internal/lsp: added a code action which generates key-value pairs of individual

fields and default values between a struct's enclosing braces

Fixes #37576

Author: luciolas

internal/lsp/cmd/test/fillstruct.go

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

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 +369,44 @@ func (r *runner) Import(t *testing.T, spn span.Span) {
 	}
 }
 
+func (r *runner) FillStruct(t *testing.T, spn span.Span) {
+	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
+	}
+	if actions[0].Kind != protocol.RefactorRewrite {
+		t.Fatal("expected refactor rewrite kind")
+	}
+	res, err := applyWorkspaceEdits(r, actions[0].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("fill struct failed for %s, expected:\n%#v\ngot:\n%#v", u.Filename(), fixed, got)
+		}
+	}
+}
+
 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 +1,132 @@
+// 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 edit string
+		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)
+			text := "\n" + label + " : " + value + ","
+			edit += text
+		}
+		edit += "\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.
+		sourceCode := string(src[beginOffset:endOffset]) + edit + "}"
+
+		buf, err := format.Source([]byte(sourceCode))
+		if err != nil {
+			return nil, err
+		}
+
+		// it is guranteed that a left brace exists.
+		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

@@ -69,6 +69,7 @@ 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

@@ -475,6 +475,7 @@ 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) FillStruct(t *testing.T, spn span.Span)                         {}
 
 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
+FillStructCount = 0
 

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

@@ -0,0 +1,10 @@
+package fillstruct
+
+type StructA struct {
+	unexportedIntField int
+	ExportedIntField   int
+}
+
+func fill() {
+	a := StructA{} //@fillstruct("}")
+}

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

@@ -0,0 +1,15 @@
+-- fill_struct_9_15 --
+package fillstruct
+
+type StructA struct {
+	unexportedIntField int
+	ExportedIntField   int
+}
+
+func fill() {
+	a := StructA{
+		unexportedIntField: 0,
+		ExportedIntField:   0,
+	} //@fillstruct("}")
+}
+

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

@@ -0,0 +1,11 @@
+package fillstruct
+
+type StructC struct {
+	StructB
+}
+
+func nested() {
+	c := StructC{
+		StructB: StructB{}, //@fillstruct("}")
+	}
+}

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

@@ -0,0 +1,15 @@
+-- fill_struct_nested_9_20 --
+package fillstruct
+
+type StructC struct {
+	StructB
+}
+
+func nested() {
+	c := StructC{
+		StructB: StructB{
+			ExportedIntField: 0,
+		}, //@fillstruct("}")
+	}
+}
+

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

@@ -0,0 +1,12 @@
+package fillstruct
+
+type StructB struct {
+	ExportedIntField int
+}
+
+func spaces() {
+	b := StructB{
+
+		//@fillstruct("")
+	}
+}

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

@@ -0,0 +1,13 @@
+-- fill_struct_spaces_10_1 --
+package fillstruct
+
+type StructB struct {
+	ExportedIntField int
+}
+
+func spaces() {
+	b := StructB{
+		ExportedIntField: 0,
+	}
+}
+

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

@@ -25,4 +25,5 @@ CaseSensitiveWorkspaceSymbolsCount = 2
 SignaturesCount = 32
 LinksCount = 8
 ImplementationsCount = 14
+FillStructCount = 4
 

internal/lsp/tests/tests.go

@@ -57,6 +57,7 @@ type FoldingRanges []span.Span
 type Formats []span.Span
 type Imports []span.Span
 type SuggestedFixes map[span.Span][]string
+type FillStructActions []span.Span
 type Definitions map[span.Span]Definition
 type Implementations map[span.Span][]span.Span
 type Highlights map[span.Span][]span.Span
@@ -87,6 +88,7 @@ type Data struct {
 	Formats                       Formats
 	Imports                       Imports
 	SuggestedFixes                SuggestedFixes
+	FillStruct                    FillStructActions
 	Definitions                   Definitions
 	Implementations               Implementations
 	Highlights                    Highlights
@@ -140,6 +142,7 @@ type Tests interface {
 	CaseSensitiveWorkspaceSymbols(*testing.T, string, []protocol.SymbolInformation, map[string]struct{})
 	SignatureHelp(*testing.T, span.Span, *protocol.SignatureHelp)
 	Link(*testing.T, span.URI, []Link)
+	FillStruct(*testing.T, span.Span)
 }
 
 type Definition struct {
@@ -331,6 +334,7 @@ func Load(t testing.TB, exporter packagestest.Exporter, dir string) []*Data {
 						Filename: goldFile,
 						Archive:  archive,
 					}
+					fmt.Printf("Trimmed : %s, goldfile: %s, ArchiveCount : %d\n", trimmed, goldFile, len(archive.Files))
 				} else if trimmed := strings.TrimSuffix(fragment, inFileSuffix); trimmed != fragment {
 					delete(m.Files, fragment)
 					m.Files[trimmed] = operation
@@ -414,6 +418,7 @@ func Load(t testing.TB, exporter packagestest.Exporter, dir string) []*Data {
 			"signature":       datum.collectSignatures,
 			"link":            datum.collectLinks,
 			"suggestedfix":    datum.collectSuggestedFixes,
+			"fillstruct":      datum.collectfillStruct,
 		}); err != nil {
 			t.Fatal(err)
 		}
@@ -588,6 +593,17 @@ func Run(t *testing.T, tests Tests, data *Data) {
 		}
 	})
 
+	t.Run("FillStruct", func(t *testing.T) {
+		t.Helper()
+
+		for _, spn := range data.FillStruct {
+			t.Run(SpanName(spn), func(t *testing.T) {
+				t.Helper()
+				tests.FillStruct(t, spn)
+			})
+		}
+	})
+
 	t.Run("SuggestedFix", func(t *testing.T) {
 		t.Helper()
 		for spn, actionKinds := range data.SuggestedFixes {
@@ -802,6 +818,7 @@ func checkData(t *testing.T, data *Data) {
 	fmt.Fprintf(buf, "SignaturesCount = %v\n", len(data.Signatures))
 	fmt.Fprintf(buf, "LinksCount = %v\n", linksCount)
 	fmt.Fprintf(buf, "ImplementationsCount = %v\n", len(data.Implementations))
+	fmt.Fprintf(buf, "FillStructCount = %v\n", len(data.FillStruct))
 
 	want := string(data.Golden("summary", summaryFile, func() ([]byte, error) {
 		return buf.Bytes(), nil
@@ -877,6 +894,7 @@ func (data *Data) Golden(tag string, target string, update func() ([]byte, error
 		}
 		file.Data = append(contents, '\n') // add trailing \n for txtar
 		golden.Modified = true
+
 	}
 	if file == nil {
 		data.t.Fatalf("could not find golden contents %v: %v", fragment, tag)
@@ -1010,6 +1028,10 @@ func (data *Data) collectSuggestedFixes(spn span.Span, actionKind string) {
 	data.SuggestedFixes[spn] = append(data.SuggestedFixes[spn], actionKind)
 }
 
+func (data *Data) collectfillStruct(spn span.Span) {
+	data.FillStruct = append(data.FillStruct, spn)
+}
+
 func (data *Data) collectDefinitions(src, target span.Span) {
 	data.Definitions[src] = Definition{
 		Src: src,