214 lines
6.7 KiB
Go
214 lines
6.7 KiB
Go
// +build !go1.9
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// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package srcimporter implements importing directly
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// from source files rather than installed packages.
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package srcimporter
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import (
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"fmt"
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"go/ast"
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"go/build"
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"go/parser"
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"go/token"
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"go/types"
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"path/filepath"
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"sync"
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)
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// An Importer provides the context for importing packages from source code.
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type Importer struct {
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ctxt *build.Context
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fset *token.FileSet
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sizes types.Sizes
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packages map[string]*types.Package
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}
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// NewImporter returns a new Importer for the given context, file set, and map
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// of packages. The context is used to resolve import paths to package paths,
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// and identifying the files belonging to the package. If the context provides
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// non-nil file system functions, they are used instead of the regular package
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// os functions. The file set is used to track position information of package
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// files; and imported packages are added to the packages map.
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func New(ctxt *build.Context, fset *token.FileSet, packages map[string]*types.Package) *Importer {
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return &Importer{
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ctxt: ctxt,
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fset: fset,
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sizes: SizesFor(ctxt.Compiler, ctxt.GOARCH), // uses go/types default if GOARCH not found
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packages: packages,
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}
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}
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// Importing is a sentinel taking the place in Importer.packages
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// for a package that is in the process of being imported.
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var importing types.Package
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// Import(path) is a shortcut for ImportFrom(path, "", 0).
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func (p *Importer) Import(path string) (*types.Package, error) {
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return p.ImportFrom(path, "", 0)
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}
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// ImportFrom imports the package with the given import path resolved from the given srcDir,
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// adds the new package to the set of packages maintained by the importer, and returns the
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// package. Package path resolution and file system operations are controlled by the context
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// maintained with the importer. The import mode must be zero but is otherwise ignored.
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// Packages that are not comprised entirely of pure Go files may fail to import because the
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// type checker may not be able to determine all exported entities (e.g. due to cgo dependencies).
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func (p *Importer) ImportFrom(path, srcDir string, mode types.ImportMode) (*types.Package, error) {
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if mode != 0 {
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panic("non-zero import mode")
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}
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// determine package path (do vendor resolution)
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var bp *build.Package
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var err error
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switch {
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default:
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if abs, err := p.absPath(srcDir); err == nil { // see issue #14282
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srcDir = abs
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}
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bp, err = p.ctxt.Import(path, srcDir, build.FindOnly)
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case build.IsLocalImport(path):
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// "./x" -> "srcDir/x"
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bp, err = p.ctxt.ImportDir(filepath.Join(srcDir, path), build.FindOnly)
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case p.isAbsPath(path):
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return nil, fmt.Errorf("invalid absolute import path %q", path)
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}
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if err != nil {
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return nil, err // err may be *build.NoGoError - return as is
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}
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// package unsafe is known to the type checker
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if bp.ImportPath == "unsafe" {
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return types.Unsafe, nil
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}
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// no need to re-import if the package was imported completely before
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pkg := p.packages[bp.ImportPath]
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if pkg != nil {
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if pkg == &importing {
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return nil, fmt.Errorf("import cycle through package %q", bp.ImportPath)
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}
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if !pkg.Complete() {
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// Package exists but is not complete - we cannot handle this
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// at the moment since the source importer replaces the package
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// wholesale rather than augmenting it (see #19337 for details).
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// Return incomplete package with error (see #16088).
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return pkg, fmt.Errorf("reimported partially imported package %q", bp.ImportPath)
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}
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return pkg, nil
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}
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p.packages[bp.ImportPath] = &importing
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defer func() {
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// clean up in case of error
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// TODO(gri) Eventually we may want to leave a (possibly empty)
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// package in the map in all cases (and use that package to
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// identify cycles). See also issue 16088.
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if p.packages[bp.ImportPath] == &importing {
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p.packages[bp.ImportPath] = nil
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}
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}()
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// collect package files
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bp, err = p.ctxt.ImportDir(bp.Dir, 0)
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if err != nil {
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return nil, err // err may be *build.NoGoError - return as is
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}
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var filenames []string
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filenames = append(filenames, bp.GoFiles...)
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filenames = append(filenames, bp.CgoFiles...)
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files, err := p.parseFiles(bp.Dir, filenames)
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if err != nil {
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return nil, err
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}
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// type-check package files
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conf := types.Config{
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IgnoreFuncBodies: true,
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FakeImportC: true,
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Importer: p,
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Sizes: p.sizes,
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}
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pkg, err = conf.Check(bp.ImportPath, p.fset, files, nil)
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if err != nil {
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// Type-checking stops after the first error (types.Config.Error is not set),
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// so the returned package is very likely incomplete. Don't return it since
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// we don't know its condition: It's very likely unsafe to use and it's also
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// not added to p.packages which may cause further problems (issue #20837).
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return nil, fmt.Errorf("type-checking package %q failed (%v)", bp.ImportPath, err)
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}
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p.packages[bp.ImportPath] = pkg
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return pkg, nil
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}
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func (p *Importer) parseFiles(dir string, filenames []string) ([]*ast.File, error) {
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open := p.ctxt.OpenFile // possibly nil
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files := make([]*ast.File, len(filenames))
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errors := make([]error, len(filenames))
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var wg sync.WaitGroup
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wg.Add(len(filenames))
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for i, filename := range filenames {
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go func(i int, filepath string) {
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defer wg.Done()
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if open != nil {
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src, err := open(filepath)
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if err != nil {
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errors[i] = fmt.Errorf("opening package file %s failed (%v)", filepath, err)
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return
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}
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files[i], errors[i] = parser.ParseFile(p.fset, filepath, src, 0)
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src.Close() // ignore Close error - parsing may have succeeded which is all we need
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} else {
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// Special-case when ctxt doesn't provide a custom OpenFile and use the
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// parser's file reading mechanism directly. This appears to be quite a
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// bit faster than opening the file and providing an io.ReaderCloser in
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// both cases.
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// TODO(gri) investigate performance difference (issue #19281)
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files[i], errors[i] = parser.ParseFile(p.fset, filepath, nil, 0)
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}
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}(i, p.joinPath(dir, filename))
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}
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wg.Wait()
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// if there are errors, return the first one for deterministic results
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for _, err := range errors {
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if err != nil {
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return nil, err
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}
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}
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return files, nil
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}
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// context-controlled file system operations
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func (p *Importer) absPath(path string) (string, error) {
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// TODO(gri) This should be using p.ctxt.AbsPath which doesn't
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// exist but probably should. See also issue #14282.
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return filepath.Abs(path)
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}
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func (p *Importer) isAbsPath(path string) bool {
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if f := p.ctxt.IsAbsPath; f != nil {
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return f(path)
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}
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return filepath.IsAbs(path)
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}
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func (p *Importer) joinPath(elem ...string) string {
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if f := p.ctxt.JoinPath; f != nil {
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return f(elem...)
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}
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return filepath.Join(elem...)
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}
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