diff --git a/src/go/types/array.go b/src/go/types/array.go new file mode 100644 index 0000000000..5b28474bb3 --- /dev/null +++ b/src/go/types/array.go @@ -0,0 +1,25 @@ +// Copyright 2011 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 types + +// An Array represents an array type. +type Array struct { + len int64 + elem Type +} + +// NewArray returns a new array type for the given element type and length. +// A negative length indicates an unknown length. +func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} } + +// Len returns the length of array a. +// A negative result indicates an unknown length. +func (a *Array) Len() int64 { return a.len } + +// Elem returns element type of array a. +func (a *Array) Elem() Type { return a.elem } + +func (t *Array) Underlying() Type { return t } +func (t *Array) String() string { return TypeString(t, nil) } diff --git a/src/go/types/basic.go b/src/go/types/basic.go new file mode 100644 index 0000000000..215923f657 --- /dev/null +++ b/src/go/types/basic.go @@ -0,0 +1,82 @@ +// Copyright 2011 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 types + +// BasicKind describes the kind of basic type. +type BasicKind int + +const ( + Invalid BasicKind = iota // type is invalid + + // predeclared types + Bool + Int + Int8 + Int16 + Int32 + Int64 + Uint + Uint8 + Uint16 + Uint32 + Uint64 + Uintptr + Float32 + Float64 + Complex64 + Complex128 + String + UnsafePointer + + // types for untyped values + UntypedBool + UntypedInt + UntypedRune + UntypedFloat + UntypedComplex + UntypedString + UntypedNil + + // aliases + Byte = Uint8 + Rune = Int32 +) + +// BasicInfo is a set of flags describing properties of a basic type. +type BasicInfo int + +// Properties of basic types. +const ( + IsBoolean BasicInfo = 1 << iota + IsInteger + IsUnsigned + IsFloat + IsComplex + IsString + IsUntyped + + IsOrdered = IsInteger | IsFloat | IsString + IsNumeric = IsInteger | IsFloat | IsComplex + IsConstType = IsBoolean | IsNumeric | IsString +) + +// A Basic represents a basic type. +type Basic struct { + kind BasicKind + info BasicInfo + name string +} + +// Kind returns the kind of basic type b. +func (b *Basic) Kind() BasicKind { return b.kind } + +// Info returns information about properties of basic type b. +func (b *Basic) Info() BasicInfo { return b.info } + +// Name returns the name of basic type b. +func (b *Basic) Name() string { return b.name } + +func (t *Basic) Underlying() Type { return t } +func (t *Basic) String() string { return TypeString(t, nil) } diff --git a/src/go/types/chan.go b/src/go/types/chan.go new file mode 100644 index 0000000000..1f7b72be30 --- /dev/null +++ b/src/go/types/chan.go @@ -0,0 +1,35 @@ +// Copyright 2011 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 types + +// A Chan represents a channel type. +type Chan struct { + dir ChanDir + elem Type +} + +// A ChanDir value indicates a channel direction. +type ChanDir int + +// The direction of a channel is indicated by one of these constants. +const ( + SendRecv ChanDir = iota + SendOnly + RecvOnly +) + +// NewChan returns a new channel type for the given direction and element type. +func NewChan(dir ChanDir, elem Type) *Chan { + return &Chan{dir: dir, elem: elem} +} + +// Dir returns the direction of channel c. +func (c *Chan) Dir() ChanDir { return c.dir } + +// Elem returns the element type of channel c. +func (c *Chan) Elem() Type { return c.elem } + +func (t *Chan) Underlying() Type { return t } +func (t *Chan) String() string { return TypeString(t, nil) } diff --git a/src/go/types/instance.go b/src/go/types/instance.go new file mode 100644 index 0000000000..c57a947060 --- /dev/null +++ b/src/go/types/instance.go @@ -0,0 +1,58 @@ +// Copyright 2011 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 types + +import "go/token" + +// An instance represents an instantiated generic type syntactically +// (without expanding the instantiation). Type instances appear only +// during type-checking and are replaced by their fully instantiated +// (expanded) types before the end of