Golang Context.OpenFile方法代码示例

// parseFiles parses the Go source files within directory dir and
// returns the ASTs of the ones that could be at least partially parsed,
// along with a list of I/O and parse errors encountered.
//
// I/O is done via ctxt, which may specify a virtual file system.
// displayPath is used to transform the filenames attached to the ASTs.
//
func parseFiles(fset *token.FileSet, ctxt *build.Context, displayPath func(string) string, dir string, files []string, mode parser.Mode) ([]*ast.File, []error) {
	if displayPath == nil {
		displayPath = func(path string) string { return path }
	}
	var wg sync.WaitGroup
	n := len(files)
	parsed := make([]*ast.File, n)
	errors := make([]error, n)
	for i, file := range files {
		if !buildutil.IsAbsPath(ctxt, file) {
			file = buildutil.JoinPath(ctxt, dir, file)
		}
		wg.Add(1)
		go func(i int, file string) {
			ioLimit <- true // wait
			defer func() {
				wg.Done()
				<-ioLimit // signal
			}()
			var rd io.ReadCloser
			var err error
			if ctxt.OpenFile != nil {
				rd, err = ctxt.OpenFile(file)
			} else {
				rd, err = os.Open(file)
			}
			if err != nil {
				errors[i] = err // open failed
				return
			}

			// ParseFile may return both an AST and an error.
			parsed[i], errors[i] = parser.ParseFile(fset, displayPath(file), rd, mode)
			rd.Close()
		}(i, file)
	}
	wg.Wait()

	// Eliminate nils, preserving order.
	var o int
	for _, f := range parsed {
		if f != nil {
			parsed[o] = f
			o++
		}
	}
	parsed = parsed[:o]

	o = 0
	for _, err := range errors {
		if err != nil {
			errors[o] = err
			o++
		}
	}
	errors = errors[:o]

	return parsed, errors
}

// FileExists returns true if the specified file exists,
// using the build context's file system interface.
func FileExists(ctxt *build.Context, path string) bool {
	if ctxt.OpenFile != nil {
		r, err := ctxt.OpenFile(path)
		if err != nil {
			return false
		}
		r.Close() // ignore error
		return true
	}
	_, err := os.Stat(path)
	return err == nil
}

// Setup configures a *build.Context to use the given VFS
// as its filesystem.
func Setup(ctx *build.Context, fs vfs.VFS) {
	ctx.JoinPath = path.Join
	ctx.SplitPathList = filepath.SplitList
	ctx.IsAbsPath = func(p string) bool {
		return p != "" && p[0] == '/'
	}
	ctx.IsDir = func(p string) bool {
		stat, err := fs.Stat(p)
		return err == nil && stat.IsDir()
	}
	ctx.HasSubdir = func(root, dir string) (string, bool) {
		root = path.Clean(root)
		if !strings.HasSuffix(root, separator) {
			root += separator
		}
		dir = path.Clean(dir)
		if !strings.HasPrefix(dir, root) {
			return "", false
		}
		return dir[len(root):], true
	}
	ctx.ReadDir = fs.ReadDir
	ctx.OpenFile = func(p string) (io.ReadCloser, error) {
		return fs.Open(p)
	}
}

// parseFiles parses the Go source files files within directory dir
// and returns their ASTs, or the first parse error if any.
//
// I/O is done via ctxt, which may specify a virtual file system.
// displayPath is used to transform the filenames attached to the ASTs.
//
func parseFiles(fset *token.FileSet, ctxt *build.Context, displayPath func(string) string, dir string, files []string, mode parser.Mode) ([]*ast.File, error) {
	if displayPath == nil {
		displayPath = func(path string) string { return path }
	}
	isAbs := filepath.IsAbs
	if ctxt.IsAbsPath != nil {
		isAbs = ctxt.IsAbsPath
	}
	joinPath := filepath.Join
	if ctxt.JoinPath != nil {
		joinPath = ctxt.JoinPath
	}
	var wg sync.WaitGroup
	n := len(files)
	parsed := make([]*ast.File, n)
	errors := make([]error, n)
	for i, file := range files {
		if !isAbs(file) {
			file = joinPath(dir, file)
		}
		wg.Add(1)
		go func(i int, file string) {
			defer wg.Done()
			var rd io.ReadCloser
			var err error
			if ctxt.OpenFile != nil {
				rd, err = ctxt.OpenFile(file)
			} else {
				rd, err = os.Open(file)
			}
			defer rd.Close()
			if err != nil {
				errors[i] = err
				return
			}
			parsed[i], errors[i] = parser.ParseFile(fset, displayPath(file), rd, mode)
		}(i, file)
	}
	wg.Wait()

	for _, err := range errors {
		if err != nil {
			return nil, err
		}
	}
	return parsed, nil
}

func (w *Walker) setMemoryContext(ctxt *build.Context) {
	ctxt.JoinPath = path.Join
	ctxt.IsAbsPath = path.IsAbs
	ctxt.IsDir = func(path string) bool { panic("unexpected") }
	ctxt.HasSubdir = func(root, dir string) (rel string, ok bool) { panic("unexpected") }
	ctxt.ReadDir = func(dir string) (fi []os.FileInfo, err error) { return w.readDir(dir) }
	ctxt.OpenFile = func(path string) (r io.ReadCloser, err error) { return w.openFile(path) }
}

