lib/src/data_uri.dart - external/github.com/dart-lang/http_parser - Git at Google

 // Copyright (c) 2015, 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 'dart:convert';

 import 'package:convert/convert.dart';
 import 'package:crypto/crypto.dart';
 import 'package:string_scanner/string_scanner.dart';

 import 'media_type.dart';
 import 'scan.dart';
 import 'utils.dart';

 /// Like [whitespace] from scan.dart, except that it matches URI-encoded
 /// whitespace rather than literal characters.
 final _whitespace = new RegExp(r'(?:(?:%0D%0A)?(?:%20|%09)+)*');

 /// A converter for percent encoding strings using UTF-8.
 final _utf8Percent = UTF8.fuse(percent);

 /// A class representing a `data:` URI that provides access to its [mediaType]
 /// and the [data] it contains.
 ///
 /// Data can be encoded as a `data:` URI using [encode] or [encodeString], and
 /// decoded using [decode].
 ///
 /// This implementation is based on [RFC 2397][rfc], but as that RFC is
 /// [notoriously ambiguous][ambiguities], some judgment calls have been made.
 /// This class tries to match browsers' data URI logic, to ensure that it can
 /// losslessly parse its own output, and to accept as much input as it can make
 /// sense of. A balance has been struck between these goals so that while none
 /// of them have been accomplished perfectly, all of them are close enough for
 /// practical use.
 ///
 /// [rfc]: http://tools.ietf.org/html/rfc2397
 /// [ambiguities]: https://simonsapin.github.io/data-urls/
 ///
 /// Some particular notes on the behavior:
 ///
 /// * When encoding, all characters that are not [reserved][] in the type,
 ///   subtype, parameter names, and parameter values of media types are
 ///   percent-encoded using UTF-8.
 ///
 /// * When decoding, the type, subtype, parameter names, and parameter values of
 ///   media types are percent-decoded using UTF-8. Parameter values are allowed
 ///   to contain non-token characters once decoded, but the other tokens are
 ///   not.
 ///
 /// * As per the spec, quoted-string parameters are not supported when decoding.
 ///
 /// * Query components are included in the decoding algorithm, but fragments are
 ///   not.
 ///
 /// * Invalid media types and parameters will raise exceptions when decoding.
 ///   This is standard for Dart parsers but contrary to browser behavior.
 ///
 /// * The URL and filename-safe base64 alphabet is accepted when decoding but
 ///   never emitted when encoding, since browsers don't support it.
 ///
 /// [lws]: https://tools.ietf.org/html/rfc2616#section-2.2
 /// [reserved]: https://tools.ietf.org/html/rfc3986#section-2.2
 class DataUri implements Uri {
   /// The inner URI to which all [Uri] methods are forwarded.
   final Uri _inner;

   /// The byte data contained in the data URI.
   final List<int> data;

   /// The media type declared for the data URI.
   ///
   /// This defaults to `text/plain;charset=US-ASCII`.
   final MediaType mediaType;

   /// The encoding declared by the `charset` parameter in [mediaType].
   ///
   /// If [mediaType] has no `charset` parameter, this defaults to [ASCII]. If
   /// the `charset` parameter declares an encoding that can't be found using
   /// [Encoding.getByName], this returns `null`.
   Encoding get declaredEncoding {
     var charset = mediaType.parameters["charset"];
     return charset == null ? ASCII : Encoding.getByName(charset);
   }

   /// Creates a new data URI with the given [mediaType] and [data].
   ///
   /// If [base64] is `true` (the default), the data is base64-encoded;
   /// otherwise, it's percent-encoded.
   ///
   /// If [encoding] is passed or [mediaType] declares a `charset` parameter,
   /// [data] is encoded using that encoding. Otherwise, it's encoded using
   /// [UTF8] or [ASCII] depending on whether it contains any non-ASCII
   /// characters.
   ///
   /// Throws [ArgumentError] if [mediaType] and [encoding] disagree on the
   /// encoding, and an [UnsupportedError] if [mediaType] defines an encoding
   /// that's not supported by [Encoding.getByName].
   factory DataUri.encodeString(String data, {bool base64: true,
       MediaType mediaType, Encoding encoding}) {
     if (mediaType == null) mediaType = new MediaType("text", "plain");

