pkg/front_end/lib/src/fasta/source/source_procedure_builder.dart

// Copyright (c) 2019, 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:kernel/ast.dart';
import 'package:kernel/type_algebra.dart';
import 'package:kernel/type_environment.dart';

import '../builder/builder.dart';
import '../builder/extension_builder.dart';
import '../builder/formal_parameter_builder.dart';
import '../builder/member_builder.dart';
import '../builder/metadata_builder.dart';
import '../builder/procedure_builder.dart';
import '../builder/type_builder.dart';
import '../builder/type_variable_builder.dart';
import '../kernel/hierarchy/class_member.dart';
import '../kernel/hierarchy/members_builder.dart';
import '../kernel/kernel_helper.dart';
import '../kernel/member_covariance.dart';
import '../source/name_scheme.dart';
import '../source/source_library_builder.dart' show SourceLibraryBuilder;
import '../source/source_loader.dart' show SourceLoader;
import 'source_class_builder.dart';
import 'source_function_builder.dart';
import 'source_member_builder.dart';

class SourceProcedureBuilder extends SourceFunctionBuilderImpl
    implements ProcedureBuilder {
  final int charOpenParenOffset;

  AsyncMarker actualAsyncModifier = AsyncMarker.Sync;

  @override
  final bool isExtensionInstanceMember;

  @override
  final TypeBuilder returnType;

  late Procedure _procedure;

  final Reference? _tearOffReference;

  /// If this is an extension instance method then [_extensionTearOff] holds
  /// the synthetically created tear off function.
  Procedure? _extensionTearOff;

  /// If this is an extension instance method then
  /// [_extensionTearOffParameterMap] holds a map from the parameters of
  /// the methods to the parameter of the closure returned in the tear-off.
  ///
  /// This map is used to set the default values on the closure parameters when
  /// these have been built.
  Map<VariableDeclaration, VariableDeclaration>? _extensionTearOffParameterMap;

  @override
  final ProcedureKind kind;

  SourceProcedureBuilder? actualOrigin;

  List<SourceProcedureBuilder>? _patches;

  SourceProcedureBuilder(
      List<MetadataBuilder>? metadata,
      int modifiers,
      this.returnType,
      String name,
      List<TypeVariableBuilder>? typeVariables,
      List<FormalParameterBuilder>? formals,
      this.kind,
      SourceLibraryBuilder libraryBuilder,
      int startCharOffset,
      int charOffset,
      this.charOpenParenOffset,
      int charEndOffset,
      Reference? procedureReference,
      this._tearOffReference,
      AsyncMarker asyncModifier,
      NameScheme nameScheme,
      {required bool isExtensionMember,
      required bool isInstanceMember,
      String? nativeMethodName,
      bool isSynthetic: false})
      // ignore: unnecessary_null_comparison
      : assert(isExtensionMember != null),
        // ignore: unnecessary_null_comparison
        assert(isInstanceMember != null),
        assert(kind != ProcedureKind.Factory),
        this.isExtensionInstanceMember = isInstanceMember && isExtensionMember,
        super(metadata, modifiers, name, typeVariables, formals, libraryBuilder,
            charOffset, nativeMethodName) {
    _procedure = new Procedure(
        nameScheme.getProcedureName(kind, name),
        isExtensionInstanceMember ? ProcedureKind.Method : kind,
        new FunctionNode(null),
        fileUri: libraryBuilder.fileUri,
        reference: procedureReference,
        isSynthetic: isSynthetic)
      ..startFileOffset = startCharOffset
      ..fileOffset = charOffset
      ..fileEndOffset = charEndOffset
      ..isNonNullableByDefault = libraryBuilder.isNonNullableByDefault;
    this.asyncModifier = asyncModifier;
    if (isExtensionMember && isInstanceMember && kind == ProcedureKind.Method) {
      _extensionTearOff ??= new Procedure(
          nameScheme.getProcedureName(ProcedureKind.Getter, name),
          ProcedureKind.Method,
          new FunctionNode(null),
          isStatic: true,
          isExtensionMember: true,
          reference: _tearOffReference,
          fileUri: fileUri)
        ..isNonNullableByDefault = libraryBuilder.isNonNullableByDefault;
    }
  }

  List<SourceProcedureBuilder>? get patchesForTesting => _patches;

  @override
  AsyncMarker get asyncModifier => actualAsyncModifier;

