lib/src/util.dart - package_config - Git at Google

 // Copyright (c) 2019, 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.

 /// Utility methods used by more than one library in the package.
 library package_config.util;

 import 'dart:io';
 import 'dart:typed_data';

 import "errors.dart";

 // All ASCII characters that are valid in a package name, with space
 // for all the invalid ones (including space).
 const String _validPackageNameCharacters =
     r"                                 !  $ &'()*+,-. 0123456789 ; =  "
     r"@ABCDEFGHIJKLMNOPQRSTUVWXYZ    _ abcdefghijklmnopqrstuvwxyz   ~ ";

 /// Tests whether something is a valid Dart package name.
 bool isValidPackageName(String string) {
   return checkPackageName(string) < 0;
 }

 /// Check if a string is a valid package name.
 ///
 /// Valid package names contain only characters in [_validPackageNameCharacters]
 /// and must contain at least one non-'.' character.
 ///
 /// Returns `-1` if the string is valid.
 /// Otherwise returns the index of the first invalid character,
 /// or `string.length` if the string contains no non-'.' character.
 int checkPackageName(String string) {
   // Becomes non-zero if any non-'.' character is encountered.
   var nonDot = 0;
   for (var i = 0; i < string.length; i++) {
     var c = string.codeUnitAt(i);
     if (c > 0x7f || _validPackageNameCharacters.codeUnitAt(c) <= $space) {
       return i;
     }
     nonDot += c ^ $dot;
   }
   if (nonDot == 0) return string.length;
   return -1;
 }

 /// Validate that a [Uri] is a valid `package:` URI.
 ///
 /// Used to validate user input.
 ///
 /// Returns the package name extracted from the package URI,
 /// which is the path segment between `package:` and the first `/`.
 String checkValidPackageUri(Uri packageUri, String name) {
   if (packageUri.scheme != "package") {
     throw PackageConfigArgumentError(packageUri, name, "Not a package: URI");
   }
   if (packageUri.hasAuthority) {
     throw PackageConfigArgumentError(
         packageUri, name, "Package URIs must not have a host part");
   }
   if (packageUri.hasQuery) {
     // A query makes no sense if resolved to a file: URI.
     throw PackageConfigArgumentError(
         packageUri, name, "Package URIs must not have a query part");
   }
   if (packageUri.hasFragment) {
     // We could leave the fragment after the URL when resolving,
     // but it would be odd if "package:foo/foo.dart#1" and
     // "package:foo/foo.dart#2" were considered different libraries.
     // Keep the syntax open in case we ever get multiple libraries in one file.
     throw PackageConfigArgumentError(
         packageUri, name, "Package URIs must not have a fragment part");
   }
   if (packageUri.path.startsWith('/')) {
     throw PackageConfigArgumentError(
         packageUri, name, "Package URIs must not start with a '/'");
   }
   var firstSlash = packageUri.path.indexOf('/');
   if (firstSlash == -1) {
     throw PackageConfigArgumentError(packageUri, name,
         "Package URIs must start with the package name followed by a '/'");
   }
   var packageName = packageUri.path.substring(0, firstSlash);
   var badIndex = checkPackageName(packageName);
   if (badIndex >= 0) {
     if (packageName.isEmpty) {
       throw PackageConfigArgumentError(
           packageUri, name, "Package names mus be non-empty");
     }
     if (badIndex == packageName.length) {
       throw PackageConfigArgumentError(packageUri, name,
           "Package names must contain at least one non-'.' character");
     }
     assert(badIndex < packageName.length);
     var badCharCode = packageName.codeUnitAt(badIndex);
     var badChar = "U+" + badCharCode.toRadixString(16).padLeft(4, '0');
     if (badCharCode >= 0x20 && badCharCode <= 0x7e) {
       // Printable character.
       badChar = "'${packageName[badIndex]}' ($badChar)";
     }
     throw PackageConfigArgumentError(
         packageUri, name, "Package names must not contain $badChar");
   }
   return packageName;
 }

 /// Checks whether URI is just an absolute directory.
 ///
 /// * It must have a scheme.
 /// * It must not have a query or fragment.
 /// * The path must end with `/`.
 bool isAbsoluteDirectoryUri(Uri uri) {
   if (uri.hasQuery) return false;
   if (uri.hasFragment) return false;
   if (!uri.hasScheme) return false;
   var path = uri.path;
   if (!path.endsWith("/")) return false;
   return true;
 }

