Index: mojo/public/dart/third_party/html/lib/src/encoding_parser.dart |
diff --git a/mojo/public/dart/third_party/html/lib/src/encoding_parser.dart b/mojo/public/dart/third_party/html/lib/src/encoding_parser.dart |
new file mode 100644 |
index 0000000000000000000000000000000000000000..fd64ff9b01047a9ef880f17d11046e1b5f104246 |
--- /dev/null |
+++ b/mojo/public/dart/third_party/html/lib/src/encoding_parser.dart |
@@ -0,0 +1,370 @@ |
+library encoding_parser; |
+ |
+import 'constants.dart'; |
+import 'inputstream.dart'; |
+ |
+// TODO(jmesserly): I converted StopIteration to StateError("No more elements"). |
+// Seems strange to throw this from outside of an iterator though. |
+/// String-like object with an associated position and various extra methods |
+/// If the position is ever greater than the string length then an exception is |
+/// raised. |
+class EncodingBytes { |
+ final String _bytes; |
+ int _position = -1; |
+ |
+ EncodingBytes(this._bytes); |
+ |
+ int get length => _bytes.length; |
+ |
+ String next() { |
+ var p = _position = _position + 1; |
+ if (p >= length) { |
+ throw new StateError("No more elements"); |
+ } else if (p < 0) { |
+ throw new RangeError(p); |
+ } |
+ return _bytes[p]; |
+ } |
+ |
+ String previous() { |
+ var p = _position; |
+ if (p >= length) { |
+ throw new StateError("No more elements"); |
+ } else if (p < 0) { |
+ throw new RangeError(p); |
+ } |
+ _position = p = p - 1; |
+ return _bytes[p]; |
+ } |
+ |
+ set position(int value) { |
+ if (_position >= length) { |
+ throw new StateError("No more elements"); |
+ } |
+ _position = value; |
+ } |
+ |
+ int get position { |
+ if (_position >= length) { |
+ throw new StateError("No more elements"); |
+ } |
+ if (_position >= 0) { |
+ return _position; |
+ } else { |
+ return 0; |
+ } |
+ } |
+ |
+ String get currentByte => _bytes[position]; |
+ |
+ /// Skip past a list of characters. Defaults to skipping [isWhitespace]. |
+ String skipChars([CharPreciate skipChars]) { |
+ if (skipChars == null) skipChars = isWhitespace; |
+ var p = position; // use property for the error-checking |
+ while (p < length) { |
+ var c = _bytes[p]; |
+ if (!skipChars(c)) { |
+ _position = p; |
+ return c; |
+ } |
+ p += 1; |
+ } |
+ _position = p; |
+ return null; |
+ } |
+ |
+ String skipUntil(CharPreciate untilChars) { |
+ var p = position; |
+ while (p < length) { |
+ var c = _bytes[p]; |
+ if (untilChars(c)) { |
+ _position = p; |
+ return c; |
+ } |
+ p += 1; |
+ } |
+ return null; |
+ } |
+ |
+ /// Look for a sequence of bytes at the start of a string. If the bytes |
+ /// are found return true and advance the position to the byte after the |
+ /// match. Otherwise return false and leave the position alone. |
+ bool matchBytes(String bytes) { |
+ var p = position; |
+ if (_bytes.length < p + bytes.length) { |
+ return false; |
+ } |
+ var data = _bytes.substring(p, p + bytes.length); |
+ if (data == bytes) { |
+ position += bytes.length; |
+ return true; |
+ } |
+ return false; |
+ } |
+ |
+ /// Look for the next sequence of bytes matching a given sequence. If |
+ /// a match is found advance the position to the last byte of the match |
+ bool jumpTo(String bytes) { |
+ var newPosition = _bytes.indexOf(bytes, position); |
