lib/src/frame.dart - stack_trace - Git at Google

 // Copyright (c) 2013, 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:path/path.dart' as path;

 import 'trace.dart';
 import 'unparsed_frame.dart';

 // #1      Foo._bar (file:///home/nweiz/code/stuff.dart:42:21)
 // #1      Foo._bar (file:///home/nweiz/code/stuff.dart:42)
 // #1      Foo._bar (file:///home/nweiz/code/stuff.dart)
 final _vmFrame = RegExp(r'^#\d+\s+(\S.*) \((.+?)((?::\d+){0,2})\)$');

 //     at Object.stringify (native)
 //     at VW.call$0 (https://example.com/stuff.dart.js:560:28)
 //     at VW.call$0 (eval as fn
 //         (https://example.com/stuff.dart.js:560:28), efn:3:28)
 //     at https://example.com/stuff.dart.js:560:28
 final _v8JsFrame =
     RegExp(r'^\s*at (?:(\S.*?)(?: \[as [^\]]+\])? \((.*)\)|(.*))$');

 // https://example.com/stuff.dart.js:560:28
 // https://example.com/stuff.dart.js:560
 //
 // Group 1: URI, required
 // Group 2: line number, required
 // Group 3: column number, optional
 final _v8JsUrlLocation = RegExp(r'^(.*?):(\d+)(?::(\d+))?$|native$');

 // With names:
 //
 //     at Error.f (wasm://wasm/0006d966:wasm-function[119]:0xbb13)
 //     at g (wasm://wasm/0006d966:wasm-function[796]:0x143b4)
 //
 // Without names:
 //
 //     at wasm://wasm/0005168a:wasm-function[119]:0xbb13
 //     at wasm://wasm/0005168a:wasm-function[796]:0x143b4
 //
 // Matches named groups:
 //
 // - "member": optional, `Error.f` in the first example, NA in the second.
 // - "uri":  `wasm://wasm/0006d966`.
 // - "index": `119`.
 // - "offset": (hex number) `bb13`.
 //
 // To avoid having multiple groups for the same part of the frame, this regex
 // matches unmatched parentheses after the member name.
 final _v8WasmFrame = RegExp(r'^\s*at (?:(?<member>.+) )?'
     r'(?:\(?(?:(?<uri>\S+):wasm-function\[(?<index>\d+)\]'
     r'\:0x(?<offset>[0-9a-fA-F]+))\)?)$');

 // eval as function (https://example.com/stuff.dart.js:560:28), efn:3:28
 // eval as function (https://example.com/stuff.dart.js:560:28)
 // eval as function (eval as otherFunction
 //     (https://example.com/stuff.dart.js:560:28))
 final _v8EvalLocation =
     RegExp(r'^eval at (?:\S.*?) \((.*)\)(?:, .*?:\d+:\d+)?$');

 // anonymous/<@https://example.com/stuff.js line 693 > Function:3:40
 // anonymous/<@https://example.com/stuff.js line 693 > eval:3:40
 final _firefoxEvalLocation =
     RegExp(r'(\S+)@(\S+) line (\d+) >.* (Function|eval):\d+:\d+');

 // .VW.call$0@https://example.com/stuff.dart.js:560
 // .VW.call$0("arg")@https://example.com/stuff.dart.js:560
 // .VW.call$0/name<@https://example.com/stuff.dart.js:560
 // .VW.call$0@https://example.com/stuff.dart.js:560:36
 // https://example.com/stuff.dart.js:560
 final _firefoxSafariJSFrame = RegExp(r'^'
     r'(?:' // Member description. Not present in some Safari frames.
     r'([^@(/]*)' // The actual name of the member.
     r'(?:\(.*\))?' // Arguments to the member, sometimes captured by Firefox.
     r'((?:/[^/]*)*)' // Extra characters indicating a nested closure.
     r'(?:\(.*\))?' // Arguments to the closure.
     r'@'
     r')?'
     r'(.*?)' // The frame's URL.
     r':'
     r'(\d*)' // The line number. Empty in Safari if it's unknown.
     r'(?::(\d*))?' // The column number. Not present in older browsers and
     // empty in Safari if it's unknown.
     r'$');