type-checking. +type instance struct { + check *Checker // for lazy instantiation + pos token.Pos // position of type instantiation; for error reporting only + base *Named // parameterized type to be instantiated + targs []Type // type arguments + poslist []token.Pos // position of each targ; for error reporting only + value Type // base(targs...) after instantiation or Typ[Invalid]; nil if not yet set +} + +// expand returns the instantiated (= expanded) type of t. +// The result is either an instantiated *Named type, or +// Typ[Invalid] if there was an error. +func (t *instance) expand() Type { + v := t.value + if v == nil { + v = t.check.instantiate(t.pos, t.base, t.targs, t.poslist) + if v == nil { + v = Typ[Invalid] + } + t.value = v + } + // After instantiation we must have an invalid or a *Named type. + if debug && v != Typ[Invalid] { + _ = v.(*Named) + } + return v +} + +// expand expands a type instance into its instantiated +// type and leaves all other types alone. expand does +// not recurse. +func expand(typ Type) Type { + if t, _ := typ.(*instance); t != nil { + return t.expand() + } + return typ +} + +// expandf is set to expand. +// Call expandf when calling expand causes compile-time cycle error. +var expandf func(Type) Type + +func init() { expandf = expand } + +func (t *instance) Underlying() Type { return t } +func (t *instance) String() string { return TypeString(t, nil) } diff --git a/src/go/types/map.go b/src/go/types/map.go new file mode 100644 index 0000000000..01e13b214e --- /dev/null +++ b/src/go/types/map.go @@ -0,0 +1,24 @@ +// Copyright 2011 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 types + +// A Map represents a map type. +type Map struct { + key, elem Type +} + +// NewMap returns a new map for the given key and element types. +func NewMap(key, elem Type) *Map { + return &Map{key: key, elem: elem} +} + +// Key returns the key type of map m. +func (m *Map) Key() Type { return m.key } + +// Elem returns the element type of map m. +func (m *Map) Elem() Type { return m.elem } + +func (t *Map) Underlying() Type { return t } +func (t *Map) String() string { return TypeString(t, nil) } diff --git a/src/go/types/named.go b/src/go/types/named.go new file mode 100644 index 0000000000..8f2e8706a1 --- /dev/null +++ b/src/go/types/named.go @@ -0,0 +1,144 @@ +// Copyright 2011 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 types + +import "sync" + +// TODO(rfindley) Clean up Named struct below; specifically the fromRHS field (can we use underlying?). + +// A Named represents a named (defined) type. +type Named struct { + check *Checker // for Named.under implementation; nilled once under has been called + info typeInfo // for cycle detection + obj *TypeName // corresponding declared object + orig *Named // original, uninstantiated type + fromRHS Type // type (on RHS of declaration) this *Named type is derived of (for cycle reporting) + underlying Type // possibly a *Named during setup; never a *Named once set up completely + tparams []*TypeName // type parameters, or nil + targs []Type // type arguments (after instantiation), or nil + methods []*Func // methods declared for this type (not the method set of this type); signatures are type-checked lazily + + resolve func(*Named) ([]*TypeName, Type, []*Func) + once sync.Once +} + +// NewNamed returns a new named type for the given type name, underlying type, and associated methods. +// If the given type name obj doesn't have a type yet, its type is set to the returned named type. +// The underlying type must not be a *Named. +func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named { + if _, ok := underlying.(*Named); ok { + panic("types.NewNamed: underlying type must not be *Named") + } + return (*Checker)(nil).newNamed(obj, nil, underlying, nil, methods) +} + +func (t *Named) expand() *Named { + if t.resolve == nil { + return t + } + + t.once.Do(func() { + // TODO(mdempsky): Since we're passing t to resolve anyway + // (necessary because types2 expects the receiver type for methods + // on defined interface types to be the Named rather than the + // underlying Interface), maybe it should just handle calling + // SetTParams, SetUnderlying, and AddMethod instead? Those + // methods would need to support reentrant calls though. It would + // also make the API more future-proof towards further extensions + // (like SetTParams). + + tparams, underlying, methods := t.resolve(t) + + switch underlying.