internal/lsp: added a fill struct code action

internal/lsp/cmd/test/refactor_rewrite.go

@@ -0,0 +1,9 @@
+package cmdtest
+
+import (
+	"testing"
+
+	"golang.org/x/tools/internal/span"
+)
+
+func (r *runner) RefactorRewrite(t *testing.T, spn span.Span, title string) {}

internal/lsp/code_action.go

@@ -143,6 +143,11 @@ func (s *Server) codeAction(ctx context.Context, params *protocol.CodeActionPara
 				})
 			}
 		}
+		fillActions, err := source.FillStruct(ctx, snapshot, fh, params.Range)
+		if err != nil {
+			return nil, err
+		}
+		codeActions = append(codeActions, fillActions...)
 	default:
 		// Unsupported file kind for a code action.
 		return nil, nil

internal/lsp/lsp_test.go

@@ -369,6 +369,49 @@ func (r *runner) Import(t *testing.T, spn span.Span) {
 	}
 }
 
+func (r *runner) RefactorRewrite(t *testing.T, spn span.Span, title string) {
+	uri := spn.URI()
+	m, err := r.data.Mapper(uri)
+	if err != nil {
+		t.Fatal(err)
+	}
+	rng, err := m.Range(spn)
+	if err != nil {
+		t.Fatal(err)
+	}
+	actions, err := r.server.CodeAction(r.ctx, &protocol.CodeActionParams{
+		TextDocument: protocol.TextDocumentIdentifier{
+			URI: protocol.URIFromSpanURI(uri),
+		},
+		Range: rng,
+	})
+
+	if len(actions) == 0 {
+		return
+	}
+	for _, action := range actions {
+		// There may be more code actions available at spn (Span),
+		// we only need the one specified in the title
+		if action.Kind != protocol.RefactorRewrite || action.Title != title {
+			continue
+		}
+		res, err := applyWorkspaceEdits(r, action.Edit)
+		if err != nil {
+			t.Fatal(err)
+		}
+		for u, got := range res {
+			fixed := string(r.data.Golden(tests.SpanName(spn), u.Filename(), func() ([]byte, error) {
+				return []byte(got), nil
+			}))
+			if fixed != got {
+				t.Errorf("%s failed for %s, expected:\n%#v\ngot:\n%#v", title, u.Filename(), fixed, got)
+			}
+		}
+		return
+	}
+	t.Fatalf("expected code action: %v but none", title)
+}
+
 func (r *runner) SuggestedFix(t *testing.T, spn span.Span, actionKinds []string) {
 	uri := spn.URI()
 	view, err := r.server.session.ViewOf(uri)

