diff options
Diffstat (limited to 'src/cmd/compile/internal/types2/scope.go')
| -rw-r--r-- | src/cmd/compile/internal/types2/scope.go | 97 |
1 files changed, 87 insertions, 10 deletions
diff --git a/src/cmd/compile/internal/types2/scope.go b/src/cmd/compile/internal/types2/scope.go index ade0a79b31..095875d94b 100644 --- a/src/cmd/compile/internal/types2/scope.go +++ b/src/cmd/compile/internal/types2/scope.go @@ -13,6 +13,7 @@ import ( "io" "sort" "strings" + "sync" ) // A Scope maintains a set of objects and links to its containing @@ -22,6 +23,7 @@ import ( type Scope struct { parent *Scope children []*Scope + number int // parent.children[number-1] is this scope; 0 if there is no parent elems map[string]Object // lazily allocated pos, end syntax.Pos // scope extent; may be invalid comment string // for debugging only @@ -31,10 +33,11 @@ type Scope struct { // NewScope returns a new, empty scope contained in the given parent // scope, if any. The comment is for debugging only. func NewScope(parent *Scope, pos, end syntax.Pos, comment string) *Scope { - s := &Scope{parent, nil, nil, pos, end, comment, false} + s := &Scope{parent, nil, 0, nil, pos, end, comment, false} // don't add children to Universe scope! if parent != nil && parent != Universe { parent.children = append(parent.children, s) + s.number = len(parent.children) } return s } @@ -66,7 +69,7 @@ func (s *Scope) Child(i int) *Scope { return s.children[i] } // Lookup returns the object in scope s with the given name if such an // object exists; otherwise the result is nil. func (s *Scope) Lookup(name string) Object { - return s.elems[name] + return resolve(name, s.elems[name]) } // LookupParent follows the parent chain of scopes starting with s until @@ -81,7 +84,7 @@ func (s *Scope) Lookup(name string) Object { // whose scope is the scope of the package that exported them. func (s *Scope) LookupParent(name string, pos syntax.Pos) (*Scope, Object) { for ; s != nil; s = s.parent { - if obj := s.elems[name]; obj != nil && (!pos.IsKnown() || obj.scopePos().Cmp(pos) <= 0) { + if obj := s.Lookup(name); obj != nil && (!pos.IsKnown() || obj.scopePos().Cmp(pos) <= 0) { return s, obj } } @@ -95,19 +98,38 @@ func (s *Scope) LookupParent(name string, pos syntax.Pos) (*Scope, Object) { // if not already set, and returns nil. func (s *Scope) Insert(obj Object) Object { name := obj.Name() - if alt := s.elems[name]; alt != nil { + if alt := s.Lookup(name); alt != nil { return alt } - if s.elems == nil { - s.elems = make(map[string]Object) - } - s.elems[name] = obj + s.insert(name, obj) if obj.Parent() == nil { obj.setParent(s) } return nil } +// InsertLazy is like Insert, but allows deferring construction of the +// inserted object until it's accessed with Lookup. The Object +// returned by resolve must have the same name as given to InsertLazy. +// If s already contains an alternative object with the same name, +// InsertLazy leaves s unchanged and returns false. Otherwise it +// records the binding and returns true. The object's parent scope +// will be set to s after resolve is called. +func (s *Scope) InsertLazy(name string, resolve func() Object) bool { + if s.elems[name] != nil { + return false + } + s.insert(name, &lazyObject{parent: s, resolve: resolve}) + return true +} + +func (s *Scope) insert(name string, obj Object) { + if s.elems == nil { + s.elems = make(map[string]Object) + } + s.elems[name] = obj +} + // Squash merges s with its parent scope p by adding all // objects of s to p, adding all children of s to the // children of p, and removing s from p's children. @@ -117,7 +139,8 @@ func (s *Scope) Insert(obj Object) Object { func (s *Scope) Squash(err func(obj, alt Object)) { p := s.parent assert(p != nil) - for _, obj := range s.elems { + for name, obj := range s.elems { + obj = resolve(name, obj) obj.setParent(nil) if alt := p.Insert(obj); alt != nil { err(obj, alt) @@ -196,7 +219,7 @@ func (s *Scope) WriteTo(w io.Writer, n int, recurse bool) { indn1 := indn + ind for _, name := range s.Names() { - fmt.Fprintf(w, "%s%s\n", indn1, s.elems[name]) + fmt.Fprintf(w, "%s%s\n", indn1, s.Lookup(name)) } if recurse { @@ -214,3 +237,57 @@ func (s *Scope) String() string { s.WriteTo(&buf, 0, false) return buf.String() } + +// A lazyObject represents an imported Object that has not been fully +// resolved yet by its importer. +type lazyObject struct { + parent *Scope + resolve func() Object + obj Object + once sync.Once +} + +// resolve returns the Object represented by obj, resolving lazy +// objects as appropriate. +func resolve(name string, obj Object) Object { + if lazy, ok := obj.(*lazyObject); ok { + lazy.once.Do(func() { + obj := lazy.resolve() + + if _, ok := obj.(*lazyObject); ok { + panic("recursive lazy object") + } + if obj.Name() != name { + panic("lazy object has unexpected name") + } + + if obj.Parent() == nil { + obj.setParent(lazy.parent) + } + lazy.obj = obj + }) + + obj = lazy.obj + } + return obj +} + +// stub implementations so *lazyObject implements Object and we can +// store them directly into Scope.elems. +func (*lazyObject) Parent() *Scope { panic("unreachable") } +func (*lazyObject) Pos() syntax.Pos { panic("unreachable") } +func (*lazyObject) Pkg() *Package { panic("unreachable") } +func (*lazyObject) Name() string { panic("unreachable") } +func (*lazyObject) Type() Type { panic("unreachable") } +func (*lazyObject) Exported() bool { panic("unreachable") } +func (*lazyObject) Id() string { panic("unreachable") } +func (*lazyObject) String() string { panic("unreachable") } +func (*lazyObject) order() uint32 { panic("unreachable") } +func (*lazyObject) color() color { panic("unreachable") } +func (*lazyObject) setType(Type) { panic("unreachable") } +func (*lazyObject) setOrder(uint32) { panic("unreachable") } +func (*lazyObject) setColor(color color) { panic("unreachable") } +func (*lazyObject) setParent(*Scope) { panic("unreachable") } +func (*lazyObject) sameId(pkg *Package, name string) bool { panic("unreachable") } +func (*lazyObject) scopePos() syntax.Pos { panic("unreachable") } +func (*lazyObject) setScopePos(pos syntax.Pos) { panic("unreachable") } |