func (pkg *pkg) parseFile(ctx *build.Context, name string) (*ast.File, error) {
	f, err := ctx.OpenFile(ctx.JoinPath(pkg.Build.Dir, name))
	if err != nil {
		return nil, err
	}
	defer f.Close()
	p, err := ioutil.ReadAll(f)
	if err != nil {
		return nil, err
	}
	// overwrite //line comments
	for _, m := range linePat.FindAllIndex(p, -1) {
		for i := m[0] + 2; i < m[1]; i++ {
			p[i] = ' '
		}
	}
	return parser.ParseFile(pkg.FSet, name, p, parser.ParseComments)
}

// Import returns details about the package in the directory.
func (dir *Directory) Import(ctx *build.Context, mode build.ImportMode) (*build.Package, error) {
	safeCopy := *ctx
	ctx = &safeCopy
	ctx.JoinPath = path.Join
	ctx.IsAbsPath = path.IsAbs
	ctx.SplitPathList = func(list string) []string { return strings.Split(list, ":") }
	ctx.IsDir = func(path string) bool { return false }
	ctx.HasSubdir = func(root, dir string) (rel string, ok bool) { return "", false }
	ctx.ReadDir = dir.readDir
	ctx.OpenFile = dir.openFile
	return ctx.ImportDir(".", mode)
}

// OpenFile behaves like os.Open,
// but uses the build context's file system interface, if any.
func OpenFile(ctxt *build.Context, path string) (io.ReadCloser, error) {
	if ctxt.OpenFile != nil {
		return ctxt.OpenFile(path)
	}
	return os.Open(path)
}

func getPackage(pkgpath string) (*gobuild.Package, error) {
	var ctx gobuild.Context = gobuild.Default
	ctx.GOARCH = GOARCH
	ctx.GOOS = GOOS
	ctx.BuildTags = append(ctx.BuildTags[:], "llgo")
	//ctx.Compiler = "llgo"

	// Attempt to find an overlay package path,
	// which we'll use in ReadDir below.
	overlayentries := make(map[string]bool)
	overlaypkgpath := llgoPkgPrefix + pkgpath
	overlaypkg, err := ctx.Import(overlaypkgpath, "", gobuild.FindOnly)
	if err != nil {
		overlaypkg = nil
	}

	// ReadDir is overridden to return a fake ".s"
	// file for each ".ll" file in the directory.
	ctx.ReadDir = func(dir string) (fi []os.FileInfo, err error) {
		fi, err = ioutil.ReadDir(dir)
		if err != nil {
			return nil, err
		}
		entries := make(map[string]os.FileInfo)
		for _, info := range fi {
			entries[info.Name()] = info
		}
		// Overlay all files in the overlay package dir.
		// If we find any .ll files, replace the suffix
		// with .s.
		if overlaypkg != nil {
			fi, err = ioutil.ReadDir(overlaypkg.Dir)
		}
		if err == nil {
			// Check for .ll files in the overlay dir if
			// we have one, else in the standard package dir.
			for _, info := range fi {
				name := info.Name()
				if strings.HasSuffix(name, ".ll") {
					name = name[:len(name)-3] + ".s"
					info = &renamedFileInfo{info, name}
				}
				overlayentries[name] = true
				entries[name] = info
			}
		}
		fi = make([]os.FileInfo, 0, len(entries))
		for _, info := range entries {
			fi = append(fi, info)
		}
		return fi, nil
	}

	// OpenFile is overridden to return the contents
	// of the ".ll" file found in ReadDir above. The
	// returned ReadCloser is wrapped to transform
	// LLVM IR comments to use "//", as expected by
	// go/build when looking for build tags.
	ctx.OpenFile = func(path string) (io.ReadCloser, error) {
		base := filepath.Base(path)
		overlay := overlayentries[base]
		if overlay {
			if overlaypkg != nil {
				path = filepath.Join(overlaypkg.Dir, base)
			}
			if strings.HasSuffix(path, ".s") {
				path := path[:len(path)-2] + ".ll"
				var r io.ReadCloser
				var err error
				r, err = os.Open(path)
				if err == nil {
					r = build.NewLLVMIRReader(r)
				}
				return r, err
			}
		}
		return os.Open(path)
	}

	pkg, err := ctx.Import(pkgpath, "", 0)
	if err != nil {
		return nil, err
	} else {
		if overlaypkg == nil {
			overlaypkg = pkg
		}
		for i, filename := range pkg.GoFiles {
			pkgdir := pkg.Dir
			if overlayentries[filename] {
				pkgdir = overlaypkg.Dir
			}
			pkg.GoFiles[i] = path.Join(pkgdir, filename)
		}
		for i, filename := range pkg.CFiles {
			pkgdir := pkg.Dir
			if overlayentries[filename] {
				pkgdir = overlaypkg.Dir
			}
			pkg.CFiles[i] = path.Join(pkgdir, filename)
		}
//.........这里部分代码省略.........