pkg/analyzer/test/src/summary/macro/declaration_text.dart

// Copyright (c) 2022, 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 'dart:async';

import 'package:_fe_analyzer_shared/src/macros/api.dart';

/*macro*/ class DeclarationTextMacro implements ClassTypesMacro {
  const DeclarationTextMacro();

  @override
  FutureOr<void> buildTypesForClass(declaration, builder) {
    final printer = _DeclarationPrinter();
    printer.writeClassDeclaration(declaration);
    final text = printer._sink.toString();

    builder.declareType(
      'x',
      DeclarationCode.fromString(
        'const x = r"""$text""";',
      ),
    );
  }
}

class _DeclarationPrinter {
  final StringBuffer _sink = StringBuffer();
  String _indent = '';

  void writeClassDeclaration(ClassDeclaration e) {
    _writeIf(e.isAbstract, 'abstract ');
    _writeIf(e.isExternal, 'external ');

    _writeln('class ${e.identifier.name}');

    _withIndent(() {
      var superclass = e.superclass;
      if (superclass != null) {
        _writeTypeAnnotation('superclass', superclass);
      }

      _writeTypeParameters(e.typeParameters);
      _writeTypeAnnotations('mixins', e.mixins);
      _writeTypeAnnotations('interfaces', e.interfaces);
    });
  }

  void _withIndent(void Function() f) {
    var savedIndent = _indent;
    _indent = '$savedIndent  ';
    f();
    _indent = savedIndent;
  }

  void _writeElements<T>(
    String name,
    Iterable<T> elements,
    void Function(T) f,
  ) {
    if (elements.isNotEmpty) {
      _writelnWithIndent(name);
      _withIndent(() {
        for (var element in elements) {
          f(element);
        }
      });
    }
  }

  void _writeIf(bool flag, String str) {
    if (flag) {
      _sink.write(str);
    }
  }

  void _writeln(String line) {
    _sink.writeln(line);
  }

  void _writelnWithIndent(String line) {
    _sink.write(_indent);
    _sink.writeln(line);
  }

  void _writeTypeAnnotation(String name, TypeAnnotation? type) {
    _sink.write(_indent);
    _sink.write('$name: ');

    if (type != null) {
      _writeln(_typeStr(type));
    } else {
      _writeln('null');
    }
  }

  void _writeTypeAnnotationLine(TypeAnnotation type) {
    var typeStr = _typeStr(type);
    _writelnWithIndent(typeStr);
  }

  void _writeTypeAnnotations(String name, Iterable<TypeAnnotation> elements) {
    _writeElements(name, elements, _writeTypeAnnotationLine);
  }

  void _writeTypeParameter(TypeParameterDeclaration e) {
    _writelnWithIndent(e.identifier.name);

    _withIndent(() {
      var bound = e.bound;
      if (bound != null) {
        _writeTypeAnnotation('bound', bound);
      }
    });
  }

  void _writeTypeParameters(Iterable<TypeParameterDeclaration> elements) {
    _writeElements('typeParameters', elements, _writeTypeParameter);
  }

  static String _typeStr(TypeAnnotation type) {
    final buffer = StringBuffer();
    _TypeStringBuilder(buffer).write(type);
    return buffer.toString();
  }
}

class _TypeStringBuilder {
  final StringSink _sink;

  _TypeStringBuilder(this._sink);

  void write(TypeAnnotation type) {
    if (type is FunctionTypeAnnotation) {
      _writeFunctionTypeAnnotation(type);
    } else if (type is NamedTypeAnnotation) {
      _writeNamedTypeAnnotation(type);
    } else if (type is OmittedTypeAnnotation) {
      _sink.write('OmittedType');
    } else {
      throw UnimplementedError('(${type.runtimeType}) $type');
    }
    if (type.isNullable) {
      _sink.write('?');
    }
  }

  void _writeFormalParameter(ParameterDeclaration node) {
    final String closeSeparator;
    if (node.isNamed) {
      _sink.write('{');
      closeSeparator = '}';
      if (node.isRequired) {
        _sink.write('required ');
      }
    } else if (!node.isRequired) {
      _sink.write('[');
      closeSeparator = ']';
    } else {
      closeSeparator = '';
    }

    write(node.type);
    _sink.write(' ');
    _sink.write(node.identifier.name);

    _sink.write(closeSeparator);
  }

  void _writeFunctionTypeAnnotation(FunctionTypeAnnotation type) {
    write(type.returnType);
    _sink.write(' Function');

    _sink.writeList(
      elements: type.typeParameters,
      write: _writeTypeParameter,
      separator: ', ',
      open: '<',
      close: '>',
    );

    _sink.write('(');
    var hasFormalParameter = false;
    for (final formalParameter in type.positionalParameters) {
      if (hasFormalParameter) {
        _sink.write(', ');
      }
      _writeFormalParameter(formalParameter);
      hasFormalParameter = true;
    }
    for (final formalParameter in type.namedParameters) {
      if (hasFormalParameter) {
        _sink.write(', ');
      }
      _writeFormalParameter(formalParameter);
      hasFormalParameter = true;
    }
    _sink.write(')');
  }

  void _writeNamedTypeAnnotation(NamedTypeAnnotation type) {
    _sink.write(type.identifier.name);
    _sink.writeList(
      elements: type.typeArguments,
      write: write,
      separator: ', ',
      open: '<',
      close: '>',
    );
  }

  void _writeTypeParameter(TypeParameterDeclaration node) {
    _sink.write(node.identifier.name);

    final bound = node.bound;
    if (bound != null) {
      _sink.write(' extends ');
      write(bound);
    }
  }
}

extension on StringSink {
  void writeList<T>({
    required Iterable<T> elements,
    required void Function(T element) write,
    required String separator,
    String? open,
    String? close,
  }) {
    elements = elements.toList();
    if (elements.isEmpty) {
      return;
    }

    if (open != null) {
      this.write(open);
    }
    var isFirst = true;
    for (var element in elements) {
      if (isFirst) {
        isFirst = false;
      } else {
        this.write(separator);
      }
      write(element);
    }
    if (close != null) {
      this.write(close);
    }
  }
}