go iimport 源码
golang iimport 代码
文件路径：/src/cmd/compile/internal/importer/iimport.go
// Copyright 2018 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.
// Indexed package import.
// See cmd/compile/internal/typecheck/iexport.go for the export data format.
package importer
import (
"cmd/compile/internal/syntax"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types2"
"encoding/binary"
"fmt"
"go/constant"
"go/token"
"io"
"math/big"
"sort"
"strings"
)
type intReader struct {
*strings.Reader
path string
}
func (r *intReader) int64() int64 {
i, err := binary.ReadVarint(r.Reader)
if err != nil {
errorf("import %q: read varint error: %v", r.path, err)
}
return i
}
func (r *intReader) uint64() uint64 {
i, err := binary.ReadUvarint(r.Reader)
if err != nil {
errorf("import %q: read varint error: %v", r.path, err)
}
return i
}
// Keep this in sync with constants in iexport.go.
const (
iexportVersionGo1_11 = 0
iexportVersionPosCol = 1
iexportVersionGenerics = 2
iexportVersionGo1_18 = 2
iexportVersionCurrent = 2
)
type ident struct {
pkg *types2.Package
name string
}
const predeclReserved = 32
type itag uint64
const (
// Types
definedType itag = iota
pointerType
sliceType
arrayType
chanType
mapType
signatureType
structType
interfaceType
typeParamType
instanceType
unionType
)
const io_SeekCurrent = 1 // io.SeekCurrent (not defined in Go 1.4)
// iImportData imports a package from the serialized package data
// and returns the number of bytes consumed and a reference to the package.
// If the export data version is not recognized or the format is otherwise
// compromised, an error is returned.
func ImportData(imports map[string]*types2.Package, data, path string) (pkg *types2.Package, err error) {
const currentVersion = iexportVersionCurrent
version := int64(-1)
defer func() {
if e := recover(); e != nil {
if version > currentVersion {
err = fmt.Errorf("cannot import %q (%v), export data is newer version - update tool", path, e)
} else {
err = fmt.Errorf("cannot import %q (%v), possibly version skew - reinstall package", path, e)
}
}
}()
r := &intReader{strings.NewReader(data), path}
version = int64(r.uint64())
switch version {
case iexportVersionGo1_18, iexportVersionPosCol, iexportVersionGo1_11:
default:
errorf("unknown iexport format version %d", version)
}
sLen := int64(r.uint64())
dLen := int64(r.uint64())
whence, _ := r.Seek(0, io_SeekCurrent)
stringData := data[whence : whence+sLen]
declData := data[whence+sLen : whence+sLen+dLen]
r.Seek(sLen+dLen, io_SeekCurrent)
p := iimporter{
exportVersion: version,
ipath: path,
version: int(version),
stringData: stringData,
pkgCache: make(map[uint64]*types2.Package),
posBaseCache: make(map[uint64]*syntax.PosBase),
declData: declData,
pkgIndex: make(map[*types2.Package]map[string]uint64),
typCache: make(map[uint64]types2.Type),
// Separate map for typeparams, keyed by their package and unique
// name (name with subscript).
tparamIndex: make(map[ident]*types2.TypeParam),
}
for i, pt := range predeclared {
p.typCache[uint64(i)] = pt
}
pkgList := make([]*types2.Package, r.uint64())
for i := range pkgList {
pkgPathOff := r.uint64()
pkgPath := p.stringAt(pkgPathOff)
pkgName := p.stringAt(r.uint64())
pkgHeight := int(r.uint64())
if pkgPath == "" {
pkgPath = path
}
pkg := imports[pkgPath]
if pkg == nil {
pkg = types2.NewPackageHeight(pkgPath, pkgName, pkgHeight)
imports[pkgPath] = pkg
} else {
if pkg.Name() != pkgName {
errorf("conflicting names %s and %s for package %q", pkg.Name(), pkgName, path)
}
if pkg.Height() != pkgHeight {
errorf("conflicting heights %v and %v for package %q", pkg.Height(), pkgHeight, path)
}
}
p.pkgCache[pkgPathOff] = pkg
nameIndex := make(map[string]uint64)
for nSyms := r.uint64(); nSyms > 0; nSyms-- {
name := p.stringAt(r.uint64())
nameIndex[name] = r.uint64()
}
p.pkgIndex[pkg] = nameIndex
pkgList[i] = pkg
}
localpkg := pkgList[0]
names := make([]string, 0, len(p.pkgIndex[localpkg]))
for name := range p.pkgIndex[localpkg] {
names = append(names, name)
}
sort.Strings(names)
for _, name := range names {
p.doDecl(localpkg, name)
}
// SetConstraint can't be called if the constraint type is not yet complete.