 // With names:
 //
 // g@http://localhost:8080/test.wasm:wasm-function[796]:0x143b4
 // f@http://localhost:8080/test.wasm:wasm-function[795]:0x143a8
 // main@http://localhost:8080/test.wasm:wasm-function[792]:0x14390
 //
 // Without names:
 //
 // @http://localhost:8080/test.wasm:wasm-function[796]:0x143b4
 // @http://localhost:8080/test.wasm:wasm-function[795]:0x143a8
 // @http://localhost:8080/test.wasm:wasm-function[792]:0x14390
 //
 // JSShell in the command line uses a different format, which this regex also
 // parses.
 //
 // With names:
 //
 // main@/home/user/test.mjs line 29 > WebAssembly.compile:wasm-function[792]:0x14378
 //
 // Without names:
 //
 // @/home/user/test.mjs line 29 > WebAssembly.compile:wasm-function[792]:0x14378
 //
 // Matches named groups:
 //
 // - "member": Function name, may be empty: `g`.
 // - "uri": `http://localhost:8080/test.wasm`.
 // - "index": `796`.
 // - "offset": (in hex) `143b4`.
 final _firefoxWasmFrame =
     RegExp(r'^(?<member>.*?)@(?:(?<uri>\S+).*?:wasm-function'
         r'\[(?<index>\d+)\]:0x(?<offset>[0-9a-fA-F]+))$');

 // With names:
 //
 // (Note: Lines below are literal text, e.g. <?> is not a placeholder, it's a
 // part of the stack frame.)
 //
 // <?>.wasm-function[g]@[wasm code]
 // <?>.wasm-function[f]@[wasm code]
 // <?>.wasm-function[main]@[wasm code]
 //
 // Without names:
 //
 // <?>.wasm-function[796]@[wasm code]
 // <?>.wasm-function[795]@[wasm code]
 // <?>.wasm-function[792]@[wasm code]
 //
 // Matches named group "member": `g` or `796`.
 final _safariWasmFrame =
     RegExp(r'^.*?wasm-function\[(?<member>.*)\]@\[wasm code\]$');

 // foo/bar.dart 10:11 Foo._bar
 // foo/bar.dart 10:11 (anonymous function).dart.fn
 // https://dart.dev/foo/bar.dart Foo._bar
 // data:... 10:11 Foo._bar
 final _friendlyFrame = RegExp(r'^(\S+)(?: (\d+)(?::(\d+))?)?\s+([^\d].*)$');

 /// A regular expression that matches asynchronous member names generated by the
 /// VM.
 final _asyncBody = RegExp(r'<(<anonymous closure>|[^>]+)_async_body>');

 final _initialDot = RegExp(r'^\.');

 /// A single stack frame. Each frame points to a precise location in Dart code.
 class Frame {
   /// The URI of the file in which the code is located.
   ///
   /// This URI will usually have the scheme `dart`, `file`, `http`, or `https`.
   final Uri uri;

   /// The line number on which the code location is located.
   ///
   /// This can be null, indicating that the line number is unknown or
   /// unimportant.
   final int? line;

   /// The column number of the code location.
   ///
   /// This can be null, indicating that the column number is unknown or
   /// unimportant.
   final int? column;

   /// The name of the member in which the code location occurs.
   ///
   /// Anonymous closures are represented as `<fn>` in this member string.
   final String? member;

   /// Whether this stack frame comes from the Dart core libraries.
   bool get isCore => uri.scheme == 'dart';

   /// Returns a human-friendly description of the library that this stack frame
   /// comes from.
   ///
   /// This will usually be the string form of [uri], but a relative URI will be
   /// used if possible. Data URIs will be truncated.
   String get library {
     if (uri.scheme == 'data') return 'data:...';
     return path.prettyUri(uri);
   }

   /// Returns the name of the package this stack frame comes from, or `null` if
   /// this stack frame doesn't come from a `package:` URL.
   String? get package {
     if (uri.scheme != 'package') return null;
     return uri.path.split('/').first;
   }

   /// A human-friendly description of the code location.
   String get location {
     if (line == null) return library;
     if (column == null) return '$library $line';
     return '$library $line:$column';
   }

   /// Returns a single frame of the current stack.
   ///
   /// By default, this will return the frame above the current method. If
   /// [level] is `0`, it will return the current method's frame; if [level] is
   /// higher than `1`, it will return higher frames.
   factory Frame.caller([int level = 1]) {
     if (level < 0) {
       throw ArgumentError('Argument [level] must be greater than or equal '
           'to 0.');
     }

     return Trace.current(level + 1).frames.first;
   }

   /// Parses a string representation of a Dart VM stack frame.
   factory Frame.parseVM(String frame) => _catchFormatException(frame, () {
         // The VM sometimes folds multiple stack frames together and replaces
         // them with "...".
         if (frame == '...') {
           return Frame(Uri(), null, null, '...');
         }

         var match = _vmFrame.firstMatch(frame);
         if (match == null) return UnparsedFrame(frame);

