packages/flutter_tools/lib/src/base/analyze_size.dart - mirrors/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. 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:meta/meta.dart';
 import 'package:vm_snapshot_analysis/treemap.dart';

 import '../base/file_system.dart';
 import '../convert.dart';
 import 'logger.dart';
 import 'process.dart';
 import 'terminal.dart';

 /// A class to analyze APK and AOT snapshot and generate a breakdown of the data.
 class SizeAnalyzer {
   SizeAnalyzer({
     @required this.fileSystem,
     @required this.logger,
     @required this.processUtils,
     this.appFilenamePattern = 'libapp.so',
   });

   final FileSystem fileSystem;
   final Logger logger;
   final ProcessUtils processUtils;
   final Pattern appFilenamePattern;
   String _appFilename;

   static const String aotSnapshotFileName = 'aot-snapshot.json';

   static const int tableWidth = 80;

   /// Analyzes [apk] and [aotSnapshot] to output a [Map] object that includes
   /// the breakdown of the both files, where the breakdown of [aotSnapshot] is placed
   /// under 'lib/arm64-v8a/$_appFilename'.
   ///
   /// The [aotSnapshot] can be either instruction sizes snapshot or v8 snapshot.
   Future<Map<String, dynamic>> analyzeApkSizeAndAotSnapshot({
     @required File apk,
     @required File aotSnapshot,
   }) async {
     logger.printStatus('▒' * tableWidth);
     _printEntitySize(
       '${apk.basename} (total compressed)',
       byteSize: apk.lengthSync(),
       level: 0,
       showColor: false,
     );
     logger.printStatus('━' * tableWidth);
     final Directory tempApkContent = fileSystem.systemTempDirectory.createTempSync('flutter_tools.');
     // TODO(peterdjlee): Implement a way to unzip the APK for Windows. See issue #62603.
     String unzipOut;
     try {
       // TODO(peterdjlee): Use zipinfo instead of unzip.
       unzipOut = (await processUtils.run(<String>[
         'unzip',
         '-o',
         '-v',
         apk.path,
         '-d',
         tempApkContent.path
       ])).stdout;
     } on Exception catch (e) {
       logger.printError(e.toString());
     } finally {
       // We just want the the stdout printout. We don't need the files.
       tempApkContent.deleteSync(recursive: true);
     }

     final _SymbolNode apkAnalysisRoot = _parseUnzipFile(unzipOut);

     // Convert an AOT snapshot file into a map.
     final Map<String, dynamic> processedAotSnapshotJson = treemapFromJson(
       json.decode(aotSnapshot.readAsStringSync()),
     );
     final _SymbolNode aotSnapshotJsonRoot = _parseAotSnapshot(processedAotSnapshotJson);

     for (final _SymbolNode firstLevelPath in apkAnalysisRoot.children) {
       _printEntitySize(
         firstLevelPath.name,
         byteSize: firstLevelPath.byteSize,
         level: 1,
       );
       // Print the expansion of lib directory to show more info for `appFilename`.
       if (firstLevelPath.name == 'lib') {
         _printLibChildrenPaths(firstLevelPath, '', aotSnapshotJsonRoot);
       }
     }

     logger.printStatus('▒' * tableWidth);

     Map<String, dynamic> apkAnalysisJson = apkAnalysisRoot.toJson();

     apkAnalysisJson['type'] = 'apk';

     // TODO(peterdjlee): Add aot snapshot for all platforms.
     assert(_appFilename != null);
     apkAnalysisJson = _addAotSnapshotDataToApkAnalysis(
       apkAnalysisJson: apkAnalysisJson,
       path: 'lib/arm64-v8a/$_appFilename (Dart AOT)'.split('/'), // Pass in a list of paths by splitting with '/'.
       aotSnapshotJson: processedAotSnapshotJson,
     );

     return apkAnalysisJson;
   }


   // Expression to match 'Size' column to group 1 and 'Name' column to group 2.
   final RegExp _parseUnzipOutput = RegExp(r'^\s*\d+\s+[\w|:]+\s+(\d+)\s+.*  (.+)$');