  @override
  Statement? get body {
    if (bodyInternal == null && !isAbstract && !isExternal) {
      bodyInternal = new EmptyStatement();
    }
    return bodyInternal;
  }

  void set asyncModifier(AsyncMarker newModifier) {
    actualAsyncModifier = newModifier;
    function.asyncMarker = actualAsyncModifier;
    function.dartAsyncMarker = actualAsyncModifier;
  }

  bool get isExtensionMethod {
    return parent is ExtensionBuilder;
  }

  @override
  Member get member => procedure;

  @override
  SourceProcedureBuilder get origin => actualOrigin ?? this;

  @override
  Procedure get procedure => isPatch ? origin.procedure : _procedure;

  Procedure get actualProcedure => _procedure;

  @override
  FunctionNode get function => _procedure.function;

  bool _typeEnsured = false;
  Set<ClassMember>? _overrideDependencies;

  void registerOverrideDependency(Set<ClassMember> overriddenMembers) {
    assert(
        overriddenMembers.every((overriddenMember) =>
            overriddenMember.classBuilder != classBuilder),
        "Unexpected override dependencies for $this: $overriddenMembers");
    _overrideDependencies ??= {};
    _overrideDependencies!.addAll(overriddenMembers);
  }

  void _ensureTypes(ClassMembersBuilder membersBuilder) {
    if (_typeEnsured) return;
    if (_overrideDependencies != null) {
      if (isGetter) {
        membersBuilder.inferGetterType(this, _overrideDependencies!);
      } else if (isSetter) {
        membersBuilder.inferSetterType(this, _overrideDependencies!);
      } else {
        membersBuilder.inferMethodType(this, _overrideDependencies!);
      }
      _overrideDependencies = null;
    }
    returnType.build(libraryBuilder, TypeUse.fieldType,
        hierarchy: membersBuilder.hierarchyBuilder);
    if (formals != null) {
      for (FormalParameterBuilder formal in formals!) {
        formal.type.build(libraryBuilder, TypeUse.parameterType,
            hierarchy: membersBuilder.hierarchyBuilder);
      }
    }
    _typeEnsured = true;
  }

  @override
  Member? get readTarget {
    switch (kind) {
      case ProcedureKind.Method:
        return extensionTearOff ?? procedure;
      case ProcedureKind.Getter:
        return procedure;
      case ProcedureKind.Factory:
        return procedure;
      case ProcedureKind.Operator:
      case ProcedureKind.Setter:
        return null;
    }
  }

  @override
  Member? get writeTarget {
    switch (kind) {
      case ProcedureKind.Setter:
        return procedure;
      case ProcedureKind.Method:
      case ProcedureKind.Getter:
      case ProcedureKind.Operator:
      case ProcedureKind.Factory:
        return null;
    }
  }

  @override
  Member? get invokeTarget {
    switch (kind) {
      case ProcedureKind.Method:
      case ProcedureKind.Getter:
      case ProcedureKind.Operator:
      case ProcedureKind.Factory:
        return procedure;
      case ProcedureKind.Setter:
        return null;
    }
  }

  @override
  Iterable<Member> get exportedMembers => [procedure];

  @override
  void buildMembers(void Function(Member, BuiltMemberKind) f) {
    _build();
    if (isExtensionMethod) {
      switch (kind) {
        case ProcedureKind.Method:
          f(_procedure, BuiltMemberKind.ExtensionMethod);
          break;
        case ProcedureKind.Getter:
          f(_procedure, BuiltMemberKind.ExtensionGetter);
          break;
        case ProcedureKind.Setter:
          f(_procedure, BuiltMemberKind.ExtensionSetter);
          break;
        case ProcedureKind.Operator:
          f(_procedure, BuiltMemberKind.ExtensionOperator);
          break;
        case ProcedureKind.Factory:
          throw new UnsupportedError(
              'Unexpected extension method kind ${kind}');
      }
      if (extensionTearOff != null) {
        f(extensionTearOff!, BuiltMemberKind.ExtensionTearOff);
      }
    } else {
      f(member, BuiltMemberKind.Method);
    }
  }

  void _build() {
    buildFunction();
    _procedure.function.fileOffset = charOpenParenOffset;
    _procedure.function.fileEndOffset = _procedure.fileEndOffset;
    _procedure.isAbstract = isAbstract;
    _procedure.isExternal = isExternal;
    _procedure.isConst = isConst;
    updatePrivateMemberName(_procedure, libraryBuilder);
    if (isExtensionMethod) {
      _procedure.isExtensionMember = true;
      _procedure.isStatic = true;
      if (isExtensionInstanceMember) {
        assert(_procedure.kind == ProcedureKind.Method);
      }
    } else {
      _procedure.isStatic = isStatic;
    }
    if (extensionTearOff != null) {
      _buildExtensionTearOff(libraryBuilder, parent as ExtensionBuilder);
      updatePrivateMemberName(extensionTearOff!, libraryBuilder);
    }
  }

