universe.go

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // This file sets up the universe scope and the unsafe package.
     6  
     7  package types2
     8  
     9  import (
    10  	"go/constant"
    11  	"strings"
    12  )
    13  
    14  // The Universe scope contains all predeclared objects of Go.
    15  // It is the outermost scope of any chain of nested scopes.
    16  var Universe *Scope
    17  
    18  // The Unsafe package is the package returned by an importer
    19  // for the import path "unsafe".
    20  var Unsafe *Package
    21  
    22  var (
    23  	universeIota       Object
    24  	universeBool       Type
    25  	universeByte       Type // uint8 alias, but has name "byte"
    26  	universeRune       Type // int32 alias, but has name "rune"
    27  	universeError      Type
    28  	universeAny        Object
    29  	universeComparable Object
    30  )
    31  
    32  // Typ contains the predeclared *Basic types indexed by their
    33  // corresponding BasicKind.
    34  //
    35  // The *Basic type for Typ[Byte] will have the name "uint8".
    36  // Use Universe.Lookup("byte").Type() to obtain the specific
    37  // alias basic type named "byte" (and analogous for "rune").
    38  var Typ = [...]*Basic{
    39  	Invalid: {Invalid, 0, "invalid type"},
    40  
    41  	Bool:          {Bool, IsBoolean, "bool"},
    42  	Int:           {Int, IsInteger, "int"},
    43  	Int8:          {Int8, IsInteger, "int8"},
    44  	Int16:         {Int16, IsInteger, "int16"},
    45  	Int32:         {Int32, IsInteger, "int32"},
    46  	Int64:         {Int64, IsInteger, "int64"},
    47  	Uint:          {Uint, IsInteger | IsUnsigned, "uint"},
    48  	Uint8:         {Uint8, IsInteger | IsUnsigned, "uint8"},
    49  	Uint16:        {Uint16, IsInteger | IsUnsigned, "uint16"},
    50  	Uint32:        {Uint32, IsInteger | IsUnsigned, "uint32"},
    51  	Uint64:        {Uint64, IsInteger | IsUnsigned, "uint64"},
    52  	Uintptr:       {Uintptr, IsInteger | IsUnsigned, "uintptr"},
    53  	Float32:       {Float32, IsFloat, "float32"},
    54  	Float64:       {Float64, IsFloat, "float64"},
    55  	Complex64:     {Complex64, IsComplex, "complex64"},
    56  	Complex128:    {Complex128, IsComplex, "complex128"},
    57  	String:        {String, IsString, "string"},
    58  	UnsafePointer: {UnsafePointer, 0, "Pointer"},
    59  
    60  	UntypedBool:    {UntypedBool, IsBoolean | IsUntyped, "untyped bool"},
    61  	UntypedInt:     {UntypedInt, IsInteger | IsUntyped, "untyped int"},
    62  	UntypedRune:    {UntypedRune, IsInteger | IsUntyped, "untyped rune"},
    63  	UntypedFloat:   {UntypedFloat, IsFloat | IsUntyped, "untyped float"},
    64  	UntypedComplex: {UntypedComplex, IsComplex | IsUntyped, "untyped complex"},
    65  	UntypedString:  {UntypedString, IsString | IsUntyped, "untyped string"},
    66  	UntypedNil:     {UntypedNil, IsUntyped, "untyped nil"},
    67  }
    68  
    69  var basicAliases = [...]*Basic{
    70  	{Byte, IsInteger | IsUnsigned, "byte"},
    71  	{Rune, IsInteger, "rune"},
    72  }
    73  
    74  func defPredeclaredTypes() {
    75  	for _, t := range Typ {
    76  		def(NewTypeName(nopos, nil, t.name, t))
    77  	}
    78  
    79  	for _, t := range basicAliases {
    80  		def(NewTypeName(nopos, nil, t.name, t))
    81  	}
    82  
    83  	// type error interface{ Error() string }
    84  	{
    85  		obj := NewTypeName(nopos, nil, "error", nil)
    86  		typ := NewNamed(obj, nil, nil)
    87  
    88  		// error.Error() string
    89  		recv := newVar(RecvVar, nopos, nil, "", typ)
    90  		res := newVar(ResultVar, nopos, nil, "", Typ[String])
    91  		sig := NewSignatureType(recv, nil, nil, nil, NewTuple(res), false)
    92  		err := NewFunc(nopos, nil, "Error", sig)
    93  
    94  		// interface{ Error() string }
    95  		ityp := &Interface{methods: []*Func{err}, complete: true}
    96  		computeInterfaceTypeSet(nil, nopos, ityp) // prevent races due to lazy computation of tset
    97  
    98  		typ.fromRHS = ityp
    99  		typ.Underlying()
   100  		def(obj)
   101  	}
   102  
   103  	// type any = interface{}
   104  	{
   105  		obj := NewTypeName(nopos, nil, "any", nil)
   106  		NewAlias(obj, &emptyInterface)
   107  		def(obj)
   108  	}
   109  
   110  	// type comparable interface{} // marked as comparable
   111  	{
   112  		obj := NewTypeName(nopos, nil, "comparable", nil)
   113  		NewNamed(obj, &Interface{complete: true, tset: &_TypeSet{nil, allTermlist, true}}, nil)
   114  		def(obj)
   115  	}
   116  }
   117  
   118  var predeclaredConsts = [...]struct {
   119  	name string
   120  	kind BasicKind
   121  	val  constant.Value
   122  }{
   123  	{"true", UntypedBool, constant.MakeBool(true)},
   124  	{"false", UntypedBool, constant.MakeBool(false)},
   125  	{"iota", UntypedInt, constant.MakeInt64(0)},
   126  }
   127  
   128  func defPredeclaredConsts() {
   129  	for _, c := range predeclaredConsts {
   130  		def(NewConst(nopos, nil, c.name, Typ[c.kind], c.val))
   131  	}
   132  }
   133  
   134  func defPredeclaredNil() {
   135  	def(&Nil{object{name: "nil", typ: Typ[UntypedNil]}})
   136  }
   137  
   138  // A builtinId is the id of a builtin function.