+ if (newPosition >= 0) { |
+ _position = newPosition + bytes.length - 1; |
+ return true; |
+ } else { |
+ throw new StateError("No more elements"); |
+ } |
+ } |
+ |
+ String slice(int start, [int end]) { |
+ if (end == null) end = length; |
+ if (end < 0) end += length; |
+ return _bytes.substring(start, end - start); |
+ } |
+} |
+ |
+/// Mini parser for detecting character encoding from meta elements. |
+class EncodingParser { |
+ final EncodingBytes data; |
+ String encoding; |
+ |
+ /// [bytes] - the data to work on for encoding detection. |
+ EncodingParser(List<int> bytes) |
+ // Note: this is intentionally interpreting bytes as codepoints. |
+ : data = new EncodingBytes(new String.fromCharCodes(bytes).toLowerCase()); |
+ |
+ String getEncoding() { |
+ final methodDispatch = [ |
+ ["<!--", handleComment], |
+ ["<meta", handleMeta], |
+ ["</", handlePossibleEndTag], |
+ ["<!", handleOther], |
+ ["<?", handleOther], |
+ ["<", handlePossibleStartTag] |
+ ]; |
+ |
+ try { |
+ for (;;) { |
+ for (var dispatch in methodDispatch) { |
+ if (data.matchBytes(dispatch[0])) { |
+ var keepParsing = dispatch[1](); |
+ if (keepParsing) break; |
+ |
+ // We found an encoding. Stop. |
+ return encoding; |
+ } |
+ } |
+ data.position += 1; |
+ } |
+ } on StateError catch (e) { |
+ // Catch this here to match behavior of Python's StopIteration |
+ // TODO(jmesserly): refactor to not use exceptions |
+ } |
+ return encoding; |
+ } |
+ |
+ /// Skip over comments. |
+ bool handleComment() => data.jumpTo("-->"); |
+ |
+ bool handleMeta() { |
+ if (!isWhitespace(data.currentByte)) { |
+ // if we have <meta not followed by a space so just keep going |
+ return true; |
+ } |
+ // We have a valid meta element we want to search for attributes |
+ while (true) { |
+ // Try to find the next attribute after the current position |
+ var attr = getAttribute(); |
+ if (attr == null) return true; |
+ |
+ if (attr[0] == "charset") { |
+ var tentativeEncoding = attr[1]; |
+ var codec = codecName(tentativeEncoding); |
+ if (codec != null) { |
+ encoding = codec; |
+ return false; |
+ } |
+ } else if (attr[0] == "content") { |
+ var contentParser = new ContentAttrParser(new EncodingBytes(attr[1])); |
+ var tentativeEncoding = contentParser.parse(); |
+ var codec = codecName(tentativeEncoding); |
+ if (codec != null) { |
+ encoding = codec; |
+ return false; |
+ } |
+ } |
+ } |
+ return true; // unreachable |
+ } |
+ |
+ bool handlePossibleStartTag() => handlePossibleTag(false); |
+ |
+ bool handlePossibleEndTag() { |
+ data.next(); |
+ return handlePossibleTag(true); |
+ } |
+ |
+ bool handlePossibleTag(bool endTag) { |
+ if (!isLetter(data.currentByte)) { |
+ //If the next byte is not an ascii letter either ignore this |
+ //fragment (possible start tag case) or treat it according to |
+ //handleOther |
+ if (endTag) { |
+ data.previous(); |
+ handleOther(); |
+ } |
+ return true; |
+ } |
+ |
+ var c = data.skipUntil(isSpaceOrAngleBracket); |
+ if (c == "<") { |
+ // return to the first step in the overall "two step" algorithm |
+ // reprocessing the < byte |
+ data.previous(); |
+ } else { |
+ //Read all attributes |
+ var attr = getAttribute(); |
+ while (attr != null) { |
+ attr = getAttribute(); |
+ } |
+ } |
+ return true; |
+ } |