     var charset = mediaType.parameters["charset"];
     var bytes;
     if (encoding != null) {
       if (charset == null) {
         mediaType = mediaType.change(parameters: {"charset": encoding.name});
       } else if (Encoding.getByName(charset) != encoding) {
         throw new ArgumentError("Media type charset '$charset' disagrees with "
             "encoding '${encoding.name}'.");
       }
       bytes = encoding.encode(data);
     } else if (charset != null) {
       encoding = Encoding.getByName(charset);
       if (encoding == null) {
         throw new UnsupportedError(
             'Unsupported media type charset "$charset".');
       }
       bytes = encoding.encode(data);
     } else if (data.codeUnits.every((codeUnit) => codeUnit < 0x80)) {
       // If the data is pure ASCII, don't bother explicitly defining a charset.
       bytes = data.codeUnits;
     } else {
       // If the data isn't pure ASCII, default to UTF-8.
       bytes = UTF8.encode(data);
       mediaType = mediaType.change(parameters: {"charset": "utf-8"});
     }

     return new DataUri.encode(bytes, base64: base64, mediaType: mediaType);
   }

   /// Creates a new data URI with the given [mediaType] and [data].
   ///
   /// If [base64] is `true` (the default), the data is base64-encoded;
   /// otherwise, it's percent-encoded.
   factory DataUri.encode(List<int> data, {bool base64: true,
       MediaType mediaType}) {
     mediaType ??= new MediaType('text', 'plain');

     var buffer = new StringBuffer();

     // Manually stringify the media type because [section 3][rfc] requires that
     // parameter values should have non-token characters URL-escaped rather than
     // emitting them as quoted-strings. This also allows us to omit text/plain
     // if possible.
     //
     // [rfc]: http://tools.ietf.org/html/rfc2397#section-3
     if (mediaType.type != 'text' || mediaType.subtype != 'plain') {
       buffer.write(_utf8Percent.encode(mediaType.type));
       buffer.write("/");
       buffer.write(_utf8Percent.encode(mediaType.subtype));
     }

     mediaType.parameters.forEach((attribute, value) {
       buffer.write(";${_utf8Percent.encode(attribute)}=");
       buffer.write(_utf8Percent.encode(value));
     });

     if (base64) {
       buffer.write(";base64,");
       // *Don't* use the URL-safe encoding scheme, since browsers don't actually
       // support it.
       buffer.write(CryptoUtils.bytesToBase64(data));
     } else {
       buffer.write(",");
       buffer.write(percent.encode(data));
     }

     return new DataUri._(data, mediaType,
         new Uri(scheme: 'data', path: buffer.toString()));
   }

   /// Decodes [uri] to make its [data] and [mediaType] available.
   ///
   /// [uri] may be a [Uri] or a [String].
   ///
   /// Throws an [ArgumentError] if [uri] is an invalid type or has a scheme
   /// other than `data:`. Throws a [FormatException] if parsing fails.
   factory DataUri.decode(uri) {
     if (uri is String) {
       uri = Uri.parse(uri);
     } else if (uri is! Uri) {
       throw new ArgumentError.value(uri, "uri", "Must be a String or a Uri.");
     }

     if (uri.scheme != 'data') {
       throw new ArgumentError.value(uri, "uri", "Can only decode a data: URI.");
     }

     return wrapFormatException("data URI", uri.toString(), () {
       // Remove the fragment, as per https://simonsapin.github.io/data-urls/.
       // TODO(nweiz): Use Uri.removeFragment once sdk#24593 is fixed.
       var string = uri.toString();
       var fragment = string.indexOf('#');
       if (fragment != -1) string = string.substring(0, fragment);
       var scanner = new StringScanner(string);
       scanner.expect('data:');

       // Manually scan the media type for three reasons:
       //
       // * Media type parameter values that aren't valid tokens are URL-encoded
       //   rather than quoted.
       //
       // * The media type may be omitted without omitting the parameters.
       //
       // * We need to be able to stop once we reach `;base64,`, even though at
       //   first it looks like a parameter.
       var type;
       var subtype;
       var implicitType = false;
       if (scanner.scan(token)) {
         type = _verifyToken(scanner);
         scanner.expect('/');
         subtype = _expectToken(scanner);
       } else {
         type = 'text';
         subtype = 'plain';
         implicitType = true;
       }

