internal/lsp/source: add a FileSource interface

Rename Snapshot.GetFile to GetVersionedFile, and make the signature of
GetFile consistent with the corresponding method on session and cache.
This allows algorithms that depend only on file state to be expressed
using this API. In a subsequent CL, this is used for building and
testing the workspace module.

Preeemptively add the FileSource interface for use in these algorithms.

Change-Id: I550906e554fd290dcdf4cac442d5f223e0f644c1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/263522
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Trust: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/cache/snapshot.go

@@ -791,12 +791,12 @@ func (s *snapshot) FindFile(uri span.URI) source.VersionedFileHandle {
 	return s.files[f.URI()]
 }
 
-// GetFile returns a File for the given URI. If the file is unknown it is added
-// to the managed set.
+// GetVersionedFile returns a File for the given URI. If the file is unknown it
+// is added to the managed set.
 //
 // GetFile succeeds even if the file does not exist. A non-nil error return
 // indicates some type of internal error, for example if ctx is cancelled.
-func (s *snapshot) GetFile(ctx context.Context, uri span.URI) (source.VersionedFileHandle, error) {
+func (s *snapshot) GetVersionedFile(ctx context.Context, uri span.URI) (source.VersionedFileHandle, error) {
 	f, err := s.view.getFile(uri)
 	if err != nil {
 		return nil, err
@@ -807,6 +807,11 @@ func (s *snapshot) GetFile(ctx context.Context, uri span.URI) (source.VersionedF
 	return s.getFileLocked(ctx, f)
 }
 
+// GetFile implements the fileSource interface by wrapping GetVersionedFile.
+func (s *snapshot) GetFile(ctx context.Context, uri span.URI) (source.FileHandle, error) {
+	return s.GetVersionedFile(ctx, uri)
+}
+
 func (s *snapshot) getFileLocked(ctx context.Context, f *fileBase) (source.VersionedFileHandle, error) {
 	if fh, ok := s.files[f.URI()]; ok {
 		return fh, nil

internal/lsp/code_action.go

@@ -282,7 +282,7 @@ func analysisFixes(ctx context.Context, snapshot source.Snapshot, pkg source.Pac
 				Edit:        protocol.WorkspaceEdit{},
 			}
 			for uri, edits := range fix.Edits {
-				fh, err := snapshot.GetFile(ctx, uri)
+				fh, err := snapshot.GetVersionedFile(ctx, uri)
 				if err != nil {
 					return nil, nil, err
 				}
@@ -481,7 +481,7 @@ func moduleQuickFixes(ctx context.Context, snapshot source.Snapshot, fh source.V
 			return nil, nil
 		}
 		var err error
-		modFH, err = snapshot.GetFile(ctx, modURI)
+		modFH, err = snapshot.GetVersionedFile(ctx, modURI)
 		if err != nil {
 			return nil, err
 		}

internal/lsp/diagnostics.go

@@ -337,7 +337,7 @@ func errorsToDiagnostic(ctx context.Context, snapshot source.Snapshot, errors []
 			Severity: protocol.SeverityError,
 			Source:   e.Category,
 		}
-		fh, err := snapshot.GetFile(ctx, e.URI)
+		fh, err := snapshot.GetVersionedFile(ctx, e.URI)
 		if err != nil {
 			return err
 		}

internal/lsp/general.go

@@ -470,7 +470,7 @@ func (s *Server) beginFileRequest(ctx context.Context, pURI protocol.DocumentURI
 		return nil, nil, false, func() {}, err
 	}
 	snapshot, release := view.Snapshot(ctx)
-	fh, err := snapshot.GetFile(ctx, uri)
+	fh, err := snapshot.GetVersionedFile(ctx, uri)
 	if err != nil {
 		release()
 		return nil, nil, false, func() {}, err

internal/lsp/lsp_test.go

@@ -467,7 +467,7 @@ func (r *runner) SuggestedFix(t *testing.T, spn span.Span, actionKinds []string)
 	snapshot, release := view.Snapshot(r.ctx)
 	defer release()
 