// When type params are created in the 'P' case of (*importReader).obj(),
// the associated constraint type may not be complete due to recursion.
// Therefore, we defer calling SetConstraint there, and call it here instead
// after all types are complete.
for _, d := range p.later {
d.t.SetConstraint(d.constraint)
}
// record all referenced packages as imports
list := append(([]*types2.Package)(nil), pkgList[1:]...)
sort.Sort(byPath(list))
localpkg.SetImports(list)
// package was imported completely and without errors
localpkg.MarkComplete()
return localpkg, nil
}
type setConstraintArgs struct {
t *types2.TypeParam
constraint types2.Type
}
type iimporter struct {
exportVersion int64
ipath string
version int
stringData string
pkgCache map[uint64]*types2.Package
posBaseCache map[uint64]*syntax.PosBase
declData string
pkgIndex map[*types2.Package]map[string]uint64
typCache map[uint64]types2.Type
tparamIndex map[ident]*types2.TypeParam
interfaceList []*types2.Interface
// Arguments for calls to SetConstraint that are deferred due to recursive types
later []setConstraintArgs
}
func (p *iimporter) doDecl(pkg *types2.Package, name string) {
// See if we've already imported this declaration.
if obj := pkg.Scope().Lookup(name); obj != nil {
return
}
off, ok := p.pkgIndex[pkg][name]
if !ok {
errorf("%v.%v not in index", pkg, name)
}
r := &importReader{p: p, currPkg: pkg}
// Reader.Reset is not available in Go 1.4.
// Use bytes.NewReader for now.
// r.declReader.Reset(p.declData[off:])
r.declReader = *strings.NewReader(p.declData[off:])
r.obj(name)
}
func (p *iimporter) stringAt(off uint64) string {
var x [binary.MaxVarintLen64]byte
n := copy(x[:], p.stringData[off:])
slen, n := binary.Uvarint(x[:n])
if n <= 0 {
errorf("varint failed")
}
spos := off + uint64(n)
return p.stringData[spos : spos+slen]
}
func (p *iimporter) pkgAt(off uint64) *types2.Package {
if pkg, ok := p.pkgCache[off]; ok {
return pkg
}
path := p.stringAt(off)
errorf("missing package %q in %q", path, p.ipath)
return nil
}
func (p *iimporter) posBaseAt(off uint64) *syntax.PosBase {
if posBase, ok := p.posBaseCache[off]; ok {
return posBase
}
filename := p.stringAt(off)
posBase := syntax.NewTrimmedFileBase(filename, true)
p.posBaseCache[off] = posBase
return posBase
}
func (p *iimporter) typAt(off uint64, base *types2.Named) types2.Type {
if t, ok := p.typCache[off]; ok && canReuse(base, t) {
return t
}
if off < predeclReserved {
errorf("predeclared type missing from cache: %v", off)
}
r := &importReader{p: p}
// Reader.Reset is not available in Go 1.4.
// Use bytes.NewReader for now.
// r.declReader.Reset(p.declData[off-predeclReserved:])
r.declReader = *strings.NewReader(p.declData[off-predeclReserved:])
t := r.doType(base)
if canReuse(base, t) {
p.typCache[off] = t
}
return t
}
// canReuse reports whether the type rhs on the RHS of the declaration for def
// may be re-used.