+ |
+ bool handleOther() => data.jumpTo(">"); |
+ |
+ /// Return a name,value pair for the next attribute in the stream, |
+ /// if one is found, or null |
+ List<String> getAttribute() { |
+ // Step 1 (skip chars) |
+ var c = data.skipChars((x) => x == "/" || isWhitespace(x)); |
+ // Step 2 |
+ if (c == ">" || c == null) { |
+ return null; |
+ } |
+ // Step 3 |
+ var attrName = []; |
+ var attrValue = []; |
+ // Step 4 attribute name |
+ while (true) { |
+ if (c == null) { |
+ return null; |
+ } else if (c == "=" && attrName.length > 0) { |
+ break; |
+ } else if (isWhitespace(c)) { |
+ // Step 6! |
+ c = data.skipChars(); |
+ c = data.next(); |
+ break; |
+ } else if (c == "/" || c == ">") { |
+ return [attrName.join(), ""]; |
+ } else if (isLetter(c)) { |
+ attrName.add(c.toLowerCase()); |
+ } else { |
+ attrName.add(c); |
+ } |
+ // Step 5 |
+ c = data.next(); |
+ } |
+ // Step 7 |
+ if (c != "=") { |
+ data.previous(); |
+ return [attrName.join(), ""]; |
+ } |
+ // Step 8 |
+ data.next(); |
+ // Step 9 |
+ c = data.skipChars(); |
+ // Step 10 |
+ if (c == "'" || c == '"') { |
+ // 10.1 |
+ var quoteChar = c; |
+ while (true) { |
+ // 10.2 |
+ c = data.next(); |
+ if (c == quoteChar) { |
+ // 10.3 |
+ data.next(); |
+ return [attrName.join(), attrValue.join()]; |
+ } else if (isLetter(c)) { |
+ // 10.4 |
+ attrValue.add(c.toLowerCase()); |
+ } else { |
+ // 10.5 |
+ attrValue.add(c); |
+ } |
+ } |
+ } else if (c == ">") { |
+ return [attrName.join(), ""]; |
+ } else if (c == null) { |
+ return null; |
+ } else if (isLetter(c)) { |
+ attrValue.add(c.toLowerCase()); |
+ } else { |
+ attrValue.add(c); |
+ } |
+ // Step 11 |
+ while (true) { |
+ c = data.next(); |
+ if (isSpaceOrAngleBracket(c)) { |
+ return [attrName.join(), attrValue.join()]; |
+ } else if (c == null) { |
+ return null; |
+ } else if (isLetter(c)) { |
+ attrValue.add(c.toLowerCase()); |
+ } else { |
+ attrValue.add(c); |
+ } |
+ } |
+ return null; // unreachable |
+ } |
+} |
+ |
+class ContentAttrParser { |
+ final EncodingBytes data; |
+ |
+ ContentAttrParser(this.data); |
+ |
+ String parse() { |
+ try { |
+ // Check if the attr name is charset |
+ // otherwise return |
+ data.jumpTo("charset"); |
+ data.position += 1; |
+ data.skipChars(); |
+ if (data.currentByte != "=") { |
+ // If there is no = sign keep looking for attrs |
+ return null; |
+ } |
+ data.position += 1; |
+ data.skipChars(); |
+ // Look for an encoding between matching quote marks |
+ if (data.currentByte == '"' || data.currentByte == "'") { |
+ var quoteMark = data.currentByte; |
+ data.position += 1; |
+ var oldPosition = data.position; |
+ if (data.jumpTo(quoteMark)) { |
+ return data.slice(oldPosition, data.position); |
+ } else { |
+ return null; |
+ } |
+ } else { |
+ // Unquoted value |
+ var oldPosition = data.position; |
+ try { |
+ data.skipUntil(isWhitespace); |
+ return data.slice(oldPosition, data.position); |
+ } on StateError catch (e) { |
+ //Return the whole remaining value |
+ return data.slice(oldPosition); |
+ } |
+ } |
+ } on StateError catch (e) { |
+ return null; |
+ } |
+ } |
+} |
+ |
+bool isSpaceOrAngleBracket(String char) { |
+ return char == ">" || char == "<" || isWhitespace(char); |
+} |
+ |
+typedef bool CharPreciate(String char); |