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pkg.go
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pkg.go
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// Copyright 2017 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 types
import (
"cmd/internal/obj"
"cmd/internal/objabi"
"fmt"
)
type Pkg struct {
Path string // string literal used in import statement, e.g. "runtime/internal/sys"
Name string // package name, e.g. "sys"
Pathsym *obj.LSym
Prefix string // escaped path for use in symbol table
Imported bool // export data of this package was parsed
Direct bool // imported directly
Syms map[string]*Sym
}
var PkgMap = make(map[string]*Pkg)
var PkgList []*Pkg
// NewPkg returns a new Pkg for the given package path and name.
// Unless name is the empty string, if the package exists already,
// the existing package name and the provided name must match.
func NewPkg(path, name string) *Pkg {
if p := PkgMap[path]; p != nil {
if name != "" && p.Name != name {
panic(fmt.Sprintf("conflicting package names %s and %s for path %q", p.Name, name, path))
}
return p
}
p := new(Pkg)
p.Path = path
p.Name = name
p.Prefix = objabi.PathToPrefix(path)
p.Syms = make(map[string]*Sym)
PkgMap[path] = p
PkgList = append(PkgList, p)
return p
}
var nopkg = &Pkg{
Syms: make(map[string]*Sym),
}
func (pkg *Pkg) Lookup(name string) *Sym {
s, _ := pkg.LookupOK(name)
return s
}
var InitSyms []*Sym
// LookupOK looks up name in pkg and reports whether it previously existed.
func (pkg *Pkg) LookupOK(name string) (s *Sym, existed bool) {
// TODO(gri) remove this check in favor of specialized lookup
if pkg == nil {
pkg = nopkg
}
if s := pkg.Syms[name]; s != nil {
return s, true
}
s = &Sym{
Name: name,
Pkg: pkg,
}
if name == "init" {
InitSyms = append(InitSyms, s)
}
pkg.Syms[name] = s
return s, false
}
func (pkg *Pkg) LookupBytes(name []byte) *Sym {
// TODO(gri) remove this check in favor of specialized lookup
if pkg == nil {
pkg = nopkg
}
if s := pkg.Syms[string(name)]; s != nil {
return s
}
str := InternString(name)
return pkg.Lookup(str)
}
var internedStrings = map[string]string{}
func InternString(b []byte) string {
s, ok := internedStrings[string(b)] // string(b) here doesn't allocate
if !ok {
s = string(b)
internedStrings[s] = s
}
return s
}