--- /dev/null
+// Copyright 2016 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.
+
+// Binary package export.
+// This file was derived from $GOROOT/src/cmd/compile/internal/gc/bexport.go;
+// see that file for specification of the format.
+
+package gcimporter
+
+import (
+ "bytes"
+ "encoding/binary"
+ "fmt"
+ "go/ast"
+ "go/constant"
+ "go/token"
+ "go/types"
+ "math"
+ "math/big"
+ "sort"
+ "strings"
+)
+
+// If debugFormat is set, each integer and string value is preceded by a marker
+// and position information in the encoding. This mechanism permits an importer
+// to recognize immediately when it is out of sync. The importer recognizes this
+// mode automatically (i.e., it can import export data produced with debugging
+// support even if debugFormat is not set at the time of import). This mode will
+// lead to massively larger export data (by a factor of 2 to 3) and should only
+// be enabled during development and debugging.
+//
+// NOTE: This flag is the first flag to enable if importing dies because of
+// (suspected) format errors, and whenever a change is made to the format.
+const debugFormat = false // default: false
+
+// If trace is set, debugging output is printed to std out.
+const trace = false // default: false
+
+// Current export format version. Increase with each format change.
+// Note: The latest binary (non-indexed) export format is at version 6.
+// This exporter is still at level 4, but it doesn't matter since
+// the binary importer can handle older versions just fine.
+// 6: package height (CL 105038) -- NOT IMPLEMENTED HERE
+// 5: improved position encoding efficiency (issue 20080, CL 41619) -- NOT IMPLEMEMTED HERE
+// 4: type name objects support type aliases, uses aliasTag
+// 3: Go1.8 encoding (same as version 2, aliasTag defined but never used)
+// 2: removed unused bool in ODCL export (compiler only)
+// 1: header format change (more regular), export package for _ struct fields
+// 0: Go1.7 encoding
+const exportVersion = 4
+
+// trackAllTypes enables cycle tracking for all types, not just named
+// types. The existing compiler invariants assume that unnamed types
+// that are not completely set up are not used, or else there are spurious
+// errors.
+// If disabled, only named types are tracked, possibly leading to slightly
+// less efficient encoding in rare cases. It also prevents the export of
+// some corner-case type declarations (but those are not handled correctly
+// with with the textual export format either).
+// TODO(gri) enable and remove once issues caused by it are fixed
+const trackAllTypes = false
+
+type exporter struct {
+ fset *token.FileSet
+ out bytes.Buffer
+
+ // object -> index maps, indexed in order of serialization
+ strIndex map[string]int
+ pkgIndex map[*types.Package]int
+ typIndex map[types.Type]int
+
+ // position encoding
+ posInfoFormat bool
+ prevFile string
+ prevLine int
+
+ // debugging support
+ written int // bytes written
+ indent int // for trace
+}
+
+// internalError represents an error generated inside this package.
+type internalError string
+
+func (e internalError) Error() string { return "gcimporter: " + string(e) }
+
+func internalErrorf(format string, args ...interface{}) error {
+ return internalError(fmt.Sprintf(format, args...))
+}
+
+// BExportData returns binary export data for pkg.
+// If no file set is provided, position info will be missing.
+func BExportData(fset *token.FileSet, pkg *types.Package) (b []byte, err error) {
+ defer func() {
+ if e := recover(); e != nil {
+ if ierr, ok := e.(internalError); ok {
+ err = ierr
+ return
+ }
+ // Not an internal error; panic again.
+ panic(e)
+ }
+ }()
+
+ p := exporter{
+ fset: fset,
+ strIndex: map[string]int{"": 0}, // empty string is mapped to 0
+ pkgIndex: make(map[*types.Package]int),
+ typIndex: make(map[types.Type]int),
+ posInfoFormat: true, // TODO(gri) might become a flag, eventually
+ }
+
+ // write version info
+ // The version string must start with "version %d" where %d is the version
+ // number. Additional debugging information may follow after a blank; that
+ // text is ignored by the importer.