       // Scan the parameters, up through ";base64" or a comma.
       var parameters = {};
       var base64 = false;
       while (scanner.scan(';')) {
         var attribute = _expectToken(scanner);

         if (attribute != 'base64') {
           scanner.expect('=');
         } else if (!scanner.scan('=')) {
           base64 = true;
           break;
         }

         // Don't use [_expectToken] because the value uses percent-encoding to
         // escape non-token characters.
         scanner.expect(token);
         parameters[attribute] = _utf8Percent.decode(scanner.lastMatch[0]);
       }
       scanner.expect(',');

       if (implicitType && parameters.isEmpty) {
         parameters = {"charset": "US-ASCII"};
       }

       var mediaType = new MediaType(type, subtype, parameters);

       var data = base64
           ? CryptoUtils.base64StringToBytes(scanner.rest)
           : percent.decode(scanner.rest);

       return new DataUri._(data, mediaType, uri);
     });
   }

   /// Returns the percent-decoded value of the last MIME token scanned by
   /// [scanner].
   ///
   /// Throws a [FormatException] if it's not a valid token after
   /// percent-decoding.
   static String _verifyToken(StringScanner scanner) {
     var value = _utf8Percent.decode(scanner.lastMatch[0]);
     if (!value.contains(nonToken)) return value;
     scanner.error("Invalid token.");
     return null;
   }

   /// Scans [scanner] through a MIME token and returns its percent-decoded
   /// value.
   ///
   /// Throws a [FormatException] if it's not a valid token after
   /// percent-decoding.
   static String _expectToken(StringScanner scanner) {
     scanner.expect(token, name: "a token");
     return _verifyToken(scanner);
   }

   DataUri._(this.data, this.mediaType, this._inner);

   /// Returns the decoded [data] decoded using [encoding].
   ///
   /// [encoding] defaults to [declaredEncoding]. If the declared encoding isn't
   /// supported by [Encoding.getByName] and [encoding] isn't passed, this throws
   /// an [UnsupportedError].
   String dataAsString({Encoding encoding}) {
     encoding ??= declaredEncoding;
     if (encoding == null) {
       throw new UnsupportedError(
           'Unsupported media type charset '
           '"${mediaType.parameters["charset"]}".');
     }

     return encoding.decode(data);
   }

   String get scheme => _inner.scheme;
   String get authority => _inner.authority;
   String get userInfo => _inner.userInfo;
   String get host => _inner.host;
   int get port => _inner.port;
   String get path => _inner.path;
   String get query => _inner.query;
   String get fragment => _inner.fragment;
   Uri replace({String scheme, String userInfo, String host, int port,
           String path, Iterable<String> pathSegments, String query,
           Map<String, String> queryParameters, String fragment}) =>
       _inner.replace(
           scheme: scheme, userInfo: userInfo, host: host, port: port,
           path: path, pathSegments: pathSegments, query: query,
           queryParameters: queryParameters, fragment: fragment);
   Uri removeFragment() => _inner.removeFragment();
   List<String> get pathSegments => _inner.pathSegments;
   Map<String, String> get queryParameters => _inner.queryParameters;
   Uri normalizePath() => _inner.normalizePath();
   bool get isAbsolute => _inner.isAbsolute;
   Uri resolve(String reference) => _inner.resolve(reference);
   Uri resolveUri(Uri reference) => _inner.resolveUri(reference);
   bool get hasScheme => _inner.hasScheme;
   bool get hasAuthority => _inner.hasAuthority;
   bool get hasPort => _inner.hasPort;
   bool get hasQuery => _inner.hasQuery;
   bool get hasFragment => _inner.hasFragment;
   bool get hasEmptyPath => _inner.hasEmptyPath;
   bool get hasAbsolutePath => _inner.hasAbsolutePath;
   String get origin => _inner.origin;
   String toFilePath({bool windows}) => _inner.toFilePath(windows: windows);
   String toString() => _inner.toString();
   bool operator==(other) => _inner == other;
   int get hashCode => _inner.hashCode;
 }
	// Copyright (c) 2015, 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 'dart:convert';

	import 'package:convert/convert.dart';
	import 'package:crypto/crypto.dart';
	import 'package:string_scanner/string_scanner.dart';

	import 'media_type.dart';
	import 'scan.dart';
	import 'utils.dart';