(type) { + case nil, *Named: + panic("invalid underlying type") + } + + t.tparams = tparams + t.underlying = underlying + t.methods = methods + }) + return t +} + +// newNamed is like NewNamed but with a *Checker receiver and additional orig argument. +func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams []*TypeName, methods []*Func) *Named { + typ := &Named{check: check, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods} + if typ.orig == nil { + typ.orig = typ + } + if obj.typ == nil { + obj.typ = typ + } + // Ensure that typ is always expanded, at which point the check field can be + // nilled out. + // + // Note that currently we cannot nil out check inside typ.under(), because + // it's possible that typ is expanded multiple times. + // + // TODO(rFindley): clean this up so that under is the only function mutating + // named types. + if check != nil { + check.later(func() { + switch typ.under().(type) { + case *Named, *instance: + panic("internal error: unexpanded underlying type") + } + typ.check = nil + }) + } + return typ +} + +// Obj returns the type name for the named type t. +func (t *Named) Obj() *TypeName { return t.obj } + +// _Orig returns the original generic type an instantiated type is derived from. +// If t is not an instantiated type, the result is t. +func (t *Named) _Orig() *Named { return t.orig } + +// TODO(gri) Come up with a better representation and API to distinguish +// between parameterized instantiated and non-instantiated types. + +// _TParams returns the type parameters of the named type t, or nil. +// The result is non-nil for an (originally) parameterized type even if it is instantiated. +func (t *Named) TParams() []*TypeName { return t.expand().tparams } + +// _SetTParams sets the type parameters of the named type t. +func (t *Named) SetTParams(tparams []*TypeName) { t.expand().tparams = tparams } + +// _TArgs returns the type arguments after instantiation of the named type t, or nil if not instantiated. +func (t *Named) TArgs() []Type { return t.targs } + +// SetTArgs sets the type arguments of the named type t. +func (t *Named) SetTArgs(args []Type) { t.targs = args } + +// NumMethods returns the number of explicit methods whose receiver is named type t. +func (t *Named) NumMethods() int { return len(t.expand().methods) } + +// Method returns the i'th method of named type t for 0 <= i < t.NumMethods(). +func (t *Named) Method(i int) *Func { return t.expand().methods[i] } + +// SetUnderlying sets the underlying type and marks t as complete. +func (t *Named) SetUnderlying(underlying Type) { + if underlying == nil { + panic("types.Named.SetUnderlying: underlying type must not be nil") + } + if _, ok := underlying.(*Named); ok { + panic("types.Named.SetUnderlying: underlying type must not be *Named") + } + t.expand().underlying = underlying +} + +// AddMethod adds method m unless it is already in the method list. +func (t *Named) AddMethod(m *Func) { + t.expand() + if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 { + t.methods = append(t.methods, m) + } +} + +func (t *Named) Underlying() Type { return t.expand().underlying } +func (t *Named) String() string { return TypeString(t, nil) } diff --git a/src/go/types/pointer.go b/src/go/types/pointer.go new file mode 100644 index 0000000000..6352ee57e2 --- /dev/null +++ b/src/go/types/pointer.go @@ -0,0 +1,19 @@ +// Copyright 2011 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 types + +// A Pointer represents a pointer type. +type Pointer struct { + base Type // element type +} + +// NewPointer returns a new pointer type for the given element (base) type. +func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} } + +// Elem