tools/gopls: add cmd support for references

This change adds command line support for references.

Example:

$ gopls references ~/tmp/foo/main.go:8:6
$ gopls references ~/tmp/foo/main.go:#53

Updates golang/go#32875

Change-Id: I9a0cf6ae8ba0a5c3d4ffc829b96fe3b42297c192
Reviewed-on: https://go-review.googlesource.com/c/tools/+/202178
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/cmd/cmd.go

@@ -144,6 +144,7 @@ func (app *Application) commands() []tool.Application {
 		&check{app: app},
 		&format{app: app},
 		&query{app: app},
+		&references{app: app},
 		&rename{app: app},
 		&version{app: app},
 	}

internal/lsp/cmd/references.go

@@ -0,0 +1,98 @@
+// 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"
+	"golang.org/x/tools/internal/lsp/protocol"
+	"golang.org/x/tools/internal/span"
+	"golang.org/x/tools/internal/tool"
+	"sort"
+)
+
+// references implements the references verb for gopls
+type references struct {
+	IncludeDeclaration bool `flag:"d" help:"include the declaration of the specified identifier in the results"`
+
+	app *Application
+}
+
+func (r *references) Name() string      { return "references" }
+func (r *references) Usage() string     { return "<position>" }
+func (r *references) ShortHelp() string { return "display selected identifier's references" }
+func (r *references) DetailedHelp(f *flag.FlagSet) {
+	fmt.Fprint(f.Output(), `
+Example:
+
+  $ # 1-indexed location (:line:column or :#offset) of the target identifier
+  $ gopls references helper/helper.go:8:6
+  $ gopls references helper/helper.go:#53
+
+  gopls references flags are:
+`)
+	f.PrintDefaults()
+}
+
+func (r *references) Run(ctx context.Context, args ...string) error {
+	if len(args) != 1 {
+		return tool.CommandLineErrorf("references expects 1 argument (position)")
+	}
+
+	conn, err := r.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.ReferenceParams{
+		Context: protocol.ReferenceContext{
+			IncludeDeclaration: r.IncludeDeclaration,
+		},
+		TextDocumentPositionParams: protocol.TextDocumentPositionParams{
+			TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
+			Position:     loc.Range.Start,
+		},
+	}
+	locations, err := conn.References(ctx, &p)
+	if err != nil {
+		return err
+	}
+
+	if len(locations) == 0 {
+		return tool.CommandLineErrorf("%v: not an identifier", from)
+	}
+
+	var spans []string
+	for _, l := range locations {
+		f := conn.AddFile(ctx, span.NewURI(l.URI))
+		// convert location to span for user-friendly 1-indexed line
+		// and column numbers
+		span, err := f.mapper.Span(l)
+		if err != nil {
+			return err
+		}
+		spans = append(spans, fmt.Sprint(span))
+	}
+
+	sort.Strings(spans)
+	for _, s := range spans {
+		fmt.Println(s)
+	}
+
+	return nil
+}

internal/lsp/cmd/test/cmdtest.go

@@ -74,10 +74,6 @@ func (r *runner) Highlight(t *testing.T, name string, locations []span.Span) {
 	//TODO: add command line highlight tests when it works
 }
 
-func (r *runner) Reference(t *testing.T, src span.Span, itemList []span.Span) {
-	//TODO: add command line references tests when it works
-}
-
 func (r *runner) PrepareRename(t *testing.T, src span.Span, want *source.PrepareItem) {
 	//TODO: add command line prepare rename tests when it works
 }

internal/lsp/cmd/test/references.go

@@ -0,0 +1,38 @@
+// 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 cmdtest
+
+import (
+	"fmt"
+	"golang.org/x/tools/internal/lsp/cmd"
+	"golang.org/x/tools/internal/tool"
+	"testing"
+
+	"golang.org/x/tools/internal/span"
+)
+
+func (r *runner) References(t *testing.T, spn span.Span, itemList []span.Span) {
+	var expect string
+	for _, i := range itemList {
+		expect += fmt.Sprintln(i)
+	}
+
+	uri := spn.URI()
+	filename := uri.Filename()
+	target := filename + fmt.Sprintf(":%v:%v", spn.Start().Line(), spn.Start().Column())
+
+	app := cmd.New("gopls-test", r.data.Config.Dir, r.data.Config.Env, r.options)
+	got := CaptureStdOut(t, func() {
+		err := tool.Run(r.ctx, app, append([]string{"-remote=internal", "references"}, target))
+		if err != nil {
+			fmt.Println(spn.Start().Line())
+			fmt.Println(err)
+		}
+	})
+
+	if expect != got {
+		t.Errorf("references failed for %s expected:\n%s\ngot:\n%s", target, expect, got)
+	}
+}

internal/lsp/lsp_test.go

@@ -458,7 +458,7 @@ func (r *runner) Highlight(t *testing.T, name string, locations []span.Span) {
 	}
 }
 
-func (r *runner) Reference(t *testing.T, src span.Span, itemList []span.Span) {
+func (r *runner) References(t *testing.T, src span.Span, itemList []span.Span) {
 	sm, err := r.data.Mapper(src.URI())
 	if err != nil {
 		t.Fatal(err)

internal/lsp/source/source_test.go

@@ -566,7 +566,7 @@ func (r *runner) Highlight(t *testing.T, name string, locations []span.Span) {
 	}
 }
 
-func (r *runner) Reference(t *testing.T, src span.Span, itemList []span.Span) {
+func (r *runner) References(t *testing.T, src span.Span, itemList []span.Span) {
 	ctx := r.ctx
 	f, err := r.view.GetFile(ctx, src.URI())
 	if err != nil {

internal/lsp/tests/tests.go

@@ -110,7 +110,7 @@ type Tests interface {
 	SuggestedFix(*testing.T, span.Span)
 	Definition(*testing.T, span.Span, Definition)
 	Highlight(*testing.T, string, []span.Span)
-	Reference(*testing.T, span.Span, []span.Span)
+	References(*testing.T, span.Span, []span.Span)
 	Rename(*testing.T, span.Span, string)
 	PrepareRename(*testing.T, span.Span, *source.PrepareItem)
 	Symbol(*testing.T, span.URI, []protocol.DocumentSymbol)
@@ -484,7 +484,7 @@ func Run(t *testing.T, tests Tests, data *Data) {
 		for src, itemList := range data.References {
 			t.Run(spanName(src), func(t *testing.T) {
 				t.Helper()
-				tests.Reference(t, src, itemList)
+				tests.References(t, src, itemList)
 			})
 		}
 	})