feat: add check unused code command

CHANGELOG.md

@@ -5,6 +5,7 @@
 * fix: ignore private variables in `avoid-global-state` rule.
 * feat: support excludes for a separate anti-pattern.
 * chore: restrict `analyzer` version to `>=2.4.0 <3.2.0`.
+* feat: add check unused code command.
 * feat: ignore private members for `check-unused-l10n` command.
 
 ## 4.9.1

README.md

@@ -206,6 +206,26 @@ Console report example:
 
 ![Console report example](https://raw.githubusercontent.com/dart-code-checker/dart-code-metrics/master/assets/unused-l10n-console-report.png)
 
+#### Check unused code
+
+Checks unused code in `*.dart` files. To execute the command, run
+
+```sh
+$ dart run dart_code_metrics:metrics check-unused-code lib
+
+# or for a Flutter package
+$ flutter pub run dart_code_metrics:metrics check-unused-code lib
+```
+
+It will produce a result in one of the format:
+
+- Console
+- JSON
+
+Console report example:
+
+![Console report example](https://raw.githubusercontent.com/dart-code-checker/dart-code-metrics/master/assets/unused-code-console-report.png)
+
 ## Troubleshooting
 
 Please read [the following guide](./TROUBLESHOOTING.md) if the plugin is not working as you'd expect it to work.

analysis_options.yaml

@@ -5,6 +5,7 @@ analyzer:
     - test/resources/*
     - test/resources/unused_files_analyzer/**
     - test/resources/unused_l10n_analyzer/**
+    - test/resources/unused_code_analyzer/**
     - test/**/examples/**
   language:
     strict-inference: true

lib/src/analyzers/unused_code_analyzer/models/file_elements_usage.dart

@@ -0,0 +1,23 @@
+import 'package:analyzer/dart/element/element.dart';
+
+/// A container with information about used imports prefixes and used imported
+/// elements.
+class FileElementsUsage {
+  /// The map of referenced prefix elements and the elements that they prefix.
+  final Map<PrefixElement, List<Element>> prefixMap = {};
+
+  /// The set of referenced top-level elements.
+  final Set<Element> elements = {};
+
+  /// The set of extensions defining members that are referenced.
+  final Set<ExtensionElement> usedExtensions = {};
+
+  final Set<String> exports = {};
+
+  void merge(FileElementsUsage other) {
+    prefixMap.addAll(other.prefixMap);
+    elements.addAll(other.elements);
+    usedExtensions.addAll(other.usedExtensions);
+    exports.addAll(other.exports);
+  }
+}

lib/src/analyzers/unused_code_analyzer/models/unused_code_file_report.dart

@@ -0,0 +1,22 @@
+import '../../../reporters/models/file_report.dart';
+import 'unused_code_issue.dart';
+
+/// Represents unused code report collected for a file
+class UnusedCodeFileReport implements FileReport {
+  /// The path to the target file.
+  @override
+  final String path;
+
+  /// The path to the target file relative to the package root.
+  @override
+  final String relativePath;
+
+  /// The issues detected in the target file.
+  final Iterable<UnusedCodeIssue> issues;
+
+  const UnusedCodeFileReport({
+    required this.path,
+    required this.relativePath,
+    required this.issues,
+  });
+}

lib/src/analyzers/unused_code_analyzer/models/unused_code_issue.dart

@@ -0,0 +1,23 @@
+import 'package:source_span/source_span.dart';
+
+/// Represents an issue detected by the unused code check.
+class UnusedCodeIssue {
+  /// The name of the unused declaration.
+  final String declarationName;
+
+  /// The type of the unused declaration.
+  final String declarationType;
+
+  /// The source location associated with this issue.
+  final SourceLocation location;
+
+  /// Initialize a newly created [UnusedCodeIssue].
+  ///
+  /// The issue is associated with the given [location]. Used for
+  /// creating an unused code report.
+  const UnusedCodeIssue({
+    required this.declarationName,
+    required this.declarationType,
+    required this.location,
+  });
+}

lib/src/analyzers/unused_code_analyzer/public_code_visitor.dart

@@ -0,0 +1,39 @@
+// ignore_for_file: public_member_api_docs
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:analyzer/dart/element/element.dart';
+
+import '../../utils/node_utils.dart';
+
+class PublicCodeVisitor extends GeneralizingAstVisitor<void> {
+  final Set<Element> topLevelElements = {};
+
+  @override
+  void visitCompilationUnitMember(CompilationUnitMember node) {
+    if (node is FunctionDeclaration) {
+      if (isEntrypoint(node.name.name, node.metadata)) {
+        return;
+      }
+    }
+
+    _getTopLevelElement(node);
+  }
+
+  @override
+  void visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
+    final variables = node.variables.variables;
+
+    if (variables.isNotEmpty) {
+      _getTopLevelElement(variables.first);
+    }
+  }
+
+  void _getTopLevelElement(Declaration node) {
+    final element = node.declaredElement;
+
+    if (element != null) {
+      topLevelElements.add(element);
+    }
+  }
+}