   // Parse the output of unzip -v which shows the zip's contents' compressed sizes.
   // Example output of unzip -v:
   //  Length   Method    Size  Cmpr    Date    Time   CRC-32   Name
   // --------  ------  ------- ---- ---------- ----- --------  ----
   //    11708  Defl:N     2592  78% 00-00-1980 00:00 07733eef  AndroidManifest.xml
   //     1399  Defl:N     1092  22% 00-00-1980 00:00 f53d952a  META-INF/CERT.RSA
   //    46298  Defl:N    14530  69% 00-00-1980 00:00 17df02b8  META-INF/CERT.SF
   _SymbolNode _parseUnzipFile(String unzipOut) {
     final Map<List<String>, int> pathsToSize = <List<String>, int>{};

     // Parse each path into pathsToSize so that the key is a list of
     // path parts and the value is the size.
     // For example:
     // 'path/to/file' where file = 1500 => pathsToSize[['path', 'to', 'file']] = 1500
     for (final String line in const LineSplitter().convert(unzipOut)) {
       final RegExpMatch match = _parseUnzipOutput.firstMatch(line);
       if (match == null) {
         continue;
       }
       const int sizeGroupIndex = 1;
       const int nameGroupIndex = 2;
       pathsToSize[match.group(nameGroupIndex).split('/')] = int.parse(match.group(sizeGroupIndex));
     }

     final _SymbolNode rootNode = _SymbolNode('Root');

     _SymbolNode currentNode = rootNode;
     for (final List<String> paths in pathsToSize.keys) {
       for (final String path in paths) {
         _SymbolNode childWithPathAsName = currentNode.childByName(path);

         if (childWithPathAsName == null) {
           childWithPathAsName = _SymbolNode(path);
           if (matchesPattern(path, pattern: appFilenamePattern) != null) {
             _appFilename = path;
             childWithPathAsName.name += ' (Dart AOT)';
           } else if (path == 'libflutter.so') {
             childWithPathAsName.name += ' (Flutter Engine)';
           }
           currentNode.addChild(childWithPathAsName);
         }
         childWithPathAsName.addSize(pathsToSize[paths]);
         currentNode = childWithPathAsName;
       }
       currentNode = rootNode;
     }

     return rootNode;
   }

   /// Prints all children paths for the lib/ directory in an APK.
   ///
   /// A brief summary of aot snapshot is printed under 'lib/arm64-v8a/$_appFilename'.
   void _printLibChildrenPaths(
     _SymbolNode currentNode,
     String totalPath,
     _SymbolNode aotSnapshotJsonRoot,
   ) {
     totalPath += currentNode.name;

     assert(_appFilename != null);
     if (currentNode.children.isNotEmpty
       && currentNode.name != '$_appFilename (Dart AOT)') {
       for (final _SymbolNode child in currentNode.children) {
         _printLibChildrenPaths(child, '$totalPath/', aotSnapshotJsonRoot);
       }
     } else {
       // Print total path and size if currentNode does not have any chilren.
       _printEntitySize(totalPath, byteSize: currentNode.byteSize, level: 2);

       // We picked this file because arm64-v8a is likely the most popular
       // architecture. Other architecture sizes should be similar.
       final String libappPath = 'lib/arm64-v8a/$_appFilename';
       // TODO(peterdjlee): Analyze aot size for all platforms.
       if (totalPath.contains(libappPath)) {
         _printAotSnapshotSummary(aotSnapshotJsonRoot);
       }
     }
   }

   /// Go through the AOT gen snapshot size JSON and print out a collapsed summary
   /// for the first package level.
   void _printAotSnapshotSummary(_SymbolNode aotSnapshotRoot, {int maxDirectoriesShown = 10}) {
     _printEntitySize(
       'Dart AOT symbols accounted decompressed size',
       byteSize: aotSnapshotRoot.byteSize,
       level: 3,
     );

     final List<_SymbolNode> sortedSymbols = aotSnapshotRoot.children.toList()
       ..sort((_SymbolNode a, _SymbolNode b) => b.byteSize.compareTo(a.byteSize));
     for (final _SymbolNode node in sortedSymbols.take(maxDirectoriesShown)) {
       _printEntitySize(node.name, byteSize: node.byteSize, level: 4);
     }
   }