returns the element type for the given pointer p. +func (p *Pointer) Elem() Type { return p.base } + +func (t *Pointer) Underlying() Type { return t } +func (t *Pointer) String() string { return TypeString(t, nil) } diff --git a/src/go/types/slice.go b/src/go/types/slice.go new file mode 100644 index 0000000000..debdd81586 --- /dev/null +++ b/src/go/types/slice.go @@ -0,0 +1,19 @@ +// Copyright 2011 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 types + +// A Slice represents a slice type. +type Slice struct { + elem Type +} + +// NewSlice returns a new slice type for the given element type. +func NewSlice(elem Type) *Slice { return &Slice{elem: elem} } + +// Elem returns the element type of slice s. +func (s *Slice) Elem() Type { return s.elem } + +func (t *Slice) Underlying() Type { return t } +func (t *Slice) String() string { return TypeString(t, nil) } diff --git a/src/go/types/tuple.go b/src/go/types/tuple.go new file mode 100644 index 0000000000..16d28bc9a6 --- /dev/null +++ b/src/go/types/tuple.go @@ -0,0 +1,36 @@ +// Copyright 2011 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 types + +// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple. +// Tuples are used as components of signatures and to represent the type of multiple +// assignments; they are not first class types of Go. +type Tuple struct { + vars []*Var +} + +// NewTuple returns a new tuple for the given variables. +func NewTuple(x ...*Var) *Tuple { + if len(x) > 0 { + return &Tuple{vars: x} + } + // TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer; + // it's too subtle and causes problems. + return nil +} + +// Len returns the number variables of tuple t. +func (t *Tuple) Len() int { + if t != nil { + return len(t.vars) + } + return 0 +} + +// At returns the i'th variable of tuple t. +func (t *Tuple) At(i int) *Var { return t.vars[i] } + +func (t *Tuple) Underlying() Type { return t } +func (t *Tuple) String() string { return TypeString(t, nil) } diff --git a/src/go/types/type.go b/src/go/types/type.go index 2adc2fa3ca..662dd859f0 100644 --- a/src/go/types/type.go +++ b/src/go/types/type.go @@ -4,12 +4,6 @@ package types -import ( - "go/token" - "sync" - "sync/atomic" -) - // A Type represents a type of Go. // All types implement the Type interface. type Type interface { @@ -22,379 +16,31 @@ type Type interface { String() string } -// BasicKind describes the kind of basic type. -type BasicKind int +// top represents the top of the type lattice. +// It is the underlying type of a type parameter that +// can be satisfied by any type (ignoring methods), +// because its type constraint contains no restrictions +// besides methods. +type top struct{} -const ( - Invalid BasicKind = iota // type is invalid +// theTop is the singleton top type. +var theTop = &top{} - // predeclared types - Bool - Int - Int8 - Int16 - Int32 - Int64 - Uint - Uint8 - Uint16 - Uint32 - Uint64 - Uintptr - Float32 - Float64 - Complex64 - Complex128 - String - UnsafePointer +func (t *top) Underlying() Type { return t } +func (t *top) String() string { return TypeString(t, nil) } - // types for untyped values - UntypedBool - UntypedInt - UntypedRune - UntypedFloat - UntypedComplex - UntypedString - UntypedNil - - // aliases - Byte = Uint8 - Rune = Int32 -) - -// BasicInfo is a set of flags describing properties of a basic type. -type BasicInfo int - -// Properties of basic types. -const ( - IsBoolean BasicInfo = 1 << iota - IsInteger - IsUnsigned - IsFloat - IsComplex - IsString - IsUntyped - - IsOrdered = IsInteger | IsFloat | IsString - IsNumeric = IsInteger | IsFloat | IsComplex - IsConstType = IsBoolean | IsNumeric | IsString -) - -// A Basic represents a basic type. -type Basic struct { - kind BasicKind - info BasicInfo - name string -} - -// Kind returns the kind of basic type b. -func (b *Basic) Kind() BasicKind { return b.kind } - -// Info returns information about properties of basic type b. -func (b *Basic) Info() BasicInfo { return b.info } - -// Name returns the name of basic type b. -func (b *Basic) Name() string { return b.name } - -// An Array represents an array type. -type Array struct { - len int64 - elem Type -} - -// NewArray returns a new array type for the given element type and length. -// A negative length indicates an unknown length. -func NewArray(elem Type, len int64) *Array { return &Array{len: len, elem: elem} } - -// Len returns the length of array a. -// A negative result indicates an unknown length. -func (a *Array) Len() int64 { return a.len } - -// Elem returns element type of array a. -func (a *Array) Elem() Type { return a.elem } - -// A Slice represents a slice type. -type Slice struct { - elem Type -} - -// NewSlice returns a new slice type for the given element type. -func NewSlice(elem Type) *Slice { return &Slice{elem: elem} } - -// Elem returns the element type of slice s. -func (s *Slice) Elem() Type { return s.elem } - -// A Pointer represents a pointer type. -type Pointer struct { - base Type // element type -} - -// NewPointer returns a new pointer type for the given element (base) type. -func NewPointer(elem Type) *Pointer { return &Pointer{base: elem} } - -// Elem returns the element type for the given pointer p. -func (p *Pointer) Elem() Type { return p.base } - -// A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple. -// Tuples are used as components of signatures and to represent the type of multiple -// assignments; they are not first class types of Go. -type Tuple struct { - vars []*Var -} - -// NewTuple returns a new tuple for the given variables. -func NewTuple(x ...*Var) *Tuple { - if len(x) > 0 { - return &Tuple{vars: x} +// under returns the true expanded underlying type. +// If it doesn't exist, the result is Typ[Invalid]. +// under must only be called when a type is known +// to be fully set up. +func under(t Type) Type { + // TODO(gri) is this correct for *Union? + if n := asNamed(t); n != nil { + return n.under() } - // TODO(gri) Don't represent empty tuples with a (*Tuple)(nil) pointer; - // it's too subtle and causes problems. - return nil -} - -// Len returns the number variables of tuple t. -func (t *Tuple) Len() int { - if t != nil { - return len(t.vars) - } - return 0 -} - -// At returns the i'th variable of tuple t. -func (t *Tuple) At(i int) *Var { return t.vars[i] } - -// A Map represents a map type. -type Map struct { - key, elem Type -} - -// NewMap returns a new map for the given key and element types. -func NewMap(key, elem Type) *Map { - return &Map{key: key, elem: elem} -} - -// Key returns the key type of map m. -func (m *Map) Key() Type { return m.key } - -// Elem returns the element type of map m. -func (m *Map) Elem() Type { return m.elem } - -// A Chan represents a channel type. -type Chan struct { - dir ChanDir - elem Type -} - -// A ChanDir value indicates a channel direction. -type ChanDir int - -// The direction of a channel is indicated by one of these constants. -const ( - SendRecv ChanDir = iota - SendOnly - RecvOnly -) - -// NewChan returns a new channel type for the given direction and element type. -func NewChan(dir ChanDir, elem Type) *Chan { - return &Chan{dir: dir, elem: elem} -} - -// Dir returns the direction of channel c. -func (c *Chan) Dir() ChanDir { return c.dir } - -// Elem returns the element type of channel c. -func (c *Chan) Elem() Type { return c.elem } - -// TODO(rfindley) Clean up Named struct below; specifically the fromRHS field (can we use underlying?). - -// A Named represents a named (defined) type. -type Named struct { - check *Checker // for Named.under implementation; nilled once under has been called - info typeInfo // for cycle detection - obj *TypeName // corresponding declared object - orig *Named // original, uninstantiated type - fromRHS Type // type (on RHS of declaration) this *Named type is derived of (for cycle reporting) - underlying Type // possibly a *Named during setup; never a *Named once set up completely - tparams []*TypeName // type parameters, or nil - targs []Type // type arguments (after instantiation), or nil - methods []*Func // methods declared for this type (not the method set of this type); signatures are type-checked lazily - - resolve func(*Named) ([]*TypeName, Type, []*Func) - once sync.Once -} - -// NewNamed returns a new named type for the given type name, underlying type, and associated methods. -// If the given type name obj doesn't have a type yet, its type is set to the returned named type. -// The underlying type must not be a *Named. -func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named { - if _, ok := underlying.