//
// Specifically, if def is non-nil and rhs is an interface type with methods, it
// may not be re-used because we have a convention of setting the receiver type
// for interface methods to def.
func canReuse(def *types2.Named, rhs types2.Type) bool {
if def == nil {
return true
}
iface, _ := rhs.(*types2.Interface)
if iface == nil {
return true
}
// Don't use iface.Empty() here as iface may not be complete.
return iface.NumEmbeddeds() == 0 && iface.NumExplicitMethods() == 0
}
type importReader struct {
p *iimporter
declReader strings.Reader
currPkg *types2.Package
prevPosBase *syntax.PosBase
prevLine int64
prevColumn int64
}
func (r *importReader) obj(name string) {
tag := r.byte()
pos := r.pos()
switch tag {
case 'A':
typ := r.typ()
r.declare(types2.NewTypeName(pos, r.currPkg, name, typ))
case 'C':
typ, val := r.value()
r.declare(types2.NewConst(pos, r.currPkg, name, typ, val))
case 'F', 'G':
var tparams []*types2.TypeParam
if tag == 'G' {
tparams = r.tparamList()
}
sig := r.signature(nil, nil, tparams)
r.declare(types2.NewFunc(pos, r.currPkg, name, sig))
case 'T', 'U':
// Types can be recursive. We need to setup a stub
// declaration before recursing.
obj := types2.NewTypeName(pos, r.currPkg, name, nil)
named := types2.NewNamed(obj, nil, nil)
// Declare obj before calling r.tparamList, so the new type name is recognized
// if used in the constraint of one of its own typeparams (see #48280).
r.declare(obj)
if tag == 'U' {
tparams := r.tparamList()
named.SetTypeParams(tparams)
}
underlying := r.p.typAt(r.uint64(), named).Underlying()
named.SetUnderlying(underlying)
if !isInterface(underlying) {
for n := r.uint64(); n > 0; n-- {
mpos := r.pos()
mname := r.ident()
recv := r.param()
// If the receiver has any targs, set those as the
// rparams of the method (since those are the
// typeparams being used in the method sig/body).
targs := baseType(recv.Type()).TypeArgs()
var rparams []*types2.TypeParam
if targs.Len() > 0 {
rparams = make([]*types2.TypeParam, targs.Len())
for i := range rparams {
rparams[i], _ = targs.At(i).(*types2.TypeParam)
}
}
msig := r.signature(recv, rparams, nil)
named.AddMethod(types2.NewFunc(mpos, r.currPkg, mname, msig))
}
}
case 'P':
// We need to "declare" a typeparam in order to have a name that
// can be referenced recursively (if needed) in the type param's
// bound.
if r.p.exportVersion < iexportVersionGenerics {
errorf("unexpected type param type")
}
name0 := typecheck.TparamName(name)
if name0 == "" {
errorf("malformed type parameter export name %s: missing prefix", name)
}
tn := types2.NewTypeName(pos, r.currPkg, name0, nil)
t := types2.NewTypeParam(tn, nil)
// To handle recursive references to the typeparam within its
// bound, save the partial type in tparamIndex before reading the bounds.
id := ident{r.currPkg, name}
r.p.tparamIndex[id] = t
var implicit bool
if r.p.exportVersion >= iexportVersionGo1_18 {
implicit = r.bool()
}
constraint := r.typ()
if implicit {
iface, _ := constraint.(*types2.Interface)
if iface == nil {
errorf("non-interface constraint marked implicit")
}
iface.MarkImplicit()
}
// The constraint type may not be complete, if we
// are in the middle of a type recursion involving type
// constraints. So, we defer SetConstraint until we have
// completely set up all types in ImportData.