+ p.rawStringln(fmt.Sprintf("version %d", exportVersion))
+ var debug string
+ if debugFormat {
+ debug = "debug"
+ }
+ p.rawStringln(debug) // cannot use p.bool since it's affected by debugFormat; also want to see this clearly
+ p.bool(trackAllTypes)
+ p.bool(p.posInfoFormat)
+
+ // --- generic export data ---
+
+ // populate type map with predeclared "known" types
+ for index, typ := range predeclared() {
+ p.typIndex[typ] = index
+ }
+ if len(p.typIndex) != len(predeclared()) {
+ return nil, internalError("duplicate entries in type map?")
+ }
+
+ // write package data
+ p.pkg(pkg, true)
+ if trace {
+ p.tracef("\n")
+ }
+
+ // write objects
+ objcount := 0
+ scope := pkg.Scope()
+ for _, name := range scope.Names() {
+ if !ast.IsExported(name) {
+ continue
+ }
+ if trace {
+ p.tracef("\n")
+ }
+ p.obj(scope.Lookup(name))
+ objcount++
+ }
+
+ // indicate end of list
+ if trace {
+ p.tracef("\n")
+ }
+ p.tag(endTag)
+
+ // for self-verification only (redundant)
+ p.int(objcount)
+
+ if trace {
+ p.tracef("\n")
+ }
+
+ // --- end of export data ---
+
+ return p.out.Bytes(), nil
+}
+
+func (p *exporter) pkg(pkg *types.Package, emptypath bool) {
+ if pkg == nil {
+ panic(internalError("unexpected nil pkg"))
+ }
+
+ // if we saw the package before, write its index (>= 0)
+ if i, ok := p.pkgIndex[pkg]; ok {
+ p.index('P', i)
+ return
+ }
+
+ // otherwise, remember the package, write the package tag (< 0) and package data
+ if trace {
+ p.tracef("P%d = { ", len(p.pkgIndex))
+ defer p.tracef("} ")
+ }
+ p.pkgIndex[pkg] = len(p.pkgIndex)
+
+ p.tag(packageTag)
+ p.string(pkg.Name())
+ if emptypath {
+ p.string("")
+ } else {
+ p.string(pkg.Path())
+ }
+}
+
+func (p *exporter) obj(obj types.Object) {
+ switch obj := obj.(type) {
+ case *types.Const:
+ p.tag(constTag)
+ p.pos(obj)
+ p.qualifiedName(obj)
+ p.typ(obj.Type())
+ p.value(obj.Val())
+
+ case *types.TypeName:
+ if obj.IsAlias() {
+ p.tag(aliasTag)
+ p.pos(obj)
+ p.qualifiedName(obj)
+ } else {
+ p.tag(typeTag)
+ }
+ p.typ(obj.Type())
+
+ case *types.Var:
+ p.tag(varTag)
+ p.pos(obj)
+ p.qualifiedName(obj)
+ p.typ(obj.Type())
+
+ case *types.Func:
+ p.tag(funcTag)
+ p.pos(obj)
+ p.qualifiedName(obj)
+ sig := obj.Type().(*types.Signature)
+ p.paramList(sig.Params(), sig.Variadic())
+ p.paramList(sig.Results(), false)
+
+ default:
+ panic(internalErrorf("unexpected object %v (%T)", obj, obj))
+ }
+}
+
+func (p *exporter) pos(obj types.Object) {
+ if !p.posInfoFormat {
+ return
+ }
+
+ file, line := p.fileLine(obj)
+ if file == p.prevFile {
+ // common case: write line delta
+ // delta == 0 means different file or no line change
+ delta := line - p.prevLine
+ p.int(delta)
+ if delta == 0 {
+ p.int(-1) // -1 means no file change
+ }
+ } else {
+ // different file
+ p.int(0)
+ // Encode filename as length of common prefix with previous
+ // filename, followed by (possibly empty) suffix. Filenames
+ // frequently share path prefixes, so this can save a lot
+ // of space and make export data size less dependent on file
+ // path length. The suffix is unlikely to be empty because
+ // file names tend to end in ".go".
