1 files changed, 119 insertions, 0 deletions
diff --git a/libgo/go/go/typechecker/scope.go b/libgo/go/go/typechecker/scope.go
new file mode 100644
index 000000000..114c93ea8
--- /dev/null
+++ b/libgo/go/go/typechecker/scope.go
@@ -0,0 +1,119 @@
+// Copyright 2010 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.
+
+// This file implements scope support functions.
+
+package typechecker
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+)
+
+
+func (tc *typechecker) openScope() *ast.Scope {
+	tc.topScope = ast.NewScope(tc.topScope)
+	return tc.topScope
+}
+
+
+func (tc *typechecker) closeScope() {
+	tc.topScope = tc.topScope.Outer
+}
+
+
+// objPos computes the source position of the declaration of an object name.
+// Only required for error reporting, so doesn't have to be fast.
+func objPos(obj *ast.Object) (pos token.Pos) {
+	switch d := obj.Decl.(type) {
+	case *ast.Field:
+		for _, n := range d.Names {
+			if n.Name == obj.Name {
+				return n.Pos()
+			}
+		}
+	case *ast.ValueSpec:
+		for _, n := range d.Names {
+			if n.Name == obj.Name {
+				return n.Pos()
+			}
+		}
+	case *ast.TypeSpec:
+		return d.Name.Pos()
+	case *ast.FuncDecl:
+		return d.Name.Pos()
+	}
+	if debug {
+		fmt.Printf("decl = %T\n", obj.Decl)
+	}
+	panic("unreachable")
+}
+
+
+// declInScope declares an object of a given kind and name in scope and sets the object's Decl and N fields.
+// It returns the newly allocated object. If an object with the same name already exists in scope, an error
+// is reported and the object is not inserted.
+// (Objects with _ name are always inserted into a scope without errors, but they cannot be found.)
+func (tc *typechecker) declInScope(scope *ast.Scope, kind ast.Kind, name *ast.Ident, decl interface{}, n int) *ast.Object {
+	obj := ast.NewObj(kind, name.Name)
+	obj.Decl = decl
+	obj.N = n
+	name.Obj = obj
+	if alt := scope.Insert(obj); alt != obj {
+		tc.Errorf(name.Pos(), "%s already declared at %s", name.Name, objPos(alt))
+	}
+	return obj
+}
+
+
+// decl is the same as declInScope(tc.topScope, ...)
+func (tc *typechecker) decl(kind ast.Kind, name *ast.Ident, decl interface{}, n int) *ast.Object {
+	return tc.declInScope(tc.topScope, kind, name, decl, n)
+}
+
+
+// find returns the object with the given name if visible in the current scope hierarchy.
+// If no such object is found, an error is reported and a bad object is returned instead.
+func (tc *typechecker) find(name *ast.Ident) (obj *ast.Object) {
+	for s := tc.topScope; s != nil && obj == nil; s = s.Outer {
+		obj = s.Lookup(name.Name)
+	}
+	if obj == nil {
+		tc.Errorf(name.Pos(), "%s not declared", name.Name)
+		obj = ast.NewObj(ast.Bad, name.Name)
+	}
+	name.Obj = obj
+	return
+}
+
+
+// findField returns the object with the given name if visible in the type's scope.
+// If no such object is found, an error is reported and a bad object is returned instead.
+func (tc *typechecker) findField(typ *ast.Type, name *ast.Ident) (obj *ast.Object) {
+	// TODO(gri) This is simplistic at the moment and ignores anonymous fields.
+	obj = typ.Scope.Lookup(name.Name)
+	if obj == nil {
+		tc.Errorf(name.Pos(), "%s not declared", name.Name)
+		obj = ast.NewObj(ast.Bad, name.Name)
+	}
+	return
+}
+
+
+// printScope prints the objects in a scope.
+func printScope(scope *ast.Scope) {
+	fmt.Printf("scope %p {", scope)
+	if scope != nil && len(scope.Objects) > 0 {
+		fmt.Println()
+		for _, obj := range scope.Objects {
+			form := "void"
+			if obj.Type != nil {
+				form = obj.Type.Form.String()
+			}
+			fmt.Printf("\t%s\t%s\n", obj.Name, form)
+		}
+	}
+	fmt.Printf("}\n")
+}