType(r.Code(pkgbits.SyncType)); tag {
default:
base.FatalfAt(src.NoXPos, "unhandled type tag: %v", tag)
panic("unreachable")
case pkgbits.TypeBasic:
return types2.Typ[r.Len()]
case pkgbits.TypeNamed:
obj, targs := r.obj()
name := obj.(*types2.TypeName)
if len(targs) != 0 {
t, _ := types2.Instantiate(r.p.ctxt, name.Type(), targs, false)
return t
}
return name.Type()
case pkgbits.TypeTypeParam:
return r.dict.tparams[r.Len()]
case pkgbits.TypeArray:
len := int64(r.Uint64())
return types2.NewArray(r.typ(), len)
case pkgbits.TypeChan:
dir := types2.ChanDir(r.Len())
return types2.NewChan(dir, r.typ())
case pkgbits.TypeMap:
return types2.NewMap(r.typ(), r.typ())
case pkgbits.TypePointer:
return types2.NewPointer(r.typ())
case pkgbits.TypeSignature:
return r.signature(nil, nil, nil)
case pkgbits.TypeSlice:
return types2.NewSlice(r.typ())
case pkgbits.TypeStruct:
return r.structType()
case pkgbits.TypeInterface:
return r.interfaceType()
case pkgbits.TypeUnion:
return r.unionType()
}
}
func (r *reader) structType() *types2.Struct {
fields := make([]*types2.Var, r.Len())
var tags []string
for i := range fields {
pos := r.pos()
pkg, name := r.selector()
ftyp := r.typ()
tag := r.String()
embedded := r.Bool()
fields[i] = types2.NewField(pos, pkg, name, ftyp, embedded)
if tag != "" {
for len(tags) < i {
tags = append(tags, "")
}
tags = append(tags, tag)
}
}
return types2.NewStruct(fields, tags)
}
func (r *reader) unionType() *types2.Union {
terms := make([]*types2.Term, r.Len())
for i := range terms {
terms[i] = types2.NewTerm(r.Bool(), r.typ())
}
return types2.NewUnion(terms)
}
func (r *reader) interfaceType() *types2.Interface {
methods := make([]*types2.Func, r.Len())
embeddeds := make([]types2.Type, r.Len())
implicit := len(methods) == 0 && len(embeddeds) == 1 && r.Bool()
for i := range methods {
pos := r.pos()
pkg, name := r.selector()
mtyp := r.signature(nil, nil, nil)
methods[i] = types2.NewFunc(pos, pkg, name, mtyp)
}
for i := range embeddeds {
embeddeds[i] = r.typ()
}
iface := types2.NewInterfaceType(methods, embeddeds)
if implicit {
iface.MarkImplicit()
}
return iface
}
func (r *reader) signature(recv *types2.Var, rtparams, tparams []*types2.TypeParam) *types2.Signature {
r.Sync(pkgbits.SyncSignature)
params := r.params()
results := r.params()
variadic := r.Bool()
return types2.NewSignatureType(recv, rtparams, tparams, params, results, variadic)
}
func (r *reader) params() *types2.Tuple {
r.Sync(pkgbits.SyncParams)
params := make([]*types2.Var, r.Len())
for i := range params {
params[i] = r.param()
}
return types2.NewTuple(params...)