         // Get the pieces out of the regexp match. Function, URI and line should
         // always be found. The column is optional.
         var member = match[1]!
             .replaceAll(_asyncBody, '<async>')
             .replaceAll('<anonymous closure>', '<fn>');
         var uri = match[2]!.startsWith('<data:')
             ? Uri.dataFromString('')
             : Uri.parse(match[2]!);

         var lineAndColumn = match[3]!.split(':');
         var line =
             lineAndColumn.length > 1 ? int.parse(lineAndColumn[1]) : null;
         var column =
             lineAndColumn.length > 2 ? int.parse(lineAndColumn[2]) : null;
         return Frame(uri, line, column, member);
       });

   /// Parses a string representation of a Chrome/V8 stack frame.
   factory Frame.parseV8(String frame) => _catchFormatException(frame, () {
         // Try to match a Wasm frame first: the Wasm frame regex won't match a
         // JS frame but the JS frame regex may match a Wasm frame.
         var match = _v8WasmFrame.firstMatch(frame);
         if (match != null) {
           final member = match.namedGroup('member');
           final uri = _uriOrPathToUri(match.namedGroup('uri')!);
           final functionIndex = match.namedGroup('index')!;
           final functionOffset =
               int.parse(match.namedGroup('offset')!, radix: 16);
           return Frame(uri, 1, functionOffset + 1, member ?? functionIndex);
         }

         match = _v8JsFrame.firstMatch(frame);
         if (match != null) {
           // v8 location strings can be arbitrarily-nested, since it adds a
           // layer of nesting for each eval performed on that line.
           Frame parseJsLocation(String location, String member) {
             var evalMatch = _v8EvalLocation.firstMatch(location);
             while (evalMatch != null) {
               location = evalMatch[1]!;
               evalMatch = _v8EvalLocation.firstMatch(location);
             }

             if (location == 'native') {
               return Frame(Uri.parse('native'), null, null, member);
             }

             var urlMatch = _v8JsUrlLocation.firstMatch(location);
             if (urlMatch == null) return UnparsedFrame(frame);

             final uri = _uriOrPathToUri(urlMatch[1]!);
             final line = int.parse(urlMatch[2]!);
             final columnMatch = urlMatch[3];
             final column = columnMatch != null ? int.parse(columnMatch) : null;
             return Frame(uri, line, column, member);
           }

           // V8 stack frames can be in two forms.
           if (match[2] != null) {
             // The first form looks like " at FUNCTION (LOCATION)". V8 proper
             // lists anonymous functions within eval as "<anonymous>", while
             // IE10 lists them as "Anonymous function".
             return parseJsLocation(
                 match[2]!,
                 match[1]!
                     .replaceAll('<anonymous>', '<fn>')
                     .replaceAll('Anonymous function', '<fn>')
                     .replaceAll('(anonymous function)', '<fn>'));
           } else {
             // The second form looks like " at LOCATION", and is used for
             // anonymous functions.
             return parseJsLocation(match[3]!, '<fn>');
           }
         }

         return UnparsedFrame(frame);
       });

   /// Parses a string representation of a JavaScriptCore stack trace.
   factory Frame.parseJSCore(String frame) => Frame.parseV8(frame);

   /// Parses a string representation of an IE stack frame.
   ///
   /// IE10+ frames look just like V8 frames. Prior to IE10, stack traces can't
   /// be retrieved.
   factory Frame.parseIE(String frame) => Frame.parseV8(frame);

   /// Parses a Firefox 'eval' or 'function' stack frame.
   ///
   /// For example:
   ///
   /// ```
   /// anonymous/<@https://example.com/stuff.js line 693 > Function:3:40
   /// anonymous/<@https://example.com/stuff.js line 693 > eval:3:40
   /// ```
   factory Frame._parseFirefoxEval(String frame) =>
       _catchFormatException(frame, () {
         final match = _firefoxEvalLocation.firstMatch(frame);
         if (match == null) return UnparsedFrame(frame);
         var member = match[1]!.replaceAll('/<', '');
         final uri = _uriOrPathToUri(match[2]!);
         final line = int.parse(match[3]!);
         if (member.isEmpty || member == 'anonymous') {
           member = '<fn>';
         }
         return Frame(uri, line, null, member);
       });

   /// Parses a string representation of a Firefox or Safari stack frame.
   factory Frame.parseFirefox(String frame) => _catchFormatException(frame, () {
         var match = _firefoxSafariJSFrame.firstMatch(frame);
         if (match != null) {
           if (match[3]!.contains(' line ')) {
             return Frame._parseFirefoxEval(frame);
           }