(*Named); ok { - panic("types.NewNamed: underlying type must not be *Named") - } - return (*Checker)(nil).newNamed(obj, nil, underlying, nil, methods) -} - -func (t *Named) expand() *Named { - if t.resolve == nil { - return t - } - - t.once.Do(func() { - // TODO(mdempsky): Since we're passing t to resolve anyway - // (necessary because types2 expects the receiver type for methods - // on defined interface types to be the Named rather than the - // underlying Interface), maybe it should just handle calling - // SetTParams, SetUnderlying, and AddMethod instead? Those - // methods would need to support reentrant calls though. It would - // also make the API more future-proof towards further extensions - // (like SetTParams). - - tparams, underlying, methods := t.resolve(t) - - switch underlying.(type) { - case nil, *Named: - panic("invalid underlying type") - } - - t.tparams = tparams - t.underlying = underlying - t.methods = methods - }) return t } -func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams []*TypeName, methods []*Func) *Named { - typ := &Named{check: check, obj: obj, orig: orig, fromRHS: underlying, underlying: underlying, tparams: tparams, methods: methods} - if typ.orig == nil { - typ.orig = typ - } - if obj.typ == nil { - obj.typ = typ - } - // Ensure that typ is always expanded, at which point the check field can be - // nilled out. - // - // Note that currently we cannot nil out check inside typ.under(), because - // it's possible that typ is expanded multiple times. - // - // TODO(rFindley): clean this up so that under is the only function mutating - // named types. - if check != nil { - check.later(func() { - switch typ.under().(type) { - case *Named, *instance: - panic("internal error: unexpanded underlying type") - } - typ.check = nil - }) - } - return typ -} - -// Obj returns the type name for the named type t. -func (t *Named) Obj() *TypeName { return t.obj } - -// _Orig returns the original generic type an instantiated type is derived from. -// If t is not an instantiated type, the result is t. -func (t *Named) _Orig() *Named { return t.orig } - -// TODO(gri) Come up with a better representation and API to distinguish -// between parameterized instantiated and non-instantiated types. - -// _TParams returns the type parameters of the named type t, or nil. -// The result is non-nil for an (originally) parameterized type even if it is instantiated. -func (t *Named) TParams() []*TypeName { return t.expand().tparams } - -// _SetTParams sets the type parameters of the named type t. -func (t *Named) SetTParams(tparams []*TypeName) { t.expand().tparams = tparams } - -// _TArgs returns the type arguments after instantiation of the named type t, or nil if not instantiated. -func (t *Named) TArgs() []Type { return t.targs } - -// SetTArgs sets the type arguments of the named type t. -func (t *Named) SetTArgs(args []Type) { t.targs = args } - -// NumMethods returns the number of explicit methods whose receiver is named type t. -func (t *Named) NumMethods() int { return len(t.expand().methods) } - -// Method returns the i'th method of named type t for 0 <= i < t.NumMethods(). -func (t *Named) Method(i int) *Func { return t.expand().methods[i] } - -// SetUnderlying sets the underlying type and marks t as complete. -func (t *Named) SetUnderlying(underlying Type) { - if underlying == nil { - panic("types.Named.SetUnderlying: underlying type must not be nil") - } - if _, ok := underlying.