-	fh, err := snapshot.GetFile(r.ctx, uri)
+	fh, err := snapshot.GetVersionedFile(r.ctx, uri)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -577,7 +577,7 @@ func (r *runner) FunctionExtraction(t *testing.T, start span.Span, end span.Span
 	snapshot, release := view.Snapshot(r.ctx)
 	defer release()
 
-	fh, err := snapshot.GetFile(r.ctx, uri)
+	fh, err := snapshot.GetVersionedFile(r.ctx, uri)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/lsp/mod/diagnostics.go

@@ -21,7 +21,7 @@ func Diagnostics(ctx context.Context, snapshot source.Snapshot) (map[source.Vers
 
 	reports := map[source.VersionedFileIdentity][]*source.Diagnostic{}
 	for _, uri := range snapshot.ModFiles() {
-		fh, err := snapshot.GetFile(ctx, uri)
+		fh, err := snapshot.GetVersionedFile(ctx, uri)
 		if err != nil {
 			return nil, err
 		}
@@ -44,7 +44,7 @@ func Diagnostics(ctx context.Context, snapshot source.Snapshot) (map[source.Vers
 			} else {
 				diag.Severity = protocol.SeverityWarning
 			}
-			fh, err := snapshot.GetFile(ctx, e.URI)
+			fh, err := snapshot.GetVersionedFile(ctx, e.URI)
 			if err != nil {
 				return nil, err
 			}

internal/lsp/rename.go

@@ -24,7 +24,7 @@ func (s *Server) rename(ctx context.Context, params *protocol.RenameParams) (*pr
 
 	var docChanges []protocol.TextDocumentEdit
 	for uri, e := range edits {
-		fh, err := snapshot.GetFile(ctx, uri)
+		fh, err := snapshot.GetVersionedFile(ctx, uri)
 		if err != nil {
 			return nil, err
 		}

internal/lsp/source/diagnostics.go

@@ -128,7 +128,7 @@ func pickAnalyzers(snapshot Snapshot, hadTypeErrors bool) map[string]Analyzer {
 }
 
 func FileDiagnostics(ctx context.Context, snapshot Snapshot, uri span.URI) (VersionedFileIdentity, []*Diagnostic, error) {
-	fh, err := snapshot.GetFile(ctx, uri)
+	fh, err := snapshot.GetVersionedFile(ctx, uri)
 	if err != nil {
 		return VersionedFileIdentity{}, nil, err
 	}

internal/lsp/source/view.go

@@ -44,9 +44,13 @@ type Snapshot interface {
 	// in the given snapshot.
 	FindFile(uri span.URI) VersionedFileHandle
 
-	// GetFile returns the FileHandle for a given URI, initializing it
-	// if it is not already part of the snapshot.
-	GetFile(ctx context.Context, uri span.URI) (VersionedFileHandle, error)
+	// GetVersionedFile returns the VersionedFileHandle for a given URI,
+	// initializing it if it is not already part of the snapshot.
+	GetVersionedFile(ctx context.Context, uri span.URI) (VersionedFileHandle, error)
+
+	// GetFile returns the FileHandle for a given URI, initializing it if it is
+	// not already part of the snapshot.
+	GetFile(ctx context.Context, uri span.URI) (FileHandle, error)
 
 	// AwaitInitialized waits until the snapshot's view is initialized.
 	AwaitInitialized(ctx context.Context)
@@ -203,6 +207,14 @@ type View interface {
 	IsGoPrivatePath(path string) bool
 }
 
+// A FileSource maps uris to FileHandles. This abstraction exists both for
+// testability, and so that algorithms can be run equally on session and
+// snapshot files.
+type FileSource interface {
+	// GetFile returns the FileHandle for a given URI.
+	GetFile(ctx context.Context, uri span.URI) (FileHandle, error)
+}
+
 type BuiltinPackage struct {
 	Package    *ast.Package
 	ParsedFile *ParsedGoFile