diff options
Diffstat (limited to 'vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go')
-rw-r--r-- | vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go | 852 |
1 files changed, 852 insertions, 0 deletions
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go b/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go new file mode 100644 index 00000000..6a9821ae --- /dev/null +++ b/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go @@ -0,0 +1,852 @@ +// 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 isAlias(obj) { + 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", +} |