Don't call completion providers inside of comments (#831)

It seems like this is handled client side by some editors, but Zed
triggered completion requests inside of comments. While we could have
each provider handle this, I think an early exit in the manager already
is a better solution, as there's unlikely to be any provider that wants
to do suggestions in a comment. If that changes in the future, we'll
handle it then.

Fixes #826

Signed-off-by: Anders Eknert <[email protected]>

internal/lsp/completions/manager.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/styrainc/regal/internal/lsp/cache"
 	"github.com/styrainc/regal/internal/lsp/completions/providers"
+	"github.com/styrainc/regal/internal/lsp/rego"
 	"github.com/styrainc/regal/internal/lsp/types"
 )
 
@@ -47,6 +48,12 @@ func NewDefaultManager(c *cache.Cache) *Manager {
 func (m *Manager) Run(params types.CompletionParams, opts *providers.Options) ([]types.CompletionItem, error) {
 	var completions []types.CompletionItem
 
+	if m.isInsideOfComment(params) {
+		// Exit early if caret position is inside a comment. Most clients won't show
+		// suggestions there anyway, and there's no need to ask providers for completions.
+		return completions, nil
+	}
+
 	for _, provider := range m.providers {
 		providerCompletions, err := provider.Run(m.c, params, opts)
 		if err != nil {
@@ -70,3 +77,19 @@ func (m *Manager) Run(params types.CompletionParams, opts *providers.Options) ([
 func (m *Manager) RegisterProvider(provider Provider) {
 	m.providers = append(m.providers, provider)
 }
+
+func (m *Manager) isInsideOfComment(params types.CompletionParams) bool {
+	if module, ok := m.c.GetModule(params.TextDocument.URI); ok {
+		for _, comment := range module.Comments {
+			cp := rego.PositionFromLocation(comment.Location)
+
+			if cp.Line == params.Position.Line {
+				if cp.Character <= params.Position.Character {
+					return true
+				}
+			}
+		}
+	}
+
+	return false
+}

internal/lsp/completions/manager_test.go

@@ -3,6 +3,8 @@ package completions
 import (
 	"testing"
 
+	"github.com/open-policy-agent/opa/ast"
+
 	"github.com/styrainc/regal/internal/lsp/cache"
 	"github.com/styrainc/regal/internal/lsp/completions/providers"
 	"github.com/styrainc/regal/internal/lsp/types"
@@ -44,3 +46,42 @@ func TestManager(t *testing.T) {
 		t.Fatalf("Expected label to be 'package', got: %v", comp.Label)
 	}
 }
+
+func TestManagerEarlyExitInsideComment(t *testing.T) {
+	t.Parallel()
+
+	c := cache.NewCache()
+	fileURI := "file:///foo/bar/file.rego"
+
+	fileContents := `package p
+
+import rego.v1 # modern rego i
+`
+
+	module := ast.MustParseModule(fileContents)
+
+	c.SetFileContents(fileURI, fileContents)
+	c.SetModule(fileURI, module)
+
+	mgr := NewManager(c, &ManagerOptions{})
+	mgr.RegisterProvider(&providers.Import{})
+
+	completionParams := types.CompletionParams{
+		TextDocument: types.TextDocumentIdentifier{
+			URI: fileURI,
+		},
+		Position: types.Position{
+			Line:      2,
+			Character: 30,
+		},
+	}
+
+	completions, err := mgr.Run(completionParams, nil)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if len(completions) != 0 {
+		t.Errorf("Expected no completions, got: %v", completions)
+	}
+}