gopls/internal/lsp/source: move Go CodeActions logic from server

This change moves all the logic in server for Go-specific
code actions to source.CodeActions. Some symbols are renamed,
documented, and unexported.

Unexporting several functions caused the brand-new unusedparams
analyzer (on whose behalf this work was done) to report unused
parameters, allowing further deletions. Yay.

No behavior changes.

Change-Id: I72b6ca45137a24bf855f3c7418bbe8b26ed0aefa
Reviewed-on: https://go-review.googlesource.com/c/tools/+/556818
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Robert Findley <[email protected]>

Author: adonovan

gopls/internal/lsp/cache/errors.go

@@ -393,31 +393,6 @@ func BuildLink(target, path, anchor string) string {
 	return link + "#" + anchor
 }
 
-// suggestedAnalysisFixes converts edit-based fixes associated
-// with a gobDiagnostic to cache.SuggestedFixes.
-// It returns the cross product of fixes and kinds.
-func suggestedAnalysisFixes(diag *gobDiagnostic, kinds []protocol.CodeActionKind) []SuggestedFix {
-	var fixes []SuggestedFix
-	for _, fix := range diag.SuggestedFixes {
-		edits := make(map[protocol.DocumentURI][]protocol.TextEdit)
-		for _, e := range fix.TextEdits {
-			uri := e.Location.URI
-			edits[uri] = append(edits[uri], protocol.TextEdit{
-				Range:   e.Location.Range,
-				NewText: string(e.NewText),
-			})
-		}
-		for _, kind := range kinds {
-			fixes = append(fixes, SuggestedFix{
-				Title:      fix.Message,
-				Edits:      edits,
-				ActionKind: kind,
-			})
-		}
-	}
-	return fixes
-}
-
 func parseGoListError(e packages.Error, dir string) (filename string, line, col8 int) {
 	input := e.Pos
 	if input == "" {

gopls/internal/lsp/source/change_quote.go

@@ -78,7 +78,7 @@ func ConvertStringLiteral(pgf *ParsedGoFile, fh file.Handle, rng protocol.Range)
 		Title: title,
 		Kind:  protocol.RefactorRewrite,
 		Edit: &protocol.WorkspaceEdit{
-			DocumentChanges: protocol.TextEditsToDocumentChanges(fh.URI(), fh.Version(), pedits),
+			DocumentChanges: documentChanges(fh, pedits),
 		},
 	}, true
 }

gopls/internal/lsp/source/change_signature.go

@@ -170,7 +170,7 @@ func RemoveUnusedParameter(ctx context.Context, fh file.Handle, rng protocol.Ran
 		if err != nil {
 			return nil, fmt.Errorf("computing edits for %s: %v", uri, err)
 		}
-		changes = append(changes, protocol.TextEditsToDocumentChanges(fh.URI(), fh.Version(), pedits)...)
+		changes = append(changes, documentChanges(fh, pedits)...)
 	}
 	return changes, nil
 }