diff options
Diffstat (limited to 'vendor/golang.org/x/tools/go/gcexportdata/gcexportdata.go')
-rw-r--r-- | vendor/golang.org/x/tools/go/gcexportdata/gcexportdata.go | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/vendor/golang.org/x/tools/go/gcexportdata/gcexportdata.go b/vendor/golang.org/x/tools/go/gcexportdata/gcexportdata.go new file mode 100644 index 00000000..4c238d10 --- /dev/null +++ b/vendor/golang.org/x/tools/go/gcexportdata/gcexportdata.go @@ -0,0 +1,109 @@ +// Copyright 2016 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 gcexportdata provides functions for locating, reading, and +// writing export data files containing type information produced by the +// gc compiler. This package supports go1.7 export data format and all +// later versions. +// +// Although it might seem convenient for this package to live alongside +// go/types in the standard library, this would cause version skew +// problems for developer tools that use it, since they must be able to +// consume the outputs of the gc compiler both before and after a Go +// update such as from Go 1.7 to Go 1.8. Because this package lives in +// golang.org/x/tools, sites can update their version of this repo some +// time before the Go 1.8 release and rebuild and redeploy their +// developer tools, which will then be able to consume both Go 1.7 and +// Go 1.8 export data files, so they will work before and after the +// Go update. (See discussion at https://github.com/golang/go/issues/15651.) +// +package gcexportdata // import "golang.org/x/tools/go/gcexportdata" + +import ( + "bufio" + "bytes" + "fmt" + "go/token" + "go/types" + "io" + "io/ioutil" + + "golang.org/x/tools/go/internal/gcimporter" +) + +// Find returns the name of an object (.o) or archive (.a) file +// containing type information for the specified import path, +// using the workspace layout conventions of go/build. +// If no file was found, an empty filename is returned. +// +// A relative srcDir is interpreted relative to the current working directory. +// +// Find also returns the package's resolved (canonical) import path, +// reflecting the effects of srcDir and vendoring on importPath. +func Find(importPath, srcDir string) (filename, path string) { + return gcimporter.FindPkg(importPath, srcDir) +} + +// NewReader returns a reader for the export data section of an object +// (.o) or archive (.a) file read from r. The new reader may provide +// additional trailing data beyond the end of the export data. +func NewReader(r io.Reader) (io.Reader, error) { + buf := bufio.NewReader(r) + _, err := gcimporter.FindExportData(buf) + // If we ever switch to a zip-like archive format with the ToC + // at the end, we can return the correct portion of export data, + // but for now we must return the entire rest of the file. + return buf, err +} + +// Read reads export data from in, decodes it, and returns type +// information for the package. +// The package name is specified by path. +// File position information is added to fset. +// +// Read may inspect and add to the imports map to ensure that references +// within the export data to other packages are consistent. The caller +// must ensure that imports[path] does not exist, or exists but is +// incomplete (see types.Package.Complete), and Read inserts the +// resulting package into this map entry. +// +// On return, the state of the reader is undefined. +func Read(in io.Reader, fset *token.FileSet, imports map[string]*types.Package, path string) (*types.Package, error) { + data, err := ioutil.ReadAll(in) + if err != nil { + return nil, fmt.Errorf("reading export data for %q: %v", path, err) + } + + if bytes.HasPrefix(data, []byte("!<arch>")) { + return nil, fmt.Errorf("can't read export data for %q directly from an archive file (call gcexportdata.NewReader first to extract export data)", path) + } + + // The App Engine Go runtime v1.6 uses the old export data format. + // TODO(adonovan): delete once v1.7 has been around for a while. + if bytes.HasPrefix(data, []byte("package ")) { + return gcimporter.ImportData(imports, path, path, bytes.NewReader(data)) + } + + // The indexed export format starts with an 'i'; the older + // binary export format starts with a 'c', 'd', or 'v' + // (from "version"). Select appropriate importer. + if len(data) > 0 && data[0] == 'i' { + _, pkg, err := gcimporter.IImportData(fset, imports, data[1:], path) + return pkg, err + } + + _, pkg, err := gcimporter.BImportData(fset, imports, data, path) + return pkg, err +} + +// Write writes encoded type information for the specified package to out. +// The FileSet provides file position information for named objects. +func Write(out io.Writer, fset *token.FileSet, pkg *types.Package) error { + b, err := gcimporter.BExportData(fset, pkg) + if err != nil { + return err + } + _, err = out.Write(b) + return err +} |