(*Named); ok { - panic("types.Named.SetUnderlying: underlying type must not be *Named") - } - t.expand().underlying = underlying -} - -// AddMethod adds method m unless it is already in the method list. -func (t *Named) AddMethod(m *Func) { - t.expand() - if i, _ := lookupMethod(t.methods, m.pkg, m.name); i < 0 { - t.methods = append(t.methods, m) - } -} - -// Note: This is a uint32 rather than a uint64 because the -// respective 64 bit atomic instructions are not available -// on all platforms. -var lastID uint32 - -// nextID returns a value increasing monotonically by 1 with -// each call, starting with 1. It may be called concurrently. -func nextID() uint64 { return uint64(atomic.AddUint32(&lastID, 1)) } - -// A TypeParam represents a type parameter type. -type TypeParam struct { - check *Checker // for lazy type bound completion - id uint64 // unique id, for debugging only - obj *TypeName // corresponding type name - index int // type parameter index in source order, starting at 0 - bound Type // *Named or *Interface; underlying type is always *Interface -} - -// NewTypeParam returns a new TypeParam. -func NewTypeParam(obj *TypeName, index int, bound Type) *TypeParam { - return (*Checker)(nil).newTypeParam(obj, index, bound) -} - -func (check *Checker) newTypeParam(obj *TypeName, index int, bound Type) *TypeParam { - assert(bound != nil) - - // Always increment lastID, even if it is not used. - id := nextID() - if check != nil { - check.nextID++ - id = check.nextID - } - - typ := &TypeParam{check: check, id: id, obj: obj, index: index, bound: bound} - if obj.typ == nil { - obj.typ = typ - } - return typ -} - -func (t *TypeParam) Bound() *Interface { - // we may not have an interface (error reported elsewhere) - iface, _ := under(t.bound).(*Interface) - if iface == nil { - return &emptyInterface - } - // use the type bound position if we have one - pos := token.NoPos - if n, _ := t.bound.(*Named); n != nil { - pos = n.obj.pos - } - // TODO(rFindley) switch this to an unexported method on Checker. - computeTypeSet(t.check, pos, iface) - return iface -} - // optype returns a type's operational type. Except for type parameters, // the operational type is the same as the underlying type (as returned // by under). For Type parameters, the operational type is determined @@ -424,102 +70,6 @@ func optype(typ Type) Type { return under(typ) } -// An instance represents an instantiated generic type syntactically -// (without expanding the instantiation). Type instances appear only -// during type-checking and are replaced by their fully instantiated -// (expanded) types before the end of type-checking. -type instance struct { - check *Checker // for lazy instantiation - pos token.Pos // position of type instantiation; for error reporting only - base *Named // parameterized type to be instantiated - targs []Type // type arguments - poslist []token.Pos // position of each targ; for error reporting only - value Type // base(targs...) after instantiation or Typ[Invalid]; nil if not yet set -} - -// expand returns the instantiated (= expanded) type of t. -// The result is either an instantiated *Named type, or -// Typ[Invalid] if there was an error. -func (t *instance) expand() Type { - v := t.value - if v == nil { - v = t.check.instantiate(t.pos, t.base, t.targs, t.poslist) - if v == nil { - v = Typ[Invalid] - } - t.value = v - } - // After instantiation we must have an invalid or a *Named type. - if debug && v != Typ[Invalid] { - _ = v.(*Named) - } - return v -} - -// expand expands a type instance into its instantiated -// type and leaves all other types alone. expand does -// not recurse. -func expand(typ Type) Type { - if t, _ := typ.