	/// Like [whitespace] from scan.dart, except that it matches URI-encoded
	/// whitespace rather than literal characters.
	final _whitespace = new RegExp(r'(?:(?:%0D%0A)?(?:%20\|%09)+)*');

	/// A converter for percent encoding strings using UTF-8.
	final _utf8Percent = UTF8.fuse(percent);

	/// A class representing a `data:` URI that provides access to its [mediaType]
	/// and the [data] it contains.
	///
	/// Data can be encoded as a `data:` URI using [encode] or [encodeString], and
	/// decoded using [decode].
	///
	/// This implementation is based on [RFC 2397][rfc], but as that RFC is
	/// [notoriously ambiguous][ambiguities], some judgment calls have been made.
	/// This class tries to match browsers' data URI logic, to ensure that it can
	/// losslessly parse its own output, and to accept as much input as it can make
	/// sense of. A balance has been struck between these goals so that while none
	/// of them have been accomplished perfectly, all of them are close enough for
	/// practical use.
	///
	/// [rfc]: http://tools.ietf.org/html/rfc2397
	/// [ambiguities]: https://simonsapin.github.io/data-urls/
	///
	/// Some particular notes on the behavior:
	///
	/// * When encoding, all characters that are not [reserved][] in the type,
	/// subtype, parameter names, and parameter values of media types are
	/// percent-encoded using UTF-8.
	///
	/// * When decoding, the type, subtype, parameter names, and parameter values of
	/// media types are percent-decoded using UTF-8. Parameter values are allowed
	/// to contain non-token characters once decoded, but the other tokens are
	/// not.
	///
	/// * As per the spec, quoted-string parameters are not supported when decoding.
	///
	/// * Query components are included in the decoding algorithm, but fragments are
	/// not.
	///
	/// * Invalid media types and parameters will raise exceptions when decoding.
	/// This is standard for Dart parsers but contrary to browser behavior.
	///
	/// * The URL and filename-safe base64 alphabet is accepted when decoding but
	/// never emitted when encoding, since browsers don't support it.
	///
	/// [lws]: https://tools.ietf.org/html/rfc2616#section-2.2
	/// [reserved]: https://tools.ietf.org/html/rfc3986#section-2.2
	class DataUri implements Uri {
	/// The inner URI to which all [Uri] methods are forwarded.
	final Uri _inner;

	/// The byte data contained in the data URI.
	final List<int> data;

	/// The media type declared for the data URI.
	///
	/// This defaults to `text/plain;charset=US-ASCII`.
	final MediaType mediaType;

	/// The encoding declared by the `charset` parameter in [mediaType].
	///
	/// If [mediaType] has no `charset` parameter, this defaults to [ASCII]. If
	/// the `charset` parameter declares an encoding that can't be found using
	/// [Encoding.getByName], this returns `null`.
	Encoding get declaredEncoding {
	var charset = mediaType.parameters["charset"];
	return charset == null ? ASCII : Encoding.getByName(charset);
	}

	/// Creates a new data URI with the given [mediaType] and [data].
	///
	/// If [base64] is `true` (the default), the data is base64-encoded;
	/// otherwise, it's percent-encoded.
	///
	/// If [encoding] is passed or [mediaType] declares a `charset` parameter,
	/// [data] is encoded using that encoding. Otherwise, it's encoded using
	/// [UTF8] or [ASCII] depending on whether it contains any non-ASCII
	/// characters.
	///
	/// Throws [ArgumentError] if [mediaType] and [encoding] disagree on the
	/// encoding, and an [UnsupportedError] if [mediaType] defines an encoding
	/// that's not supported by [Encoding.getByName].
	factory DataUri.encodeString(String data, {bool base64: true,
	MediaType mediaType, Encoding encoding}) {
	if (mediaType == null) mediaType = new MediaType("text", "plain");