   /// Adds breakdown of aot snapshot data as the children of the node at the given path.
   Map<String, dynamic> _addAotSnapshotDataToApkAnalysis({
     @required Map<String, dynamic> apkAnalysisJson,
     @required List<String> path,
     @required Map<String, dynamic> aotSnapshotJson,
   }) {
     Map<String, dynamic> currentLevel = apkAnalysisJson;
     while (path.isNotEmpty) {
       final List<Map<String, dynamic>> children = currentLevel['children'] as List<Map<String, dynamic>>;
       final Map<String, dynamic> childWithPathAsName = children.firstWhere(
         (Map<String, dynamic> child) => child['n'] as String == path.first,
       );
       path.removeAt(0);
       currentLevel = childWithPathAsName;
     }
     currentLevel['children'] = aotSnapshotJson['children'];
     return apkAnalysisJson;
   }

   /// Print an entity's name with its size on the same line.
   void _printEntitySize(
     String entityName, {
     @required int byteSize,
     @required int level,
     bool showColor = true,
   }) {
     final bool emphasis = level <= 1;
     final String formattedSize = _prettyPrintBytes(byteSize);

     TerminalColor color = TerminalColor.green;
     if (formattedSize.endsWith('MB')) {
       color = TerminalColor.cyan;
     } else if (formattedSize.endsWith('KB')) {
       color = TerminalColor.yellow;
     }

     final int spaceInBetween = tableWidth - level * 2 - entityName.length - formattedSize.length;
     logger.printStatus(
       entityName + ' ' * spaceInBetween,
       newline: false,
       emphasis: emphasis,
       indent: level * 2,
     );
     logger.printStatus(formattedSize, color: showColor ? color : null);
   }

   String _prettyPrintBytes(int numBytes) {
     const int kB = 1024;
     const int mB = kB * 1024;
     if (numBytes < kB) {
       return '$numBytes B';
     } else if (numBytes < mB) {
       return '${(numBytes / kB).round()} KB';
     } else {
       return '${(numBytes / mB).round()} MB';
     }
   }

   _SymbolNode _parseAotSnapshot(Map<String, dynamic> aotSnapshotJson) {
     final bool isLeafNode = aotSnapshotJson['children'] == null;
     if (!isLeafNode) {
       return _buildNodeWithChildren(aotSnapshotJson);
     } else {
       // TODO(peterdjlee): Investigate why there are leaf nodes with size of null.
       final int byteSize = aotSnapshotJson['value'] as int;
       if (byteSize == null) {
         return null;
       }
       return _buildNode(aotSnapshotJson, byteSize);
     }
   }

   _SymbolNode _buildNode(
     Map<String, dynamic> aotSnapshotJson,
     int byteSize, {
     List<_SymbolNode> children = const <_SymbolNode>[],
   }) {
     final String name = aotSnapshotJson['n'] as String;
     final Map<String, _SymbolNode> childrenMap = <String, _SymbolNode>{};

     for (final _SymbolNode child in children) {
       childrenMap[child.name] = child;
     }

     return _SymbolNode(
       name,
       byteSize: byteSize,
     )..addAllChildren(children);
   }

   /// Builds a node by recursively building all of its children first
   /// in order to calculate the sum of its children's sizes.
   _SymbolNode _buildNodeWithChildren(Map<String, dynamic> aotSnapshotJson) {
     final List<dynamic> rawChildren = aotSnapshotJson['children'] as List<dynamic>;
     final List<_SymbolNode> symbolNodeChildren = <_SymbolNode>[];
     int totalByteSize = 0;

     // Given a child, build its subtree.
     for (final dynamic child in rawChildren) {
       final _SymbolNode childTreemapNode = _parseAotSnapshot(child as Map<String, dynamic>);
       symbolNodeChildren.add(childTreemapNode);
       totalByteSize += childTreemapNode.byteSize;
     }