           // Normally this is a URI, but in a jsshell trace it can be a path.
           var uri = _uriOrPathToUri(match[3]!);

           var member = match[1];
           if (member != null) {
             member +=
                 List.filled('/'.allMatches(match[2]!).length, '.<fn>').join();
             if (member == '') member = '<fn>';

             // Some Firefox members have initial dots. We remove them for
             // consistency with other platforms.
             member = member.replaceFirst(_initialDot, '');
           } else {
             member = '<fn>';
           }

           var line = match[4] == '' ? null : int.parse(match[4]!);
           var column =
               match[5] == null || match[5] == '' ? null : int.parse(match[5]!);
           return Frame(uri, line, column, member);
         }

         match = _firefoxWasmFrame.firstMatch(frame);
         if (match != null) {
           final member = match.namedGroup('member')!;
           final uri = _uriOrPathToUri(match.namedGroup('uri')!);
           final functionIndex = match.namedGroup('index')!;
           final functionOffset =
               int.parse(match.namedGroup('offset')!, radix: 16);
           return Frame(uri, 1, functionOffset + 1,
               member.isNotEmpty ? member : functionIndex);
         }

         match = _safariWasmFrame.firstMatch(frame);
         if (match != null) {
           final member = match.namedGroup('member')!;
           return Frame(Uri(path: 'wasm code'), null, null, member);
         }

         return UnparsedFrame(frame);
       });

   /// Parses a string representation of a Safari 6.0 stack frame.
   @Deprecated('Use Frame.parseSafari instead.')
   factory Frame.parseSafari6_0(String frame) => Frame.parseFirefox(frame);

   /// Parses a string representation of a Safari 6.1+ stack frame.
   @Deprecated('Use Frame.parseSafari instead.')
   factory Frame.parseSafari6_1(String frame) => Frame.parseFirefox(frame);

   /// Parses a string representation of a Safari stack frame.
   factory Frame.parseSafari(String frame) => Frame.parseFirefox(frame);

   /// Parses this package's string representation of a stack frame.
   factory Frame.parseFriendly(String frame) => _catchFormatException(frame, () {
         var match = _friendlyFrame.firstMatch(frame);
         if (match == null) {
           throw FormatException(
               "Couldn't parse package:stack_trace stack trace line '$frame'.");
         }
         // Fake truncated data urls generated by the friendly stack trace format
         // cause Uri.parse to throw an exception so we have to special case
         // them.
         var uri = match[1] == 'data:...'
             ? Uri.dataFromString('')
             : Uri.parse(match[1]!);
         // If there's no scheme, this is a relative URI. We should interpret it
         // as relative to the current working directory.
         if (uri.scheme == '') {
           uri = path.toUri(path.absolute(path.fromUri(uri)));
         }

         var line = match[2] == null ? null : int.parse(match[2]!);
         var column = match[3] == null ? null : int.parse(match[3]!);
         return Frame(uri, line, column, match[4]);
       });

   /// A regular expression matching an absolute URI.
   static final _uriRegExp = RegExp(r'^[a-zA-Z][-+.a-zA-Z\d]*://');

   /// A regular expression matching a Windows path.
   static final _windowsRegExp = RegExp(r'^([a-zA-Z]:[\\/]|\\\\)');

   /// Converts [uriOrPath], which can be a URI, a Windows path, or a Posix path,
   /// to a URI (absolute if possible).
   static Uri _uriOrPathToUri(String uriOrPath) {
     if (uriOrPath.contains(_uriRegExp)) {
       return Uri.parse(uriOrPath);
     } else if (uriOrPath.contains(_windowsRegExp)) {
       return Uri.file(uriOrPath, windows: true);
     } else if (uriOrPath.startsWith('/')) {
       return Uri.file(uriOrPath, windows: false);
     }

     // As far as I've seen, Firefox and V8 both always report absolute paths in
     // their stack frames. However, if we do get a relative path, we should
     // handle it gracefully.
     if (uriOrPath.contains('\\')) return path.windows.toUri(uriOrPath);
     return Uri.parse(uriOrPath);
   }

   /// Runs [body] and returns its result.
   ///
   /// If [body] throws a [FormatException], returns an [UnparsedFrame] with
   /// [text] instead.
   static Frame _catchFormatException(String text, Frame Function() body) {
     try {
       return body();
     } on FormatException catch (_) {
       return UnparsedFrame(text);
     }
   }

   Frame(this.uri, this.line, this.column, this.member);

