pkg/analyzer/lib/src/dart/micro/utils.dart

// Copyright (c) 2021, 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.

import 'package:_fe_analyzer_shared/src/base/syntactic_entity.dart';
import 'package:analyzer/dart/ast/visitor.dart';
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/src/dart/ast/ast.dart';
import 'package:analyzer/src/dart/ast/element_locator.dart';
import 'package:analyzer/src/dart/ast/extensions.dart';
import 'package:analyzer/src/dart/element/element.dart';
import 'package:analyzer/src/utilities/extensions/element.dart';

/// Return the [Element] of the given [node], or `null` if [node] is `null` or
/// does not have an element.
Element? getElementOfNode(AstNode? node) {
  if (node == null) {
    return null;
  }
  if (node is NameWithTypeParameters) {
    node = node.parent2;
  }
  if (node is DottedName) {
    node = node.parent2;
  }
  if (node is StringLiteral && node.parent2 is UriBasedDirective) {
    return null;
  }

  Element? element;
  switch (node) {
    case ImportDirective():
      return MockLibraryImportElement(node.libraryImport!);
    case ImportPrefixReference():
      element = node.element;
    case ConstructorDeclaration():
      return node.declaredFragment?.element;
    case PrimaryConstructorDeclaration():
      return node.declaredFragment?.element;
    default:
      element = ElementLocatorV2.locate(node);
  }

  if (node is ImportPrefixReference && element is PrefixElement) {
    element = _getImportElementInfoFromReference(node);
  }

  return element;
}

/// Return the [Element] of the given V1 [node], or `null` if [node] is `null`
/// or does not have an element.
@ToBeDeprecated('Use getElementOfNode2 instead')
Element? getElementOfNodeV1(AstNode? node) {
  if (node == null) {
    return null;
  }
  if (node is NameWithTypeParameters) {
    node = node.parent;
  }
  if (node is DottedName) {
    node = node.parent;
  }
  if (node is StringLiteral && node.parent is UriBasedDirective) {
    return null;
  }

  Element? element;
  switch (node) {
    case ImportDirective():
      return MockLibraryImportElement(node.libraryImport!);
    case ImportPrefixReference():
      element = node.element;
    case ConstructorDeclaration():
      return node.declaredFragment?.element;
    case PrimaryConstructorDeclaration():
      return node.declaredFragment?.element;
    default:
      element = ElementLocator.locate(node);
  }

  if (node is SimpleIdentifier && element is PrefixElement) {
    var parent = node.parent;
    if (parent is ImportDirective) {
      element = MockLibraryImportElement(parent.libraryImport!);
    } else {
      element = _getImportElementInfoV1(node);
    }
  } else if (node is ImportPrefixReference && element is PrefixElement) {
    element = _getImportElementInfoFromReferenceV1(node);
  }

  return element;
}

/// If the given [constructor] is a synthetic constructor created for a
/// [ClassTypeAlias], return the actual constructor of a [ClassDeclaration]
/// which is invoked.  Return `null` if a redirection cycle is detected.
ConstructorElement? _getActualConstructorElement(
  ConstructorElement? constructor,
) {
  var seenConstructors = <ConstructorElement?>{};
  while (constructor is ConstructorElementImpl &&
      constructor.isOriginMixinApplication) {
    var enclosing = constructor.enclosingElement;
    if (enclosing is ClassElementImpl && enclosing.isMixinApplication) {
      var superInvocation = constructor.constantInitializers
          .whereType<SuperConstructorInvocation>()
          .singleOrNull;
      if (superInvocation != null) {
        constructor = superInvocation.element;
      }
    } else {
      break;
    }
    // fail if a cycle is detected
    if (!seenConstructors.add(constructor)) {
      return null;
    }
  }
  return constructor;
}

/// Returns the [MockLibraryImportElement] that is referenced by [prefixNode]
/// with a [PrefixElement], maybe `null`.
MockLibraryImportElement? _getImportElementInfoFromReference(
  ImportPrefixReference prefixNode,
) {
  // prepare environment
  var unit = prefixNode.thisOrAncestorOfType2<CompilationUnitImpl>();
  var libraryFragment = unit?.declaredFragment;
  if (libraryFragment == null) {
    return null;
  }

  // prepare used element
  Element? usedElement;
  var parent = prefixNode.parent2;
  if (parent is ExtensionOverride2) {
    usedElement = parent.element;
  } else if (parent is NamedType) {
    usedElement = parent.element;
  } else if (parent is ImportPrefixedAssignmentTarget) {
    usedElement = switch (parent.write) {
      InvalidNamedWriteResolution(:var recoveryElement) => recoveryElement,
      _ => parent.write?.element ?? parent.read?.elementOrRecovery,
    };
  }
  if (usedElement == null) {
    return null;
  }

