cmd/godex/print.go - tools - Git at Google

 // Copyright 2014 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 main

 import (
 	"bytes"
 	"fmt"
 	"go/constant"
 	"go/token"
 	"go/types"
 	"io"
 	"math/big"
 )

 // TODO(gri) use tabwriter for alignment?

 func print(w io.Writer, pkg *types.Package, filter func(types.Object) bool) {
 	var p printer
 	p.pkg = pkg
 	p.printPackage(pkg, filter)
 	p.printGccgoExtra(pkg)
 	io.Copy(w, &p.buf)
 }

 type printer struct {
 	pkg    *types.Package
 	buf    bytes.Buffer
 	indent int  // current indentation level
 	last   byte // last byte written
 }

 func (p *printer) print(s string) {
 	// Write the string one byte at a time. We care about the presence of
 	// newlines for indentation which we will see even in the presence of
 	// (non-corrupted) Unicode; no need to read one rune at a time.
 	for i := 0; i < len(s); i++ {
 		ch := s[i]
 		if ch != '\n' && p.last == '\n' {
 			// Note: This could lead to a range overflow for very large
 			// indentations, but it's extremely unlikely to happen for
 			// non-pathological code.
 			p.buf.WriteString("\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t"[:p.indent])
 		}
 		p.buf.WriteByte(ch)
 		p.last = ch
 	}
 }

 func (p *printer) printf(format string, args ...interface{}) {
 	p.print(fmt.Sprintf(format, args...))
 }

 // methodsFor returns the named type and corresponding methods if the type
 // denoted by obj is not an interface and has methods. Otherwise it returns
 // the zero value.
 func methodsFor(obj *types.TypeName) (*types.Named, []*types.Selection) {
 	named, _ := obj.Type().(*types.Named)
 	if named == nil {
 		// A type name's type can also be the
 		// exported basic type unsafe.Pointer.
 		return nil, nil
 	}
 	if _, ok := named.Underlying().(*types.Interface); ok {
 		// ignore interfaces
 		return nil, nil
 	}
 	methods := combinedMethodSet(named)
 	if len(methods) == 0 {
 		return nil, nil
 	}
 	return named, methods
 }

 func (p *printer) printPackage(pkg *types.Package, filter func(types.Object) bool) {
 	// collect objects by kind
 	var (
 		consts   []*types.Const
 		typem    []*types.Named    // non-interface types with methods
 		typez    []*types.TypeName // interfaces or types without methods
 		vars     []*types.Var
 		funcs    []*types.Func
 		builtins []*types.Builtin
 		methods  = make(map[*types.Named][]*types.Selection) // method sets for named types
 	)
 	scope := pkg.Scope()
 	for _, name := range scope.Names() {
 		obj := scope.Lookup(name)
 		if obj.Exported() {
 			// collect top-level exported and possibly filtered objects
 			if filter == nil || filter(obj) {
 				switch obj := obj.(type) {
 				case *types.Const:
 					consts = append(consts, obj)
 				case *types.TypeName:
 					// group into types with methods and types without
 					if named, m := methodsFor(obj); named != nil {
 						typem = append(typem, named)
 						methods[named] = m
 					} else {
 						typez = append(typez, obj)
 					}
 				case *types.Var:
 					vars = append(vars, obj)
 				case *types.Func:
 					funcs = append(funcs, obj)
 				case *types.Builtin:
 					// for unsafe.Sizeof, etc.
 					builtins = append(builtins, obj)
 				}
 			}
 		} else if filter == nil {
 			// no filtering: collect top-level unexported types with methods
 			if obj, _ := obj.(*types.TypeName); obj != nil {
 				// see case *types.TypeName above
 				if named, m := methodsFor(obj); named != nil {
 					typem = append(typem, named)
 					methods[named] = m
 				}
 			}
 		}
 	}

 	p.printf("package %s  // %q\n", pkg.Name(), pkg.Path())

 	p.printDecl("const", len(consts), func() {
 		for _, obj := range consts {
 			p.printObj(obj)
 			p.print("\n")
 		}
 	})

 	p.printDecl("var", len(vars), func() {
 		for _, obj := range vars {
 			p.printObj(obj)
 			p.print("\n")
 		}
 	})

 	p.printDecl("type", len(typez), func() {
 		for _, obj := range typez {
 			p.printf("%s ", obj.Name())
 			typ := obj.Type()
 			if isAlias(obj) {
 				p.print("= ")
 				p.writeType(p.pkg, typ)
 			} else {
 				p.writeType(p.pkg, typ.Underlying())
 			}
 			p.print("\n")
 		}
 	})