   @override
   String toString() => '$location in $member';
 }
	// Copyright (c) 2013, 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:path/path.dart' as path;

	import 'trace.dart';
	import 'unparsed_frame.dart';

	// #1 Foo._bar (file:///home/nweiz/code/stuff.dart:42:21)
	// #1 Foo._bar (file:///home/nweiz/code/stuff.dart:42)
	// #1 Foo._bar (file:///home/nweiz/code/stuff.dart)
	final _vmFrame = RegExp(r'^#\d+\s+(\S.*) \((.+?)((?::\d+){0,2})\)$');

	// at Object.stringify (native)
	// at VW.call$0 (https://example.com/stuff.dart.js:560:28)
	// at VW.call$0 (eval as fn
	// (https://example.com/stuff.dart.js:560:28), efn:3:28)
	// at https://example.com/stuff.dart.js:560:28
	final _v8JsFrame =
	RegExp(r'^\sat (?:(\S.?)(?: \[as [^\]]+\])? \((.)\)\|(.))$');

	// https://example.com/stuff.dart.js:560:28
	// https://example.com/stuff.dart.js:560
	//
	// Group 1: URI, required
	// Group 2: line number, required
	// Group 3: column number, optional
	final _v8JsUrlLocation = RegExp(r'^(.*?):(\d+)(?::(\d+))?$\|native$');

	// With names:
	//
	// at Error.f (wasm://wasm/0006d966:wasm-function[119]:0xbb13)
	// at g (wasm://wasm/0006d966:wasm-function[796]:0x143b4)
	//
	// Without names:
	//
	// at wasm://wasm/0005168a:wasm-function[119]:0xbb13
	// at wasm://wasm/0005168a:wasm-function[796]:0x143b4
	//
	// Matches named groups:
	//
	// - "member": optional, `Error.f` in the first example, NA in the second.
	// - "uri": `wasm://wasm/0006d966`.
	// - "index": `119`.
	// - "offset": (hex number) `bb13`.
	//
	// To avoid having multiple groups for the same part of the frame, this regex
	// matches unmatched parentheses after the member name.
	final _v8WasmFrame = RegExp(r'^\s*at (?:(?<member>.+) )?'
	r'(?:\(?(?:(?<uri>\S+):wasm-function\[(?<index>\d+)\]'
	r'\:0x(?<offset>[0-9a-fA-F]+))\)?)$');

	// eval as function (https://example.com/stuff.dart.js:560:28), efn:3:28
	// eval as function (https://example.com/stuff.dart.js:560:28)
	// eval as function (eval as otherFunction
	// (https://example.com/stuff.dart.js:560:28))
	final _v8EvalLocation =
	RegExp(r'^eval at (?:\S.?) \((.)\)(?:, .*?:\d+:\d+)?$');

	// anonymous/<@https://example.com/stuff.js line 693 > Function:3:40
	// anonymous/<@https://example.com/stuff.js line 693 > eval:3:40
	final _firefoxEvalLocation =
	RegExp(r'(\S+)@(\S+) line (\d+) >.* (Function\|eval):\d+:\d+');

	// .VW.call$0@https://example.com/stuff.dart.js:560
	// .VW.call$0("arg")@https://example.com/stuff.dart.js:560
	// .VW.call$0/name<@https://example.com/stuff.dart.js:560
	// .VW.call$0@https://example.com/stuff.dart.js:560:36
	// https://example.com/stuff.dart.js:560
	final _firefoxSafariJSFrame = RegExp(r'^'
	r'(?:' // Member description. Not present in some Safari frames.
	r'([^@(/]*)' // The actual name of the member.
	r'(?:\(.*\))?' // Arguments to the member, sometimes captured by Firefox.
	r'((?:/[^/]))' // Extra characters indicating a nested closure.
	r'(?:\(.*\))?' // Arguments to the closure.
	r'@'
	r')?'
	r'(.*?)' // The frame's URL.
	r':'
	r'(\d*)' // The line number. Empty in Safari if it's unknown.
	r'(?::(\d*))?' // The column number. Not present in older browsers and
	// empty in Safari if it's unknown.
	r'$');