  // find ImportElement
  var prefix = prefixNode.name.lexeme;
  var importElementsMap = <LibraryImport, Set<Element>>{};
  return _getMockImportElement(
    libraryFragment,
    prefix,
    usedElement,
    importElementsMap,
  );
}

/// Returns the [MockLibraryImportElement] that is referenced by the V1
/// [prefixNode] with a [PrefixElement], maybe `null`.
@ToBeDeprecated('Use _getImportElementInfoFromReference instead')
MockLibraryImportElement? _getImportElementInfoFromReferenceV1(
  ImportPrefixReference prefixNode,
) {
  // prepare environment
  var unit = prefixNode.thisOrAncestorOfType<CompilationUnitImpl>();
  var libraryFragment = unit?.declaredFragment;
  if (libraryFragment == null) {
    return null;
  }

  // prepare used element
  Element? usedElement;
  var parent = prefixNode.parent;
  if (parent is ExtensionOverride) {
    usedElement = parent.element;
  } else if (parent is NamedType) {
    usedElement = parent.element;
  }
  if (usedElement == null) {
    return null;
  }

  // find ImportElement
  var prefix = prefixNode.name.lexeme;
  var importElementsMap = <LibraryImport, Set<Element>>{};
  return _getMockImportElement(
    libraryFragment,
    prefix,
    usedElement,
    importElementsMap,
  );
}

/// Returns the [MockLibraryImportElement] that is referenced by the V1
/// [prefixNode] with a [PrefixElement], maybe `null`.
@ToBeDeprecated('Use _getImportElementInfo2 instead')
MockLibraryImportElement? _getImportElementInfoV1(SimpleIdentifier prefixNode) {
  // prepare environment
  var parent = prefixNode.parent;
  var unit = prefixNode.thisOrAncestorOfType<CompilationUnitImpl>();
  var libraryFragment = unit?.declaredFragment;
  if (libraryFragment == null) {
    return null;
  }
  // prepare used element
  Element? usedElement;
  if (parent case PrefixedIdentifier prefixed) {
    if (prefixed.prefix == prefixNode) {
      usedElement = prefixed.element;
    }
  } else if (parent case MethodInvocation invocation) {
    if (invocation.target == prefixNode) {
      usedElement = invocation.methodName.element;
    }
  }
  // we need used Element
  if (usedElement == null) {
    return null;
  }
  // find ImportElement
  var prefix = prefixNode.name;
  var importElementsMap = <LibraryImport, Set<Element>>{};
  return _getMockImportElement(
    libraryFragment,
    prefix,
    usedElement,
    importElementsMap,
  );
}

/// Returns the [MockLibraryImportElement] that declared [prefix] and imports
/// [element].
///
/// [libraryFragment] - the [LibraryFragmentImpl] where reference is.
/// [prefix] - the import prefix, maybe `null`.
/// [element] - the referenced element.
/// [importElementsMap] - the cache of [Element]s imported by [LibraryImport]s.
MockLibraryImportElement? _getMockImportElement(
  LibraryFragmentImpl libraryFragment,
  String prefix,
  Element element,
  Map<LibraryImport, Set<Element>> importElementsMap,
) {
  if (element.enclosingElement is! LibraryElement) {
    return null;
  }
  var usedLibrary = element.library;
  // find ImportElement that imports used library with used prefix
  List<LibraryImport>? candidates;
  var libraryImports = libraryFragment.withEnclosing2
      .expand((fragment) => fragment.libraryImports)
      .toList();
  for (var importElement in libraryImports) {
    // required library
    if (importElement.importedLibrary != usedLibrary) {
      continue;
    }
    // required prefix
    var prefixElement = importElement.prefix?.element;
    if (prefixElement == null) {
      continue;
    }
    if (prefix != prefixElement.name) {
      continue;
    }
    // no combinators => only possible candidate
    if (importElement.combinators.isEmpty) {
      return MockLibraryImportElement(importElement);
    }
    // OK, we have candidate
    candidates ??= [];
    candidates.add(importElement);
  }
  // no candidates, probably element is defined in this library
  if (candidates == null) {
    return null;
  }
  // one candidate
  if (candidates.length == 1) {
    return MockLibraryImportElement(candidates[0]);
  }
  // ensure that each ImportElement has set of elements
  for (var importElement in candidates) {
    if (importElementsMap.containsKey(importElement)) {
      continue;
    }
    var namespace = importElement.namespace;
    var elements = namespace.definedNames2.values.toSet();
    importElementsMap[importElement] = elements;
  }
  // use import namespace to choose correct one
  for (var entry in importElementsMap.entries) {
    var importElement = entry.key;
    var elements = entry.value;
    if (elements.contains(element)) {
      return MockLibraryImportElement(importElement);
    }
  }
  // not found
  return null;
}

class MatchInfo {
  final int offset;
  final int length;
  final MatchKind matchKind;

