Add basic completion for self fields and locals (#72)

* Fix benchstat
Run sequentially to get good comparison

* Add basic completion
Supports `self` fields and locals
Closes #3

* Oops, install benchstat

.github/workflows/benchstat-pr.yml

@@ -1,50 +1,43 @@
-name: Benchstat
+name: benchstat
 
 on: [pull_request]
 
 jobs:
-  incoming:
+  benchstat:
     runs-on: ubuntu-latest
     steps:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
           go-version: '1.19'
+
+      # Generate benchmark report for main branch
       - name: Checkout
         uses: actions/checkout@v3
+        with:
+          ref: main
       - name: Benchmark
         run: go test ./... -count=5 -run=Benchmark -bench=. | tee -a bench.txt
       - name: Upload Benchmark
         uses: actions/upload-artifact@v3
         with:
-          name: bench-incoming
+          name: bench-current
           path: bench.txt
-  current:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Install Go
-        uses: actions/setup-go@v3
-        with:
-          go-version: '1.19'
+
+      # Generate benchmark report for the PR
       - name: Checkout
         uses: actions/checkout@v3
-        with:
-          ref: main
       - name: Benchmark
         run: go test ./... -count=5 -run=Benchmark -bench=. | tee -a bench.txt
       - name: Upload Benchmark
         uses: actions/upload-artifact@v3
         with:
-          name: bench-current
+          name: bench-incoming
           path: bench.txt
-  benchstat:
-    needs: [incoming, current]
-    runs-on: ubuntu-latest
-    steps:
-      - name: Install Go
-        uses: actions/setup-go@v3
-        with:
-          go-version: '1.19'
+
+      # Compare the two reports
+      - name: Checkout
+        uses: actions/checkout@v3
       - name: Install benchstat
         run: go install golang.org/x/perf/cmd/benchstat@latest
       - name: Download Incoming
@@ -79,4 +72,4 @@ jobs:
             ${{ steps.benchstat_content.outputs.content }}
             ```
           comment_includes: 'Benchstat (compared to main):'
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

pkg/server/completion.go

@@ -4,8 +4,13 @@ import (
 	"context"
 	"strings"
 
+	"github.com/google/go-jsonnet/ast"
+	"github.com/grafana/jsonnet-language-server/pkg/ast/processing"
+	"github.com/grafana/jsonnet-language-server/pkg/nodestack"
+	position "github.com/grafana/jsonnet-language-server/pkg/position_conversion"
 	"github.com/grafana/jsonnet-language-server/pkg/utils"
 	"github.com/jdbaldry/go-language-server-protocol/lsp/protocol"
+	log "github.com/sirupsen/logrus"
 )
 
 func (s *Server) Completion(ctx context.Context, params *protocol.CompletionParams) (*protocol.CompletionList, error) {
@@ -14,14 +19,98 @@ func (s *Server) Completion(ctx context.Context, params *protocol.CompletionPara
 		return nil, utils.LogErrorf("Completion: %s: %w", errorRetrievingDocument, err)
 	}
 
-	items := []protocol.CompletionItem{}
+	line := getCompletionLine(doc.item.Text, params.Position)
+
+	// Short-circuit if it's a stdlib completion
+	if items := s.completionStdLib(line); len(items) > 0 {
+		return &protocol.CompletionList{IsIncomplete: false, Items: items}, nil
+	}
+
+	// Otherwise, parse the AST and search for completions
+	if doc.ast == nil {
+		log.Errorf("Completion: document was never successfully parsed, can't autocomplete")
+		return nil, nil
+	}
+
+	searchStack, err := processing.FindNodeByPosition(doc.ast, position.ProtocolToAST(params.Position))
+	if err != nil {
+		log.Errorf("Completion: error computing node: %v", err)
+		return nil, nil
+	}
+
+	items := s.completionFromStack(line, searchStack)
+	return &protocol.CompletionList{IsIncomplete: false, Items: items}, nil
+}
 
-	line := strings.Split(doc.item.Text, "\n")[params.Position.Line]
-	charIndex := int(params.Position.Character)
+func getCompletionLine(fileContent string, position protocol.Position) string {
+	line := strings.Split(fileContent, "\n")[position.Line]
+	charIndex := int(position.Character)
 	if charIndex > len(line) {
 		charIndex = len(line)
 	}
 	line = line[:charIndex]
+	return line
+}
+
+func (s *Server) completionFromStack(line string, stack *nodestack.NodeStack) []protocol.CompletionItem {
+	var items []protocol.CompletionItem
+
+	lineWords := strings.Split(line, " ")
+	lastWord := lineWords[len(lineWords)-1]
+
+	indexes := strings.Split(lastWord, ".")
+	firstIndex, indexes := indexes[0], indexes[1:]
+
+	if firstIndex == "self" && len(indexes) > 0 {
+		fieldPrefix := indexes[0]
+
+		for !stack.IsEmpty() {
+			curr := stack.Pop()
+
+			switch curr := curr.(type) {
+			case *ast.Binary:
+				stack.Push(curr.Left)
+				stack.Push(curr.Right)
+			case *ast.DesugaredObject:
+				for _, field := range curr.Fields {
+					label := processing.FieldNameToString(field.Name)
+					// Ignore fields that don't match the prefix
+					if !strings.HasPrefix(label, fieldPrefix) {
+						continue
+					}
+
+					// Ignore the current field
+					if strings.Contains(line, label+":") {
+						continue
+					}
+
+					items = append(items, createCompletionItem(label, "self."+label, protocol.FieldCompletion, field.Body))
+				}
+			}
+		}
+	} else if len(indexes) == 0 {
+		// firstIndex is a variable (local) completion
+		for !stack.IsEmpty() {
+			if curr, ok := stack.Pop().(*ast.Local); ok {
+				for _, bind := range curr.Binds {
+					label := string(bind.Variable)
+
+					if !strings.HasPrefix(label, firstIndex) {
+						continue
+					}
+
+					items = append(items, createCompletionItem(label, label, protocol.VariableCompletion, bind.Body))
+				}
+			}
+		}
+	}
+
+	return items
+}
+
+func (s *Server) completionStdLib(line string) []protocol.CompletionItem {
+	items := []protocol.CompletionItem{}
+
 	stdIndex := strings.LastIndex(line, "std.")
 	if stdIndex != -1 {
 		userInput := line[stdIndex+4:]
@@ -55,5 +144,26 @@ func (s *Server) Completion(ctx context.Context, params *protocol.CompletionPara
 		items = append(items, funcContains...)
 	}
 
-	return &protocol.CompletionList{IsIncomplete: false, Items: items}, nil
+	return items
+}
+
+func createCompletionItem(label, detail string, kind protocol.CompletionItemKind, body ast.Node) protocol.CompletionItem {
+	insertText := label
+	if asFunc, ok := body.(*ast.Function); ok {
+		kind = protocol.FunctionCompletion
+		params := []string{}
+		for _, param := range asFunc.Parameters {
+			params = append(params, string(param.Name))
+		}
+		paramsString := "(" + strings.Join(params, ", ") + ")"
+		detail += paramsString
+		insertText += paramsString
+	}
+
+	return protocol.CompletionItem{
+		Label:      label,
+		Detail:     detail,
+		Kind:       kind,
+		InsertText: insertText,
+	}
 }