  /// Creates a top level function that creates a tear off of an extension
  /// instance method.
  ///
  /// For this declaration
  ///
  ///     extension E<T> on A<T> {
  ///       X method<S>(S s, Y y) {}
  ///     }
  ///
  /// we create the top level function
  ///
  ///     X E|method<T, S>(A<T> #this, S s, Y y) {}
  ///
  /// and the tear off function
  ///
  ///     X Function<S>(S, Y) E|get#method<T>(A<T> #this) {
  ///       return (S s, Y y) => E|method<T, S>(#this, s, y);
  ///     }
  ///
  void _buildExtensionTearOff(SourceLibraryBuilder sourceLibraryBuilder,
      ExtensionBuilder extensionBuilder) {
    assert(
        _extensionTearOff != null, "No extension tear off created for $this.");

    _extensionTearOffParameterMap = {};

    int fileOffset = _procedure.fileOffset;
    int fileEndOffset = _procedure.fileEndOffset;

    int extensionTypeParameterCount =
        extensionBuilder.typeParameters?.length ?? 0;

    List<TypeParameter> typeParameters = <TypeParameter>[];

    Map<TypeParameter, DartType> substitutionMap = {};
    List<DartType> typeArguments = <DartType>[];
    for (TypeParameter typeParameter in function.typeParameters) {
      TypeParameter newTypeParameter = new TypeParameter(typeParameter.name);
      typeParameters.add(newTypeParameter);
      typeArguments.add(substitutionMap[typeParameter] =
          new TypeParameterType.forAlphaRenaming(
              typeParameter, newTypeParameter));
    }

    List<TypeParameter> tearOffTypeParameters = <TypeParameter>[];
    List<TypeParameter> closureTypeParameters = <TypeParameter>[];
    Substitution substitution = Substitution.fromMap(substitutionMap);
    for (int index = 0; index < typeParameters.length; index++) {
      TypeParameter newTypeParameter = typeParameters[index];
      newTypeParameter.bound =
          substitution.substituteType(function.typeParameters[index].bound);
      newTypeParameter.defaultType = function.typeParameters[index].defaultType;
      if (index < extensionTypeParameterCount) {
        tearOffTypeParameters.add(newTypeParameter);
      } else {
        closureTypeParameters.add(newTypeParameter);
      }
    }

    VariableDeclaration copyParameter(
        VariableDeclaration parameter, DartType type,
        {required bool isOptional}) {
      VariableDeclaration newParameter = new VariableDeclaration(parameter.name,
          type: type,
          isFinal: parameter.isFinal,
          isLowered: parameter.isLowered)
        ..fileOffset = parameter.fileOffset;
      _extensionTearOffParameterMap![parameter] = newParameter;
      return newParameter;
    }

    VariableDeclaration extensionThis = copyParameter(
        function.positionalParameters.first,
        substitution.substituteType(function.positionalParameters.first.type),
        isOptional: false);

    DartType closureReturnType =
        substitution.substituteType(function.returnType);
    List<VariableDeclaration> closurePositionalParameters = [];
    List<Expression> closurePositionalArguments = [];

    for (int position = 0;
        position < function.positionalParameters.length;
        position++) {
      VariableDeclaration parameter = function.positionalParameters[position];
      if (position == 0) {
        /// Pass `this` as a captured variable.
        closurePositionalArguments
            .add(new VariableGet(extensionThis)..fileOffset = fileOffset);
      } else {
        DartType type = substitution.substituteType(parameter.type);
        VariableDeclaration newParameter = copyParameter(parameter, type,
            isOptional: position >= function.requiredParameterCount);
        closurePositionalParameters.add(newParameter);
        closurePositionalArguments
            .add(new VariableGet(newParameter)..fileOffset = fileOffset);
      }
    }
    List<VariableDeclaration> closureNamedParameters = [];
    List<NamedExpression> closureNamedArguments = [];
    for (VariableDeclaration parameter in function.namedParameters) {
      DartType type = substitution.substituteType(parameter.type);
      VariableDeclaration newParameter =
          copyParameter(parameter, type, isOptional: true);
      closureNamedParameters.add(newParameter);
      closureNamedArguments.add(new NamedExpression(parameter.name!,
          new VariableGet(newParameter)..fileOffset = fileOffset));
    }

    Statement closureBody = new ReturnStatement(
        new StaticInvocation(
            _procedure,
            new Arguments(closurePositionalArguments,
                types: typeArguments, named: closureNamedArguments))
          ..fileOffset = fileOffset)
      ..fileOffset = fileOffset;