  MatchInfo(this.offset, this.length, this.matchKind);
}

/// Instances of the enum [MatchKind] represent the kind of reference that was
/// found when a match represents a reference to an element.
class MatchKind {
  /// A declaration of an element.
  static const MatchKind DECLARATION = MatchKind('DECLARATION');

  /// A reference to an element in which it is being read.
  static const MatchKind READ = MatchKind('READ');

  /// A reference to an element in which it is being both read and written.
  static const MatchKind READ_WRITE = MatchKind('READ_WRITE');

  /// A reference to an element in which it is being written.
  static const MatchKind WRITE = MatchKind('WRITE');

  /// A reference to an element in which it is being invoked.
  static const MatchKind INVOCATION = MatchKind('INVOCATION');

  /// An invocation of an enum constructor from an enum constant without
  /// arguments.
  static const MatchKind INVOCATION_BY_ENUM_CONSTANT_WITHOUT_ARGUMENTS =
      MatchKind('INVOCATION_BY_ENUM_CONSTANT_WITHOUT_ARGUMENTS');

  /// A reference to an element in which it is referenced.
  static const MatchKind REFERENCE = MatchKind('REFERENCE');

  /// A tear-off reference to a constructor.
  static const MatchKind REFERENCE_BY_CONSTRUCTOR_TEAR_OFF = MatchKind(
    'REFERENCE_BY_CONSTRUCTOR_TEAR_OFF',
  );

  final String name;

  const MatchKind(this.name);

  @override
  String toString() => name;
}

class ReferencesCollector extends RecursiveAstVisitor2<void> {
  final Element element;
  final List<MatchInfo> references = [];

  ReferencesCollector(this.element);

  @override
  void visitCascadeMethodInvocation(CascadeMethodInvocation node) {
    _visitNamedFunctionInvocation(node);
  }

  @override
  visitCommentReference(CommentReference node) {
    var components = node.components;
    if (components.length == 2 && node.element is ConstructorElement) {
      var offset = components.first.name.end;
      references.add(
        MatchInfo(
          offset,
          components.last.name.end - offset,
          MatchKind.REFERENCE,
        ),
      );
    }
  }

  @override
  void visitCompoundAssignment(CompoundAssignment node) {
    var target = node.target;
    // Import-prefixed targets are recorded by their own visitor.
    if (target is NamedAssignmentTarget &&
        target is! ImportPrefixedAssignmentTarget) {
      _recordNamedReadWriteTarget(target);
    }
    super.visitCompoundAssignment(node);
  }

  @override
  visitConstructorDeclaration(covariant ConstructorDeclarationImpl node) {
    var constructorElement = node.declaredFragment?.element;
    if (node.typeName2 case var typeName?) {
      if (constructorElement?.enclosingElement == element &&
          typeName.lexeme == element.name) {
        references.add(
          MatchInfo(typeName.offset, typeName.length, MatchKind.REFERENCE),
        );
      }
    }

    if (constructorElement == element) {
      if (node.name case var name?) {
        var offset = node.period?.offset ?? name.offset;
        var length = name.end - offset;
        references.add(MatchInfo(offset, length, MatchKind.DECLARATION));
      } else {
        var end = (node.typeName2 ?? node.newKeyword)!.end;
        references.add(MatchInfo(end, 0, MatchKind.DECLARATION));
      }
    }
    super.visitConstructorDeclaration(node);
  }

  @override
  void visitConstructorInvocation(ConstructorInvocation node) {
    node.constructorReference.accept2(this);
    node.argumentList.accept2(this);
  }

  @override
  void visitConstructorReference2(ConstructorReference2 node) {
    var e = node.element?.baseElement;
    e = _getActualConstructorElement(e);
    if (e == element) {
      if (node.selector case var selector?) {
        var offset = selector.period.offset;
        var length = selector.name2.end - offset;
        references.add(
          MatchInfo(offset, length, _constructorReferenceKind(node)),
        );
      } else {
        references.add(
          MatchInfo(node.typeReference.end, 0, _constructorReferenceKind(node)),
        );
      }
    } else if (e != null && e.enclosingElement == element) {
      var name = node.typeReference.name;
      references.add(MatchInfo(name.offset, name.length, MatchKind.REFERENCE));
    }
    node.typeReference.typeArguments?.accept2(this);
  }

