--- /dev/null
+// 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 singlechecker defines the main function for an analysis
+// driver with only a single analysis.
+// This package makes it easy for a provider of an analysis package to
+// also provide a standalone tool that runs just that analysis.
+//
+// For example, if example.org/findbadness is an analysis package,
+// all that is needed to define a standalone tool is a file,
+// example.org/findbadness/cmd/findbadness/main.go, containing:
+//
+// // The findbadness command runs an analysis.
+// package main
+//
+// import (
+// "example.org/findbadness"
+// "golang.org/x/tools/go/analysis/singlechecker"
+// )
+//
+// func main() { singlechecker.Main(findbadness.Analyzer) }
+//
+package singlechecker
+
+import (
+ "flag"
+ "fmt"
+ "log"
+ "os"
+ "strings"
+
+ "golang.org/x/tools/go/analysis"
+ "golang.org/x/tools/go/analysis/internal/analysisflags"
+ "golang.org/x/tools/go/analysis/internal/checker"
+ "golang.org/x/tools/go/analysis/unitchecker"
+)
+
+// Main is the main function for a checker command for a single analysis.
+func Main(a *analysis.Analyzer) {
+ log.SetFlags(0)
+ log.SetPrefix(a.Name + ": ")
+
+ analyzers := []*analysis.Analyzer{a}
+
+ if err := analysis.Validate(analyzers); err != nil {
+ log.Fatal(err)
+ }
+
+ checker.RegisterFlags()
+
+ flag.Usage = func() {
+ paras := strings.Split(a.Doc, "\n\n")
+ fmt.Fprintf(os.Stderr, "%s: %s\n\n", a.Name, paras[0])
+ fmt.Fprintf(os.Stderr, "Usage: %s [-flag] [package]\n\n", a.Name)
+ if len(paras) > 1 {
+ fmt.Fprintln(os.Stderr, strings.Join(paras[1:], "\n\n"))
+ }
+ fmt.Fprintln(os.Stderr, "\nFlags:")
+ flag.PrintDefaults()
+ }
+
+ analyzers = analysisflags.Parse(analyzers, false)
+
+ args := flag.Args()
+ if len(args) == 0 {
+ flag.Usage()
+ os.Exit(1)
+ }
+
+ if len(args) == 1 && strings.HasSuffix(args[0], ".cfg") {
+ unitchecker.Run(args[0], analyzers)
+ panic("unreachable")
+ }
+
+ os.Exit(checker.Run(args, analyzers))
+}