 /// Whether the former URI is a prefix of the latter.
 bool isUriPrefix(Uri prefix, Uri path) {
   assert(!prefix.hasFragment);
   assert(!prefix.hasQuery);
   assert(!path.hasQuery);
   assert(!path.hasFragment);
   assert(prefix.path.endsWith('/'));
   return path.toString().startsWith(prefix.toString());
 }

 /// Finds the first non-JSON-whitespace character in a file.
 ///
 /// Used to heuristically detect whether a file is a JSON file or an .ini file.
 int firstNonWhitespaceChar(List<int> bytes) {
   for (var i = 0; i < bytes.length; i++) {
     var char = bytes[i];
     if (char != 0x20 && char != 0x09 && char != 0x0a && char != 0x0d) {
       return char;
     }
   }
   return -1;
 }

 /// Attempts to return a relative path-only URI for [uri].
 ///
 /// First removes any query or fragment part from [uri].
 ///
 /// If [uri] is already relative (has no scheme), it's returned as-is.
 /// If that is not desired, the caller can pass `baseUri.resolveUri(uri)`
 /// as the [uri] instead.
 ///
 /// If the [uri] has a scheme or authority part which differs from
 /// the [baseUri], or if there is no overlap in the paths of the
 /// two URIs at all, the [uri] is returned as-is.
 ///
 /// Otherwise the result is a path-only URI which satsifies
 /// `baseUri.resolveUri(result) == uri`,
 ///
 /// The `baseUri` must be absolute.
 Uri relativizeUri(Uri uri, Uri /*?*/ baseUri) {
   if (baseUri == null) return uri;
   assert(baseUri.isAbsolute);
   if (uri.hasQuery || uri.hasFragment) {
     uri = Uri(
         scheme: uri.scheme,
         userInfo: uri.hasAuthority ? uri.userInfo : null,
         host: uri.hasAuthority ? uri.host : null,
         port: uri.hasAuthority ? uri.port : null,
         path: uri.path);
   }

   // Already relative. We assume the caller knows what they are doing.
   if (!uri.isAbsolute) return uri;

   if (baseUri.scheme != uri.scheme) {
     return uri;
   }

   // If authority differs, we could remove the scheme, but it's not worth it.
   if (uri.hasAuthority != baseUri.hasAuthority) return uri;
   if (uri.hasAuthority) {
     if (uri.userInfo != baseUri.userInfo ||
         uri.host.toLowerCase() != baseUri.host.toLowerCase() ||
         uri.port != baseUri.port) {
       return uri;
     }
   }

   baseUri = baseUri.normalizePath();
   var base = [...baseUri.pathSegments];
   if (base.isNotEmpty) base.removeLast();
   uri = uri.normalizePath();
   var target = [...uri.pathSegments];
   if (target.isNotEmpty && target.last.isEmpty) target.removeLast();
   var index = 0;
   while (index < base.length && index < target.length) {
     if (base[index] != target[index]) {
       break;
     }
     index++;
   }
   if (index == base.length) {
     if (index == target.length) {
       return Uri(path: "./");
     }
     return Uri(path: target.skip(index).join('/'));
   } else if (index > 0) {
     var buffer = StringBuffer();
     for (var n = base.length - index; n > 0; --n) {
       buffer.write("../");
     }
     buffer.writeAll(target.skip(index), "/");
     return Uri(path: buffer.toString());
   } else {
     return uri;
   }
 }

 Future<Uint8List> defaultLoader(Uri uri) async {
   if (uri.isScheme("file")) {
     var file = File.fromUri(uri);
     try {
       return file.readAsBytes();
     } catch (_) {
       return null;
     }
   }
   if (uri.isScheme("http") || uri.isScheme("https")) {
     return _httpGet(uri);
   }
   throw UnsupportedError("Default URI unsupported scheme: $uri");
 }

 Future<Uint8List /*?*/ > _httpGet(Uri uri) async {
   assert(uri.isScheme("http") || uri.isScheme("https"));
   var client = HttpClient();
   var request = await client.getUrl(uri);
   var response = await request.close();
   if (response.statusCode != HttpStatus.ok) {
     return null;
   }
   var splitContent = await response.toList();
   var totalLength = 0;
   if (splitContent.length == 1) {
     var part = splitContent[0];
     if (part is Uint8List) {
       return part;
     }
   }
   for (var list in splitContent) {
     totalLength += list.length;
   }
   var result = Uint8List(totalLength);
   var offset = 0;
   for (Uint8List contentPart in splitContent) {
     result.setRange(offset, offset + contentPart.length, contentPart);
     offset += contentPart.length;
   }
   return result;
 }