+ n := commonPrefixLen(p.prevFile, file)
+ p.int(n) // n >= 0
+ p.string(file[n:]) // write suffix only
+ p.prevFile = file
+ p.int(line)
+ }
+ p.prevLine = line
+}
+
+func (p *exporter) fileLine(obj types.Object) (file string, line int) {
+ if p.fset != nil {
+ pos := p.fset.Position(obj.Pos())
+ file = pos.Filename
+ line = pos.Line
+ }
+ return
+}
+
+func commonPrefixLen(a, b string) int {
+ if len(a) > len(b) {
+ a, b = b, a
+ }
+ // len(a) <= len(b)
+ i := 0
+ for i < len(a) && a[i] == b[i] {
+ i++
+ }
+ return i
+}
+
+func (p *exporter) qualifiedName(obj types.Object) {
+ p.string(obj.Name())
+ p.pkg(obj.Pkg(), false)
+}
+
+func (p *exporter) typ(t types.Type) {
+ if t == nil {
+ panic(internalError("nil type"))
+ }
+
+ // Possible optimization: Anonymous pointer types *T where
+ // T is a named type are common. We could canonicalize all
+ // such types *T to a single type PT = *T. This would lead
+ // to at most one *T entry in typIndex, and all future *T's
+ // would be encoded as the respective index directly. Would
+ // save 1 byte (pointerTag) per *T and reduce the typIndex
+ // size (at the cost of a canonicalization map). We can do
+ // this later, without encoding format change.
+
+ // if we saw the type before, write its index (>= 0)
+ if i, ok := p.typIndex[t]; ok {
+ p.index('T', i)
+ return
+ }
+
+ // otherwise, remember the type, write the type tag (< 0) and type data
+ if trackAllTypes {
+ if trace {
+ p.tracef("T%d = {>\n", len(p.typIndex))
+ defer p.tracef("<\n} ")
+ }
+ p.typIndex[t] = len(p.typIndex)
+ }
+
+ switch t := t.(type) {
+ case *types.Named:
+ if !trackAllTypes {
+ // if we don't track all types, track named types now
+ p.typIndex[t] = len(p.typIndex)
+ }
+
+ p.tag(namedTag)
+ p.pos(t.Obj())
+ p.qualifiedName(t.Obj())
+ p.typ(t.Underlying())
+ if !types.IsInterface(t) {
+ p.assocMethods(t)
+ }
+
+ case *types.Array:
+ p.tag(arrayTag)
+ p.int64(t.Len())
+ p.typ(t.Elem())
+
+ case *types.Slice:
+ p.tag(sliceTag)
+ p.typ(t.Elem())
+
+ case *dddSlice:
+ p.tag(dddTag)
+ p.typ(t.elem)
+
+ case *types.Struct:
+ p.tag(structTag)
+ p.fieldList(t)
+
+ case *types.Pointer:
+ p.tag(pointerTag)
+ p.typ(t.Elem())
+
+ case *types.Signature:
+ p.tag(signatureTag)
+ p.paramList(t.Params(), t.Variadic())
+ p.paramList(t.Results(), false)
+
+ case *types.Interface:
+ p.tag(interfaceTag)
+ p.iface(t)
+
+ case *types.Map:
+ p.tag(mapTag)
+ p.typ(t.Key())
+ p.typ(t.Elem())
+
+ case *types.Chan:
+ p.tag(chanTag)
+ p.int(int(3 - t.Dir())) // hack
+ p.typ(t.Elem())
+
+ default:
+ panic(internalErrorf("unexpected type %T: %s", t, t))
+ }
+}
+
+func (p *exporter) assocMethods(named *types.Named) {
+ // Sort methods (for determinism).