 	// non-interface types with methods
 	for _, named := range typem {
 		first := true
 		if obj := named.Obj(); obj.Exported() {
 			if first {
 				p.print("\n")
 				first = false
 			}
 			p.printf("type %s ", obj.Name())
 			p.writeType(p.pkg, named.Underlying())
 			p.print("\n")
 		}
 		for _, m := range methods[named] {
 			if obj := m.Obj(); obj.Exported() {
 				if first {
 					p.print("\n")
 					first = false
 				}
 				p.printFunc(m.Recv(), obj.(*types.Func))
 				p.print("\n")
 			}
 		}
 	}

 	if len(funcs) > 0 {
 		p.print("\n")
 		for _, obj := range funcs {
 			p.printFunc(nil, obj)
 			p.print("\n")
 		}
 	}

 	// TODO(gri) better handling of builtins (package unsafe only)
 	if len(builtins) > 0 {
 		p.print("\n")
 		for _, obj := range builtins {
 			p.printf("func %s() // builtin\n", obj.Name())
 		}
 	}

 	p.print("\n")
 }

 func (p *printer) printDecl(keyword string, n int, printGroup func()) {
 	switch n {
 	case 0:
 		// nothing to do
 	case 1:
 		p.printf("\n%s ", keyword)
 		printGroup()
 	default:
 		p.printf("\n%s (\n", keyword)
 		p.indent++
 		printGroup()
 		p.indent--
 		p.print(")\n")
 	}
 }

 // absInt returns the absolute value of v as a *big.Int.
 // v must be a numeric value.
 func absInt(v constant.Value) *big.Int {
 	// compute big-endian representation of v
 	b := constant.Bytes(v) // little-endian
 	for i, j := 0, len(b)-1; i < j; i, j = i+1, j-1 {
 		b[i], b[j] = b[j], b[i]
 	}
 	return new(big.Int).SetBytes(b)
 }

 var (
 	one = big.NewRat(1, 1)
 	ten = big.NewRat(10, 1)
 )

 // floatString returns the string representation for a
 // numeric value v in normalized floating-point format.
 func floatString(v constant.Value) string {
 	if constant.Sign(v) == 0 {
 		return "0.0"
 	}
 	// x != 0

 	// convert |v| into a big.Rat x
 	x := new(big.Rat).SetFrac(absInt(constant.Num(v)), absInt(constant.Denom(v)))

 	// normalize x and determine exponent e
 	// (This is not very efficient, but also not speed-critical.)
 	var e int
 	for x.Cmp(ten) >= 0 {
 		x.Quo(x, ten)
 		e++
 	}
 	for x.Cmp(one) < 0 {
 		x.Mul(x, ten)
 		e--
 	}

 	// TODO(gri) Values such as 1/2 are easier to read in form 0.5
 	// rather than 5.0e-1. Similarly, 1.0e1 is easier to read as
 	// 10.0. Fine-tune best exponent range for readability.

 	s := x.FloatString(100) // good-enough precision

 	// trim trailing 0's
 	i := len(s)
 	for i > 0 && s[i-1] == '0' {
 		i--
 	}
 	s = s[:i]

 	// add a 0 if the number ends in decimal point
 	if len(s) > 0 && s[len(s)-1] == '.' {
 		s += "0"
 	}

 	// add exponent and sign
 	if e != 0 {
 		s += fmt.Sprintf("e%+d", e)
 	}
 	if constant.Sign(v) < 0 {
 		s = "-" + s
 	}

