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Unified Diff: mojo/public/dart/third_party/html/lib/src/encoding_parser.dart

Issue 1346773002: Stop running pub get at gclient sync time and fix build bugs (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: Created 5 years, 3 months ago
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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);

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