  @override
  void visitConstructorTearOff(ConstructorTearOff node) {
    var e = node.element?.baseElement;
    e = _getActualConstructorElement(e);
    if (e == element) {
      references.add(
        MatchInfo(
          node.selector.period.offset,
          node.selector.end - node.selector.period.offset,
          MatchKind.REFERENCE_BY_CONSTRUCTOR_TEAR_OFF,
        ),
      );
    }
    node.visitChildren2(this);
  }

  @override
  void visitConstructorTypeReference(ConstructorTypeReference node) {
    if (node.element == element) {
      references.add(
        MatchInfo(node.name.offset, node.name.length, MatchKind.REFERENCE),
      );
    }

    node.typeArguments?.accept2(this);
  }

  @override
  void visitDirectAssignment(DirectAssignment node) {
    var target = node.target;
    // Import-prefixed targets are recorded by their own visitor.
    if (target is ImportPrefixedAssignmentTarget) {
      super.visitDirectAssignment(node);
      return;
    }
    switch (target.write) {
      case WriteResolution(element: PropertyAccessorElement writeElement):
        if (_matches(writeElement)) {
          var entity = switch (target) {
            PropertyAssignmentTarget() => target.name,
            _ => target,
          };
          references.add(
            MatchInfo(entity.offset, entity.length, MatchKind.WRITE),
          );
        }
      case InvalidNamedWriteResolution(:var recoveryElement):
        if (_matches(recoveryElement)) {
          references.add(
            MatchInfo(target.offset, target.length, MatchKind.REFERENCE),
          );
        }
      default:
    }
    super.visitDirectAssignment(node);
  }

  @override
  void visitEnumConstantDeclaration(EnumConstantDeclaration node) {
    var constructorElement = node.constructorElement;
    if (constructorElement != null && constructorElement == element) {
      int offset;
      int length;
      var constructorSelector = node.arguments?.constructorSelector;
      if (constructorSelector != null) {
        offset = constructorSelector.period.offset;
        length = constructorSelector.name2.end - offset;
      } else {
        offset = node.name.end;
        length = 0;
      }
      var kind = node.arguments == null
          ? MatchKind.INVOCATION_BY_ENUM_CONSTANT_WITHOUT_ARGUMENTS
          : MatchKind.INVOCATION;
      references.add(MatchInfo(offset, length, kind));
    }
  }

  @override
  void visitIfNullAssignment(IfNullAssignment node) {
    var target = node.target;
    if (target is NamedAssignmentTarget &&
        target is! ImportPrefixedAssignmentTarget) {
      _recordNamedReadWriteTarget(target);
    }
    super.visitIfNullAssignment(node);
  }

  @override
  void visitImportPrefixedAssignmentTarget(
    ImportPrefixedAssignmentTarget node,
  ) {
    var readMatches = _matches(node.read?.element);
    var writeMatches = _matches(node.write?.element);
    var kind = switch ((readMatches, writeMatches)) {
      (true, true) => MatchKind.READ_WRITE,
      (true, false) => MatchKind.READ,
      (false, true) => MatchKind.WRITE,
      (false, false) => null,
    };
    if (node.write case InvalidNamedWriteResolution(
      :var recoveryElement,
    ) when kind == null && _matches(recoveryElement)) {
      kind = MatchKind.REFERENCE;
    }
    if (kind != null) {
      references.add(MatchInfo(node.name.offset, node.name.length, kind));
    }
    node.importPrefix.accept2(this);
  }

  @override
  void visitImportPrefixedFunctionInvocation(
    ImportPrefixedFunctionInvocation node,
  ) {
    _visitNamedFunctionInvocation(node);
  }

  @override
  void visitImportPrefixedNameExpression(ImportPrefixedNameExpression node) {
    _recordNamedRead(node.name, node.resolution);
    super.visitImportPrefixedNameExpression(node);
  }

