github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/tools/go_generics/globals/scope.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package globals
    16  
    17  import (
    18  	"go/token"
    19  )
    20  
    21  // SymKind specifies the kind of a global symbol. For example, a variable, const
    22  // function, etc.
    23  type SymKind int
    24  
    25  // Constants for different kinds of symbols.
    26  const (
    27  	KindUnknown SymKind = iota
    28  	KindImport
    29  	KindType
    30  	KindVar
    31  	KindConst
    32  	KindFunction
    33  	KindReceiver
    34  	KindParameter
    35  	KindResult
    36  	KindTag
    37  )
    38  
    39  type symbol struct {
    40  	kind  SymKind
    41  	pos   token.Pos
    42  	scope *scope
    43  }
    44  
    45  type scope struct {
    46  	outer *scope
    47  	syms  map[string]*symbol
    48  }
    49  
    50  func newScope(outer *scope) *scope {
    51  	return &scope{
    52  		outer: outer,
    53  		syms:  make(map[string]*symbol),
    54  	}
    55  }
    56  
    57  func (s *scope) isGlobal() bool {
    58  	return s.outer == nil
    59  }
    60  
    61  func (s *scope) lookup(n string) *symbol {
    62  	return s.syms[n]
    63  }
    64  
    65  func (s *scope) deepLookup(n string) *symbol {
    66  	for x := s; x != nil; x = x.outer {
    67  		if sym := x.lookup(n); sym != nil {
    68  			return sym
    69  		}
    70  	}
    71  	return nil
    72  }
    73  
    74  func (s *scope) add(name string, kind SymKind, pos token.Pos) {
    75  	if s.syms[name] != nil {
    76  		return
    77  	}
    78  
    79  	s.syms[name] = &symbol{
    80  		kind:  kind,
    81  		pos:   pos,
    82  		scope: s,
    83  	}
    84  }