	// With names:
	//
	// g@http://localhost:8080/test.wasm:wasm-function[796]:0x143b4
	// f@http://localhost:8080/test.wasm:wasm-function[795]:0x143a8
	// main@http://localhost:8080/test.wasm:wasm-function[792]:0x14390
	//
	// Without names:
	//
	// @http://localhost:8080/test.wasm:wasm-function[796]:0x143b4
	// @http://localhost:8080/test.wasm:wasm-function[795]:0x143a8
	// @http://localhost:8080/test.wasm:wasm-function[792]:0x14390
	//
	// JSShell in the command line uses a different format, which this regex also
	// parses.
	//
	// With names:
	//
	// main@/home/user/test.mjs line 29 > WebAssembly.compile:wasm-function[792]:0x14378
	//
	// Without names:
	//
	// @/home/user/test.mjs line 29 > WebAssembly.compile:wasm-function[792]:0x14378
	//
	// Matches named groups:
	//
	// - "member": Function name, may be empty: `g`.
	// - "uri": `http://localhost:8080/test.wasm`.
	// - "index": `796`.
	// - "offset": (in hex) `143b4`.
	final _firefoxWasmFrame =
	RegExp(r'^(?<member>.?)@(?:(?<uri>\S+).?:wasm-function'
	r'\[(?<index>\d+)\]:0x(?<offset>[0-9a-fA-F]+))$');

	// With names:
	//
	// (Note: Lines below are literal text, e.g. <?> is not a placeholder, it's a
	// part of the stack frame.)
	//
	// <?>.wasm-function[g]@[wasm code]
	// <?>.wasm-function[f]@[wasm code]
	// <?>.wasm-function[main]@[wasm code]
	//
	// Without names:
	//
	// <?>.wasm-function[796]@[wasm code]
	// <?>.wasm-function[795]@[wasm code]
	// <?>.wasm-function[792]@[wasm code]
	//
	// Matches named group "member": `g` or `796`.
	final _safariWasmFrame =
	RegExp(r'^.?wasm-function\[(?<member>.)\]@\[wasm code\]$');

	// foo/bar.dart 10:11 Foo._bar
	// foo/bar.dart 10:11 (anonymous function).dart.fn
	// https://dart.dev/foo/bar.dart Foo._bar
	// data:... 10:11 Foo._bar
	final _friendlyFrame = RegExp(r'^(\S+)(?: (\d+)(?::(\d+))?)?\s+([^\d].*)$');

	/// A regular expression that matches asynchronous member names generated by the
	/// VM.
	final _asyncBody = RegExp(r'<(<anonymous closure>\|[^>]+)_async_body>');

	final _initialDot = RegExp(r'^\.');

	/// A single stack frame. Each frame points to a precise location in Dart code.
	class Frame {
	/// The URI of the file in which the code is located.
	///
	/// This URI will usually have the scheme `dart`, `file`, `http`, or `https`.
	final Uri uri;

	/// The line number on which the code location is located.
	///
	/// This can be null, indicating that the line number is unknown or
	/// unimportant.
	final int? line;

	/// The column number of the code location.
	///
	/// This can be null, indicating that the column number is unknown or
	/// unimportant.
	final int? column;

	/// The name of the member in which the code location occurs.
	///
	/// Anonymous closures are represented as `<fn>` in this member string.
	final String? member;

	/// Whether this stack frame comes from the Dart core libraries.
	bool get isCore => uri.scheme == 'dart';

	/// Returns a human-friendly description of the library that this stack frame
	/// comes from.
	///
	/// This will usually be the string form of [uri], but a relative URI will be
	/// used if possible. Data URIs will be truncated.
	String get library {
	if (uri.scheme == 'data') return 'data:...';
	return path.prettyUri(uri);
	}

	/// Returns the name of the package this stack frame comes from, or `null` if
	/// this stack frame doesn't come from a `package:` URL.
	String? get package {
	if (uri.scheme != 'package') return null;
	return uri.path.split('/').first;
	}

	/// A human-friendly description of the code location.
	String get location {
	if (line == null) return library;
	if (column == null) return '$library $line';
	return '$library $line:$column';
	}

	/// Returns a single frame of the current stack.
	///
	/// By default, this will return the frame above the current method. If
	/// [level] is `0`, it will return the current method's frame; if [level] is
	/// higher than `1`, it will return higher frames.
	factory Frame.caller([int level = 1]) {
	if (level < 0) {
	throw ArgumentError('Argument [level] must be greater than or equal '
	'to 0.');
	}

	return Trace.current(level + 1).frames.first;
	}

	/// Parses a string representation of a Dart VM stack frame.
	factory Frame.parseVM(String frame) => _catchFormatException(frame, () {
	// The VM sometimes folds multiple stack frames together and replaces
	// them with "...".
	if (frame == '...') {
	return Frame(Uri(), null, null, '...');
	}

	var match = _vmFrame.firstMatch(frame);
	if (match == null) return UnparsedFrame(frame);

