Import minimal version of gazel, a BUILD file generator

WORKSPACE

@@ -25,3 +25,14 @@ new_git_repository(
     commit = "23def4e6c14b4da8ac2ed8007337bc5eb5007998",
     remote = "https://github.com/golang/glog.git",
 )
+
+git_repository(
+    name = "io_bazel_buildifier",
+    commit = "0ca1d7991357ae7a7555589af88930d82cf07c0a",
+    remote = "https://github.com/bazelbuild/buildifier.git",
+)
+
+local_repository(
+    name = "io_bazel_rules_go",
+    path = ".",
+)

go/tools/gazel/gazel/BUILD

@@ -0,0 +1,10 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_binary")
+
+go_binary(
+    name = "gazel",
+    srcs = ["main.go"],
+    deps = [
+        "@io_bazel_buildifier//core:go_default_library",
+        "//go/tools/gazel/generator:go_default_library",
+    ],
+)

go/tools/gazel/gazel/main.go

@@ -0,0 +1,86 @@
+/* Copyright 2016 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Command gazel is a BUILD file generator for Go projects.
+// See "gazel --help" for more details.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+
+	bzl "github.com/bazelbuild/buildifier/core"
+	"github.com/bazelbuild/rules_go/go/tools/gazel/generator"
+)
+
+var (
+	repoRoot = flag.String("repo_root", "", "path to a root directory of a repository")
+)
+
+func run(dirs []string) error {
+	g, err := generator.New(*repoRoot)
+	if err != nil {
+		return err
+	}
+
+	for _, d := range dirs {
+		files, err := g.Generate(d)
+		if err != nil {
+			return err
+		}
+		for _, f := range files {
+			if _, err := os.Stdout.Write(bzl.Format(f)); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func usage() {
+	fmt.Fprintln(os.Stderr, `usage: gazel [flags...] [package-dirs...]
+
+Gazel is a BUILD file generator for Go projects.
+
+Currently its primary usage is to generate BUILD files for external dependencies
+in a go_vendor repository rule.
+You can still use Gazel for other purposes, but its interface can change without
+notice.
+
+It takes a list of paths to Go package directories.
+It recursively traverses its subpackages.
+All the directories must be under the directory specified in -repo_root.
+
+FLAGS:
+`)
+	flag.PrintDefaults()
+}
+
+func main() {
+	flag.Usage = usage
+	flag.Parse()
+
+	if *repoRoot == "" {
+		if flag.NArg() != 1 {
+			log.Fatal("-repo_root is required")
+		}
+		*repoRoot = flag.Arg(0)
+	}
+	if err := run(flag.Args()); err != nil {
+		log.Fatal(err)
+	}
+}

go/tools/gazel/generator/BUILD

@@ -0,0 +1,21 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["generator.go"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "@io_bazel_buildifier//core:go_default_library",
+        "//go/tools/gazel/packages:go_default_library",
+        "//go/tools/gazel/rules:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["generator_test.go"],
+    library = ":go_default_library",
+    deps = [
+        "//go/tools/gazel/testdata:go_default_library",
+    ],
+)

go/tools/gazel/generator/generator.go

@@ -0,0 +1,104 @@
+/* Copyright 2016 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package generator provides core functionality of
+// BUILD file generation in gazel.
+package generator
+
+import (
+	"fmt"
+	"go/build"
+	"path/filepath"
+	"strings"
+
+	bzl "github.com/bazelbuild/buildifier/core"
+	"github.com/bazelbuild/rules_go/go/tools/gazel/packages"
+	"github.com/bazelbuild/rules_go/go/tools/gazel/rules"
+)
+
+// Generator generates BUILD files for a Go repository.
+type Generator struct {
+	repoRoot string
+	bctx     build.Context
+	g        rules.Generator
+}
+
+// New returns a new Generator which is responsible for a Go repository.
+//
+// "repoRoot" is a path to the root directory of the repository.
+func New(repoRoot string) (*Generator, error) {
+	bctx := build.Default
+	// Ignore source files in $GOROOT and $GOPATH
+	bctx.GOROOT = ""
+	bctx.GOPATH = ""
+
+	repoRoot, err := filepath.Abs(repoRoot)
+	if err != nil {
+		return nil, err
+	}
+	return &Generator{
+		repoRoot: filepath.Clean(repoRoot),
+		bctx:     bctx,
+		g:        rules.NewGenerator(),
+	}, nil
+}
+
+// Generate generates a BUILD file for each Go package found under
+// the given directory.
+// The directory must be the repository root directory the caller
+// passed to New, or its subdirectory.
+func (g *Generator) Generate(dir string) ([]*bzl.File, error) {
+	dir, err := filepath.Abs(dir)
+	if err != nil {
+		return nil, err
+	}
+	dir = filepath.Clean(dir)
+	if !isDescendingDir(dir, g.repoRoot) {
+		return nil, fmt.Errorf("dir %s is not under the repository root %s", dir, g.repoRoot)
+	}
+
+	var files []*bzl.File
+	err = packages.Walk(g.bctx, dir, func(pkg *build.Package) error {
+		rel, err := filepath.Rel(g.repoRoot, pkg.Dir)
+		if err != nil {
+			return err
+		}
+		if rel == "." {
+			rel = ""
+		}
+
+		rs, err := g.g.Generate(filepath.ToSlash(rel), pkg)
+		if err != nil {
+			return err
+		}
+		file := &bzl.File{Path: filepath.Join(rel, "BUILD")}
+		for _, r := range rs {
+			file.Stmt = append(file.Stmt, r.Call)
+		}
+		files = append(files, file)
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return files, nil
+}
+
+func isDescendingDir(dir, root string) bool {
+	if dir == root {
+		return true
+	}
+	return strings.HasPrefix(dir, fmt.Sprintf("%s%c", root, filepath.Separator))
+}