     // If none of the children matched the diff tree type
     if (totalByteSize == 0) {
       return null;
     } else {
       return _buildNode(
         aotSnapshotJson,
         totalByteSize,
         children: symbolNodeChildren,
       );
     }
   }
 }

 /// A node class that represents a single symbol for AOT size snapshots.
 class _SymbolNode {
   _SymbolNode(
     this.name, {
     this.byteSize = 0,
   })  : assert(name != null),
         assert(byteSize != null),
         _children = <String, _SymbolNode>{};

   /// The human friendly identifier for this node.
   String name;

   int byteSize;
   void addSize(int sizeToBeAdded) {
     byteSize += sizeToBeAdded;
   }

   _SymbolNode get parent => _parent;
   _SymbolNode _parent;

   Iterable<_SymbolNode> get children => _children.values;
   final Map<String, _SymbolNode> _children;

   _SymbolNode childByName(String name) => _children[name];

   _SymbolNode addChild(_SymbolNode child) {
     assert(child.parent == null);
     assert(!_children.containsKey(child.name),
         'Cannot add duplicate child key ${child.name}');

     child._parent = this;
     _children[child.name] = child;
     return child;
   }

   void addAllChildren(List<_SymbolNode> children) {
     children.forEach(addChild);
   }

   Map<String, dynamic> toJson() {
     final Map<String, dynamic> json = <String, dynamic>{
       'n': name,
       'value': byteSize
     };
     final List<Map<String, dynamic>> childrenAsJson = <Map<String, dynamic>>[];
     for (final _SymbolNode child in children) {
       childrenAsJson.add(child.toJson());
     }
     if (childrenAsJson.isNotEmpty) {
       json['children'] = childrenAsJson;
     }
     return json;
   }
 }

 /// Matches `pattern` against the entirety of `string`.
 @visibleForTesting
 Match matchesPattern(String string, {@required Pattern pattern}) {
   final Match match = pattern.matchAsPrefix(string);
   return (match != null && match.end == string.length) ? match : null;
 }
	// Copyright 2014 The Flutter Authors. 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:meta/meta.dart';
	import 'package:vm_snapshot_analysis/treemap.dart';

	import '../base/file_system.dart';
	import '../convert.dart';
	import 'logger.dart';
	import 'process.dart';
	import 'terminal.dart';

	/// A class to analyze APK and AOT snapshot and generate a breakdown of the data.
	class SizeAnalyzer {
	SizeAnalyzer({
	@required this.fileSystem,
	@required this.logger,
	@required this.processUtils,
	this.appFilenamePattern = 'libapp.so',
	});

	final FileSystem fileSystem;
	final Logger logger;
	final ProcessUtils processUtils;
	final Pattern appFilenamePattern;
	String _appFilename;

	static const String aotSnapshotFileName = 'aot-snapshot.json';

	static const int tableWidth = 80;

	/// Analyzes [apk] and [aotSnapshot] to output a [Map] object that includes
	/// the breakdown of the both files, where the breakdown of [aotSnapshot] is placed
	/// under 'lib/arm64-v8a/$_appFilename'.
	///
	/// The [aotSnapshot] can be either instruction sizes snapshot or v8 snapshot.
	Future<Map<String, dynamic>> analyzeApkSizeAndAotSnapshot({
	@required File apk,
	@required File aotSnapshot,
	}) async {
	logger.printStatus('▒' * tableWidth);
	_printEntitySize(
	'${apk.basename} (total compressed)',
	byteSize: apk.lengthSync(),
	level: 0,
	showColor: false,
	);
	logger.printStatus('━' * tableWidth);
	final Directory tempApkContent = fileSystem.systemTempDirectory.createTempSync('flutter_tools.');
	// TODO(peterdjlee): Implement a way to unzip the APK for Windows. See issue #62603.
	String unzipOut;
	try {
	// TODO(peterdjlee): Use zipinfo instead of unzip.
	unzipOut = (await processUtils.run(<String>[
	'unzip',
	'-o',
	'-v',
	apk.path,
	'-d',
	tempApkContent.path
	])).stdout;
	} on Exception catch (e) {
	logger.printError(e.toString());
	} finally {
	// We just want the the stdout printout. We don't need the files.
	tempApkContent.deleteSync(recursive: true);
	}

	final _SymbolNode apkAnalysisRoot = _parseUnzipFile(unzipOut);

