extract LabelContributor from local reference contributor

pkg/analysis_server/lib/src/services/completion/dart/label_contributor.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library services.completion.contributor.dart.local_ref;
+
+import 'dart:async';
+
+import 'package:analysis_server/plugin/protocol/protocol.dart' as protocol
+    show Element, ElementKind;
+import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
+import 'package:analysis_server/src/services/completion/dart/completion_manager.dart'
+    show DartCompletionRequestImpl;
+import 'package:analysis_server/src/services/completion/local_declaration_visitor.dart'
+    show LocalDeclarationVisitor;
+import 'package:analysis_server/src/services/completion/optype.dart';
+import 'package:analyzer/src/generated/ast.dart';
+import 'package:analyzer/src/generated/scanner.dart';
+import 'package:analyzer/src/generated/source.dart';
+
+import '../../../protocol_server.dart'
+    show CompletionSuggestion, CompletionSuggestionKind, Location;
+
+const DYNAMIC = 'dynamic';
+
+final TypeName NO_RETURN_TYPE = new TypeName(
+    new SimpleIdentifier(new StringToken(TokenType.IDENTIFIER, '', 0)), null);
+
+/**
+ * A contributor for calculating label suggestions.
+ */
+class LabelContributor extends DartCompletionContributor {
+  @override
+  Future<List<CompletionSuggestion>> computeSuggestions(
+      DartCompletionRequest request) async {
+    OpType optype = (request as DartCompletionRequestImpl).opType;
+
+    // Collect suggestions from the specific child [AstNode] that contains
+    // the completion offset and all of its parents recursively.
+    List<CompletionSuggestion> suggestions = <CompletionSuggestion>[];
+    if (!optype.isPrefixed) {
+      if (optype.includeStatementLabelSuggestions ||
+          optype.includeCaseLabelSuggestions) {
+        new _LabelVisitor(request, optype.includeStatementLabelSuggestions,
+                optype.includeCaseLabelSuggestions, suggestions)
+            .visit(request.target.containingNode);
+      }
+    }
+    return suggestions;
+  }
+}
+
+/**
+ * A visitor for collecting suggestions for break and continue labels.
+ */
+class _LabelVisitor extends LocalDeclarationVisitor {
+  final DartCompletionRequest request;
+  final List<CompletionSuggestion> suggestions;
+
+  /**
+   * True if statement labels should be included as suggestions.
+   */
+  final bool includeStatementLabels;
+
+  /**
+   * True if case labels should be included as suggestions.
+   */
+  final bool includeCaseLabels;
+
+  _LabelVisitor(DartCompletionRequest request, this.includeStatementLabels,
+      this.includeCaseLabels, this.suggestions)
+      : super(request.offset),
+        request = request;
+
+  @override
+  void declaredClass(ClassDeclaration declaration) {
+    // ignored
+  }
+
+  @override
+  void declaredClassTypeAlias(ClassTypeAlias declaration) {
+    // ignored
+  }
+
+  @override
+  void declaredField(FieldDeclaration fieldDecl, VariableDeclaration varDecl) {
+    // ignored
+  }
+
+  @override
+  void declaredFunction(FunctionDeclaration declaration) {
+    // ignored
+  }
+
+  @override
+  void declaredFunctionTypeAlias(FunctionTypeAlias declaration) {
+    // ignored
+  }
+
+  @override
+  void declaredLabel(Label label, bool isCaseLabel) {
+    if (isCaseLabel ? includeCaseLabels : includeStatementLabels) {
+      CompletionSuggestion suggestion = _addSuggestion(label.label);
+      if (suggestion != null) {
+        suggestion.element = createLocalElement(
+            request.source, protocol.ElementKind.LABEL, label.label,
+            returnType: NO_RETURN_TYPE);
+      }
+    }
+  }
+
+  @override
+  void declaredLocalVar(SimpleIdentifier name, TypeName type) {
+    // ignored
+  }
+
+  @override
+  void declaredMethod(MethodDeclaration declaration) {
+    // ignored
+  }
+
+  @override
+  void declaredParam(SimpleIdentifier name, TypeName type) {
+    // ignored
+  }
+
+  @override
+  void declaredTopLevelVar(
+      VariableDeclarationList varList, VariableDeclaration varDecl) {
+    // ignored
+  }
+
+  @override
+  void visitFunctionExpression(FunctionExpression node) {
+    // Labels are only accessible within the local function, so stop visiting
+    // once we reach a function boundary.
+    finished();
+  }
+
+  @override
+  void visitMethodDeclaration(MethodDeclaration node) {
+    // Labels are only accessible within the local function, so stop visiting
+    // once we reach a function boundary.