}
func (r *reader) param() *types2.Var {
r.Sync(pkgbits.SyncParam)
pos := r.pos()
pkg, name := r.localIdent()
typ := r.typ()
return types2.NewParam(pos, pkg, name, typ)
}
// @@@ Objects
func (r *reader) obj() (types2.Object, []types2.Type) {
r.Sync(pkgbits.SyncObject)
assert(!r.Bool())
pkg, name := r.p.objIdx(r.Reloc(pkgbits.RelocObj))
obj := pkg.Scope().Lookup(name)
targs := make([]types2.Type, r.Len())
for i := range targs {
targs[i] = r.typ()
}
return obj, targs
}
func (pr *pkgReader) objIdx(idx pkgbits.Index) (*types2.Package, string) {
rname := pr.newReader(pkgbits.RelocName, idx, pkgbits.SyncObject1)
objPkg, objName := rname.qualifiedIdent()
assert(objName != "")
tag := pkgbits.CodeObj(rname.Code(pkgbits.SyncCodeObj))
if tag == pkgbits.ObjStub {
base.Assertf(objPkg == nil || objPkg == types2.Unsafe, "unexpected stub package: %v", objPkg)
return objPkg, objName
}
objPkg.Scope().InsertLazy(objName, func() types2.Object {
dict := pr.objDictIdx(idx)
r := pr.newReader(pkgbits.RelocObj, idx, pkgbits.SyncObject1)
r.dict = dict
switch tag {
default:
panic("weird")
case pkgbits.ObjAlias:
pos := r.pos()
typ := r.typ()
return types2.NewTypeName(pos, objPkg, objName, typ)
case pkgbits.ObjConst:
pos := r.pos()
typ := r.typ()
val := r.Value()
return types2.NewConst(pos, objPkg, objName, typ, val)
case pkgbits.ObjFunc:
pos := r.pos()
tparams := r.typeParamNames()
sig := r.signature(nil, nil, tparams)
return types2.NewFunc(pos, objPkg, objName, sig)
case pkgbits.ObjType:
pos := r.pos()
return types2.NewTypeNameLazy(pos, objPkg, objName, func(named *types2.Named) (tparams []*types2.TypeParam, underlying types2.Type, methods []*types2.Func) {
tparams = r.typeParamNames()
// TODO(mdempsky): Rewrite receiver types to underlying is an
// Interface? The go/types importer does this (I think because
// unit tests expected that), but cmd/compile doesn't care
// about it, so maybe we can avoid worrying about that here.
underlying = r.typ().Underlying()
methods = make([]*types2.Func, r.Len())
for i := range methods {
methods[i] = r.method()
}
return
})
case pkgbits.ObjVar:
pos := r.pos()
typ := r.typ()
return types2.NewVar(pos, objPkg, objName, typ)
}
})
return objPkg, objName
}
func (pr *pkgReader) objDictIdx(idx pkgbits.Index) *readerDict {
r := pr.newReader(pkgbits.RelocObjDict, idx, pkgbits.SyncObject1)
var dict readerDict
if implicits := r.Len(); implicits != 0 {
base.Fatalf("unexpected object with %v implicit type parameter(s)", implicits)
}
dict.bounds = make([]typeInfo, r.Len())
for i := range dict.bounds {
dict.bounds[i] = r.typInfo()
}
dict.derived = make([]derivedInfo, r.Len())
dict.derivedTypes = make([]types2.Type, len(dict.derived))
for i := range dict.derived {
dict.derived[i] = derivedInfo{r.Reloc(pkgbits.RelocType), r.Bool()}
}
// function references follow, but reader doesn't need those
return &dict
}
func (r *reader) typeParamNames() []*types2.TypeParam {
r.Sync(pkgbits.SyncTypeParamNames)
// Note: This code assumes it only processes objects without
// implement type parameters. This is currently fine, because
// reader is only used to read in exported declarations, which are
// always package scoped.
if len(r.dict.bounds) == 0 {
return nil
}
// Careful: Type parameter lists may have cycles. To allow for this,
// we construct the type parameter list in two passes: first we
// create all the TypeNames and TypeParams, then we construct and
// set the bound type.
r.dict.tparams = make([]*types2.TypeParam, len(r.dict.bounds))
for i := range r.dict.bounds {
pos := r.pos()
pkg, name := r.localIdent()
tname := types2.NewTypeName(pos, pkg, name, nil)
r.dict.tparams[i] = types2.NewTypeParam(tname, nil)
}
for i, bound := range r.dict.bounds {
r.dict.tparams[i].SetConstraint(r.p.typIdx(bound, r.dict))
}
return r.dict.tparams
}
func (r *reader) method() *types2.Func {
r.Sync(pkgbits.SyncMethod)
pos := r.pos()
pkg, name := r.selector()
rtparams := r.typeParamNames()
sig := r.signature(r.param(), rtparams, nil)
_ = r.pos() // TODO(mdempsky): Remove; this is a hacker for linker.go.
return types2.NewFunc(pos, pkg, name, sig)
}
func (r *reader) qualifiedIdent() (*types2.Package, string) { return r.ident(pkgbits.SyncSym) }
func (r *reader) localIdent() (*types2.Package, string) { return r.ident(pkgbits.SyncLocalIdent) }
func (r *reader) selector() (*types2.Package, string) { return r.ident(pkgbits.SyncSelector) }
func (r *reader) ident(marker pkgbits.SyncMarker) (*types2.Package, string) {
r.Sync(marker)
return r.pkg(), r.String()
}
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