	// Convert an AOT snapshot file into a map.
	final Map<String, dynamic> processedAotSnapshotJson = treemapFromJson(
	json.decode(aotSnapshot.readAsStringSync()),
	);
	final _SymbolNode aotSnapshotJsonRoot = _parseAotSnapshot(processedAotSnapshotJson);

	for (final _SymbolNode firstLevelPath in apkAnalysisRoot.children) {
	_printEntitySize(
	firstLevelPath.name,
	byteSize: firstLevelPath.byteSize,
	level: 1,
	);
	// Print the expansion of lib directory to show more info for `appFilename`.
	if (firstLevelPath.name == 'lib') {
	_printLibChildrenPaths(firstLevelPath, '', aotSnapshotJsonRoot);
	}
	}

	logger.printStatus('▒' * tableWidth);

	Map<String, dynamic> apkAnalysisJson = apkAnalysisRoot.toJson();

	apkAnalysisJson['type'] = 'apk';

	// TODO(peterdjlee): Add aot snapshot for all platforms.
	assert(_appFilename != null);
	apkAnalysisJson = _addAotSnapshotDataToApkAnalysis(
	apkAnalysisJson: apkAnalysisJson,
	path: 'lib/arm64-v8a/$_appFilename (Dart AOT)'.split('/'), // Pass in a list of paths by splitting with '/'.
	aotSnapshotJson: processedAotSnapshotJson,
	);

	return apkAnalysisJson;
	}


	// Expression to match 'Size' column to group 1 and 'Name' column to group 2.
	final RegExp _parseUnzipOutput = RegExp(r'^\s\d+\s+[\w\|:]+\s+(\d+)\s+. (.+)$');

	// Parse the output of unzip -v which shows the zip's contents' compressed sizes.
	// Example output of unzip -v:
	// Length Method Size Cmpr Date Time CRC-32 Name
	// -------- ------ ------- ---- ---------- ----- -------- ----
	// 11708 Defl:N 2592 78% 00-00-1980 00:00 07733eef AndroidManifest.xml
	// 1399 Defl:N 1092 22% 00-00-1980 00:00 f53d952a META-INF/CERT.RSA
	// 46298 Defl:N 14530 69% 00-00-1980 00:00 17df02b8 META-INF/CERT.SF
	_SymbolNode _parseUnzipFile(String unzipOut) {
	final Map<List<String>, int> pathsToSize = <List<String>, int>{};

	// Parse each path into pathsToSize so that the key is a list of
	// path parts and the value is the size.
	// For example:
	// 'path/to/file' where file = 1500 => pathsToSize[['path', 'to', 'file']] = 1500
	for (final String line in const LineSplitter().convert(unzipOut)) {
	final RegExpMatch match = _parseUnzipOutput.firstMatch(line);
	if (match == null) {
	continue;
	}
	const int sizeGroupIndex = 1;
	const int nameGroupIndex = 2;
	pathsToSize[match.group(nameGroupIndex).split('/')] = int.parse(match.group(sizeGroupIndex));
	}

	final _SymbolNode rootNode = _SymbolNode('Root');