lib/src/analyzers/unused_code_analyzer/reporters/reporter_factory.dart

@@ -0,0 +1,21 @@
+import 'dart:io';
+
+import '../../../../unused_code_analyzer.dart';
+import '../../../reporters/models/console_reporter.dart';
+import '../../../reporters/models/json_reporter.dart';
+import '../../../reporters/models/reporter.dart';
+
+final _implementedReports = <String,
+    Reporter<UnusedCodeFileReport, void, void> Function(IOSink output)>{
+  ConsoleReporter.id: (output) => UnusedCodeConsoleReporter(output),
+  JsonReporter.id: (output) => UnusedCodeJsonReporter(output),
+};
+
+Reporter<UnusedCodeFileReport, void, void>? reporter({
+  required String name,
+  required IOSink output,
+}) {
+  final constructor = _implementedReports[name];
+
+  return constructor != null ? constructor(output) : null;
+}

lib/src/analyzers/unused_code_analyzer/reporters/reporters_list/console/unused_code_console_reporter.dart

@@ -0,0 +1,57 @@
+import 'dart:io';
+
+import '../../../../../reporters/models/console_reporter.dart';
+import '../../../models/unused_code_file_report.dart';
+
+/// Unused code console reporter.
+///
+/// Use it to create reports in console format.
+class UnusedCodeConsoleReporter
+    extends ConsoleReporter<UnusedCodeFileReport, void, void> {
+  UnusedCodeConsoleReporter(IOSink output) : super(output);
+
+  @override
+  Future<void> report(
+    Iterable<UnusedCodeFileReport> records, {
+    Iterable<void> summary = const [],
+    void additionalParams,
+  }) async {
+    if (records.isEmpty) {
+      output.writeln('${okPen('✔')} no unused code found!');
+
+      return;
+    }
+
+    final sortedRecords = records.toList()
+      ..sort((a, b) => a.relativePath.compareTo(b.relativePath));
+
+    var warnings = 0;
+
+    for (final analysisRecord in sortedRecords) {
+      output.writeln('${analysisRecord.relativePath}:');
+
+      for (final issue in analysisRecord.issues) {
+        final line = issue.location.line;
+        final column = issue.location.column;
+        final path = analysisRecord.relativePath;
+
+        final offset = ''.padRight(3);
+        final pathOffset = offset.padRight(5);
+
+        output
+          ..writeln(
+            '$offset ${warningPen('⚠')} unused ${issue.declarationType} ${issue.declarationName}',
+          )
+          ..writeln('$pathOffset at $path:$line:$column');
+      }
+
+      warnings += analysisRecord.issues.length;
+
+      output.writeln('');
+    }
+
+    output.writeln(
+      '${alarmPen('✖')} total unused code (classes, functions, variables, extensions, enums, mixins and type aliases) - ${alarmPen(warnings)}',
+    );
+  }
+}

lib/src/analyzers/unused_code_analyzer/reporters/reporters_list/json/unused_code_json_reporter.dart

@@ -0,0 +1,49 @@
+import 'dart:convert';
+import 'dart:io';
+
+import '../../../../../reporters/models/json_reporter.dart';
+import '../../../models/unused_code_file_report.dart';
+import '../../../models/unused_code_issue.dart';
+
+/// Unused code JSON reporter.
+///
+/// Use it to create reports in JSON format.
+class UnusedCodeJsonReporter
+    extends JsonReporter<UnusedCodeFileReport, void, void> {
+  const UnusedCodeJsonReporter(IOSink output) : super(output, 2);
+
+  @override
+  Future<void> report(
+    Iterable<UnusedCodeFileReport> records, {
+    Iterable<void> summary = const [],
+    void additionalParams,
+  }) async {
+    if (records.isEmpty) {
+      return;
+    }
+
+    final encodedReport = json.encode({
+      'formatVersion': formatVersion,
+      'timestamp': getTimestamp(),
+      'unusedCode': records.map(_unusedCodeFileReportToJson).toList(),
+    });
+
+    output.write(encodedReport);
+  }
+
+  Map<String, Object> _unusedCodeFileReportToJson(
+    UnusedCodeFileReport report,
+  ) =>
+      {
+        'path': report.relativePath,
+        'issues': report.issues.map(_issueToJson).toList(),
+      };
+
+  Map<String, Object> _issueToJson(UnusedCodeIssue issue) => {
+        'declarationType': issue.declarationType,
+        'declarationName': issue.declarationName,
+        'column': issue.location.column,
+        'line': issue.location.line,
+        'offset': issue.location.offset,
+      };
+}

lib/src/analyzers/unused_code_analyzer/unused_code_analysis_config.dart

@@ -0,0 +1,12 @@
+import 'package:glob/glob.dart';
+
+/// Represents converted unused code config which contains parsed entities.
+class UnusedCodeAnalysisConfig {
+  final Iterable<Glob> globalExcludes;
+  final Iterable<Glob> analyzerExcludedPatterns;
+
+  const UnusedCodeAnalysisConfig(
+    this.globalExcludes,
+    this.analyzerExcludedPatterns,
+  );
+}