	var charset = mediaType.parameters["charset"];
	var bytes;
	if (encoding != null) {
	if (charset == null) {
	mediaType = mediaType.change(parameters: {"charset": encoding.name});
	} else if (Encoding.getByName(charset) != encoding) {
	throw new ArgumentError("Media type charset '$charset' disagrees with "
	"encoding '${encoding.name}'.");
	}
	bytes = encoding.encode(data);
	} else if (charset != null) {
	encoding = Encoding.getByName(charset);
	if (encoding == null) {
	throw new UnsupportedError(
	'Unsupported media type charset "$charset".');
	}
	bytes = encoding.encode(data);
	} else if (data.codeUnits.every((codeUnit) => codeUnit < 0x80)) {
	// If the data is pure ASCII, don't bother explicitly defining a charset.
	bytes = data.codeUnits;
	} else {
	// If the data isn't pure ASCII, default to UTF-8.
	bytes = UTF8.encode(data);
	mediaType = mediaType.change(parameters: {"charset": "utf-8"});
	}

	return new DataUri.encode(bytes, base64: base64, mediaType: mediaType);
	}

	/// Creates a new data URI with the given [mediaType] and [data].
	///
	/// If [base64] is `true` (the default), the data is base64-encoded;
	/// otherwise, it's percent-encoded.
	factory DataUri.encode(List<int> data, {bool base64: true,
	MediaType mediaType}) {
	mediaType ??= new MediaType('text', 'plain');

	var buffer = new StringBuffer();

	// Manually stringify the media type because [section 3][rfc] requires that
	// parameter values should have non-token characters URL-escaped rather than
	// emitting them as quoted-strings. This also allows us to omit text/plain
	// if possible.
	//
	// [rfc]: http://tools.ietf.org/html/rfc2397#section-3
	if (mediaType.type != 'text' \|\| mediaType.subtype != 'plain') {
	buffer.write(_utf8Percent.encode(mediaType.type));
	buffer.write("/");
	buffer.write(_utf8Percent.encode(mediaType.subtype));
	}

	mediaType.parameters.forEach((attribute, value) {
	buffer.write(";${_utf8Percent.encode(attribute)}=");
	buffer.write(_utf8Percent.encode(value));
	});

	if (base64) {
	buffer.write(";base64,");
	// Don't use the URL-safe encoding scheme, since browsers don't actually
	// support it.
	buffer.write(CryptoUtils.bytesToBase64(data));
	} else {
	buffer.write(",");
	buffer.write(percent.encode(data));
	}

	return new DataUri._(data, mediaType,
	new Uri(scheme: 'data', path: buffer.toString()));
	}

	/// Decodes [uri] to make its [data] and [mediaType] available.
	///
	/// [uri] may be a [Uri] or a [String].
	///
	/// Throws an [ArgumentError] if [uri] is an invalid type or has a scheme
	/// other than `data:`. Throws a [FormatException] if parsing fails.
	factory DataUri.decode(uri) {
	if (uri is String) {
	uri = Uri.parse(uri);
	} else if (uri is! Uri) {
	throw new ArgumentError.value(uri, "uri", "Must be a String or a Uri.");
	}

	if (uri.scheme != 'data') {
	throw new ArgumentError.value(uri, "uri", "Can only decode a data: URI.");
	}

	return wrapFormatException("data URI", uri.toString(), () {
	// Remove the fragment, as per https://simonsapin.github.io/data-urls/.
	// TODO(nweiz): Use Uri.removeFragment once sdk#24593 is fixed.
	var string = uri.toString();
	var fragment = string.indexOf('#');
	if (fragment != -1) string = string.substring(0, fragment);
	var scanner = new StringScanner(string);
	scanner.expect('data:');

	// Manually scan the media type for three reasons:
	//
	// * Media type parameter values that aren't valid tokens are URL-encoded
	// rather than quoted.
	//
	// * The media type may be omitted without omitting the parameters.
	//
	// * We need to be able to stop once we reach `;base64,`, even though at
	// first it looks like a parameter.
	var type;
	var subtype;
	var implicitType = false;
	if (scanner.scan(token)) {
	type = _verifyToken(scanner);
	scanner.expect('/');
	subtype = _expectToken(scanner);
	} else {
	type = 'text';
	subtype = 'plain';
	implicitType = true;
	}

