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// Copyright 2018 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 packages
import (
"fmt"
"os"
"sort"
)
// Visit visits all the packages in the import graph whose roots are
// pkgs, calling the optional pre function the first time each package
// is encountered (preorder), and the optional post function after a
// package's dependencies have been visited (postorder).
// The boolean result of pre(pkg) determines whether
// the imports of package pkg are visited.
func Visit(pkgs []*Package, pre func(*Package) bool, post func(*Package)) {
seen := make(map[*Package]bool)
var visit func(*Package)
visit = func(pkg *Package) {
if !seen[pkg] {
seen[pkg] = true
if pre == nil || pre(pkg) {
paths := make([]string, 0, len(pkg.Imports))
for path := range pkg.Imports {
paths = append(paths, path)
}
sort.Strings(paths) // Imports is a map, this makes visit stable
for _, path := range paths {
visit(pkg.Imports[path])
}
}
if post != nil {
post(pkg)
}
}
}
for _, pkg := range pkgs {
visit(pkg)
}
}
// PrintErrors prints to os.Stderr the accumulated errors of all
// packages in the import graph rooted at pkgs, dependencies first.
// PrintErrors returns the number of errors printed.
func PrintErrors(pkgs []*Package) int {
var n int
Visit(pkgs, nil, func(pkg *Package) {
for _, err := range pkg.Errors {
fmt.Fprintln(os.Stderr, err)
n++
}
})
return n
}