--- /dev/null
+// 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"
+ "sort"
+
+ "golang.org/x/tools/internal/lsp/protocol"
+ "golang.org/x/tools/internal/span"
+ "golang.org/x/tools/internal/tool"
+)
+
+// implementation implements the implementation verb for gopls
+type implementation struct {
+ app *Application
+}
+
+func (i *implementation) Name() string { return "implementation" }
+func (i *implementation) Usage() string { return "<position>" }
+func (i *implementation) ShortHelp() string { return "display selected identifier's implementation" }
+func (i *implementation) DetailedHelp(f *flag.FlagSet) {
+ fmt.Fprint(f.Output(), `
+Example:
+
+ $ # 1-indexed location (:line:column or :#offset) of the target identifier
+ $ gopls implementation helper/helper.go:8:6
+ $ gopls implementation helper/helper.go:#53
+
+ gopls implementation flags are:
+`)
+ f.PrintDefaults()
+}
+
+func (i *implementation) Run(ctx context.Context, args ...string) error {
+ if len(args) != 1 {
+ return tool.CommandLineErrorf("implementation expects 1 argument (position)")
+ }
+
+ conn, err := i.app.connect(ctx)
+ if err != nil {
+ return err
+ }
+ defer conn.terminate(ctx)
+
+ from := span.Parse(args[0])
+ file := conn.AddFile(ctx, from.URI())
+ if file.err != nil {
+ return file.err
+ }
+
+ loc, err := file.mapper.Location(from)
+ if err != nil {
+ return err
+ }
+
+ p := protocol.ImplementationParams{
+ TextDocumentPositionParams: protocol.TextDocumentPositionParams{
+ TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
+ Position: loc.Range.Start,
+ },
+ }
+
+ implementations, err := conn.Implementation(ctx, &p)
+ if err != nil {
+ return err
+ }
+
+ var spans []string
+ for _, impl := range implementations {
+ f := conn.AddFile(ctx, fileURI(impl.URI))
+ span, err := f.mapper.Span(impl)
+ if err != nil {
+ return err
+ }
+ spans = append(spans, fmt.Sprint(span))
+ }
+ sort.Strings(spans)
+
+ for _, s := range spans {
+ fmt.Println(s)
+ }
+
+ return nil
+}