	// Get the pieces out of the regexp match. Function, URI and line should
	// always be found. The column is optional.
	var member = match[1]!
	.replaceAll(_asyncBody, '<async>')
	.replaceAll('<anonymous closure>', '<fn>');
	var uri = match[2]!.startsWith('<data:')
	? Uri.dataFromString('')
	: Uri.parse(match[2]!);

	var lineAndColumn = match[3]!.split(':');
	var line =
	lineAndColumn.length > 1 ? int.parse(lineAndColumn[1]) : null;
	var column =
	lineAndColumn.length > 2 ? int.parse(lineAndColumn[2]) : null;
	return Frame(uri, line, column, member);
	});

	/// Parses a string representation of a Chrome/V8 stack frame.
	factory Frame.parseV8(String frame) => _catchFormatException(frame, () {
	// Try to match a Wasm frame first: the Wasm frame regex won't match a
	// JS frame but the JS frame regex may match a Wasm frame.
	var match = _v8WasmFrame.firstMatch(frame);
	if (match != null) {
	final member = match.namedGroup('member');
	final uri = _uriOrPathToUri(match.namedGroup('uri')!);
	final functionIndex = match.namedGroup('index')!;
	final functionOffset =
	int.parse(match.namedGroup('offset')!, radix: 16);
	return Frame(uri, 1, functionOffset + 1, member ?? functionIndex);
	}

	match = _v8JsFrame.firstMatch(frame);
	if (match != null) {
	// v8 location strings can be arbitrarily-nested, since it adds a
	// layer of nesting for each eval performed on that line.
	Frame parseJsLocation(String location, String member) {
	var evalMatch = _v8EvalLocation.firstMatch(location);
	while (evalMatch != null) {
	location = evalMatch[1]!;
	evalMatch = _v8EvalLocation.firstMatch(location);
	}

	if (location == 'native') {
	return Frame(Uri.parse('native'), null, null, member);
	}

	var urlMatch = _v8JsUrlLocation.firstMatch(location);
	if (urlMatch == null) return UnparsedFrame(frame);

	final uri = _uriOrPathToUri(urlMatch[1]!);
	final line = int.parse(urlMatch[2]!);
	final columnMatch = urlMatch[3];
	final column = columnMatch != null ? int.parse(columnMatch) : null;
	return Frame(uri, line, column, member);
	}

	// V8 stack frames can be in two forms.
	if (match[2] != null) {
	// The first form looks like " at FUNCTION (LOCATION)". V8 proper
	// lists anonymous functions within eval as "<anonymous>", while
	// IE10 lists them as "Anonymous function".
	return parseJsLocation(
	match[2]!,
	match[1]!
	.replaceAll('<anonymous>', '<fn>')
	.replaceAll('Anonymous function', '<fn>')
	.replaceAll('(anonymous function)', '<fn>'));
	} else {
	// The second form looks like " at LOCATION", and is used for
	// anonymous functions.
	return parseJsLocation(match[3]!, '<fn>');
	}
	}

	return UnparsedFrame(frame);
	});

	/// Parses a string representation of a JavaScriptCore stack trace.
	factory Frame.parseJSCore(String frame) => Frame.parseV8(frame);

	/// Parses a string representation of an IE stack frame.
	///
	/// IE10+ frames look just like V8 frames. Prior to IE10, stack traces can't
	/// be retrieved.
	factory Frame.parseIE(String frame) => Frame.parseV8(frame);

	/// Parses a Firefox 'eval' or 'function' stack frame.
	///
	/// For example:
	///
	/// ```
	/// anonymous/<@https://example.com/stuff.js line 693 > Function:3:40
	/// anonymous/<@https://example.com/stuff.js line 693 > eval:3:40
	/// ```
	factory Frame._parseFirefoxEval(String frame) =>
	_catchFormatException(frame, () {
	final match = _firefoxEvalLocation.firstMatch(frame);
	if (match == null) return UnparsedFrame(frame);
	var member = match[1]!.replaceAll('/<', '');
	final uri = _uriOrPathToUri(match[2]!);
	final line = int.parse(match[3]!);
	if (member.isEmpty \|\| member == 'anonymous') {
	member = '<fn>';
	}
	return Frame(uri, line, null, member);
	});

	/// Parses a string representation of a Firefox or Safari stack frame.
	factory Frame.parseFirefox(String frame) => _catchFormatException(frame, () {
	var match = _firefoxSafariJSFrame.firstMatch(frame);
	if (match != null) {
	if (match[3]!.contains(' line ')) {
	return Frame._parseFirefoxEval(frame);
	}

