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Unified Diff: packages/analyzer/lib/src/util/fast_uri.dart

Issue 2990843002: Removed fixed dependencies (Closed)
Patch Set: Created 3 years, 5 months ago
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Index: packages/analyzer/lib/src/util/fast_uri.dart
diff --git a/packages/analyzer/lib/src/util/fast_uri.dart b/packages/analyzer/lib/src/util/fast_uri.dart
new file mode 100644
index 0000000000000000000000000000000000000000..40681bdaae7ca21ecad90589b55ef8e265b8316c
--- /dev/null
+++ b/packages/analyzer/lib/src/util/fast_uri.dart
@@ -0,0 +1,324 @@
+// Copyright (c) 2016, 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:collection';
+
+/**
+ * Implementation of [Uri] that understands only a limited set of valid
+ * URI formats, but works fast. In practice Dart code almost always uses such
+ * limited URI format, so almost always can be processed fast.
+ */
+class FastUri implements Uri {
+ /***
+ * The maximum [_cache] length before we flush it and start a new generation.
+ */
+ static const int _MAX_CACHE_LENGTH_BEFORE_FLUSH = 50000;
+
+ static HashMap<String, Uri> _cache = new HashMap<String, Uri>();
+ static int _currentCacheLength = 0;
+ static int _currentCacheGeneration = 0;
+
+ static bool _hashUsingText = _shouldComputeHashCodeUsingText();
+
+ final int _cacheGeneration;
+ final String _text;
+ final String _scheme;
+ final bool _hasEmptyAuthority;
+ final String _path;
+
+ /**
+ * The offset of the last `/` in [_text], or `null` if there isn't any.
+ */
+ final int _lastSlashIndex;
+
+ /**
+ * The cached hash code.
+ */
+ int _hashCode;
+
+ Uri _cachedFallbackUri;
+
+ FastUri._(this._cacheGeneration, this._text, this._scheme,
+ this._hasEmptyAuthority, this._path, this._lastSlashIndex);
+
+ @override
+ String get authority => '';
+
+ @override
+ UriData get data => null;
+
+ @override
+ String get fragment => '';
+
+ @override
+ bool get hasAbsolutePath => path.startsWith('/');
+
+ @override
+ bool get hasAuthority => _hasEmptyAuthority;
+
+ @override
+ bool get hasEmptyPath => _path.isEmpty;
+
+ @override
+ bool get hasFragment => false;
+
+ @override
+ int get hashCode {
+ return _hashCode ??= _hashUsingText
+ ? _computeHashUsingText(this)
+ : _computeHashUsingCombine(this);
+ }
+
+ @override
+ bool get hasPort => false;
+
+ @override
+ bool get hasQuery => false;
+
+ @override
+ bool get hasScheme => _scheme.isNotEmpty;
+
+ @override
+ String get host => '';
+
+ @override
+ bool get isAbsolute => hasScheme;
+
+ @override
+ String get origin => _fallbackUri.origin;
+
+ @override
+ String get path => _path;
+
+ @override
+ List<String> get pathSegments => _fallbackUri.pathSegments;
+
+ @override
+ int get port => 0;
+
+ @override
+ String get query => '';
+
+ @override
+ Map<String, String> get queryParameters => const <String, String>{};
+
+ @override
+ Map<String, List<String>> get queryParametersAll =>
+ const <String, List<String>>{};
+
+ @override
+ String get scheme => _scheme;
+
+ @override
+ String get userInfo => '';
+
+ /**
+ * Full [Uri] object computed on demand; we fall back to this for some of the
+ * more complex methods of [Uri] that are less in need of a fast
+ * implementation.
+ */
+ Uri get _fallbackUri => _cachedFallbackUri ??= Uri.parse(_text);
+
+ @override
+ bool operator ==(other) {
+ if (other is FastUri) {
+ if (other._cacheGeneration == _cacheGeneration) {
+ return identical(other, this);
+ }
+ return _text == other._text;
+ } else if (other is Uri) {
+ return _fallbackUri == other;
+ }
+ return false;
+ }
+
+ @override
+ Uri normalizePath() {
+ return this;
+ }
+
+ @override
+ Uri removeFragment() {
+ return this;
+ }
+
+ @override
+ Uri replace(
+ {String scheme,
+ String userInfo,
+ String host,
+ int port,
+ String path,
+ Iterable<String> pathSegments,
+ String query,
+ Map<String, dynamic> queryParameters,
+ String fragment}) {
+ return _fallbackUri.replace(
+ scheme: scheme,
+ userInfo: userInfo,
+ host: host,
+ port: port,
+ path: path,
+ pathSegments: pathSegments,
+ query: query,
+ queryParameters: queryParameters,
+ fragment: fragment);
+ }
+
+ @override
+ Uri resolve(String reference) {
+ // TODO: maybe implement faster
+ return _fallbackUri.resolve(reference);
+ }
+
+ @override
+ Uri resolveUri(Uri reference) {
+ if (reference.hasScheme) {
+ return reference;
+ }
+ String refPath = reference.path;
+ if (refPath.startsWith('./')) {
+ refPath = refPath.substring(2);
+ }
+ if (refPath.startsWith('../') ||
+ refPath.contains('/../') ||
+ refPath.contains('/./')) {
+ Uri slowResult = _fallbackUri.resolveUri(reference);
+ return FastUri.parse(slowResult.toString());
+ }
+ String newText;
+ if (_lastSlashIndex != null) {
+ newText = _text.substring(0, _lastSlashIndex + 1) + refPath;
+ } else {
+ newText = _text + '/' + refPath;
+ }
+ return FastUri.parse(newText);
+ }
+
+ @override
+ String toFilePath({bool windows}) {
+ return _fallbackUri.toFilePath(windows: windows);
+ }
+
+ @override
+ String toString() => _text;
+
+ /**
+ * Parse the given URI [text] and return the corresponding [Uri] instance. If
+ * the [text] can be represented as a [FastUri], then it is returned. If the
+ * [text] is more complex, then `dart:core` [Uri] is created and returned.