	_SymbolNode currentNode = rootNode;
	for (final List<String> paths in pathsToSize.keys) {
	for (final String path in paths) {
	_SymbolNode childWithPathAsName = currentNode.childByName(path);

	if (childWithPathAsName == null) {
	childWithPathAsName = _SymbolNode(path);
	if (matchesPattern(path, pattern: appFilenamePattern) != null) {
	_appFilename = path;
	childWithPathAsName.name += ' (Dart AOT)';
	} else if (path == 'libflutter.so') {
	childWithPathAsName.name += ' (Flutter Engine)';
	}
	currentNode.addChild(childWithPathAsName);
	}
	childWithPathAsName.addSize(pathsToSize[paths]);
	currentNode = childWithPathAsName;
	}
	currentNode = rootNode;
	}

	return rootNode;
	}

	/// Prints all children paths for the lib/ directory in an APK.
	///
	/// A brief summary of aot snapshot is printed under 'lib/arm64-v8a/$_appFilename'.
	void _printLibChildrenPaths(
	_SymbolNode currentNode,
	String totalPath,
	_SymbolNode aotSnapshotJsonRoot,
	) {
	totalPath += currentNode.name;

	assert(_appFilename != null);
	if (currentNode.children.isNotEmpty
	&& currentNode.name != '$_appFilename (Dart AOT)') {
	for (final _SymbolNode child in currentNode.children) {
	_printLibChildrenPaths(child, '$totalPath/', aotSnapshotJsonRoot);
	}
	} else {
	// Print total path and size if currentNode does not have any chilren.
	_printEntitySize(totalPath, byteSize: currentNode.byteSize, level: 2);

	// We picked this file because arm64-v8a is likely the most popular
	// architecture. Other architecture sizes should be similar.
	final String libappPath = 'lib/arm64-v8a/$_appFilename';
	// TODO(peterdjlee): Analyze aot size for all platforms.
	if (totalPath.contains(libappPath)) {
	_printAotSnapshotSummary(aotSnapshotJsonRoot);
	}
	}
	}

	/// Go through the AOT gen snapshot size JSON and print out a collapsed summary
	/// for the first package level.
	void _printAotSnapshotSummary(_SymbolNode aotSnapshotRoot, {int maxDirectoriesShown = 10}) {
	_printEntitySize(
	'Dart AOT symbols accounted decompressed size',
	byteSize: aotSnapshotRoot.byteSize,
	level: 3,
	);

	final List<_SymbolNode> sortedSymbols = aotSnapshotRoot.children.toList()
	..sort((_SymbolNode a, _SymbolNode b) => b.byteSize.compareTo(a.byteSize));
	for (final _SymbolNode node in sortedSymbols.take(maxDirectoriesShown)) {
	_printEntitySize(node.name, byteSize: node.byteSize, level: 4);
	}
	}

	/// Adds breakdown of aot snapshot data as the children of the node at the given path.
	Map<String, dynamic> _addAotSnapshotDataToApkAnalysis({
	@required Map<String, dynamic> apkAnalysisJson,
	@required List<String> path,
	@required Map<String, dynamic> aotSnapshotJson,
	}) {
	Map<String, dynamic> currentLevel = apkAnalysisJson;
	while (path.isNotEmpty) {
	final List<Map<String, dynamic>> children = currentLevel['children'] as List<Map<String, dynamic>>;
	final Map<String, dynamic> childWithPathAsName = children.firstWhere(
	(Map<String, dynamic> child) => child['n'] as String == path.first,
	);
	path.removeAt(0);
	currentLevel = childWithPathAsName;
	}
	currentLevel['children'] = aotSnapshotJson['children'];
	return apkAnalysisJson;
	}

	/// Print an entity's name with its size on the same line.
	void _printEntitySize(
	String entityName, {
	@required int byteSize,
	@required int level,
	bool showColor = true,
	}) {
	final bool emphasis = level <= 1;
	final String formattedSize = _prettyPrintBytes(byteSize);

	TerminalColor color = TerminalColor.green;
	if (formattedSize.endsWith('MB')) {
	color = TerminalColor.cyan;
	} else if (formattedSize.endsWith('KB')) {
	color = TerminalColor.yellow;
	}

	final int spaceInBetween = tableWidth - level * 2 - entityName.length - formattedSize.length;
	logger.printStatus(
	entityName + ' ' * spaceInBetween,
	newline: false,
	emphasis: emphasis,
	indent: level * 2,
	);
	logger.printStatus(formattedSize, color: showColor ? color : null);
	}