 	// TODO(gri) If v is a "small" fraction (i.e., numerator and denominator
 	// are just a small number of decimal digits), add the exact fraction as
 	// a comment. For instance: 3.3333...e-1 /* = 1/3 */

 	return s
 }

 // valString returns the string representation for the value v.
 // Setting floatFmt forces an integer value to be formatted in
 // normalized floating-point format.
 // TODO(gri) Move this code into package constant.
 func valString(v constant.Value, floatFmt bool) string {
 	switch v.Kind() {
 	case constant.Int:
 		if floatFmt {
 			return floatString(v)
 		}
 	case constant.Float:
 		return floatString(v)
 	case constant.Complex:
 		re := constant.Real(v)
 		im := constant.Imag(v)
 		var s string
 		if constant.Sign(re) != 0 {
 			s = floatString(re)
 			if constant.Sign(im) >= 0 {
 				s += " + "
 			} else {
 				s += " - "
 				im = constant.UnaryOp(token.SUB, im, 0) // negate im
 			}
 		}
 		// im != 0, otherwise v would be constant.Int or constant.Float
 		return s + floatString(im) + "i"
 	}
 	return v.String()
 }

 func (p *printer) printObj(obj types.Object) {
 	p.print(obj.Name())

 	typ, basic := obj.Type().Underlying().(*types.Basic)
 	if basic && typ.Info()&types.IsUntyped != 0 {
 		// don't write untyped types
 	} else {
 		p.print(" ")
 		p.writeType(p.pkg, obj.Type())
 	}

 	if obj, ok := obj.(*types.Const); ok {
 		floatFmt := basic && typ.Info()&(types.IsFloat|types.IsComplex) != 0
 		p.print(" = ")
 		p.print(valString(obj.Val(), floatFmt))
 	}
 }

 func (p *printer) printFunc(recvType types.Type, obj *types.Func) {
 	p.print("func ")
 	sig := obj.Type().(*types.Signature)
 	if recvType != nil {
 		p.print("(")
 		p.writeType(p.pkg, recvType)
 		p.print(") ")
 	}
 	p.print(obj.Name())
 	p.writeSignature(p.pkg, sig)
 }

 // combinedMethodSet returns the method set for a named type T
 // merged with all the methods of *T that have different names than
 // the methods of T.
 //
 // combinedMethodSet is analogous to types/typeutil.IntuitiveMethodSet
 // but doesn't require a MethodSetCache.
 // TODO(gri) If this functionality doesn't change over time, consider
 // just calling IntuitiveMethodSet eventually.
 func combinedMethodSet(T *types.Named) []*types.Selection {
 	// method set for T
 	mset := types.NewMethodSet(T)
 	var res []*types.Selection
 	for i, n := 0, mset.Len(); i < n; i++ {
 		res = append(res, mset.At(i))
 	}

 	// add all *T methods with names different from T methods
 	pmset := types.NewMethodSet(types.NewPointer(T))
 	for i, n := 0, pmset.Len(); i < n; i++ {
 		pm := pmset.At(i)
 		if obj := pm.Obj(); mset.Lookup(obj.Pkg(), obj.Name()) == nil {
 			res = append(res, pm)
 		}
 	}

 	return res
 }
	// Copyright 2014 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 main

	import (
	"bytes"
	"fmt"
	"go/constant"
	"go/token"
	"go/types"
	"io"
	"math/big"
	)

	// TODO(gri) use tabwriter for alignment?

	func print(w io.Writer, pkg *types.Package, filter func(types.Object) bool) {
	var p printer
	p.pkg = pkg
	p.printPackage(pkg, filter)
	p.printGccgoExtra(pkg)
	io.Copy(w, &p.buf)
	}

	type printer struct {
	pkg *types.Package
	buf bytes.Buffer
	indent int // current indentation level
	last byte // last byte written
	}

	func (p *printer) print(s string) {
	// Write the string one byte at a time. We care about the presence of
	// newlines for indentation which we will see even in the presence of
	// (non-corrupted) Unicode; no need to read one rune at a time.
	for i := 0; i < len(s); i++ {
	ch := s[i]
	if ch != '\n' && p.last == '\n' {
	// Note: This could lead to a range overflow for very large
	// indentations, but it's extremely unlikely to happen for
	// non-pathological code.
	p.buf.WriteString("\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t"[:p.indent])
	}
	p.buf.WriteByte(ch)
	p.last = ch
	}
	}

	func (p *printer) printf(format string, args ...interface{}) {
	p.print(fmt.Sprintf(format, args...))
	}

