Scrapes Dart codebases to collect data on sequential numbered parameters and type parameters

parameter_numbers.dart

import 'dart:collection';

import 'package:analyzer/dart/ast/ast.dart';
import 'package:path/path.dart' as p;
import 'package:scrape/scrape.dart';

final _numberSuffix = RegExp(r'^([a-zA-Z_]+)([0-9]+)$');

final Map<String, Pkg> _packages = {};

void main(List<String> arguments) {
  Scrape()
    ..addHistogram('Parameters')
    ..addHistogram('Parameters start')
    ..addHistogram('Type parameters')
    ..addHistogram('Type parameters start')
    ..addHistogram('Numbered names')
    // ..addHistogram('Non-numbered names')
    ..addHistogram('Start')
    ..addHistogram('Package')
    ..addHistogram('By package')
    ..addHistogram('Zero packages')
    ..addHistogram('One packages')
    ..addVisitor(() => OrdinalVisitor())
    ..runCommandLine(arguments);

  var hist = Histogram();
  _packages.forEach((name, pkg) {
    if (pkg.hasZero && pkg.hasOne) {
      hist.add('Both zero-based and one-based');
    } else if (pkg.hasZero) {
      hist.add('Only zero-based');
    } else if (pkg.hasOne) {
      hist.add('Only one-based');
    // } else {
    //   hist.add('No sequences starting at zero or one');
    }
  });
  hist.printCounts('By package/author');
}

class Pkg {
  bool hasZero = false;
  bool hasOne = false;
}

class OrdinalVisitor extends ScrapeVisitor {
  @override
  void visitCompilationUnit(CompilationUnit node) {
    super.visitCompilationUnit(node);
  }

  @override
  void visitFormalParameterList(FormalParameterList node) {
    _checkOrdinals('Parameters',
        node.parameters.map((p) => p.name?.lexeme).whereType<String>());
  }

  @override
  void visitTypeParameterList(TypeParameterList node) {
    _checkOrdinals(
        'Type parameters', node.typeParameters.map((p) => p.name.lexeme));
  }

  void _checkOrdinals(String label, Iterable<String> names) {
    var numbered = <String, SplayTreeSet<int>>{};

    for (var name in names) {
      var match = _numberSuffix.firstMatch(name);
      if (match != null) {
        record('Numbered names', name);
        numbered
            .putIfAbsent(match[1]!, () => SplayTreeSet())
            .add(int.parse(match[2]!));
      } else {
        // record('Non-numbered names', name);
      }
    }

    if (numbered.isNotEmpty) {
      var package = p.split(path).first;
      record('Package', package);

      var pkg = _packages.putIfAbsent(package, () => Pkg());

      for (var prefix in numbered.keys) {
        var numbers = numbered[prefix]!.toList();
        if (numbers.length > 1) {
          record(label, numbers.join(','));

          record('$label start', numbers[0]);
          record('Start', numbers[0]);

          if (numbers[0] == 0) {
            record('Zero packages', package);
            pkg.hasZero = true;
          } else if (numbers[0] == 1) {
            record('One packages', package);
            pkg.hasOne = true;
          }
        }
      }
    } else {
      record(label, 'Not numbered');
    }
  }
}