  @override
  void visitNamedType(NamedType node) {
    if (node.element == element) {
      references.add(
        MatchInfo(node.name.offset, node.name.length, MatchKind.REFERENCE),
      );
    }

    node.importPrefix?.accept2(this);
    node.typeArguments?.accept2(this);
  }

  @override
  visitPrimaryConstructorDeclaration(
    covariant PrimaryConstructorDeclarationImpl node,
  ) {
    if (node.declaredFragment?.element == element) {
      if (node.constructorName case var constructorName?) {
        var offset = constructorName.period.offset;
        var length = constructorName.name.end - offset;
        references.add(MatchInfo(offset, length, MatchKind.DECLARATION));
      } else {
        var end = node.typeName.end;
        references.add(MatchInfo(end, 0, MatchKind.DECLARATION));
      }
    }
    super.visitPrimaryConstructorDeclaration(node);
  }

  @override
  void visitReceiverMethodInvocation(ReceiverMethodInvocation node) {
    _visitNamedFunctionInvocation(node);
  }

  @override
  void visitReceiverPropertyExtraction(ReceiverPropertyExtraction node) {
    _recordNamedRead(node.name, node.resolution);
    super.visitReceiverPropertyExtraction(node);
  }

  @override
  void visitRedirectingConstructorInvocation(
    RedirectingConstructorInvocation node,
  ) {
    var e = node.element;
    if (e == element) {
      if (node.constructorSelector case var selector?) {
        int offset = selector.period.offset;
        int length = selector.name2.end - offset;
        references.add(MatchInfo(offset, length, MatchKind.INVOCATION));
      } else {
        int offset = node.thisKeyword.end;
        references.add(MatchInfo(offset, 0, MatchKind.INVOCATION));
      }
    }
  }

  @override
  void visitStaticQualifier(StaticQualifier node) {
    if (node.element == element) {
      references.add(
        MatchInfo(node.name.offset, node.name.length, MatchKind.REFERENCE),
      );
    }
    node.importPrefix?.accept2(this);
  }

  @override
  void visitSuperConstructorInvocation(SuperConstructorInvocation node) {
    var e = node.element;
    if (e == element) {
      if (node.constructorSelector case var selector?) {
        int offset = selector.period.offset;
        int length = selector.name2.end - offset;
        references.add(MatchInfo(offset, length, MatchKind.INVOCATION));
      } else {
        int offset = node.superKeyword.end;
        references.add(MatchInfo(offset, 0, MatchKind.INVOCATION));
      }
    }
  }

  @override
  void visitUnqualifiedFunctionInvocation(UnqualifiedFunctionInvocation node) {
    _visitNamedFunctionInvocation(node);
  }

  @override
  void visitUnqualifiedNameExpression(UnqualifiedNameExpression node) {
    _recordNamedRead(node.name, node.resolution);
  }

  MatchKind _constructorReferenceKind(ConstructorReference2 node) {
    return switch (node.parent2) {
      ConstructorInvocation() => MatchKind.INVOCATION,
      ConstructorDeclaration() => MatchKind.REFERENCE,
      _ => throw StateError(
        'Unexpected ConstructorReference2 parent: ${node.parent2.runtimeType}',
      ),
    };
  }

  bool _matches(Element? candidate) =>
      candidate == element ||
      candidate is PropertyAccessorElement && candidate.variable == element;

  void _recordNamedRead(
    SyntacticEntity entity,
    NamedReadResolution? resolution,
  ) {
    if (resolution case InvalidNamedReadResolution(:var recoveryElement)) {
      if (_matches(recoveryElement)) {
        references.add(
          MatchInfo(entity.offset, entity.length, MatchKind.REFERENCE),
        );
      }
      return;
    }

    var readElement = resolution?.element;
    if (readElement == element) {
      references.add(
        MatchInfo(entity.offset, entity.length, MatchKind.REFERENCE),
      );
    } else if (readElement is GetterElement &&
        readElement.variable == element) {
      references.add(MatchInfo(entity.offset, entity.length, MatchKind.READ));
    }
  }

  void _recordNamedReadWriteTarget(NamedAssignmentTarget target) {
    var readMatches = _matches(target.read?.element);
    var writeMatches = _matches(target.write?.element);
    var kind = switch ((readMatches, writeMatches)) {
      (true, true) => MatchKind.READ_WRITE,
      (true, false) => MatchKind.READ,
      (false, true) => MatchKind.WRITE,
      (false, false) => null,
    };
    if (kind != null) {
      references.add(MatchInfo(target.name.offset, target.name.length, kind));
    }
  }

  void _visitNamedFunctionInvocation(NamedFunctionInvocation node) {
    var invokedElement = ElementLocatorV2.locate(node)?.baseElement;
    if (invokedElement == element) {
      references.add(
        MatchInfo(node.name.offset, node.name.length, MatchKind.REFERENCE),
      );
    }
    node.visitChildren2(this);
  }
}