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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"
"sort"
"sync"
)
// pkgMap maps a package path to a package.
var pkgMap = make(map[string]*Pkg)
// MaxPkgHeight is a height greater than any likely package height.
const MaxPkgHeight = 1e9
type Pkg struct {
Path string // string literal used in import statement, e.g. "runtime/internal/sys"
Name string // package name, e.g. "sys"
Prefix string // escaped path for use in symbol table
Syms map[string]*Sym
Pathsym *obj.LSym
// Height is the package's height in the import graph. Leaf
// packages (i.e., packages with no imports) have height 0,
// and all other packages have height 1 plus the maximum
// height of their imported packages.
Height int
Direct bool // imported directly
}
// 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
return p
}
// ImportedPkgList returns the list of directly imported packages.
// The list is sorted by package path.
func ImportedPkgList() []*Pkg {
var list []*Pkg
for _, p := range pkgMap {
if p.Direct {
list = append(list, p)
}
}
sort.Sort(byPath(list))
return list
}
type byPath []*Pkg
func (a byPath) Len() int { return len(a) }
func (a byPath) Less(i, j int) bool { return a[i].Path < a[j].Path }
func (a byPath) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
var nopkg = &Pkg{
Syms: make(map[string]*Sym),
}
func (pkg *Pkg) Lookup(name string) *Sym {
s, _ := pkg.LookupOK(name)
return s
}
// 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,
}
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 (
internedStringsmu sync.Mutex // protects internedStrings
internedStrings = map[string]string{}
)
func InternString(b []byte) string {
internedStringsmu.Lock()
s, ok := internedStrings[string(b)] // string(b) here doesn't allocate
if !ok {
s = string(b)
internedStrings[s] = s
}
internedStringsmu.Unlock()
return s
}
// CleanroomDo invokes f in an environment with no preexisting packages.
// For testing of import/export only.
func CleanroomDo(f func()) {
saved := pkgMap
pkgMap = make(map[string]*Pkg)
f()
pkgMap = saved
}
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