	String _prettyPrintBytes(int numBytes) {
	const int kB = 1024;
	const int mB = kB * 1024;
	if (numBytes < kB) {
	return '$numBytes B';
	} else if (numBytes < mB) {
	return '${(numBytes / kB).round()} KB';
	} else {
	return '${(numBytes / mB).round()} MB';
	}
	}

	_SymbolNode _parseAotSnapshot(Map<String, dynamic> aotSnapshotJson) {
	final bool isLeafNode = aotSnapshotJson['children'] == null;
	if (!isLeafNode) {
	return _buildNodeWithChildren(aotSnapshotJson);
	} else {
	// TODO(peterdjlee): Investigate why there are leaf nodes with size of null.
	final int byteSize = aotSnapshotJson['value'] as int;
	if (byteSize == null) {
	return null;
	}
	return _buildNode(aotSnapshotJson, byteSize);
	}
	}

	_SymbolNode _buildNode(
	Map<String, dynamic> aotSnapshotJson,
	int byteSize, {
	List<_SymbolNode> children = const <_SymbolNode>[],
	}) {
	final String name = aotSnapshotJson['n'] as String;
	final Map<String, _SymbolNode> childrenMap = <String, _SymbolNode>{};

	for (final _SymbolNode child in children) {
	childrenMap[child.name] = child;
	}

	return _SymbolNode(
	name,
	byteSize: byteSize,
	)..addAllChildren(children);
	}

	/// Builds a node by recursively building all of its children first
	/// in order to calculate the sum of its children's sizes.
	_SymbolNode _buildNodeWithChildren(Map<String, dynamic> aotSnapshotJson) {
	final List<dynamic> rawChildren = aotSnapshotJson['children'] as List<dynamic>;
	final List<_SymbolNode> symbolNodeChildren = <_SymbolNode>[];
	int totalByteSize = 0;

	// Given a child, build its subtree.
	for (final dynamic child in rawChildren) {
	final _SymbolNode childTreemapNode = _parseAotSnapshot(child as Map<String, dynamic>);
	symbolNodeChildren.add(childTreemapNode);
	totalByteSize += childTreemapNode.byteSize;
	}

	// If none of the children matched the diff tree type
	if (totalByteSize == 0) {
	return null;
	} else {
	return _buildNode(
	aotSnapshotJson,
	totalByteSize,
	children: symbolNodeChildren,
	);
	}
	}
	}

	/// A node class that represents a single symbol for AOT size snapshots.
	class _SymbolNode {
	_SymbolNode(
	this.name, {
	this.byteSize = 0,
	}) : assert(name != null),
	assert(byteSize != null),
	_children = <String, _SymbolNode>{};

	/// The human friendly identifier for this node.
	String name;

	int byteSize;
	void addSize(int sizeToBeAdded) {
	byteSize += sizeToBeAdded;
	}

	_SymbolNode get parent => _parent;
	_SymbolNode _parent;

	Iterable<_SymbolNode> get children => _children.values;
	final Map<String, _SymbolNode> _children;

	_SymbolNode childByName(String name) => _children[name];

	_SymbolNode addChild(_SymbolNode child) {
	assert(child.parent == null);
	assert(!_children.containsKey(child.name),
	'Cannot add duplicate child key ${child.name}');

	child._parent = this;
	_children[child.name] = child;
	return child;
	}

	void addAllChildren(List<_SymbolNode> children) {
	children.forEach(addChild);
	}

	Map<String, dynamic> toJson() {
	final Map<String, dynamic> json = <String, dynamic>{
	'n': name,
	'value': byteSize
	};
	final List<Map<String, dynamic>> childrenAsJson = <Map<String, dynamic>>[];
	for (final _SymbolNode child in children) {
	childrenAsJson.add(child.toJson());
	}
	if (childrenAsJson.isNotEmpty) {
	json['children'] = childrenAsJson;
	}
	return json;
	}
	}

	/// Matches `pattern` against the entirety of `string`.
	@visibleForTesting
	Match matchesPattern(String string, {@required Pattern pattern}) {
	final Match match = pattern.matchAsPrefix(string);
	return (match != null && match.end == string.length) ? match : null;
	}