	// Scan the parameters, up through ";base64" or a comma.
	var parameters = {};
	var base64 = false;
	while (scanner.scan(';')) {
	var attribute = _expectToken(scanner);

	if (attribute != 'base64') {
	scanner.expect('=');
	} else if (!scanner.scan('=')) {
	base64 = true;
	break;
	}

	// Don't use [_expectToken] because the value uses percent-encoding to
	// escape non-token characters.
	scanner.expect(token);
	parameters[attribute] = _utf8Percent.decode(scanner.lastMatch[0]);
	}
	scanner.expect(',');

	if (implicitType && parameters.isEmpty) {
	parameters = {"charset": "US-ASCII"};
	}

	var mediaType = new MediaType(type, subtype, parameters);

	var data = base64
	? CryptoUtils.base64StringToBytes(scanner.rest)
	: percent.decode(scanner.rest);

	return new DataUri._(data, mediaType, uri);
	});
	}

	/// Returns the percent-decoded value of the last MIME token scanned by
	/// [scanner].
	///
	/// Throws a [FormatException] if it's not a valid token after
	/// percent-decoding.
	static String _verifyToken(StringScanner scanner) {
	var value = _utf8Percent.decode(scanner.lastMatch[0]);
	if (!value.contains(nonToken)) return value;
	scanner.error("Invalid token.");
	return null;
	}

	/// Scans [scanner] through a MIME token and returns its percent-decoded
	/// value.
	///
	/// Throws a [FormatException] if it's not a valid token after
	/// percent-decoding.
	static String _expectToken(StringScanner scanner) {
	scanner.expect(token, name: "a token");
	return _verifyToken(scanner);
	}

	DataUri._(this.data, this.mediaType, this._inner);

	/// Returns the decoded [data] decoded using [encoding].
	///
	/// [encoding] defaults to [declaredEncoding]. If the declared encoding isn't
	/// supported by [Encoding.getByName] and [encoding] isn't passed, this throws
	/// an [UnsupportedError].
	String dataAsString({Encoding encoding}) {
	encoding ??= declaredEncoding;
	if (encoding == null) {
	throw new UnsupportedError(
	'Unsupported media type charset '
	'"${mediaType.parameters["charset"]}".');
	}

	return encoding.decode(data);
	}

	String get scheme => _inner.scheme;
	String get authority => _inner.authority;
	String get userInfo => _inner.userInfo;
	String get host => _inner.host;
	int get port => _inner.port;
	String get path => _inner.path;
	String get query => _inner.query;
	String get fragment => _inner.fragment;
	Uri replace({String scheme, String userInfo, String host, int port,
	String path, Iterable<String> pathSegments, String query,
	Map<String, String> queryParameters, String fragment}) =>
	_inner.replace(
	scheme: scheme, userInfo: userInfo, host: host, port: port,
	path: path, pathSegments: pathSegments, query: query,
	queryParameters: queryParameters, fragment: fragment);
	Uri removeFragment() => _inner.removeFragment();
	List<String> get pathSegments => _inner.pathSegments;
	Map<String, String> get queryParameters => _inner.queryParameters;
	Uri normalizePath() => _inner.normalizePath();
	bool get isAbsolute => _inner.isAbsolute;
	Uri resolve(String reference) => _inner.resolve(reference);
	Uri resolveUri(Uri reference) => _inner.resolveUri(reference);
	bool get hasScheme => _inner.hasScheme;
	bool get hasAuthority => _inner.hasAuthority;
	bool get hasPort => _inner.hasPort;
	bool get hasQuery => _inner.hasQuery;
	bool get hasFragment => _inner.hasFragment;
	bool get hasEmptyPath => _inner.hasEmptyPath;
	bool get hasAbsolutePath => _inner.hasAbsolutePath;
	String get origin => _inner.origin;
	String toFilePath({bool windows}) => _inner.toFilePath(windows: windows);
	String toString() => _inner.toString();
	bool operator==(other) => _inner == other;
	int get hashCode => _inner.hashCode;
	}