+ var methods []*types.Func
+ for i := 0; i < named.NumMethods(); i++ {
+ methods = append(methods, named.Method(i))
+ }
+ sort.Sort(methodsByName(methods))
+
+ p.int(len(methods))
+
+ if trace && methods != nil {
+ p.tracef("associated methods {>\n")
+ }
+
+ for i, m := range methods {
+ if trace && i > 0 {
+ p.tracef("\n")
+ }
+
+ p.pos(m)
+ name := m.Name()
+ p.string(name)
+ if !exported(name) {
+ p.pkg(m.Pkg(), false)
+ }
+
+ sig := m.Type().(*types.Signature)
+ p.paramList(types.NewTuple(sig.Recv()), false)
+ p.paramList(sig.Params(), sig.Variadic())
+ p.paramList(sig.Results(), false)
+ p.int(0) // dummy value for go:nointerface pragma - ignored by importer
+ }
+
+ if trace && methods != nil {
+ p.tracef("<\n} ")
+ }
+}
+
+type methodsByName []*types.Func
+
+func (x methodsByName) Len() int { return len(x) }
+func (x methodsByName) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
+func (x methodsByName) Less(i, j int) bool { return x[i].Name() < x[j].Name() }
+
+func (p *exporter) fieldList(t *types.Struct) {
+ if trace && t.NumFields() > 0 {
+ p.tracef("fields {>\n")
+ defer p.tracef("<\n} ")
+ }
+
+ p.int(t.NumFields())
+ for i := 0; i < t.NumFields(); i++ {
+ if trace && i > 0 {
+ p.tracef("\n")
+ }
+ p.field(t.Field(i))
+ p.string(t.Tag(i))
+ }
+}
+
+func (p *exporter) field(f *types.Var) {
+ if !f.IsField() {
+ panic(internalError("field expected"))
+ }
+
+ p.pos(f)
+ p.fieldName(f)
+ p.typ(f.Type())
+}
+
+func (p *exporter) iface(t *types.Interface) {
+ // TODO(gri): enable importer to load embedded interfaces,
+ // then emit Embeddeds and ExplicitMethods separately here.
+ p.int(0)
+
+ n := t.NumMethods()
+ if trace && n > 0 {
+ p.tracef("methods {>\n")
+ defer p.tracef("<\n} ")
+ }
+ p.int(n)
+ for i := 0; i < n; i++ {
+ if trace && i > 0 {
+ p.tracef("\n")
+ }
+ p.method(t.Method(i))
+ }
+}
+
+func (p *exporter) method(m *types.Func) {
+ sig := m.Type().(*types.Signature)
+ if sig.Recv() == nil {
+ panic(internalError("method expected"))
+ }
+
+ p.pos(m)
+ p.string(m.Name())
+ if m.Name() != "_" && !ast.IsExported(m.Name()) {
+ p.pkg(m.Pkg(), false)
+ }
+
+ // interface method; no need to encode receiver.
+ p.paramList(sig.Params(), sig.Variadic())
+ p.paramList(sig.Results(), false)
+}
+
+func (p *exporter) fieldName(f *types.Var) {
+ name := f.Name()
+
+ if f.Anonymous() {
+ // anonymous field - we distinguish between 3 cases:
+ // 1) field name matches base type name and is exported
+ // 2) field name matches base type name and is not exported
+ // 3) field name doesn't match base type name (alias name)
+ bname := basetypeName(f.Type())
+ if name == bname {
+ if ast.IsExported(name) {
+ name = "" // 1) we don't need to know the field name or package
+ } else {
+ name = "?" // 2) use unexported name "?" to force package export
+ }
+ } else {
+ // 3) indicate alias and export name as is
+ // (this requires an extra "@" but this is a rare case)
+ p.string("@")
+ }
+ }
+
+ p.string(name)
+ if name != "" && !ast.IsExported(name) {
+ p.pkg(f.Pkg(), false)
+ }
+}
+
+func basetypeName(typ types.Type) string {
+ switch typ := deref(typ).(type) {
+ case *types.Basic:
+ return typ.Name()
+ case *types.Named:
+ return typ.Obj().Name()
+ default:
+ return "" // unnamed type
+ }
+}
+
+func (p *exporter) paramList(params *types.Tuple, variadic bool) {
+ // use negative length to indicate unnamed parameters
+ // (look at the first parameter only since either all
+ // names are present or all are absent)
+ n := params.Len()
+ if n > 0 && params.At(0).Name() == "" {
+ n = -n
+ }
+ p.int(n)
+ for i := 0; i < params.Len(); i++ {
+ q := params.At(i)
+ t := q.Type()
+ if variadic && i == params.Len()-1 {
+ t = &dddSlice{t.(*types.Slice).Elem()}
+ }
+ p.typ(t)
+ if n > 0 {
+ name := q.Name()
+ p.string(name)
+ if name != "_" {
+ p.pkg(q.Pkg(), false)
+ }
+ }
+ p.string("") // no compiler-specific info
+ }
+}
+
+func (p *exporter) value(x constant.Value) {
+ if trace {