    FunctionExpression closure = new FunctionExpression(
        new FunctionNode(closureBody,
            typeParameters: closureTypeParameters,
            positionalParameters: closurePositionalParameters,
            namedParameters: closureNamedParameters,
            requiredParameterCount:
                _procedure.function.requiredParameterCount - 1,
            returnType: closureReturnType)
          ..fileOffset = fileOffset
          ..fileEndOffset = fileEndOffset)
      ..fileOffset = fileOffset;

    _extensionTearOff!
      ..function = (new FunctionNode(
          new ReturnStatement(closure)..fileOffset = fileOffset,
          typeParameters: tearOffTypeParameters,
          positionalParameters: [extensionThis],
          requiredParameterCount: 1,
          returnType:
              closure.function.computeFunctionType(libraryBuilder.nonNullable))
        ..fileOffset = fileOffset
        ..fileEndOffset = fileEndOffset)
      ..fileUri = fileUri
      ..fileOffset = fileOffset
      ..fileEndOffset = fileEndOffset;
    _extensionTearOff!.function.parent = _extensionTearOff;
  }

  Procedure? get extensionTearOff => _extensionTearOff;

  @override
  VariableDeclaration? getTearOffParameter(int index) {
    return _extensionTearOffParameterMap?[getFormalParameter(index)];
  }

  List<ClassMember>? _localMembers;
  List<ClassMember>? _localSetters;

  @override
  List<ClassMember> get localMembers => _localMembers ??= isSetter
      ? const <ClassMember>[]
      : <ClassMember>[new SourceProcedureMember(this)];

  @override
  List<ClassMember> get localSetters =>
      _localSetters ??= isSetter && !isConflictingSetter
          ? <ClassMember>[new SourceProcedureMember(this)]
          : const <ClassMember>[];

  @override
  void becomeNative(SourceLoader loader) {
    _procedure.isExternal = true;
    super.becomeNative(loader);
  }

  @override
  void applyPatch(Builder patch) {
    if (patch is SourceProcedureBuilder) {
      if (checkPatch(patch)) {
        patch.actualOrigin = this;
        (_patches ??= []).add(patch);
      }
    } else {
      reportPatchMismatch(patch);
    }
  }

  @override
  int finishPatch() {
    if (!isPatch) return 0;

    finishProcedurePatch(origin.procedure, _procedure);
    return 1;
  }

  @override
  void checkVariance(
      SourceClassBuilder sourceClassBuilder, TypeEnvironment typeEnvironment) {
    sourceClassBuilder.checkVarianceInFunction(
        procedure, typeEnvironment, sourceClassBuilder.cls.typeParameters);
    List<SourceProcedureBuilder>? patches = _patches;
    if (patches != null) {
      for (SourceProcedureBuilder patch in patches) {
        patch.checkVariance(sourceClassBuilder, typeEnvironment);
      }
    }
  }

  @override
  void checkTypes(
      SourceLibraryBuilder library, TypeEnvironment typeEnvironment) {
    library.checkTypesInFunctionBuilder(this, typeEnvironment);
    List<SourceProcedureBuilder>? patches = _patches;
    if (patches != null) {
      for (SourceProcedureBuilder patch in patches) {
        patch.checkTypes(library, typeEnvironment);
      }
    }
  }
}

class SourceProcedureMember extends BuilderClassMember {
  @override
  final SourceProcedureBuilder memberBuilder;

  Covariance? _covariance;

  SourceProcedureMember(this.memberBuilder);

  @override
  bool get isSourceDeclaration => true;

  @override
  void inferType(ClassMembersBuilder membersBuilder) {
    memberBuilder._ensureTypes(membersBuilder);
  }

  @override
  void registerOverrideDependency(Set<ClassMember> overriddenMembers) {
    memberBuilder.registerOverrideDependency(overriddenMembers);
  }

  @override
  Member getMember(ClassMembersBuilder membersBuilder) {
    memberBuilder._ensureTypes(membersBuilder);
    return memberBuilder.member;
  }

  @override
  Covariance getCovariance(ClassMembersBuilder membersBuilder) {
    return _covariance ??= new Covariance.fromMember(getMember(membersBuilder),
        forSetter: forSetter);
  }

  @override
  bool get forSetter => isSetter;

  @override
  bool get isProperty =>
      memberBuilder.kind == ProcedureKind.Getter ||
      memberBuilder.kind == ProcedureKind.Setter;

  @override
  bool isSameDeclaration(ClassMember other) {
    return other is SourceProcedureMember &&
        memberBuilder == other.memberBuilder;
  }
}