	// Normally this is a URI, but in a jsshell trace it can be a path.
	var uri = _uriOrPathToUri(match[3]!);

	var member = match[1];
	if (member != null) {
	member +=
	List.filled('/'.allMatches(match[2]!).length, '.<fn>').join();
	if (member == '') member = '<fn>';

	// Some Firefox members have initial dots. We remove them for
	// consistency with other platforms.
	member = member.replaceFirst(_initialDot, '');
	} else {
	member = '<fn>';
	}

	var line = match[4] == '' ? null : int.parse(match[4]!);
	var column =
	match[5] == null \|\| match[5] == '' ? null : int.parse(match[5]!);
	return Frame(uri, line, column, member);
	}

	match = _firefoxWasmFrame.firstMatch(frame);
	if (match != null) {
	final member = match.namedGroup('member')!;
	final uri = _uriOrPathToUri(match.namedGroup('uri')!);
	final functionIndex = match.namedGroup('index')!;
	final functionOffset =
	int.parse(match.namedGroup('offset')!, radix: 16);
	return Frame(uri, 1, functionOffset + 1,
	member.isNotEmpty ? member : functionIndex);
	}

	match = _safariWasmFrame.firstMatch(frame);
	if (match != null) {
	final member = match.namedGroup('member')!;
	return Frame(Uri(path: 'wasm code'), null, null, member);
	}

	return UnparsedFrame(frame);
	});

	/// Parses a string representation of a Safari 6.0 stack frame.
	@Deprecated('Use Frame.parseSafari instead.')
	factory Frame.parseSafari6_0(String frame) => Frame.parseFirefox(frame);

	/// Parses a string representation of a Safari 6.1+ stack frame.
	@Deprecated('Use Frame.parseSafari instead.')
	factory Frame.parseSafari6_1(String frame) => Frame.parseFirefox(frame);

	/// Parses a string representation of a Safari stack frame.
	factory Frame.parseSafari(String frame) => Frame.parseFirefox(frame);

	/// Parses this package's string representation of a stack frame.
	factory Frame.parseFriendly(String frame) => _catchFormatException(frame, () {
	var match = _friendlyFrame.firstMatch(frame);
	if (match == null) {
	throw FormatException(
	"Couldn't parse package:stack_trace stack trace line '$frame'.");
	}
	// Fake truncated data urls generated by the friendly stack trace format
	// cause Uri.parse to throw an exception so we have to special case
	// them.
	var uri = match[1] == 'data:...'
	? Uri.dataFromString('')
	: Uri.parse(match[1]!);
	// If there's no scheme, this is a relative URI. We should interpret it
	// as relative to the current working directory.
	if (uri.scheme == '') {
	uri = path.toUri(path.absolute(path.fromUri(uri)));
	}

	var line = match[2] == null ? null : int.parse(match[2]!);
	var column = match[3] == null ? null : int.parse(match[3]!);
	return Frame(uri, line, column, match[4]);
	});

	/// A regular expression matching an absolute URI.
	static final _uriRegExp = RegExp(r'^[a-zA-Z][-+.a-zA-Z\d]*://');

	/// A regular expression matching a Windows path.
	static final _windowsRegExp = RegExp(r'^([a-zA-Z]:[\\/]\|\\\\)');

	/// Converts [uriOrPath], which can be a URI, a Windows path, or a Posix path,
	/// to a URI (absolute if possible).
	static Uri _uriOrPathToUri(String uriOrPath) {
	if (uriOrPath.contains(_uriRegExp)) {
	return Uri.parse(uriOrPath);
	} else if (uriOrPath.contains(_windowsRegExp)) {
	return Uri.file(uriOrPath, windows: true);
	} else if (uriOrPath.startsWith('/')) {
	return Uri.file(uriOrPath, windows: false);
	}

	// As far as I've seen, Firefox and V8 both always report absolute paths in
	// their stack frames. However, if we do get a relative path, we should
	// handle it gracefully.
	if (uriOrPath.contains('\\')) return path.windows.toUri(uriOrPath);
	return Uri.parse(uriOrPath);
	}

	/// Runs [body] and returns its result.
	///
	/// If [body] throws a [FormatException], returns an [UnparsedFrame] with
	/// [text] instead.
	static Frame _catchFormatException(String text, Frame Function() body) {
	try {
	return body();
	} on FormatException catch (_) {
	return UnparsedFrame(text);
	}
	}

	Frame(this.uri, this.line, this.column, this.member);

	@override
	String toString() => '$location in $member';
	}