internal/lsp/source/fill_struct.go

@@ -0,0 +1,144 @@
+// Copyright 2020 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 source
+
+import (
+	"context"
+	"fmt"
+	"go/format"
+	"go/types"
+	"strings"
+
+	"golang.org/x/tools/go/ast/astutil"
+	"golang.org/x/tools/internal/lsp/protocol"
+)
+
+// FillStruct completes all of targeted struct's fields with their default values.
+func FillStruct(ctx context.Context, snapshot Snapshot, fh FileHandle, protoRng protocol.Range) ([]protocol.CodeAction, error) {
+
+	pkg, pgh, err := getParsedFile(ctx, snapshot, fh, NarrowestPackageHandle)
+	if err != nil {
+		return nil, fmt.Errorf("getting file for struct fill code action: %v", err)
+	}
+	file, src, m, _, err := pgh.Cached()
+	if err != nil {
+		return nil, err
+	}
+	spn, err := m.PointSpan(protoRng.Start)
+	if err != nil {
+		return nil, err
+	}
+	spanRng, err := spn.Range(m.Converter)
+	if err != nil {
+		return nil, err
+	}
+	path, _ := astutil.PathEnclosingInterval(file, spanRng.Start, spanRng.End)
+	if path == nil {
+		return nil, nil
+	}
+
+	ecl := enclosingCompositeLiteral(path, spanRng.Start, pkg.GetTypesInfo())
+	if ecl == nil || !ecl.isStruct() {
+		return nil, nil
+	}
+
+	// If in F{ Bar<> : V} or anywhere in F{Bar : V, ...}
+	// we should not fill the struct.
+	if ecl.inKey || len(ecl.cl.Elts) != 0 {
+		return nil, nil
+	}
+
+	var codeActions []protocol.CodeAction
+	qfFunc := qualifier(file, pkg.GetTypes(), pkg.GetTypesInfo())
+	switch obj := ecl.clType.(type) {
+	case *types.Struct:
+		fieldCount := obj.NumFields()
+		if fieldCount == 0 {
+			return nil, nil
+		}
+		var fieldSourceCode strings.Builder
+		for i := 0; i < fieldCount; i++ {
+			field := obj.Field(i)
+			// Ignore fields that are not accessible in the current package.
+			if field.Pkg() != nil && field.Pkg() != pkg.GetTypes() && !field.Exported() {
+				continue
+			}
+
+			label := field.Name()
+			value := formatZeroValue(field.Type(), qfFunc)
+			fieldSourceCode.WriteString("\n")
+			fieldSourceCode.WriteString(label)
+			fieldSourceCode.WriteString(" : ")
+			fieldSourceCode.WriteString(value)
+			fieldSourceCode.WriteString(",")
+		}
+
+		if fieldSourceCode.Len() == 0 {
+			return nil, nil
+		}
+
+		fieldSourceCode.WriteString("\n")
+
+		// the range of all text between '<>', inclusive. E.g.  {<> ...  <}>
+		mappedRange := newMappedRange(snapshot.View().Session().Cache().FileSet(), m, ecl.cl.Lbrace, ecl.cl.Rbrace+1)
+		protoRange, err := mappedRange.Range()
+		if err != nil {
+			return nil, err
+		}
+		// consider formatting from the first character of the line the lbrace is on.
+		// ToOffset is 1-based
+		beginOffset, err := m.Converter.ToOffset(int(protoRange.Start.Line)+1, 1)
+		if err != nil {
+			return nil, err
+		}
+
+		endOffset, err := m.Converter.ToOffset(int(protoRange.Start.Line)+1, int(protoRange.Start.Character)+1)
+		if err != nil {
+			return nil, err
+		}
+
+		// An increment to make sure the lbrace is included in the slice.
+		endOffset++
+		// Append the edits. Then append the closing brace.
+		var newSourceCode strings.Builder
+		newSourceCode.Grow(endOffset - beginOffset + fieldSourceCode.Len() + 1)
+		newSourceCode.WriteString(string(src[beginOffset:endOffset]))
+		newSourceCode.WriteString(fieldSourceCode.String())
+		newSourceCode.WriteString("}")
+
+		buf, err := format.Source([]byte(newSourceCode.String()))
+		if err != nil {
+			return nil, err
+		}
+
+		// it is guaranteed that a left brace exists.
+		var edit = string(buf[strings.IndexByte(string(buf), '{'):])
+
+		codeActions = append(codeActions, protocol.CodeAction{
+			Title: "Fill struct",
+			Kind:  protocol.RefactorRewrite,
+			Edit: protocol.WorkspaceEdit{
+				DocumentChanges: []protocol.TextDocumentEdit{
+					{
+						TextDocument: protocol.VersionedTextDocumentIdentifier{
+							Version: fh.Identity().Version,
+							TextDocumentIdentifier: protocol.TextDocumentIdentifier{
+								URI: protocol.URIFromSpanURI(fh.Identity().URI),
+							},
+						},
+						Edits: []protocol.TextEdit{
+							{
+								Range:   protoRange,
+								NewText: edit,
+							},
+						},
+					},
+				},
+			},
+		})
+	}
+
+	return codeActions, nil
+}

internal/lsp/source/options.go

@@ -89,6 +89,7 @@ func DefaultOptions() Options {
 					protocol.SourceFixAll:          true,
 					protocol.SourceOrganizeImports: true,
 					protocol.QuickFix:              true,
+					protocol.RefactorRewrite:       true,
 				},
 				Mod: {
 					protocol.SourceOrganizeImports: true,

internal/lsp/source/source_test.go

@@ -473,6 +473,7 @@ func (r *runner) Import(t *testing.T, spn span.Span) {
 }
 
 func (r *runner) SuggestedFix(t *testing.T, spn span.Span, actionKinds []string) {}
+func (r *runner) RefactorRewrite(t *testing.T, spn span.Span, title string)      {}
 
 func (r *runner) Definition(t *testing.T, spn span.Span, d tests.Definition) {
 	_, srcRng, err := spanToRange(r.data, d.Src)

