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PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 80 insertions, 0 deletions

diff --git a/tools/go_generics/globals/scope.go b/tools/go_generics/globals/scope.go
new file mode 100644
index 000000000..18743bdee
--- /dev/null
+++ b/tools/go_generics/globals/scope.go
@@ -0,0 +1,80 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package globals
+
+import (
+	"go/token"
+)
+
+// SymKind specifies the kind of a global symbol. For example, a variable, const
+// function, etc.
+type SymKind int
+
+// Constants for different kinds of symbols.
+const (
+	KindUnknown SymKind = iota
+	KindImport
+	KindType
+	KindVar
+	KindConst
+	KindFunction
+	KindReceiver
+	KindParameter
+	KindResult
+	KindTag
+)
+
+type symbol struct {
+	kind  SymKind
+	pos   token.Pos
+	scope *scope
+}
+
+type scope struct {
+	outer *scope
+	syms  map[string]*symbol
+}
+
+func newScope(outer *scope) *scope {
+	return &scope{
+		outer: outer,
+		syms:  make(map[string]*symbol),
+	}
+}
+
+func (s *scope) isGlobal() bool {
+	return s.outer == nil
+}
+
+func (s *scope) lookup(n string) *symbol {
+	return s.syms[n]
+}
+
+func (s *scope) deepLookup(n string) *symbol {
+	for x := s; x != nil; x = x.outer {
+		if sym := x.lookup(n); sym != nil {
+			return sym
+		}
+	}
+	return nil
+}
+
+func (s *scope) add(name string, kind SymKind, pos token.Pos) {
+	s.syms[name] = &symbol{
+		kind:  kind,
+		pos:   pos,
+		scope: s,
+	}
+}