1 files changed, 130 insertions, 0 deletions
diff --git a/gopls/internal/lsp/cmd/rename.go b/gopls/internal/lsp/cmd/rename.go
new file mode 100644
index 000000000..14c789cbb
--- /dev/null
+++ b/gopls/internal/lsp/cmd/rename.go
@@ -0,0 +1,130 @@
+// Copyright 2019 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 cmd
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+
+	"golang.org/x/tools/gopls/internal/lsp/protocol"
+	"golang.org/x/tools/gopls/internal/lsp/source"
+	"golang.org/x/tools/gopls/internal/span"
+	"golang.org/x/tools/internal/diff"
+	"golang.org/x/tools/internal/tool"
+)
+
+// rename implements the rename verb for gopls.
+type rename struct {
+	Diff     bool `flag:"d,diff" help:"display diffs instead of rewriting files"`
+	Write    bool `flag:"w,write" help:"write result to (source) file instead of stdout"`
+	Preserve bool `flag:"preserve" help:"preserve original files"`
+
+	app *Application
+}
+
+func (r *rename) Name() string      { return "rename" }
+func (r *rename) Parent() string    { return r.app.Name() }
+func (r *rename) Usage() string     { return "[rename-flags] <position> <name>" }
+func (r *rename) ShortHelp() string { return "rename selected identifier" }
+func (r *rename) DetailedHelp(f *flag.FlagSet) {
+	fmt.Fprint(f.Output(), `
+Example:
+
+	$ # 1-based location (:line:column or :#position) of the thing to change
+	$ gopls rename helper/helper.go:8:6 Foo
+	$ gopls rename helper/helper.go:#53 Foo
+
+rename-flags:
+`)
+	printFlagDefaults(f)
+}
+
+// Run renames the specified identifier and either;
+// - if -w is specified, updates the file(s) in place;
+// - if -d is specified, prints out unified diffs of the changes; or
+// - otherwise, prints the new versions to stdout.
+func (r *rename) Run(ctx context.Context, args ...string) error {
+	if len(args) != 2 {
+		return tool.CommandLineErrorf("definition expects 2 arguments (position, new name)")
+	}
+	conn, err := r.app.connect(ctx)
+	if err != nil {
+		return err
+	}
+	defer conn.terminate(ctx)
+
+	from := span.Parse(args[0])
+	file := conn.openFile(ctx, from.URI())
+	if file.err != nil {
+		return file.err
+	}
+	loc, err := file.mapper.SpanLocation(from)
+	if err != nil {
+		return err
+	}
+	p := protocol.RenameParams{
+		TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
+		Position:     loc.Range.Start,
+		NewName:      args[1],
+	}
+	edit, err := conn.Rename(ctx, &p)
+	if err != nil {
+		return err
+	}
+	var orderedURIs []string
+	edits := map[span.URI][]protocol.TextEdit{}
+	for _, c := range edit.DocumentChanges {
+		if c.TextDocumentEdit != nil {
+			uri := fileURI(c.TextDocumentEdit.TextDocument.URI)
+			edits[uri] = append(edits[uri], c.TextDocumentEdit.Edits...)
+			orderedURIs = append(orderedURIs, string(uri))
+		}
+	}
+	sort.Strings(orderedURIs)
+	changeCount := len(orderedURIs)
+
+	for _, u := range orderedURIs {
+		uri := span.URIFromURI(u)
+		cmdFile := conn.openFile(ctx, uri)
+		filename := cmdFile.uri.Filename()
+
+		newContent, renameEdits, err := source.ApplyProtocolEdits(cmdFile.mapper, edits[uri])
+		if err != nil {
+			return fmt.Errorf("%v: %v", edits, err)
+		}
+
+		switch {
+		case r.Write:
+			fmt.Fprintln(os.Stderr, filename)
+			if r.Preserve {
+				if err := os.Rename(filename, filename+".orig"); err != nil {
+					return fmt.Errorf("%v: %v", edits, err)
+				}
+			}
+			ioutil.WriteFile(filename, newContent, 0644)
+		case r.Diff:
+			unified, err := diff.ToUnified(filename+".orig", filename, string(cmdFile.mapper.Content), renameEdits)
+			if err != nil {
+				return err
+			}
+			fmt.Print(unified)
+		default:
+			if len(orderedURIs) > 1 {
+				fmt.Printf("%s:\n", filepath.Base(filename))
+			}
+			os.Stdout.Write(newContent)
+			if changeCount > 1 { // if this wasn't last change, print newline
+				fmt.Println()
+			}
+			changeCount -= 1
+		}
+	}
+	return nil
+}