r.p.later = append(r.p.later, setConstraintArgs{t: t, constraint: constraint})
case 'V':
typ := r.typ()
r.declare(types2.NewVar(pos, r.currPkg, name, typ))
default:
errorf("unexpected tag: %v", tag)
}
}
func (r *importReader) declare(obj types2.Object) {
obj.Pkg().Scope().Insert(obj)
}
func (r *importReader) value() (typ types2.Type, val constant.Value) {
typ = r.typ()
if r.p.exportVersion >= iexportVersionGo1_18 {
// TODO: add support for using the kind
_ = constant.Kind(r.int64())
}
switch b := typ.Underlying().(*types2.Basic); b.Info() & types2.IsConstType {
case types2.IsBoolean:
val = constant.MakeBool(r.bool())
case types2.IsString:
val = constant.MakeString(r.string())
case types2.IsInteger:
var x big.Int
r.mpint(&x, b)
val = constant.Make(&x)
case types2.IsFloat:
val = r.mpfloat(b)
case types2.IsComplex:
re := r.mpfloat(b)
im := r.mpfloat(b)
val = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
default:
errorf("unexpected type %v", typ) // panics
panic("unreachable")
}
return
}
func intSize(b *types2.Basic) (signed bool, maxBytes uint) {
if (b.Info() & types2.IsUntyped) != 0 {
return true, 64
}
switch b.Kind() {
case types2.Float32, types2.Complex64:
return true, 3
case types2.Float64, types2.Complex128:
return true, 7
}
signed = (b.Info() & types2.IsUnsigned) == 0
switch b.Kind() {
case types2.Int8, types2.Uint8:
maxBytes = 1
case types2.Int16, types2.Uint16:
maxBytes = 2
case types2.Int32, types2.Uint32:
maxBytes = 4
default:
maxBytes = 8
}
return
}
func (r *importReader) mpint(x *big.Int, typ *types2.Basic) {
signed, maxBytes := intSize(typ)
maxSmall := 256 - maxBytes
if signed {
maxSmall = 256 - 2*maxBytes
}
if maxBytes == 1 {
maxSmall = 256
}
n, _ := r.declReader.ReadByte()
if uint(n) < maxSmall {
v := int64(n)
if signed {
v >>= 1
if n&1 != 0 {
v = ^v
}
}
x.SetInt64(v)
return
}
v := -n
if signed {
v = -(n &^ 1) >> 1
}
if v < 1 || uint(v) > maxBytes {
errorf("weird decoding: %v, %v => %v", n, signed, v)
}
b := make([]byte, v)
io.ReadFull(&r.declReader, b)
x.SetBytes(b)
if signed && n&1 != 0 {
x.Neg(x)
}
}
func (r *importReader) mpfloat(typ *types2.Basic) constant.Value {
var mant big.Int
r.mpint(&mant, typ)
var f big.Float
f.SetInt(&mant)
if f.Sign() != 0 {
f.SetMantExp(&f, int(r.int64()))
}
return constant.Make(&f)
}
func (r *importReader) ident() string {
return r.string()
}
func (r *importReader) qualifiedIdent() (*types2.Package, string) {
name := r.string()
pkg := r.pkg()
return pkg, name
}
func (r *importReader) pos() syntax.Pos {
if r.p.version >= 1 {
r.posv1()
} else {
r.posv0()
}
if (r.prevPosBase == nil || r.prevPosBase.Filename() == "") && r.prevLine == 0 && r.prevColumn == 0 {
return syntax.Pos{}
}
return syntax.MakePos(r.prevPosBase, uint(r.prevLine), uint(r.prevColumn))
}
func (r *importReader) posv0() {
delta := r.int64()
if delta != deltaNewFile {
r.prevLine += delta
} else if l := r.int64(); l == -1 {
r.prevLine += deltaNewFile
} else {
r.prevPosBase = r.posBase()
r.prevLine = l
}
}
func (r *importReader) posv1() {
delta := r.int64()
r.prevColumn += delta >> 1
if delta&1 != 0 {
delta = r.int64()
r.prevLine += delta >> 1
if delta&1 != 0 {
r.prevPosBase = r.posBase()
}
}
}
func (r *importReader) typ() types2.Type {
return r.p.typAt(r.uint64(), nil)
}
func isInterface(t types2.Type) bool {
_, ok := t.(*types2.Interface)
return ok
}
func (r *importReader) pkg() *types2.Package { return r.p.pkgAt(r.uint64()) }
func (r *importReader) string() string { return r.p.stringAt(r.uint64()) }
func (r *importReader) posBase() *syntax.PosBase { return r.p.posBaseAt(r.uint64()) }
func (r *importReader) doType(base *types2.Named) types2.Type {
switch k := r.kind(); k {
default:
errorf("unexpected kind tag in %q: %v", r.p.ipath, k)
return nil
case definedType:
pkg, name := r.qualifiedIdent()
r.p.doDecl(pkg, name)
return pkg.Scope().Lookup(name).(*types2.TypeName).Type()
case pointerType:
return types2.NewPointer(r.typ())
case sliceType:
return types2.NewSlice(r.typ())
case arrayType:
n := r.uint64()
return types2.NewArray(r.typ(), int64(n))
case chanType:
dir := chanDir(int(r.uint64()))
return types2.NewChan(dir, r.typ())
case mapType:
return types2.NewMap(r.typ(), r.typ())
case signatureType:
r.currPkg = r.pkg()
return r.signature(nil, nil, nil)
case structType:
r.currPkg = r.pkg()
fields := make([]*types2.Var, r.uint64())
tags := make([]string, len(fields))
for i := range fields {
fpos := r.pos()
fname := r.ident()
ftyp := r.typ()
emb := r.bool()
tag := r.string()
fields[i] = types2.NewField(fpos, r.currPkg, fname, ftyp, emb)
tags[i] = tag
}
return types2.NewStruct(fields, tags)
case interfaceType:
r.currPkg = r.pkg()
embeddeds := make([]types2.Type, r.uint64())
for i := range embeddeds {
_ = r.pos()
embeddeds[i] = r.typ()
}
methods := make([]*types2.Func, r.uint64())
for i := range methods {
mpos := r.pos()
mname := r.ident()
// TODO(mdempsky): Matches bimport.go, but I
// don't agree with this.