+ p.tracef("= ")
+ }
+
+ switch x.Kind() {
+ case constant.Bool:
+ tag := falseTag
+ if constant.BoolVal(x) {
+ tag = trueTag
+ }
+ p.tag(tag)
+
+ case constant.Int:
+ if v, exact := constant.Int64Val(x); exact {
+ // common case: x fits into an int64 - use compact encoding
+ p.tag(int64Tag)
+ p.int64(v)
+ return
+ }
+ // uncommon case: large x - use float encoding
+ // (powers of 2 will be encoded efficiently with exponent)
+ p.tag(floatTag)
+ p.float(constant.ToFloat(x))
+
+ case constant.Float:
+ p.tag(floatTag)
+ p.float(x)
+
+ case constant.Complex:
+ p.tag(complexTag)
+ p.float(constant.Real(x))
+ p.float(constant.Imag(x))
+
+ case constant.String:
+ p.tag(stringTag)
+ p.string(constant.StringVal(x))
+
+ case constant.Unknown:
+ // package contains type errors
+ p.tag(unknownTag)
+
+ default:
+ panic(internalErrorf("unexpected value %v (%T)", x, x))
+ }
+}
+
+func (p *exporter) float(x constant.Value) {
+ if x.Kind() != constant.Float {
+ panic(internalErrorf("unexpected constant %v, want float", x))
+ }
+ // extract sign (there is no -0)
+ sign := constant.Sign(x)
+ if sign == 0 {
+ // x == 0
+ p.int(0)
+ return
+ }
+ // x != 0
+
+ var f big.Float
+ if v, exact := constant.Float64Val(x); exact {
+ // float64
+ f.SetFloat64(v)
+ } else if num, denom := constant.Num(x), constant.Denom(x); num.Kind() == constant.Int {
+ // TODO(gri): add big.Rat accessor to constant.Value.
+ r := valueToRat(num)
+ f.SetRat(r.Quo(r, valueToRat(denom)))
+ } else {
+ // Value too large to represent as a fraction => inaccessible.
+ // TODO(gri): add big.Float accessor to constant.Value.
+ f.SetFloat64(math.MaxFloat64) // FIXME
+ }
+
+ // extract exponent such that 0.5 <= m < 1.0
+ var m big.Float
+ exp := f.MantExp(&m)
+
+ // extract mantissa as *big.Int
+ // - set exponent large enough so mant satisfies mant.IsInt()
+ // - get *big.Int from mant
+ m.SetMantExp(&m, int(m.MinPrec()))
+ mant, acc := m.Int(nil)
+ if acc != big.Exact {
+ panic(internalError("internal error"))
+ }
+
+ p.int(sign)
+ p.int(exp)
+ p.string(string(mant.Bytes()))
+}
+
+func valueToRat(x constant.Value) *big.Rat {
+ // Convert little-endian to big-endian.
+ // I can't believe this is necessary.
+ bytes := constant.Bytes(x)
+ for i := 0; i < len(bytes)/2; i++ {
+ bytes[i], bytes[len(bytes)-1-i] = bytes[len(bytes)-1-i], bytes[i]
+ }
+ return new(big.Rat).SetInt(new(big.Int).SetBytes(bytes))
+}
+
+func (p *exporter) bool(b bool) bool {
+ if trace {
+ p.tracef("[")
+ defer p.tracef("= %v] ", b)
+ }
+
+ x := 0
+ if b {
+ x = 1
+ }
+ p.int(x)
+ return b
+}
+
+// ----------------------------------------------------------------------------
+// Low-level encoders
+
+func (p *exporter) index(marker byte, index int) {
+ if index < 0 {
+ panic(internalError("invalid index < 0"))
+ }
+ if debugFormat {
+ p.marker('t')
+ }
+ if trace {
+ p.tracef("%c%d ", marker, index)
+ }
+ p.rawInt64(int64(index))
+}
+
+func (p *exporter) tag(tag int) {
+ if tag >= 0 {
+ panic(internalError("invalid tag >= 0"))
+ }
+ if debugFormat {
+ p.marker('t')
+ }
+ if trace {
+ p.tracef("%s ", tagString[-tag])
+ }
+ p.rawInt64(int64(tag))
+}
+
+func (p *exporter) int(x int) {
+ p.int64(int64(x))
+}
+
+func (p *exporter) int64(x int64) {
+ if debugFormat {
+ p.marker('i')
+ }
+ if trace {
+ p.tracef("%d ", x)
+ }
+ p.rawInt64(x)
+}
+
+func (p *exporter) string(s string) {
+ if debugFormat {
+ p.marker('s')
+ }
+ if trace {
+ p.tracef("%q ", s)
+ }
+ // if we saw the string before, write its index (>= 0)
+ // (the empty string is mapped to 0)
+ if i, ok := p.strIndex[s]; ok {
+ p.rawInt64(int64(i))
+ return
+ }
+ // otherwise, remember string and write its negative length and bytes
+ p.strIndex[s] = len(p.strIndex)
+ p.rawInt64(-int64(len(s)))
+ for i := 0; i < len(s); i++ {
+ p.rawByte(s[i])
+ }
+}
+
+// marker emits a marker byte and position information which makes
+// it easy for a reader to detect if it is "out of sync". Used for
+// debugFormat format only.