go/tools/gazel/generator/generator_test.go

@@ -0,0 +1,105 @@
+/* Copyright 2016 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package generator
+
+import (
+	"fmt"
+	"go/build"
+	"path/filepath"
+	"reflect"
+	"sort"
+	"strings"
+	"testing"
+
+	bzl "github.com/bazelbuild/buildifier/core"
+	"github.com/bazelbuild/rules_go/go/tools/gazel/testdata"
+)
+
+func TestGenerator(t *testing.T) {
+	stub := stubRuleGen{
+		fixtures: map[string][]*bzl.Rule{
+			"lib": {
+				{
+					Call: &bzl.CallExpr{
+						X: &bzl.LiteralExpr{Token: "go_library"},
+					},
+				},
+			},
+			"bin": {
+				{
+					Call: &bzl.CallExpr{
+						X: &bzl.LiteralExpr{Token: "go_binary"},
+					},
+				},
+			},
+		},
+	}
+
+	repo := filepath.Join(testdata.Dir(), "repo")
+	g, err := New(repo)
+	if err != nil {
+		t.Errorf("New(%q) failed with %v; want success", repo, err)
+		return
+	}
+	g.g = stub
+
+	got, err := g.Generate(repo)
+	if err != nil {
+		t.Errorf("g.Generate(%q) failed with %v; want success", repo, err)
+	}
+	sort.Sort(fileSlice(got))
+
+	want := []*bzl.File{
+		{
+			Path: "lib/BUILD",
+			Stmt: []bzl.Expr{stub.fixtures["lib"][0].Call},
+		},
+		{
+			Path: "bin/BUILD",
+			Stmt: []bzl.Expr{stub.fixtures["bin"][0].Call},
+		},
+	}
+	sort.Sort(fileSlice(want))
+
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("g.Generate(%q) = %v; want %v", repo, prettyFiles(got), prettyFiles(want))
+	}
+}
+
+type prettyFiles []*bzl.File
+
+func (p prettyFiles) String() string {
+	var items []string
+	for _, f := range p {
+		items = append(items, fmt.Sprintf("{Path: %q, Stmt: %q", f.Path, string(bzl.Format(f))))
+	}
+	return fmt.Sprintf("[%s]", strings.Join(items, ","))
+}
+
+type fileSlice []*bzl.File
+
+func (p fileSlice) Less(i, j int) bool { return strings.Compare(p[i].Path, p[j].Path) < 0 }
+func (p fileSlice) Len() int           { return len(p) }
+func (p fileSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
+
+// stubRuleGen is a test stub implementation of rules.Generator
+type stubRuleGen struct {
+	fixtures map[string][]*bzl.Rule
+}
+
+func (s stubRuleGen) Generate(rel string, pkg *build.Package) ([]*bzl.Rule, error) {
+	return s.fixtures[rel], nil
+}

go/tools/gazel/packages/BUILD

@@ -0,0 +1,16 @@
+load("//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "doc.go",
+        "walk.go",
+    ],
+    visibility = ["//visibility:public"],
+)
+
+go_test(
+    name = "go_default_xtest",
+    srcs = ["walk_test.go"],
+    deps = [":go_default_library"],
+)

go/tools/gazel/packages/doc.go

@@ -0,0 +1,17 @@
+/* Copyright 2016 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package packages provides Go package traversal in a Bazel repository.
+package packages