+    finished();
+  }
+
+  CompletionSuggestion _addSuggestion(SimpleIdentifier id) {
+    if (id != null) {
+      String completion = id.name;
+      if (completion != null && completion.length > 0 && completion != '_') {
+        CompletionSuggestion suggestion = new CompletionSuggestion(
+            CompletionSuggestionKind.IDENTIFIER,
+            DART_RELEVANCE_DEFAULT,
+            completion,
+            completion.length,
+            0,
+            false,
+            false);
+        suggestions.add(suggestion);
+        return suggestion;
+      }
+    }
+    return null;
+  }
+}
+
+/**
+* Create a new protocol Element for inclusion in a completion suggestion.
+*/
+protocol.Element createLocalElement(
+    Source source, protocol.ElementKind kind, SimpleIdentifier id,
+    {String parameters,
+    TypeName returnType,
+    bool isAbstract: false,
+    bool isDeprecated: false}) {
+  String name;
+  Location location;
+  if (id != null) {
+    name = id.name;
+    // TODO(danrubel) use lineInfo to determine startLine and startColumn
+    location = new Location(source.fullName, id.offset, id.length, 0, 0);
+  } else {
+    name = '';
+    location = new Location(source.fullName, -1, 0, 1, 0);
+  }
+  int flags = protocol.Element.makeFlags(
+      isAbstract: isAbstract,
+      isDeprecated: isDeprecated,
+      isPrivate: Identifier.isPrivateName(name));
+  return new protocol.Element(kind, name, flags,
+      location: location,
+      parameters: parameters,
+      returnType: nameForType(returnType));
+}
+
+/**
+* Create a new suggestion for the given field.
+* Return the new suggestion or `null` if it could not be created.
+*/
+CompletionSuggestion createLocalFieldSuggestion(
+    Source source, FieldDeclaration fieldDecl, VariableDeclaration varDecl) {
+  bool deprecated = isDeprecated(fieldDecl) || isDeprecated(varDecl);
+  TypeName type = fieldDecl.fields.type;
+  return createLocalSuggestion(
+      varDecl.name, deprecated, DART_RELEVANCE_LOCAL_FIELD, type,
+      classDecl: fieldDecl.parent,
+      element: createLocalElement(
+          source, protocol.ElementKind.FIELD, varDecl.name,
+          returnType: type, isDeprecated: deprecated));
+}
+
+/**
+* Create a new suggestion based upon the given information.
+* Return the new suggestion or `null` if it could not be created.
+*/
+CompletionSuggestion createLocalSuggestion(SimpleIdentifier id,
+    bool isDeprecated, int defaultRelevance, TypeName returnType,
+    {ClassDeclaration classDecl, protocol.Element element}) {
+  if (id == null) {
+    return null;
+  }
+  String completion = id.name;
+  if (completion == null || completion.length <= 0 || completion == '_') {
+    return null;
+  }
+  CompletionSuggestion suggestion = new CompletionSuggestion(
+      CompletionSuggestionKind.INVOCATION,
+      isDeprecated ? DART_RELEVANCE_LOW : defaultRelevance,
+      completion,
+      completion.length,
+      0,
+      isDeprecated,
+      false,
+      returnType: nameForType(returnType),
+      element: element);
+  if (classDecl != null) {
+    SimpleIdentifier classId = classDecl.name;
+    if (classId != null) {
+      String className = classId.name;
+      if (className != null && className.length > 0) {
+        suggestion.declaringType = className;
+      }
+    }
+  }
+  return suggestion;
+}
+
+/**
+* Return `true` if the @deprecated annotation is present
+*/
+bool isDeprecated(AnnotatedNode node) {
+  if (node != null) {
+    NodeList<Annotation> metadata = node.metadata;
+    if (metadata != null) {
+      return metadata.any((Annotation a) {
+        return a.name is SimpleIdentifier && a.name.name == 'deprecated';
+      });
+    }
+  }
+  return false;
+}
+
+/**
+* Return the name for the given type.
+*/
+String nameForType(TypeName type) {
+  if (type == NO_RETURN_TYPE) {
+    return null;
+  }
+  if (type == null) {
+    return DYNAMIC;
+  }
+  Identifier id = type.name;
+  if (id == null) {
+    return DYNAMIC;
+  }
+  String name = id.name;
+  if (name == null || name.length <= 0) {
+    return DYNAMIC;
+  }
+  TypeArgumentList typeArgs = type.typeArguments;
+  if (typeArgs != null) {
+    //TODO (danrubel) include type arguments
+  }
+  return name;
+}