 /// The file name of a path.
 ///
 /// The file name is everything after the last occurrence of
 /// [Platform.pathSeparator], or the entire string if no
 /// path separator occurs in the string.
 String fileName(String path) {
   var separator = Platform.pathSeparator;
   var lastSeparator = path.lastIndexOf(separator);
   if (lastSeparator < 0) return path;
   return path.substring(lastSeparator + separator.length);
 }

 /// The directory name of a path.
 ///
 /// The directory name is everything before the last occurrence of
 /// [Platform.pathSeparator], or the empty string if no
 /// path separator occurs in the string.
 String dirName(String path) {
   var separator = Platform.pathSeparator;
   var lastSeparator = path.lastIndexOf(separator);
   if (lastSeparator < 0) return "";
   return path.substring(0, lastSeparator);
 }

 /// Join path parts with the [Platform.pathSeparator].
 ///
 /// If a part ends with a path separator, then no extra separator is
 /// inserted.
 String pathJoin(String part1, String part2, [String part3]) {
   var separator = Platform.pathSeparator;
   var separator1 = part1.endsWith(separator) ? "" : separator;
   if (part3 == null) {
     return "$part1$separator1$part2";
   }
   var separator2 = part2.endsWith(separator) ? "" : separator;
   return "$part1$separator1$part2$separator2$part3";
 }

 /// Join an unknown number of path parts with [Platform.pathSeparator].
 ///
 /// If a part ends with a path separator, then no extra separator is
 /// inserted.
 String pathJoinAll(Iterable<String> parts) {
   var buffer = StringBuffer();
   var separator = "";
   for (var part in parts) {
     buffer..write(separator)..write(part);
     separator =
         part.endsWith(Platform.pathSeparator) ? "" : Platform.pathSeparator;
   }
   return buffer.toString();
 }

 // Character constants used by this package.
 /// "Line feed" control character.
 const int $lf = 0x0a;

 /// "Carriage return" control character.
 const int $cr = 0x0d;

 /// Space character.
 const int $space = 0x20;

 /// Character `#`.
 const int $hash = 0x23;

 /// Character `.`.
 const int $dot = 0x2e;

 /// Character `:`.
 const int $colon = 0x3a;

 /// Character `?`.
 const int $question = 0x3f;

 /// Character `{`.
 const int $lbrace = 0x7b;
	// Copyright (c) 2019, 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.

	/// Utility methods used by more than one library in the package.
	library package_config.util;

	import 'dart:io';
	import 'dart:typed_data';

	import "errors.dart";

	// All ASCII characters that are valid in a package name, with space
	// for all the invalid ones (including space).
	const String _validPackageNameCharacters =
	r" ! $ &'()*+,-. 0123456789 ; = "
	r"@ABCDEFGHIJKLMNOPQRSTUVWXYZ _ abcdefghijklmnopqrstuvwxyz ~ ";

	/// Tests whether something is a valid Dart package name.
	bool isValidPackageName(String string) {
	return checkPackageName(string) < 0;
	}

	/// Check if a string is a valid package name.
	///
	/// Valid package names contain only characters in [_validPackageNameCharacters]
	/// and must contain at least one non-'.' character.
	///
	/// Returns `-1` if the string is valid.
	/// Otherwise returns the index of the first invalid character,
	/// or `string.length` if the string contains no non-'.' character.
	int checkPackageName(String string) {
	// Becomes non-zero if any non-'.' character is encountered.
	var nonDot = 0;
	for (var i = 0; i < string.length; i++) {
	var c = string.codeUnitAt(i);
	if (c > 0x7f \|\| _validPackageNameCharacters.codeUnitAt(c) <= $space) {
	return i;
	}
	nonDot += c ^ $dot;
	}
	if (nonDot == 0) return string.length;
	return -1;
	}