	// methodsFor returns the named type and corresponding methods if the type
	// denoted by obj is not an interface and has methods. Otherwise it returns
	// the zero value.
	func methodsFor(obj types.TypeName) (types.Named, []*types.Selection) {
	named, _ := obj.Type().(*types.Named)
	if named == nil {
	// A type name's type can also be the
	// exported basic type unsafe.Pointer.
	return nil, nil
	}
	if _, ok := named.Underlying().(*types.Interface); ok {
	// ignore interfaces
	return nil, nil
	}
	methods := combinedMethodSet(named)
	if len(methods) == 0 {
	return nil, nil
	}
	return named, methods
	}

	func (p printer) printPackage(pkg types.Package, filter func(types.Object) bool) {
	// collect objects by kind
	var (
	consts []*types.Const
	typem []*types.Named // non-interface types with methods
	typez []*types.TypeName // interfaces or types without methods
	vars []*types.Var
	funcs []*types.Func
	builtins []*types.Builtin
	methods = make(map[types.Named][]types.Selection) // method sets for named types
	)
	scope := pkg.Scope()
	for _, name := range scope.Names() {
	obj := scope.Lookup(name)
	if obj.Exported() {
	// collect top-level exported and possibly filtered objects
	if filter == nil \|\| filter(obj) {
	switch obj := obj.(type) {
	case *types.Const:
	consts = append(consts, obj)
	case *types.TypeName:
	// group into types with methods and types without
	if named, m := methodsFor(obj); named != nil {
	typem = append(typem, named)
	methods[named] = m
	} else {
	typez = append(typez, obj)
	}
	case *types.Var:
	vars = append(vars, obj)
	case *types.Func:
	funcs = append(funcs, obj)
	case *types.Builtin:
	// for unsafe.Sizeof, etc.
	builtins = append(builtins, obj)
	}
	}
	} else if filter == nil {
	// no filtering: collect top-level unexported types with methods
	if obj, _ := obj.(*types.TypeName); obj != nil {
	// see case *types.TypeName above
	if named, m := methodsFor(obj); named != nil {
	typem = append(typem, named)
	methods[named] = m
	}
	}
	}
	}

	p.printf("package %s // %q\n", pkg.Name(), pkg.Path())

	p.printDecl("const", len(consts), func() {
	for _, obj := range consts {
	p.printObj(obj)
	p.print("\n")
	}
	})

	p.printDecl("var", len(vars), func() {
	for _, obj := range vars {
	p.printObj(obj)
	p.print("\n")
	}
	})

	p.printDecl("type", len(typez), func() {
	for _, obj := range typez {
	p.printf("%s ", obj.Name())
	typ := obj.Type()
	if isAlias(obj) {
	p.print("= ")
	p.writeType(p.pkg, typ)
	} else {
	p.writeType(p.pkg, typ.Underlying())
	}
	p.print("\n")
	}
	})

	// non-interface types with methods
	for _, named := range typem {
	first := true
	if obj := named.Obj(); obj.Exported() {
	if first {
	p.print("\n")
	first = false
	}
	p.printf("type %s ", obj.Name())
	p.writeType(p.pkg, named.Underlying())
	p.print("\n")
	}
	for _, m := range methods[named] {
	if obj := m.Obj(); obj.Exported() {
	if first {
	p.print("\n")
	first = false
	}
	p.printFunc(m.Recv(), obj.(*types.Func))
	p.print("\n")
	}
	}
	}

	if len(funcs) > 0 {
	p.print("\n")
	for _, obj := range funcs {
	p.printFunc(nil, obj)
	p.print("\n")
	}
	}

	// TODO(gri) better handling of builtins (package unsafe only)
	if len(builtins) > 0 {
	p.print("\n")
	for _, obj := range builtins {
	p.printf("func %s() // builtin\n", obj.Name())
	}
	}

	p.print("\n")
	}

	func (p *printer) printDecl(keyword string, n int, printGroup func()) {
	switch n {
	case 0:
	// nothing to do
	case 1:
	p.printf("\n%s ", keyword)
	printGroup()
	default:
	p.printf("\n%s (\n", keyword)
	p.indent++
	printGroup()
	p.indent--
	p.print(")\n")
	}
	}

	// absInt returns the absolute value of v as a *big.Int.
	// v must be a numeric value.
	func absInt(v constant.Value) *big.Int {
	// compute big-endian representation of v
	b := constant.Bytes(v) // little-endian
	for i, j := 0, len(b)-1; i < j; i, j = i+1, j-1 {
	b[i], b[j] = b[j], b[i]
	}
	return new(big.Int).SetBytes(b)
	}

	var (
	one = big.NewRat(1, 1)
	ten = big.NewRat(10, 1)
	)

