Index: mojo/public/dart/third_party/string_scanner/lib/src/string_scanner.dart |
diff --git a/mojo/public/dart/third_party/string_scanner/lib/src/string_scanner.dart b/mojo/public/dart/third_party/string_scanner/lib/src/string_scanner.dart |
new file mode 100644 |
index 0000000000000000000000000000000000000000..d9c1c2fd3c109c692671508a2e514a6bd5e9ec16 |
--- /dev/null |
+++ b/mojo/public/dart/third_party/string_scanner/lib/src/string_scanner.dart |
@@ -0,0 +1,176 @@ |
+// Copyright (c) 2014, 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. |
+ |
+library string_scanner.string_scanner; |
+ |
+import 'package:source_span/source_span.dart'; |
+ |
+import 'exception.dart'; |
+import 'utils.dart'; |
+ |
+/// When compiled to JS, forward slashes are always escaped in [RegExp.pattern]. |
+/// |
+/// See issue 17998. |
+final _slashAutoEscape = new RegExp("/").pattern == "\\/"; |
+ |
+/// A class that scans through a string using [Pattern]s. |
+class StringScanner { |
+ /// The URL of the source of the string being scanned. |
+ /// |
+ /// This is used for error reporting. It may be `null`, indicating that the |
+ /// source URL is unknown or unavailable. |
+ final Uri sourceUrl; |
+ |
+ /// The string being scanned through. |
+ final String string; |
+ |
+ /// The current position of the scanner in the string, in characters. |
+ int get position => _position; |
+ set position(int position) { |
+ if (position < 0 || position > string.length) { |
+ throw new ArgumentError("Invalid position $position"); |
+ } |
+ |
+ _position = position; |
+ } |
+ int _position = 0; |
+ |
+ /// The data about the previous match made by the scanner. |
+ /// |
+ /// If the last match failed, this will be `null`. |
+ Match get lastMatch => _lastMatch; |
+ Match _lastMatch; |
+ |
+ /// The portion of the string that hasn't yet been scanned. |
+ String get rest => string.substring(position); |
+ |
+ /// Whether the scanner has completely consumed [string]. |
+ bool get isDone => position == string.length; |
+ |
+ /// Creates a new [StringScanner] that starts scanning from [position]. |
+ /// |
+ /// [position] defaults to 0, the beginning of the string. [sourceUrl] is the |
+ /// URL of the source of the string being scanned, if available. It can be |
+ /// a [String], a [Uri], or `null`. |
+ StringScanner(this.string, {sourceUrl, int position}) |
+ : sourceUrl = sourceUrl is String ? Uri.parse(sourceUrl) : sourceUrl { |
+ if (position != null) this.position = position; |
+ } |
+ |
+ /// Consumes a single character and returns its character code. |
+ /// |
+ /// This throws a [FormatException] if the string has been fully consumed. It |
+ /// doesn't affect [lastMatch]. |
+ int readChar() { |
+ if (isDone) _fail("more input"); |
+ return string.codeUnitAt(_position++); |
+ } |
+ |
+ /// Returns the character code of the character [offset] away from [position]. |
+ /// |
+ /// [offset] defaults to zero, and may be negative to inspect already-consumed |
+ /// characters. |
+ /// |
+ /// This returns `null` if [offset] points outside the string. It doesn't |
+ /// affect [lastMatch]. |
+ int peekChar([int offset]) { |
+ if (offset == null) offset = 0; |
+ var index = position + offset; |
+ if (index < 0 || index >= string.length) return null; |
+ return string.codeUnitAt(index); |
+ } |
+ |
+ /// If [pattern] matches at the current position of the string, scans forward |
+ /// until the end of the match. |
+ /// |
+ /// Returns whether or not [pattern] matched. |
+ bool scan(Pattern pattern) { |
+ var success = matches(pattern); |
+ if (success) _position = _lastMatch.end; |
+ return success; |
+ } |
+ |
+ /// If [pattern] matches at the current position of the string, scans forward |
+ /// until the end of the match. |
+ /// |
+ /// If [pattern] did not match, throws a [FormatException] describing the |
+ /// position of the failure. [name] is used in this error as the expected name |
+ /// of the pattern being matched; if it's `null`, the pattern itself is used |
+ /// instead. |
+ void expect(Pattern pattern, {String name}) { |
+ if (scan(pattern)) return; |
+ |
+ if (name == null) { |
+ if (pattern is RegExp) { |
+ var source = pattern.pattern; |
+ if (!_slashAutoEscape) source = source.replaceAll("/", "\\/"); |
+ name = "/$source/"; |
+ } else { |
+ name = |
+ pattern.toString().replaceAll("\\", "\\\\").replaceAll('"', '\\"'); |
+ name = '"$name"'; |
+ } |
+ } |
+ _fail(name); |
+ } |
+ |
+ /// If the string has not been fully consumed, this throws a |
+ /// [FormatException]. |
+ void expectDone() { |
+ if (isDone) return; |
+ _fail("no more input"); |
+ } |
+ |
+ /// Returns whether or not [pattern] matches at the current position of the |
+ /// string. |
+ /// |
+ /// This doesn't move the scan pointer forward. |
+ bool matches(Pattern pattern) { |
+ _lastMatch = pattern.matchAsPrefix(string, position); |
+ return _lastMatch != null; |
+ } |
+ |
+ /// Returns the substring of [string] between [start] and [end]. |
+ /// |
+ /// Unlike [String.substring], [end] defaults to [position] rather than the |
+ /// end of the string. |
+ String substring(int start, [int end]) { |
+ if (end == null) end = position; |
+ return string.substring(start, end); |
+ } |
+ |
+ /// Throws a [FormatException] with [message] as well as a detailed |
+ /// description of the location of the error in the string. |
+ /// |
+ /// [match] is the match information for the span of the string with which the |
+ /// error is associated. This should be a match returned by this scanner's |
+ /// [lastMatch] property. By default, the error is associated with the last |
+ /// match. |
+ /// |
+ /// If [position] and/or [length] are passed, they are used as the error span |
+ /// instead. If only [length] is passed, [position] defaults to the current |
+ /// position; if only [position] is passed, [length] defaults to 1. |
+ /// |
+ /// It's an error to pass [match] at the same time as [position] or [length]. |
+ void error(String message, {Match match, int position, int length}) { |
+ validateErrorArgs(string, match, position, length); |
+ |
+ if (match == null && position == null && length == null) match = lastMatch; |
+ if (position == null) { |
+ position = match == null ? this.position : match.start; |
+ } |
+ if (length == null) length = match == null ? 1 : match.end - match.start; |
+ |
+ var sourceFile = new SourceFile(string, url: sourceUrl); |
+ var span = sourceFile.span(position, position + length); |
+ throw new StringScannerException(message, span, string); |
+ } |
+ |
+ // TODO(nweiz): Make this handle long lines more gracefully. |
+ /// Throws a [FormatException] describing that [name] is expected at the |
+ /// current position in the string. |
+ void _fail(String name) { |
+ error("expected $name.", position: this.position, length: 0); |
+ } |
+} |