	/// Validate that a [Uri] is a valid `package:` URI.
	///
	/// Used to validate user input.
	///
	/// Returns the package name extracted from the package URI,
	/// which is the path segment between `package:` and the first `/`.
	String checkValidPackageUri(Uri packageUri, String name) {
	if (packageUri.scheme != "package") {
	throw PackageConfigArgumentError(packageUri, name, "Not a package: URI");
	}
	if (packageUri.hasAuthority) {
	throw PackageConfigArgumentError(
	packageUri, name, "Package URIs must not have a host part");
	}
	if (packageUri.hasQuery) {
	// A query makes no sense if resolved to a file: URI.
	throw PackageConfigArgumentError(
	packageUri, name, "Package URIs must not have a query part");
	}
	if (packageUri.hasFragment) {
	// We could leave the fragment after the URL when resolving,
	// but it would be odd if "package:foo/foo.dart#1" and
	// "package:foo/foo.dart#2" were considered different libraries.
	// Keep the syntax open in case we ever get multiple libraries in one file.
	throw PackageConfigArgumentError(
	packageUri, name, "Package URIs must not have a fragment part");
	}
	if (packageUri.path.startsWith('/')) {
	throw PackageConfigArgumentError(
	packageUri, name, "Package URIs must not start with a '/'");
	}
	var firstSlash = packageUri.path.indexOf('/');
	if (firstSlash == -1) {
	throw PackageConfigArgumentError(packageUri, name,
	"Package URIs must start with the package name followed by a '/'");
	}
	var packageName = packageUri.path.substring(0, firstSlash);
	var badIndex = checkPackageName(packageName);
	if (badIndex >= 0) {
	if (packageName.isEmpty) {
	throw PackageConfigArgumentError(
	packageUri, name, "Package names mus be non-empty");
	}
	if (badIndex == packageName.length) {
	throw PackageConfigArgumentError(packageUri, name,
	"Package names must contain at least one non-'.' character");
	}
	assert(badIndex < packageName.length);
	var badCharCode = packageName.codeUnitAt(badIndex);
	var badChar = "U+" + badCharCode.toRadixString(16).padLeft(4, '0');
	if (badCharCode >= 0x20 && badCharCode <= 0x7e) {
	// Printable character.
	badChar = "'${packageName[badIndex]}' ($badChar)";
	}
	throw PackageConfigArgumentError(
	packageUri, name, "Package names must not contain $badChar");
	}
	return packageName;
	}

	/// Checks whether URI is just an absolute directory.
	///
	/// * It must have a scheme.
	/// * It must not have a query or fragment.
	/// * The path must end with `/`.
	bool isAbsoluteDirectoryUri(Uri uri) {
	if (uri.hasQuery) return false;
	if (uri.hasFragment) return false;
	if (!uri.hasScheme) return false;
	var path = uri.path;
	if (!path.endsWith("/")) return false;
	return true;
	}

	/// Whether the former URI is a prefix of the latter.
	bool isUriPrefix(Uri prefix, Uri path) {
	assert(!prefix.hasFragment);
	assert(!prefix.hasQuery);
	assert(!path.hasQuery);
	assert(!path.hasFragment);
	assert(prefix.path.endsWith('/'));
	return path.toString().startsWith(prefix.toString());
	}

	/// Finds the first non-JSON-whitespace character in a file.
	///
	/// Used to heuristically detect whether a file is a JSON file or an .ini file.
	int firstNonWhitespaceChar(List<int> bytes) {
	for (var i = 0; i < bytes.length; i++) {
	var char = bytes[i];
	if (char != 0x20 && char != 0x09 && char != 0x0a && char != 0x0d) {
	return char;
	}
	}
	return -1;
	}

	/// Attempts to return a relative path-only URI for [uri].
	///
	/// First removes any query or fragment part from [uri].
	///
	/// If [uri] is already relative (has no scheme), it's returned as-is.
	/// If that is not desired, the caller can pass `baseUri.resolveUri(uri)`
	/// as the [uri] instead.
	///
	/// If the [uri] has a scheme or authority part which differs from
	/// the [baseUri], or if there is no overlap in the paths of the
	/// two URIs at all, the [uri] is returned as-is.
	///
	/// Otherwise the result is a path-only URI which satsifies
	/// `baseUri.resolveUri(result) == uri`,
	///
	/// The `baseUri` must be absolute.
	Uri relativizeUri(Uri uri, Uri /?/ baseUri) {
	if (baseUri == null) return uri;
	assert(baseUri.isAbsolute);
	if (uri.hasQuery \|\| uri.hasFragment) {
	uri = Uri(
	scheme: uri.scheme,
	userInfo: uri.hasAuthority ? uri.userInfo : null,
	host: uri.hasAuthority ? uri.host : null,
	port: uri.hasAuthority ? uri.port : null,
	path: uri.path);
	}