	// floatString returns the string representation for a
	// numeric value v in normalized floating-point format.
	func floatString(v constant.Value) string {
	if constant.Sign(v) == 0 {
	return "0.0"
	}
	// x != 0

	// convert \|v\| into a big.Rat x
	x := new(big.Rat).SetFrac(absInt(constant.Num(v)), absInt(constant.Denom(v)))

	// normalize x and determine exponent e
	// (This is not very efficient, but also not speed-critical.)
	var e int
	for x.Cmp(ten) >= 0 {
	x.Quo(x, ten)
	e++
	}
	for x.Cmp(one) < 0 {
	x.Mul(x, ten)
	e--
	}

	// TODO(gri) Values such as 1/2 are easier to read in form 0.5
	// rather than 5.0e-1. Similarly, 1.0e1 is easier to read as
	// 10.0. Fine-tune best exponent range for readability.

	s := x.FloatString(100) // good-enough precision

	// trim trailing 0's
	i := len(s)
	for i > 0 && s[i-1] == '0' {
	i--
	}
	s = s[:i]

	// add a 0 if the number ends in decimal point
	if len(s) > 0 && s[len(s)-1] == '.' {
	s += "0"
	}

	// add exponent and sign
	if e != 0 {
	s += fmt.Sprintf("e%+d", e)
	}
	if constant.Sign(v) < 0 {
	s = "-" + s
	}

	// TODO(gri) If v is a "small" fraction (i.e., numerator and denominator
	// are just a small number of decimal digits), add the exact fraction as
	// a comment. For instance: 3.3333...e-1 /* = 1/3 */

	return s
	}

	// valString returns the string representation for the value v.
	// Setting floatFmt forces an integer value to be formatted in
	// normalized floating-point format.
	// TODO(gri) Move this code into package constant.
	func valString(v constant.Value, floatFmt bool) string {
	switch v.Kind() {
	case constant.Int:
	if floatFmt {
	return floatString(v)
	}
	case constant.Float:
	return floatString(v)
	case constant.Complex:
	re := constant.Real(v)
	im := constant.Imag(v)
	var s string
	if constant.Sign(re) != 0 {
	s = floatString(re)
	if constant.Sign(im) >= 0 {
	s += " + "
	} else {
	s += " - "
	im = constant.UnaryOp(token.SUB, im, 0) // negate im
	}
	}
	// im != 0, otherwise v would be constant.Int or constant.Float
	return s + floatString(im) + "i"
	}
	return v.String()
	}

	func (p *printer) printObj(obj types.Object) {
	p.print(obj.Name())

	typ, basic := obj.Type().Underlying().(*types.Basic)
	if basic && typ.Info()&types.IsUntyped != 0 {
	// don't write untyped types
	} else {
	p.print(" ")
	p.writeType(p.pkg, obj.Type())
	}

	if obj, ok := obj.(*types.Const); ok {
	floatFmt := basic && typ.Info()&(types.IsFloat\|types.IsComplex) != 0
	p.print(" = ")
	p.print(valString(obj.Val(), floatFmt))
	}
	}

	func (p printer) printFunc(recvType types.Type, obj types.Func) {
	p.print("func ")
	sig := obj.Type().(*types.Signature)
	if recvType != nil {
	p.print("(")
	p.writeType(p.pkg, recvType)
	p.print(") ")
	}
	p.print(obj.Name())
	p.writeSignature(p.pkg, sig)
	}

	// combinedMethodSet returns the method set for a named type T
	// merged with all the methods of *T that have different names than
	// the methods of T.
	//
	// combinedMethodSet is analogous to types/typeutil.IntuitiveMethodSet
	// but doesn't require a MethodSetCache.
	// TODO(gri) If this functionality doesn't change over time, consider
	// just calling IntuitiveMethodSet eventually.
	func combinedMethodSet(T types.Named) []types.Selection {
	// method set for T
	mset := types.NewMethodSet(T)
	var res []*types.Selection
	for i, n := 0, mset.Len(); i < n; i++ {
	res = append(res, mset.At(i))
	}

	// add all *T methods with names different from T methods
	pmset := types.NewMethodSet(types.NewPointer(T))
	for i, n := 0, pmset.Len(); i < n; i++ {
	pm := pmset.At(i)
	if obj := pm.Obj(); mset.Lookup(obj.Pkg(), obj.Name()) == nil {
	res = append(res, pm)
	}
	}

	return res
	}