var recv *types2.Var
if base != nil {
recv = types2.NewVar(syntax.Pos{}, r.currPkg, "", base)
}
msig := r.signature(recv, nil, nil)
methods[i] = types2.NewFunc(mpos, r.currPkg, mname, msig)
}
typ := types2.NewInterfaceType(methods, embeddeds)
r.p.interfaceList = append(r.p.interfaceList, typ)
return typ
case typeParamType:
if r.p.exportVersion < iexportVersionGenerics {
errorf("unexpected type param type")
}
pkg, name := r.qualifiedIdent()
id := ident{pkg, name}
if t, ok := r.p.tparamIndex[id]; ok {
// We're already in the process of importing this typeparam.
return t
}
// Otherwise, import the definition of the typeparam now.
r.p.doDecl(pkg, name)
return r.p.tparamIndex[id]
case instanceType:
if r.p.exportVersion < iexportVersionGenerics {
errorf("unexpected instantiation type")
}
// pos does not matter for instances: they are positioned on the original
// type.
_ = r.pos()
len := r.uint64()
targs := make([]types2.Type, len)
for i := range targs {
targs[i] = r.typ()
}
baseType := r.typ()
// The imported instantiated type doesn't include any methods, so
// we must always use the methods of the base (orig) type.
// TODO provide a non-nil *Context
t, _ := types2.Instantiate(nil, baseType, targs, false)
return t
case unionType:
if r.p.exportVersion < iexportVersionGenerics {
errorf("unexpected instantiation type")
}
terms := make([]*types2.Term, r.uint64())
for i := range terms {
terms[i] = types2.NewTerm(r.bool(), r.typ())
}
return types2.NewUnion(terms)
}
}
func (r *importReader) kind() itag {
return itag(r.uint64())
}
func (r *importReader) signature(recv *types2.Var, rparams, tparams []*types2.TypeParam) *types2.Signature {
params := r.paramList()
results := r.paramList()
variadic := params.Len() > 0 && r.bool()
return types2.NewSignatureType(recv, rparams, tparams, params, results, variadic)
}
func (r *importReader) tparamList() []*types2.TypeParam {
n := r.uint64()
if n == 0 {
return nil
}
xs := make([]*types2.TypeParam, n)
for i := range xs {
xs[i] = r.typ().(*types2.TypeParam)
}
return xs
}
func (r *importReader) paramList() *types2.Tuple {
xs := make([]*types2.Var, r.uint64())
for i := range xs {
xs[i] = r.param()
}
return types2.NewTuple(xs...)
}
func (r *importReader) param() *types2.Var {
pos := r.pos()
name := r.ident()
typ := r.typ()
return types2.NewParam(pos, r.currPkg, name, typ)
}
func (r *importReader) bool() bool {
return r.uint64() != 0
}
func (r *importReader) int64() int64 {
n, err := binary.ReadVarint(&r.declReader)
if err != nil {
errorf("readVarint: %v", err)
}
return n
}
func (r *importReader) uint64() uint64 {
n, err := binary.ReadUvarint(&r.declReader)
if err != nil {
errorf("readUvarint: %v", err)
}
return n
}
func (r *importReader) byte() byte {
x, err := r.declReader.ReadByte()
if err != nil {
errorf("declReader.ReadByte: %v", err)
}
return x
}
func baseType(typ types2.Type) *types2.Named {
// pointer receivers are never types2.Named types
if p, _ := typ.(*types2.Pointer); p != nil {
typ = p.Elem()
}
// receiver base types are always (possibly generic) types2.Named types
n, _ := typ.(*types2.Named)
return n
}
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