	// Already relative. We assume the caller knows what they are doing.
	if (!uri.isAbsolute) return uri;

	if (baseUri.scheme != uri.scheme) {
	return uri;
	}

	// If authority differs, we could remove the scheme, but it's not worth it.
	if (uri.hasAuthority != baseUri.hasAuthority) return uri;
	if (uri.hasAuthority) {
	if (uri.userInfo != baseUri.userInfo \|\|
	uri.host.toLowerCase() != baseUri.host.toLowerCase() \|\|
	uri.port != baseUri.port) {
	return uri;
	}
	}

	baseUri = baseUri.normalizePath();
	var base = [...baseUri.pathSegments];
	if (base.isNotEmpty) base.removeLast();
	uri = uri.normalizePath();
	var target = [...uri.pathSegments];
	if (target.isNotEmpty && target.last.isEmpty) target.removeLast();
	var index = 0;
	while (index < base.length && index < target.length) {
	if (base[index] != target[index]) {
	break;
	}
	index++;
	}
	if (index == base.length) {
	if (index == target.length) {
	return Uri(path: "./");
	}
	return Uri(path: target.skip(index).join('/'));
	} else if (index > 0) {
	var buffer = StringBuffer();
	for (var n = base.length - index; n > 0; --n) {
	buffer.write("../");
	}
	buffer.writeAll(target.skip(index), "/");
	return Uri(path: buffer.toString());
	} else {
	return uri;
	}
	}

	Future<Uint8List> defaultLoader(Uri uri) async {
	if (uri.isScheme("file")) {
	var file = File.fromUri(uri);
	try {
	return file.readAsBytes();
	} catch (_) {
	return null;
	}
	}
	if (uri.isScheme("http") \|\| uri.isScheme("https")) {
	return _httpGet(uri);
	}
	throw UnsupportedError("Default URI unsupported scheme: $uri");
	}

	Future<Uint8List /?/ > _httpGet(Uri uri) async {
	assert(uri.isScheme("http") \|\| uri.isScheme("https"));
	var client = HttpClient();
	var request = await client.getUrl(uri);
	var response = await request.close();
	if (response.statusCode != HttpStatus.ok) {
	return null;
	}
	var splitContent = await response.toList();
	var totalLength = 0;
	if (splitContent.length == 1) {
	var part = splitContent[0];
	if (part is Uint8List) {
	return part;
	}
	}
	for (var list in splitContent) {
	totalLength += list.length;
	}
	var result = Uint8List(totalLength);
	var offset = 0;
	for (Uint8List contentPart in splitContent) {
	result.setRange(offset, offset + contentPart.length, contentPart);
	offset += contentPart.length;
	}
	return result;
	}

	/// The file name of a path.
	///
	/// The file name is everything after the last occurrence of
	/// [Platform.pathSeparator], or the entire string if no
	/// path separator occurs in the string.
	String fileName(String path) {
	var separator = Platform.pathSeparator;
	var lastSeparator = path.lastIndexOf(separator);
	if (lastSeparator < 0) return path;
	return path.substring(lastSeparator + separator.length);
	}

	/// The directory name of a path.
	///
	/// The directory name is everything before the last occurrence of
	/// [Platform.pathSeparator], or the empty string if no
	/// path separator occurs in the string.
	String dirName(String path) {
	var separator = Platform.pathSeparator;
	var lastSeparator = path.lastIndexOf(separator);
	if (lastSeparator < 0) return "";
	return path.substring(0, lastSeparator);
	}

	/// Join path parts with the [Platform.pathSeparator].
	///
	/// If a part ends with a path separator, then no extra separator is
	/// inserted.
	String pathJoin(String part1, String part2, [String part3]) {
	var separator = Platform.pathSeparator;
	var separator1 = part1.endsWith(separator) ? "" : separator;
	if (part3 == null) {
	return "$part1$separator1$part2";
	}
	var separator2 = part2.endsWith(separator) ? "" : separator;
	return "$part1$separator1$part2$separator2$part3";
	}

	/// Join an unknown number of path parts with [Platform.pathSeparator].
	///
	/// If a part ends with a path separator, then no extra separator is
	/// inserted.
	String pathJoinAll(Iterable<String> parts) {
	var buffer = StringBuffer();
	var separator = "";
	for (var part in parts) {
	buffer..write(separator)..write(part);
	separator =
	part.endsWith(Platform.pathSeparator) ? "" : Platform.pathSeparator;
	}
	return buffer.toString();
	}

	// Character constants used by this package.
	/// "Line feed" control character.
	const int $lf = 0x0a;

	/// "Carriage return" control character.
	const int $cr = 0x0d;

	/// Space character.
	const int $space = 0x20;

	/// Character `#`.
	const int $hash = 0x23;

	/// Character `.`.
	const int $dot = 0x2e;

	/// Character `:`.
	const int $colon = 0x3a;

	/// Character `?`.
	const int $question = 0x3f;

	/// Character `{`.
	const int $lbrace = 0x7b;