Scrape script to look at what kinds of parameters are most common

parameter_kinds.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.
import 'package:analyzer/dart/ast/ast.dart';
import 'package:scrape/scrape.dart';

void main(List<String> arguments) {
  Scrape()
    ..addHistogram('Signatures')
    ..addHistogram('Parameters')
    ..addVisitor(() => ParameterVisitor())
    ..runCommandLine(arguments);
}

class ParameterVisitor extends ScrapeVisitor {
  @override
  void visitFunctionDeclaration(FunctionDeclaration node) {
    recordParameters(node.functionExpression.parameters);
    super.visitFunctionDeclaration(node);
  }

  @override
  void visitMethodDeclaration(MethodDeclaration node) {
    recordParameters(node.parameters);
    super.visitMethodDeclaration(node);
  }

  void recordParameters(FormalParameterList? parameters) {
    if (parameters == null) return;

    var signature = <String>[];
    for (var parameter in parameters.parameters) {
      if (parameter.isRequiredPositional) {
        record('Parameters', 'required positional');
        signature.add('P');
      } else if (parameter.isOptionalPositional) {
        record('Parameters', 'optional positional');
        signature.add('O');
      } else if (parameter.isRequiredNamed) {
        record('Parameters', 'required named');
        signature.add('R');
      } else if (parameter.isOptionalNamed) {
        record('Parameters', 'optional named');
        signature.add('N');
      }
    }

    record('Signatures', '(${signature.join(',')})');
  }
}