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// Copyright 2014 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 buildutil provides utilities related to the go/build
// package in the standard library.
//
// All I/O is done via the build.Context file system interface, which must
// be concurrency-safe.
package buildutil // import "golang.org/x/tools/go/buildutil"
import (
"go/build"
"os"
"path/filepath"
"sort"
"strings"
"sync"
)
// AllPackages returns the package path of each Go package in any source
// directory of the specified build context (e.g. $GOROOT or an element
// of $GOPATH). Errors are ignored. The results are sorted.
// All package paths are canonical, and thus may contain "/vendor/".
//
// The result may include import paths for directories that contain no
// *.go files, such as "archive" (in $GOROOT/src).
//
// All I/O is done via the build.Context file system interface,
// which must be concurrency-safe.
//
func AllPackages(ctxt *build.Context) []string {
var list []string
ForEachPackage(ctxt, func(pkg string, _ error) {
list = append(list, pkg)
})
sort.Strings(list)
return list
}
// ForEachPackage calls the found function with the package path of
// each Go package it finds in any source directory of the specified
// build context (e.g. $GOROOT or an element of $GOPATH).
// All package paths are canonical, and thus may contain "/vendor/".
//
// If the package directory exists but could not be read, the second
// argument to the found function provides the error.
//
// All I/O is done via the build.Context file system interface,
// which must be concurrency-safe.
//
func ForEachPackage(ctxt *build.Context, found func(importPath string, err error)) {
ch := make(chan item)
var wg sync.WaitGroup
for _, root := range ctxt.SrcDirs() {
root := root
wg.Add(1)
go func() {
allPackages(ctxt, root, ch)
wg.Done()
}()
}
go func() {
wg.Wait()
close(ch)
}()
// All calls to found occur in the caller's goroutine.
for i := range ch {
found(i.importPath, i.err)
}
}
type item struct {
importPath string
err error // (optional)
}
// We use a process-wide counting semaphore to limit
// the number of parallel calls to ReadDir.
var ioLimit = make(chan bool, 20)
func allPackages(ctxt *build.Context, root string, ch chan<- item) {
root = filepath.Clean(root) + string(os.PathSeparator)
var wg sync.WaitGroup
var walkDir func(dir string)
walkDir = func(dir string) {
// Avoid .foo, _foo, and testdata directory trees.
base := filepath.Base(dir)
if base == "" || base[0] == '.' || base[0] == '_' || base == "testdata" {
return
}
pkg := filepath.ToSlash(strings.TrimPrefix(dir, root))
// Prune search if we encounter any of these import paths.
switch pkg {
case "builtin":
return
}
ioLimit <- true
files, err := ReadDir(ctxt, dir)
<-ioLimit
if pkg != "" || err != nil {
ch <- item{pkg, err}
}
for _, fi := range files {
fi := fi
if fi.IsDir() {
wg.Add(1)
go func() {
walkDir(filepath.Join(dir, fi.Name()))
wg.Done()
}()
}
}
}
walkDir(root)
wg.Wait()
}
// ExpandPatterns returns the set of packages matched by patterns,
// which may have the following forms:
//
// golang.org/x/tools/cmd/guru # a single package
// golang.org/x/tools/... # all packages beneath dir
// ... # the entire workspace.
//
// Order is significant: a pattern preceded by '-' removes matching
// packages from the set. For example, these patterns match all encoding
// packages except encoding/xml:
//
// encoding/... -encoding/xml
//
// A trailing slash in a pattern is ignored. (Path components of Go
// package names are separated by slash, not the platform's path separator.)
//
func ExpandPatterns(ctxt *build.Context, patterns []string) map[string]bool {
// TODO(adonovan): support other features of 'go list':
// - "std"/"cmd"/"all" meta-packages
// - "..." not at the end of a pattern
// - relative patterns using "./" or "../" prefix
pkgs := make(map[string]bool)
doPkg := func(pkg string, neg bool) {
if neg {
delete(pkgs, pkg)
} else {
pkgs[pkg] = true
}
}
// Scan entire workspace if wildcards are present.
// TODO(adonovan): opt: scan only the necessary subtrees of the workspace.
var all []string
for _, arg := range patterns {
if strings.HasSuffix(arg, "...") {
all = AllPackages(ctxt)
break
}
}
for _, arg := range patterns {
if arg == "" {
continue
}
neg := arg[0] == '-'
if neg {
arg = arg[1:]
}
if arg == "..." {
// ... matches all packages
for _, pkg := range all {
doPkg(pkg, neg)
}
} else if dir := strings.TrimSuffix(arg, "/..."); dir != arg {
// dir/... matches all packages beneath dir
for _, pkg := range all {
if strings.HasPrefix(pkg, dir) &&
(len(pkg) == len(dir) || pkg[len(dir)] == '/') {
doPkg(pkg, neg)
}
}
} else {
// single package
doPkg(strings.TrimSuffix(arg, "/"), neg)
}
}
return pkgs
}