(*instance); t != nil { - return t.expand() - } - return typ -} - -// expandf is set to expand. -// Call expandf when calling expand causes compile-time cycle error. -var expandf func(Type) Type - -func init() { expandf = expand } - -// top represents the top of the type lattice. -// It is the underlying type of a type parameter that -// can be satisfied by any type (ignoring methods), -// because its type constraint contains no restrictions -// besides methods. -type top struct{} - -// theTop is the singleton top type. -var theTop = &top{} - -// Type-specific implementations of Underlying. -func (t *Basic) Underlying() Type { return t } -func (t *Array) Underlying() Type { return t } -func (t *Slice) Underlying() Type { return t } -func (t *Pointer) Underlying() Type { return t } -func (t *Tuple) Underlying() Type { return t } -func (t *Map) Underlying() Type { return t } -func (t *Chan) Underlying() Type { return t } -func (t *Named) Underlying() Type { return t.expand().underlying } -func (t *TypeParam) Underlying() Type { return t } -func (t *instance) Underlying() Type { return t } -func (t *top) Underlying() Type { return t } - -// Type-specific implementations of String. -func (t *Basic) String() string { return TypeString(t, nil) } -func (t *Array) String() string { return TypeString(t, nil) } -func (t *Slice) String() string { return TypeString(t, nil) } -func (t *Pointer) String() string { return TypeString(t, nil) } -func (t *Tuple) String() string { return TypeString(t, nil) } -func (t *Map) String() string { return TypeString(t, nil) } -func (t *Chan) String() string { return TypeString(t, nil) } -func (t *Named) String() string { return TypeString(t, nil) } -func (t *TypeParam) String() string { return TypeString(t, nil) } -func (t *instance) String() string { return TypeString(t, nil) } -func (t *top) String() string { return TypeString(t, nil) } - -// under returns the true expanded underlying type. -// If it doesn't exist, the result is Typ[Invalid]. -// under must only be called when a type is known -// to be fully set up. -func under(t Type) Type { - // TODO(gri) is this correct for *Union? - if n := asNamed(t); n != nil { - return n.under() - } - return t -} - // Converters // // A converter must only be called when a type is diff --git a/src/go/types/typeparam.go b/src/go/types/typeparam.go new file mode 100644 index 0000000000..e134508855 --- /dev/null +++ b/src/go/types/typeparam.go @@ -0,0 +1,72 @@ +// Copyright 2011 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 types + +import ( + "go/token" + "sync/atomic" +) + +// Note: This is a uint32 rather than a uint64 because the +// respective 64 bit atomic instructions are not available +// on all platforms. +var lastID uint32 + +// nextID returns a value increasing monotonically by 1 with +// each call, starting with 1. It may be called concurrently. +func nextID() uint64 { return uint64(atomic.AddUint32(&lastID, 1)) } + +// A TypeParam represents a type parameter type. +type TypeParam struct { + check *Checker // for lazy type bound completion + id uint64 // unique id, for debugging only + obj *TypeName // corresponding type name + index int // type parameter index in source order, starting at 0 + bound Type // *Named or *Interface; underlying type is always *Interface +} + +// NewTypeParam returns a new TypeParam. +func NewTypeParam(obj *TypeName, index int, bound Type) *TypeParam { + return (*Checker)(nil).newTypeParam(obj, index, bound) +} + +// TODO(rfindley): this is factored slightly differently in types2. +func (check *Checker) newTypeParam(obj *TypeName, index int, bound Type) *TypeParam { + assert(bound != nil) + + // Always increment lastID, even if it is not used. + id := nextID() + if check != nil { + check.nextID++ + id = check.nextID + } + + typ := &TypeParam{check: check, id: id, obj: obj, index: index, bound: bound} + if obj.typ == nil { + obj.typ = typ + } + return typ +} + +// TODO(rfindley): types2 to has Index and SetID. Should we add them here? + +func (t *TypeParam) Bound() *Interface { + // we may not have an interface (error reported elsewhere) + iface, _ := under(t.bound).(*Interface) + if iface == nil { + return &emptyInterface + } + // use the type bound position if we have one + pos := token.NoPos + if n, _ := t.bound.(*Named); n != nil { + pos = n.obj.pos + } + // TODO(rFindley) switch this to an unexported method on Checker. + computeTypeSet(t.check, pos, iface) + return iface +} + +func (t *TypeParam) Underlying() Type { return t } +func (t *TypeParam) String() string { return TypeString(t, nil) }