+func (p *exporter) marker(m byte) {
+ p.rawByte(m)
+ // Enable this for help tracking down the location
+ // of an incorrect marker when running in debugFormat.
+ if false && trace {
+ p.tracef("#%d ", p.written)
+ }
+ p.rawInt64(int64(p.written))
+}
+
+// rawInt64 should only be used by low-level encoders.
+func (p *exporter) rawInt64(x int64) {
+ var tmp [binary.MaxVarintLen64]byte
+ n := binary.PutVarint(tmp[:], x)
+ for i := 0; i < n; i++ {
+ p.rawByte(tmp[i])
+ }
+}
+
+// rawStringln should only be used to emit the initial version string.
+func (p *exporter) rawStringln(s string) {
+ for i := 0; i < len(s); i++ {
+ p.rawByte(s[i])
+ }
+ p.rawByte('\n')
+}
+
+// rawByte is the bottleneck interface to write to p.out.
+// rawByte escapes b as follows (any encoding does that
+// hides '$'):
+//
+// '$' => '|' 'S'
+// '|' => '|' '|'
+//
+// Necessary so other tools can find the end of the
+// export data by searching for "$$".
+// rawByte should only be used by low-level encoders.
+func (p *exporter) rawByte(b byte) {
+ switch b {
+ case '$':
+ // write '$' as '|' 'S'
+ b = 'S'
+ fallthrough
+ case '|':
+ // write '|' as '|' '|'
+ p.out.WriteByte('|')
+ p.written++
+ }
+ p.out.WriteByte(b)
+ p.written++
+}
+
+// tracef is like fmt.Printf but it rewrites the format string
+// to take care of indentation.
+func (p *exporter) tracef(format string, args ...interface{}) {
+ if strings.ContainsAny(format, "<>\n") {
+ var buf bytes.Buffer
+ for i := 0; i < len(format); i++ {
+ // no need to deal with runes
+ ch := format[i]
+ switch ch {
+ case '>':
+ p.indent++
+ continue
+ case '<':
+ p.indent--
+ continue
+ }
+ buf.WriteByte(ch)
+ if ch == '\n' {
+ for j := p.indent; j > 0; j-- {
+ buf.WriteString(". ")
+ }
+ }
+ }
+ format = buf.String()
+ }
+ fmt.Printf(format, args...)
+}
+
+// Debugging support.
+// (tagString is only used when tracing is enabled)
+var tagString = [...]string{
+ // Packages
+ -packageTag: "package",
+
+ // Types
+ -namedTag: "named type",
+ -arrayTag: "array",
+ -sliceTag: "slice",
+ -dddTag: "ddd",
+ -structTag: "struct",
+ -pointerTag: "pointer",
+ -signatureTag: "signature",
+ -interfaceTag: "interface",
+ -mapTag: "map",
+ -chanTag: "chan",
+
+ // Values
+ -falseTag: "false",
+ -trueTag: "true",
+ -int64Tag: "int64",
+ -floatTag: "float",
+ -fractionTag: "fraction",
+ -complexTag: "complex",
+ -stringTag: "string",
+ -unknownTag: "unknown",
+
+ // Type aliases
+ -aliasTag: "alias",
+}
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