+ * This method also performs memoization, so that usually the same instance
+ * of [FastUri] or [Uri] is returned for the same [text].
+ */
+ static Uri parse(String text) {
+ Uri uri = _cache[text];
+ if (uri == null) {
+ uri = _parse(text);
+ uri ??= Uri.parse(text);
+ _cache[text] = uri;
+ _currentCacheLength++;
+ // If the cache is too big, start a new generation.
+ if (_currentCacheLength > _MAX_CACHE_LENGTH_BEFORE_FLUSH) {
+ _cache.clear();
+ _currentCacheLength = 0;
+ _currentCacheGeneration++;
+ }
+ }
+ return uri;
+ }
+
+ /**
+ * This implementation was used before 'fast-URI' in Dart VM.
+ */
+ static int _computeHashUsingCombine(FastUri uri) {
+ // This code is copied from the standard Uri implementation.
+ // It is important that Uri and FastUri generate compatible hashCodes
+ // because Uri and FastUri may be used as keys in the same map.
+ int combine(part, current) {
+ // The sum is truncated to 30 bits to make sure it fits into a Smi.
+ return (current * 31 + part.hashCode) & 0x3FFFFFFF;
+ }
+
+ return combine(
+ uri.scheme,
+ combine(
+ uri.userInfo,
+ combine(
+ uri.host,
+ combine(
+ uri.port,
+ combine(uri.path,
+ combine(uri.query, combine(uri.fragment, 1)))))));
+ }
+
+ /**
+ * This implementation should be used with 'fast-URI' in Dart VM.
+ * https://github.com/dart-lang/sdk/commit/afbbbb97cfcd86a64d0ba5dcfe1ab758954adaf4
+ */
+ static int _computeHashUsingText(FastUri uri) {
+ return uri._text.hashCode;
+ }
+
+ static bool _isAlphabetic(int char) {
+ return char >= 'A'.codeUnitAt(0) && char <= 'Z'.codeUnitAt(0) ||
+ char >= 'a'.codeUnitAt(0) && char <= 'z'.codeUnitAt(0);
+ }
+
+ static bool _isDigit(int char) {
+ return char >= '0'.codeUnitAt(0) && char <= '9'.codeUnitAt(0);
+ }
+
+ /**
+ * Parse the given [text] into a new [FastUri]. If the [text] uses URI
+ * features that are not supported by [FastUri], return `null`.
+ */
+ static FastUri _parse(String text) {
+ int schemeEnd = null;
+ int pathStart = 0;
+ int lastSlashIndex = null;
+ for (int i = 0; i < text.length; i++) {
+ int char = text.codeUnitAt(i);
+ if (_isAlphabetic(char) ||
+ _isDigit(char) ||
+ char == '.'.codeUnitAt(0) ||
+ char == '-'.codeUnitAt(0) ||
+ char == '_'.codeUnitAt(0)) {
+ // Valid characters.
+ } else if (char == '/'.codeUnitAt(0)) {
+ lastSlashIndex = i;
+ } else if (char == ':'.codeUnitAt(0)) {
+ if (schemeEnd != null) {
+ return null;
+ }
+ schemeEnd = i;
+ pathStart = i + 1;
+ } else {
+ return null;
+ }
+ }
+ String scheme = schemeEnd != null ? text.substring(0, schemeEnd) : '';
+ bool hasEmptyAuthority = false;
+ String path = text.substring(pathStart);
+ if (path.startsWith('//')) {
+ hasEmptyAuthority = true;
+ path = path.substring(2);
+ if (!path.startsWith('/')) {
+ return null;
+ }
+ }
+ return new FastUri._(_currentCacheGeneration, text, scheme,
+ hasEmptyAuthority, path, lastSlashIndex);
+ }
+
+ /**
+ * Determine whether VM has the text based hash code computation in [Uri],
+ * or the old combine style.
+ *
+ * See https://github.com/dart-lang/sdk/issues/27159 for details.
+ */
+ static bool _shouldComputeHashCodeUsingText() {
+ String text = 'package:foo/foo.dart';
+ return Uri.parse(text).hashCode == text.hashCode;
+ }
+}
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