Add first completion target with multiple matches (#59)

When a completion target has multiple matches, such as when editing Go code that uses generated Protobuf packages that have the same method name at multiple levels of hierarchy, insert the first match always, and display the rest in an Acme window called `/LSP/Completions` similar to `/LSP/Diagnostics`.

This behaviour can be triggered by passing `-E` to `L comp` instead of `-e`. The existing behaviour for `-e` is preserved as is.

Closes #56

cmd/L/main.go

@@ -40,10 +40,13 @@ attempt to find the focused window ID by connecting to acmefocused
 
 List of sub-commands:
 
- comp [-e]
+ comp [-e] [-E]
  Print candidate completions at the cursor position. If
  -e (edit) flag is given and there is only one candidate,
- the completion is applied instead of being printed.
+ the completion is applied instead of being printed. If
+ -E (Edit) flag is given, the first matching candidate is
+ applied, and all matches will be displayed in a dedicated
+ Acme window named /LSP/Completions.
 
  def [-p]
  Find where the symbol at the cursor position is defined
@@ -206,7 +209,18 @@ func run(cfg *config.Config, args []string) error {
  switch args[0] {
  case "comp":
  args = args[1:]
- return rc.Completion(ctx, len(args) > 0 && args[0] == "-e")
+
+ var kind acmelsp.CompletionKind
+ if len(args) > 0 {
+ switch args[0] {
+ case "-e":
+ kind = acmelsp.CompleteInsertOnlyMatch
+ case "-E":
+ kind = acmelsp.CompleteInsertFirstMatch
+ }
+ }
+
+ return rc.Completion(ctx, kind)
  case "def":
  args = args[1:]
  return rc.Definition(ctx, len(args) > 0 && args[0] == "-p")

cmd/Lone/main.go

@@ -142,7 +142,7 @@ func run(cfg *config.Config, args []string) error {
 
  switch args[0] {
  case "comp":
- err = rc.Completion(ctx, false)
+ err = rc.Completion(ctx, acmelsp.CompleteNoEdit)
  case "def":
  err = rc.Definition(ctx, false)
  case "fmt":

internal/lsp/acmelsp/assist.go

@@ -220,7 +220,7 @@ func (w *outputWin) Update(fw *focusWin, server proxy.Server, cmd string) {
  w.Clear()
  switch cmd {
  case "comp":
- err := rc.Completion(ctx, false)
+ err := rc.Completion(ctx, CompleteNoEdit)
  if err != nil {
  dprintf("Completion failed: %v\n", err)
  }

internal/lsp/acmelsp/remote.go

@@ -73,7 +73,15 @@ func (rc *RemoteCmd) DidChange(ctx context.Context) error {
  })
 }
 
-func (rc *RemoteCmd) Completion(ctx context.Context, edit bool) error {
+type CompletionKind int
+
+const (
+ CompleteNoEdit CompletionKind = iota
+ CompleteInsertOnlyMatch
+ CompleteInsertFirstMatch
+)
+
+func (rc *RemoteCmd) Completion(ctx context.Context, kind CompletionKind) error {
  w, err := acmeutil.OpenWin(rc.winid)
  if err != nil {
  return err
@@ -90,7 +98,8 @@ func (rc *RemoteCmd) Completion(ctx context.Context, edit bool) error {
  if err != nil {
  return err
  }
- if edit && len(result.Items) == 1 {
+
+ if (kind == CompleteInsertFirstMatch && len(result.Items) >= 1) || (kind == CompleteInsertOnlyMatch && len(result.Items) == 1) {
  textEdit := result.Items[0].TextEdit
  if textEdit == nil {
  // TODO(fhs): Use insertText or label instead.
@@ -99,14 +108,41 @@ func (rc *RemoteCmd) Completion(ctx context.Context, edit bool) error {
  if err := text.Edit(w, []protocol.TextEdit{*textEdit}); err != nil {
  return fmt.Errorf("failed to apply completion edit: %v", err)
  }
- return nil
+
+ if len(result.Items) == 1 {
+ return nil
+ }
  }
+
+ var sb strings.Builder
+
  if len(result.Items) == 0 {
- fmt.Fprintf(rc.Stderr, "no completion\n")
+ fmt.Fprintf(&sb, "no completion\n")
  }
+
  for _, item := range result.Items {
- fmt.Fprintf(rc.Stdout, "%v %v\n", item.Label, item.Detail)
+ fmt.Fprintf(&sb, "%v\t%v\n", item.Label, item.Detail)
  }
+
+ if kind == CompleteInsertFirstMatch {
+ cw, err := acmeutil.Hijack("/LSP/Completions")
+ if err != nil {
+ cw, err = acmeutil.NewWin()
+ if err != nil {
+ return err
+ }
+
+ cw.Name("/LSP/Completions")
+ }
+
+ defer cw.Win.Ctl("clean")
+
+ cw.Clear()
+ cw.PrintTabbed(sb.String())
+ } else {
+ fmt.Println(sb.String())
+ }
+
  return nil
 }
 

internal/lsp/text/edit.go

@@ -65,6 +65,7 @@ func Edit(f File, edits []protocol.TextEdit) error {
  q1 := off.LineToOffset(int(e.Range.End.Line), int(e.Range.End.Character))
  f.WriteAt(q0, q1, []byte(e.NewText))
  }
+
  return nil
 }