pkg/compiler/lib/src/kernel/transformations/lowering.dart

// Copyright (c) 2020, 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.

// @dart=2.12

import 'package:kernel/ast.dart';
import 'package:kernel/class_hierarchy.dart' show ClassHierarchy;
import 'package:kernel/core_types.dart' show CoreTypes;

import '../../options.dart';
import 'factory_specializer.dart';
import 'late_lowering.dart';

/// dart2js-specific lowering transformations and optimizations combined into a
/// single transformation pass.
///
/// Each transformation is applied locally to AST nodes of certain types after
/// transforming children nodes.
void transformLibraries(List<Library> libraries, CoreTypes coreTypes,
    ClassHierarchy hierarchy, CompilerOptions? options) {
  final transformer = _Lowering(coreTypes, hierarchy, options);
  libraries.forEach(transformer.visitLibrary);

  // Do a second pass to remove/replace now-unused nodes.

  // Since the transformer API doesn't visit `Library.additionalExports`, we
  // have to manually replace references to transformed nodes.
  libraries.forEach(transformer.transformAdditionalExports);
}

class _Lowering extends Transformer {
  final FactorySpecializer factorySpecializer;
  final LateLowering _lateLowering;

  Member? _currentMember;

  _Lowering(
      CoreTypes coreTypes, ClassHierarchy hierarchy, CompilerOptions? _options)
      : factorySpecializer = FactorySpecializer(coreTypes, hierarchy),
        _lateLowering = LateLowering(coreTypes, _options);

  void transformAdditionalExports(Library node) {
    _lateLowering.transformAdditionalExports(node);
  }

  @override
  TreeNode defaultMember(Member node) {
    _currentMember = node;
    return super.defaultMember(node);
  }

  @override
  TreeNode visitStaticInvocation(StaticInvocation node) {
    node.transformChildren(this);
    return factorySpecializer.transformStaticInvocation(node, _currentMember!);
  }

  @override
  TreeNode visitFunctionNode(FunctionNode node) {
    _lateLowering.enterFunction();
    node.transformChildren(this);
    _lateLowering.exitFunction();
    return node;
  }

  @override
  TreeNode visitVariableDeclaration(VariableDeclaration node) {
    node.transformChildren(this);
    return _lateLowering.transformVariableDeclaration(node, _currentMember);
  }

  @override
  TreeNode visitVariableGet(VariableGet node) {
    node.transformChildren(this);
    return _lateLowering.transformVariableGet(node, _currentMember!);
  }

  @override
  TreeNode visitVariableSet(VariableSet node) {
    node.transformChildren(this);
    return _lateLowering.transformVariableSet(node, _currentMember!);
  }

  @override
  TreeNode visitField(Field node) {
    _currentMember = node;
    node.transformChildren(this);
    return _lateLowering.transformField(node, _currentMember!);
  }

  @override
  TreeNode visitFieldInitializer(FieldInitializer node) {
    node.transformChildren(this);
    return _lateLowering.transformFieldInitializer(node, _currentMember!);
  }

  @override
  TreeNode visitStaticGet(StaticGet node) {
    node.transformChildren(this);
    return _lateLowering.transformStaticGet(node, _currentMember!);
  }

  @override
  TreeNode visitStaticSet(StaticSet node) {
    node.transformChildren(this);
    return _lateLowering.transformStaticSet(node, _currentMember!);
  }
}