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// Copyright 2009 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 eval
import (
"eval";
)
func NewRootScope() *Scope {
return &Scope{nil, make(map[string] Def), 0};
}
func (s *Scope) Fork() *Scope {
return &Scope{s, make(map[string] Def), 0};
}
func (s *Scope) DefineVar(name string, t Type) *Variable {
if _, ok := s.defs[name]; ok {
return nil;
}
v := &Variable{s.numVars, t};
s.numVars++;
s.defs[name] = v;
return v;
}
func (s *Scope) DefineConst(name string, v Value) *Constant {
if _, ok := s.defs[name]; ok {
return nil;
}
c := &Constant{v.Type(), v};
s.defs[name] = c;
return c;
}
func (s *Scope) DefineType(name string, t Type) bool {
if _, ok := s.defs[name]; ok {
return false;
}
s.defs[name] = t;
return true;
}
func (s *Scope) Lookup(name string) (Def, *Scope) {
for s != nil {
if d, ok := s.defs[name]; ok {
return d, s;
}
s = s.outer;
}
return nil, nil;
}
func (f *Frame) Get(s *Scope, index int) Value {
for f.Scope != s {
f = f.Outer;
}
return f.Vars[index];
}
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