internal/lsp: change File.Read to a File.GetContent accessor

Like the previous change to the FIle interface, we treat Read as if it were an
accessor, we remember the content part but not the error part, and we may fill
it in asynchronously, so this change makes it explicit.
In the future we should probably trap the error in the read and push it back
through another channel though, it will be the root cause of later errors.

Change-Id: I3d374dd557178b4e8c5544813cd77f5c0faefe5b
Reviewed-on: https://go-review.googlesource.com/c/162403
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/cache/file.go

@@ -24,11 +24,12 @@ type File struct {
 	pkg     *packages.Package
 }
 
-// Read returns the contents of the file, reading it from file system if needed.
-func (f *File) Read() ([]byte, error) {
+// GetContent returns the contents of the file, reading it from file system if needed.
+func (f *File) GetContent() []byte {
 	f.view.mu.Lock()
 	defer f.view.mu.Unlock()
-	return f.read()
+	f.read()
+	return f.content
 }
 
 func (f *File) GetFileSet() *token.FileSet {
@@ -69,19 +70,18 @@ func (f *File) GetPackage() *packages.Package {
 }
 
 // read is the internal part of Read that presumes the lock is already held
-func (f *File) read() ([]byte, error) {
+func (f *File) read() {
 	if f.content != nil {
-		return f.content, nil
+		return
 	}
 	// we don't know the content yet, so read it
 	filename, err := f.URI.Filename()
 	if err != nil {
-		return nil, err
+		return
 	}
 	content, err := ioutil.ReadFile(filename)
 	if err != nil {
-		return nil, err
+		return
 	}
 	f.content = content
-	return f.content, nil
 }

internal/lsp/format.go

@@ -2,7 +2,6 @@ package lsp
 
 import (
 	"context"
-	"go/token"
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
@@ -26,21 +25,19 @@ func formatRange(ctx context.Context, v source.View, uri protocol.DocumentURI, r
 	} else {
 		r = fromProtocolRange(tok, *rng)
 	}
-	content, err := f.Read()
-	if err != nil {
-		return nil, err
-	}
 	edits, err := source.Format(ctx, f, r)
 	if err != nil {
 		return nil, err
 	}
-	return toProtocolEdits(tok, content, edits), nil
+	return toProtocolEdits(f, edits), nil
 }
 
-func toProtocolEdits(tok *token.File, content []byte, edits []source.TextEdit) []protocol.TextEdit {
+func toProtocolEdits(f source.File, edits []source.TextEdit) []protocol.TextEdit {
 	if edits == nil {
 		return nil
 	}
+	tok := f.GetToken()
+	content := f.GetContent()
 	// When a file ends with an empty line, the newline character is counted
 	// as part of the previous line. This causes the formatter to insert
 	// another unnecessary newline on each formatting. We handle this case by

internal/lsp/imports.go

@@ -25,13 +25,9 @@ func organizeImports(ctx context.Context, v source.View, uri protocol.DocumentUR
 		Start: tok.Pos(0),
 		End:   tok.Pos(tok.Size()),
 	}
-	content, err := f.Read()
+	edits, err := source.Imports(ctx, f, r)
 	if err != nil {
 		return nil, err
 	}
-	edits, err := source.Imports(ctx, tok, content, r)
-	if err != nil {
-		return nil, err
-	}
-	return toProtocolEdits(tok, content, edits), nil
+	return toProtocolEdits(f, edits), nil
 }

internal/lsp/lsp_test.go

@@ -374,10 +374,6 @@ func (f formats) test(t *testing.T, s *server) {
 		if err != nil {
 			t.Error(err)
 		}
-		original, err := f.Read()
-		if err != nil {
-			t.Error(err)
-		}
 		var ops []*diff.Op
 		for _, edit := range edits {
 			start := int(edit.Range.Start.Line)
@@ -400,7 +396,7 @@ func (f formats) test(t *testing.T, s *server) {
 				})
 			}
 		}
-		split := strings.SplitAfter(string(original), "\n")
+		split := strings.SplitAfter(string(f.GetContent()), "\n")
 		got := strings.Join(diff.ApplyEdits(split, ops), "")
 		if gofmted != got {
 			t.Errorf("format failed for %s: expected '%v', got '%v'", filename, gofmted, got)

internal/lsp/source/diagnostics.go

@@ -80,11 +80,7 @@ func Diagnostics(ctx context.Context, v View, uri URI) (map[string][]Diagnostic,
 			continue
 		}
 		diagTok := diagFile.GetToken()
-		content, err := diagFile.Read()
-		if err != nil {
-			continue
-		}
-		end, err := identifierEnd(content, pos.Line, pos.Column)
+		end, err := identifierEnd(diagFile.GetContent(), pos.Line, pos.Column)
 		// Don't set a range if it's anything other than a type error.
 		if err != nil || diag.Kind != packages.TypeError {
 			end = 0

internal/lsp/source/format.go

@@ -52,25 +52,21 @@ func Format(ctx context.Context, f File, rng Range) ([]TextEdit, error) {
 	if err := format.Node(buf, fset, node); err != nil {
 		return nil, err
 	}
-	content, err := f.Read()
-	if err != nil {
-		return nil, err
-	}
-	tok := f.GetToken()
-	return computeTextEdits(rng, tok, string(content), buf.String()), nil
+	return computeTextEdits(rng, f, buf.String()), nil
 }
 
 // Imports formats a file using the goimports tool.
-func Imports(ctx context.Context, tok *token.File, content []byte, rng Range) ([]TextEdit, error) {
-	formatted, err := imports.Process(tok.Name(), content, nil)
+func Imports(ctx context.Context, f File, rng Range) ([]TextEdit, error) {
+	formatted, err := imports.Process(f.GetToken().Name(), f.GetContent(), nil)
 	if err != nil {
 		return nil, err
 	}
-	return computeTextEdits(rng, tok, string(content), string(formatted)), nil
+	return computeTextEdits(rng, f, string(formatted)), nil
 }
 
-func computeTextEdits(rng Range, tok *token.File, unformatted, formatted string) (edits []TextEdit) {
-	u := strings.SplitAfter(unformatted, "\n")
+func computeTextEdits(rng Range, file File, formatted string) (edits []TextEdit) {
+	u := strings.SplitAfter(string(file.GetContent()), "\n")
+	tok := file.GetToken()
 	f := strings.SplitAfter(formatted, "\n")
 	for _, op := range diff.Operations(u, f) {
 		start := lineStart(tok, op.I1+1)

internal/lsp/source/view.go

@@ -31,7 +31,7 @@ type File interface {
 	GetFileSet() *token.FileSet
 	GetPackage() *packages.Package
 	GetToken() *token.File
-	Read() ([]byte, error)
+	GetContent() []byte
 }
 
 // Range represents a start and end position.