internal/lsp/testdata/indirect/summary.txt.golden

@@ -25,4 +25,5 @@ CaseSensitiveWorkspaceSymbolsCount = 0
 SignaturesCount = 0
 LinksCount = 0
 ImplementationsCount = 0
+RefactorRewriteCount = 0
 

internal/lsp/testdata/lsp/primarymod/fillstruct/data/a.go

@@ -0,0 +1,6 @@
+package data
+
+type A struct {
+	ExportedInt   int
+	unexportedInt int
+}

internal/lsp/testdata/lsp/primarymod/fillstruct/fill_struct.go

@@ -0,0 +1,23 @@
+package fillstruct
+
+type StructA struct {
+	unexportedIntField int
+	ExportedIntField   int
+	MapA               map[int]string
+	Array              []int
+	StructB
+}
+
+type StructA2 struct {
+	B *StructB
+}
+
+type StructA3 struct {
+	B StructB
+}
+
+func fill() {
+	a := StructA{}  //@refactorrewrite("}", "Fill struct")
+	b := StructA2{} //@refactorrewrite("}", "Fill struct")
+	c := StructA3{} //@refactorrewrite("}", "Fill struct")
+}

internal/lsp/testdata/lsp/primarymod/fillstruct/fill_struct.go.golden

@@ -0,0 +1,85 @@
+-- fill_struct_20_15 --
+package fillstruct
+
+type StructA struct {
+	unexportedIntField int
+	ExportedIntField   int
+	MapA               map[int]string
+	Array              []int
+	StructB
+}
+
+type StructA2 struct {
+	B *StructB
+}
+
+type StructA3 struct {
+	B StructB
+}
+
+func fill() {
+	a := StructA{
+		unexportedIntField: 0,
+		ExportedIntField:   0,
+		MapA:               nil,
+		Array:              nil,
+		StructB:            StructB{},
+	}  //@refactorrewrite("}", "Fill struct")
+	b := StructA2{} //@refactorrewrite("}", "Fill struct")
+	c := StructA3{} //@refactorrewrite("}", "Fill struct")
+}
+
+-- fill_struct_21_16 --
+package fillstruct
+
+type StructA struct {
+	unexportedIntField int
+	ExportedIntField   int
+	MapA               map[int]string
+	Array              []int
+	StructB
+}
+
+type StructA2 struct {
+	B *StructB
+}
+
+type StructA3 struct {
+	B StructB
+}
+
+func fill() {
+	a := StructA{}  //@refactorrewrite("}", "Fill struct")
+	b := StructA2{
+		B: nil,
+	} //@refactorrewrite("}", "Fill struct")
+	c := StructA3{} //@refactorrewrite("}", "Fill struct")
+}
+
+-- fill_struct_22_16 --
+package fillstruct
+
+type StructA struct {
+	unexportedIntField int
+	ExportedIntField   int
+	MapA               map[int]string
+	Array              []int
+	StructB
+}
+
+type StructA2 struct {
+	B *StructB
+}
+
+type StructA3 struct {
+	B StructB
+}
+
+func fill() {
+	a := StructA{}  //@refactorrewrite("}", "Fill struct")
+	b := StructA2{} //@refactorrewrite("}", "Fill struct")
+	c := StructA3{
+		B: StructB{},
+	} //@refactorrewrite("}", "Fill struct")
+}
+

internal/lsp/testdata/lsp/primarymod/fillstruct/fill_struct_nested.go

@@ -0,0 +1,15 @@
+package fillstruct
+
+type StructB struct {
+	StructC
+}
+
+type StructC struct {
+	unexportedInt int
+}
+
+func nested() {
+	c := StructB{
+		StructC: StructC{}, //@refactorrewrite("}", "Fill struct")
+	}
+}

internal/lsp/testdata/lsp/primarymod/fillstruct/fill_struct_nested.go.golden

@@ -0,0 +1,19 @@
+-- fill_struct_nested_13_20 --
+package fillstruct
+
+type StructB struct {
+	StructC
+}
+
+type StructC struct {
+	unexportedInt int
+}
+
+func nested() {
+	c := StructB{
+		StructC: StructC{
+			unexportedInt: 0,
+		}, //@refactorrewrite("}", "Fill struct")
+	}
+}
+