forked from golang/tools
/
bexport.go
703 lines (608 loc) · 14.6 KB
/
bexport.go
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// 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/types"
"log"
"math"
"math/big"
"sort"
"strings"
)
const exportVersion = "v0"
const (
debugFormat = false // use debugging format for export data (emits a lot of additional data)
trace = false
)
// BExportData returns binary export data for pkg.
//
// It is not safe to call this function on a package containing errors.
// TODO(adonovan): add InvalidType to the protocol and lift this restriction.
func BExportData(pkg *types.Package) []byte {
p := exporter{
pkgIndex: make(map[*types.Package]int),
typIndex: make(map[types.Type]int),
}
// write low-level encoding format
var format byte = 'c' // compact
if debugFormat {
format = 'd'
}
p.byte(format)
// --- generic export data ---
if trace {
p.tracef("\n--- generic export data ---\n")
if p.indent != 0 {
log.Fatalf("incorrect indentation %d", p.indent)
}
}
p.string(exportVersion)
if trace {
p.tracef("\n")
}
// populate type map with predeclared "known" types
for index, typ := range predeclared {
p.typIndex[typ] = index
}
if len(p.typIndex) != len(predeclared) {
log.Fatalf("duplicate entries in type map?")
}
// write package data
p.pkg(pkg, true)
// write compiler-specific flags
p.string("")
if trace {
p.tracef("\n")
}
// Collect objects to export, already sorted by name.
var consts []*types.Const
var vars []*types.Var
var funcs []*types.Func
var typs []*types.TypeName
scope := pkg.Scope()
for _, name := range scope.Names() {
if !ast.IsExported(name) {
continue
}
switch obj := scope.Lookup(name).(type) {
case *types.Const:
consts = append(consts, obj)
case *types.Var:
vars = append(vars, obj)
case *types.Func:
funcs = append(funcs, obj)
case *types.TypeName:
typs = append(typs, obj)
}
}
// write consts
p.int(len(consts))
for _, obj := range consts {
p.string(obj.Name())
p.typ(obj.Type())
p.value(obj.Val())
}
// write vars
p.int(len(vars))
for _, obj := range vars {
p.string(obj.Name())
p.typ(obj.Type())
}
// write funcs
p.int(len(funcs))
for _, obj := range funcs {
p.string(obj.Name())
// The type can only be a signature for functions. However, by always
// writing the complete type specification (rather than just a signature)
// we keep the option open of sharing common signatures across multiple
// functions as a means to further compress the export data.
p.typ(obj.Type())
p.int(-1) // no inlined function bodies
}
// Determine which types are still left to write.
i := 0
for _, t := range typs {
if _, ok := p.typIndex[t.Type()]; !ok {
typs[i] = t
i++
}
}
typs = typs[:i]
// Write types.
p.int(len(typs))
for _, t := range typs {
// Writing a type may further reduce the number of types
// that are left to be written, but at this point we don't
// care.
p.typ(t.Type())
}
if trace {
p.tracef("\n")
}
// --- compiler-specific export data ---
if trace {
p.tracef("\n--- compiler specific export data ---\n")
if p.indent != 0 {
log.Fatalf("incorrect indentation")
}
}
if trace {
p.tracef("\n")
}
// --- end of export data ---
return p.out.Bytes()
}
type exporter struct {
out bytes.Buffer
pkgIndex map[*types.Package]int
typIndex map[types.Type]int
written int // bytes written
indent int // for trace
trace bool
}
func (p *exporter) pkg(pkg *types.Package, emptypath bool) {
if pkg == nil {
log.Fatalf("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) typ(t types.Type) {
if t == nil {
log.Fatalf("nil type")
}
if t == types.Typ[types.Invalid] {
log.Fatal("BExportData invoked on package with errors")
}
// 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
index := len(p.typIndex)
if trace {
p.tracef("T%d = {>\n", index)
defer p.tracef("<\n} ")
}
p.typIndex[t] = index
switch t := t.(type) {
case *types.Named:
p.tag(namedTag)
p.qualifiedName(t.Obj())
p.typ(t.Underlying())
if !types.IsInterface(t) {
p.declaredMethods(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:
log.Fatalf("unexpected type %T: %s", t, t)
}
}
func (p *exporter) declaredMethods(named *types.Named) {
p.int(named.NumMethods())
// 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))
if trace && methods != nil {
p.tracef("associated methods {>\n")
}
for i, m := range methods {
if trace && i > 0 {
p.tracef("\n")
}
p.string(m.Name())
sig := m.Type().(*types.Signature)
p.recv(sig.Recv())
p.paramList(sig.Params(), sig.Variadic())
p.paramList(sig.Results(), false)
p.int(-1) // no inlining
}
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) recv(recv *types.Var) {
// Use negative length to indicate unnamed parameter.
if recv.Name() == "" {
p.int(-1)
p.typ(recv.Type())
} else {
p.int(1)
p.typ(recv.Type())
p.string(recv.Name())
}
p.string("")
}
func (p *exporter) qualifiedName(obj types.Object) {
p.string(obj.Name())
p.pkg(obj.Pkg(), false)
}
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() {
log.Fatalf("field expected")
}
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 {
log.Fatalf("method expected")
}
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)
}
// fieldName is like qualifiedName but it doesn't record the package
// for blank (_) or exported names.
func (p *exporter) fieldName(f *types.Var) {
name := f.Name()
// anonymous field with unexported base type name: use "?" as field name
// (bname != "" per spec, but we are conservative in case of errors)
if f.Anonymous() {
base := f.Type()
if ptr, ok := base.(*types.Pointer); ok {
base = ptr.Elem()
}
if named, ok := base.(*types.Named); ok && !named.Obj().Exported() {
name = "?"
}
}
p.string(name)
if name == "?" || name != "_" && !f.Exported() {
p.pkg(f.Pkg(), false)
}
}
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 {
p.string(q.Name())
}
p.string("")
}
}
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))
default:
log.Fatalf("unexpected value %v (%T)", x, x)
}
}
func (p *exporter) float(x constant.Value) {
if x.Kind() != constant.Float {
log.Fatalf("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 {
log.Fatalf("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))
}
// ----------------------------------------------------------------------------
// Low-level encoders
func (p *exporter) index(marker byte, index int) {
if index < 0 {
log.Fatalf("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 {
log.Fatalf("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)
}
p.rawInt64(int64(len(s)))
for i := 0; i < len(s); i++ {
p.byte(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.byte(m)
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.byte(tmp[i])
}
}
// byte is the bottleneck interface to write to p.out.
// byte 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 "$$".
func (p *exporter) byte(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.IndexAny(format, "<>\n") >= 0 {
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",
}