   139  type builtinId int
   140  
   141  const (
   142  	// universe scope
   143  	_Append builtinId = iota
   144  	_Cap
   145  	_Clear
   146  	_Close
   147  	_Complex
   148  	_Copy
   149  	_Delete
   150  	_Imag
   151  	_Len
   152  	_Make
   153  	_Max
   154  	_Min
   155  	_New
   156  	_Panic
   157  	_Print
   158  	_Println
   159  	_Real
   160  	_Recover
   161  
   162  	// package unsafe
   163  	_Add
   164  	_Alignof
   165  	_Offsetof
   166  	_Sizeof
   167  	_Slice
   168  	_SliceData
   169  	_String
   170  	_StringData
   171  
   172  	// testing support
   173  	_Assert
   174  	_Trace
   175  )
   176  
   177  var predeclaredFuncs = [...]struct {
   178  	name     string
   179  	nargs    int
   180  	variadic bool
   181  	kind     exprKind
   182  }{
   183  	_Append:  {"append", 1, true, expression},
   184  	_Cap:     {"cap", 1, false, expression},
   185  	_Clear:   {"clear", 1, false, statement},
   186  	_Close:   {"close", 1, false, statement},
   187  	_Complex: {"complex", 2, false, expression},
   188  	_Copy:    {"copy", 2, false, statement},
   189  	_Delete:  {"delete", 2, false, statement},
   190  	_Imag:    {"imag", 1, false, expression},
   191  	_Len:     {"len", 1, false, expression},
   192  	_Make:    {"make", 1, true, expression},
   193  	// To disable max/min, remove the next two lines.
   194  	_Max:     {"max", 1, true, expression},
   195  	_Min:     {"min", 1, true, expression},
   196  	_New:     {"new", 1, false, expression},
   197  	_Panic:   {"panic", 1, false, statement},
   198  	_Print:   {"print", 0, true, statement},
   199  	_Println: {"println", 0, true, statement},
   200  	_Real:    {"real", 1, false, expression},
   201  	_Recover: {"recover", 0, false, statement},
   202  
   203  	_Add:        {"Add", 2, false, expression},
   204  	_Alignof:    {"Alignof", 1, false, expression},
   205  	_Offsetof:   {"Offsetof", 1, false, expression},
   206  	_Sizeof:     {"Sizeof", 1, false, expression},
   207  	_Slice:      {"Slice", 2, false, expression},
   208  	_SliceData:  {"SliceData", 1, false, expression},
   209  	_String:     {"String", 2, false, expression},
   210  	_StringData: {"StringData", 1, false, expression},
   211  
   212  	_Assert: {"assert", 1, false, statement},
   213  	_Trace:  {"trace", 0, true, statement},
   214  }
   215  
   216  func defPredeclaredFuncs() {
   217  	for i := range predeclaredFuncs {
   218  		id := builtinId(i)
   219  		if id == _Assert || id == _Trace {
   220  			continue // only define these in testing environment
   221  		}
   222  		def(newBuiltin(id))
   223  	}
   224  }
   225  
   226  // DefPredeclaredTestFuncs defines the assert and trace built-ins.
   227  // These built-ins are intended for debugging and testing of this
   228  // package only.
   229  func DefPredeclaredTestFuncs() {
   230  	if Universe.Lookup("assert") != nil {
   231  		return // already defined
   232  	}
   233  	def(newBuiltin(_Assert))
   234  	def(newBuiltin(_Trace))
   235  }
   236  
   237  func init() {
   238  	Universe = NewScope(nil, nopos, nopos, "universe")
   239  	Unsafe = NewPackage("unsafe", "unsafe")
   240  	Unsafe.complete = true
   241  
   242  	defPredeclaredTypes()
   243  	defPredeclaredConsts()
   244  	defPredeclaredNil()
   245  	defPredeclaredFuncs()
   246  
   247  	universeIota = Universe.Lookup("iota")
   248  	universeBool = Universe.Lookup("bool").Type()
   249  	universeByte = Universe.Lookup("byte").Type()
   250  	universeRune = Universe.Lookup("rune").Type()
   251  	universeError = Universe.Lookup("error").Type()
   252  	universeAny = Universe.Lookup("any")
   253  	universeComparable = Universe.Lookup("comparable")
   254  }
   255  
   256  // Objects with names containing blanks are internal and not entered into
   257  // a scope. Objects with exported names are inserted in the unsafe package
   258  // scope; other objects are inserted in the universe scope.
   259  func def(obj Object) {
   260  	assert(obj.Type() != nil)
   261  	name := obj.Name()
   262  	if strings.Contains(name, " ") {
   263  		return // nothing to do
   264  	}
   265  	// fix Obj link for named types
   266  	if typ := asNamed(obj.Type()); typ != nil {
   267  		typ.obj = obj.(*TypeName)
   268  	}
   269  	// exported identifiers go into package unsafe
   270  	scope := Universe
   271  	if obj.Exported() {
   272  		scope = Unsafe.scope
   273  		// set Pkg field
   274  		switch obj := obj.(type) {
   275  		case *TypeName:
   276  			obj.pkg = Unsafe
   277  		case *Builtin:
   278  			obj.pkg = Unsafe
   279  		default:
   280  			panic("unreachable")
   281  		}
   282  	}
   283  	if scope.Insert(obj) != nil {
   284  		panic("double declaration of predeclared identifier")
   285  	}
   286  }
   287
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