dgrove@google.com
4bc64b8c2b
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@7 260f80e4-7a28-3924-810f-c04153c831b5
487 lines
13 KiB
Dart
487 lines
13 KiB
Dart
// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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/**
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* Base class for simple recursive descent parsers.
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* Handles the lower level stuff, i.e. what a scanner/tokenizer would do.
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*/
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class _Parser {
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static final WHITESPACE = ' \r\n\t';
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// TODO(jmesserly): shouldn't need this optimization, but dart_json parser
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// found that they needed this.
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static final A_BIG = 65; // 'A'.charCodeAt(0)
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static final Z_BIG = 90; // 'Z'.charCodeAt(0)
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static final A_SMALL = 97; // 'a'.charCodeAt(0)
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static final Z_SMALL = 122; // 'z'.charCodeAt(0)
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static final TAB = 9; // '\t'.charCodeAt(0)
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static final NEW_LINE = 10; // '\n'.charCodeAt(0)
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static final LINE_FEED = 13; // '\r'.charCodeAt(0)
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static final SPACE = 32; // ' '.charCodeAt(0)
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static final ZERO = 48; // '0'.charCodeAt(0)
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static final NINE = 57; // '9'.charCodeAt(0)
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static final DOT = 46; // '.'.charCodeAt(0)
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static final R_PAREN = 41; // ')'.charCodeAt(0)
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final String _src;
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int _offset;
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// TODO(jmesserly): should be this._offset = 0, see bug 5332175.
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_Parser(this._src) : _offset = 0;
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// TODO(jmesserly): these should exist in the standard lib.
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// I took this from dart_json.dart
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static bool _isWhitespace(int c) {
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switch (c) {
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case SPACE:
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case TAB:
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case NEW_LINE:
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case LINE_FEED:
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return true;
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}
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return false;
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}
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static bool _isDigit(int c) {
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return (ZERO <= c) && (c <= NINE);
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}
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static bool _isLetter(int c) {
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return (A_SMALL <= c) && (c <= Z_SMALL) || (A_BIG <= c) && (c <= Z_BIG);
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}
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void _error(String msg) {
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throw new SyntaxErrorException(msg, _src, _offset);
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}
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int get length() => _src.length;
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int get remaining() => _src.length - _offset;
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int _peekChar() => _src.charCodeAt(_offset);
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bool get endOfInput() => _offset >= _src.length;
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bool _maybeEatWhitespace() {
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int start = _offset;
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while (_offset < length && _isWhitespace(_peekChar())) {
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_offset++;
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}
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return _offset != start;
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}
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bool _maybeEatMultiLineComment() {
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if (_maybeEat('/*', /*eatWhitespace:*/false)) {
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while (!_maybeEat('*/', /*eatWhitespace:*/false)) {
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if (_offset >= length) {
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_error('expected */');
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}
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_offset++;
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}
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return true;
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}
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return false;
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}
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void _maybeEatWhitespaceOrComments() {
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while (_maybeEatWhitespace() || _maybeEatMultiLineComment()) {}
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}
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void _eatEnd() {
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_maybeEatWhitespaceOrComments();
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if (!endOfInput) {
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_error('expected end of input');
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}
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}
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bool _maybeEat(String value, [bool eatWhitespace = true]) {
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if (eatWhitespace) {
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_maybeEatWhitespaceOrComments();
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}
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if (remaining < value.length) {
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return false;
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}
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for (int i = 0; i < value.length; i++) {
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if (_src[_offset + i] != value[i]) {
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return false;
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}
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}
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// If we're eating something that's like a word, make sure
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// it's not followed by more characters.
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// This is ugly. Proper tokenization would make this cleaner.
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if (_isLetter(value.charCodeAt(value.length - 1))) {
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int i = _offset + value.length;
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if (i < _src.length && _isLetter(_src.charCodeAt(i))) {
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return false;
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}
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}
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_offset += value.length;
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return true;
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}
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void _eat(String value, [bool eatWhitespace = true]) {
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if (!_maybeEat(value)) {
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_error('expected "$value"');
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}
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}
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String _maybeEatString() {
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// TODO(jmesserly): make this match CSS string parsing
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String quote = "'";
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if (!_maybeEat(quote)) {
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quote = '"';
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if (!_maybeEat(quote)) {
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return null;
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}
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}
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bool hasEscape = false;
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int start = _offset;
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while (!_maybeEat(quote)) {
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if (endOfInput) {
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_error('expected "$quote"');
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}
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if (_maybeEat('\\')) {
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hasEscape = true;
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}
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_offset++;
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}
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String result = _src.substring(start, _offset - 1);
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if (hasEscape) {
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// TODO(jmesserly): more escape sequences
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result = result.replaceFirst('\\', '');
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}
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return result;
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}
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/** Eats something like a keyword. */
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String _eatWord() {
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int start = _offset;
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while (_offset < length && _isLetter(_peekChar())) {
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_offset++;
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}
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return _src.substring(start, _offset);
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}
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/** Eats an integer. */
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int _maybeEatInt() {
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int start = _offset;
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bool dot = false;
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while (_offset < length && _isDigit(_peekChar())) {
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_offset++;
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}
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if (start == _offset) {
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return null;
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}
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return Math.parseInt(_src.substring(start, _offset));
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}
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/** Eats an integer. */
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int _eatInt() {
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int result = _maybeEatInt();
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if (result == null) {
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_error('expected positive integer');
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}
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return result;
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}
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/** Eats something like a positive decimal: 12.345. */
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num _eatDouble() {
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int start = _offset;
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bool dot = false;
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while (_offset < length) {
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int c = _peekChar();
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if (!_isDigit(c)) {
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if (c == DOT && !dot) {
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dot = true;
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} else {
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// Not a digit or decimal seperator
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break;
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}
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}
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_offset++;
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}
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if (start == _offset) {
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_error('expected positive decimal number');
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}
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return Math.parseDouble(_src.substring(start, _offset));
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}
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}
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/** Parses a grid template. */
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class _GridTemplateParser extends _Parser {
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_GridTemplateParser._internal(String src) : super(src);
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/** Parses the grid-rows and grid-columns CSS properties into object form. */
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static GridTemplate parse(String str) {
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if (str == null) return null;
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final p = new _GridTemplateParser._internal(str);
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final result = p._parseTemplate();
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p._eatEnd();
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return result;
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}
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/** Parses a grid-cell value. */
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static String parseCell(String str) {
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if (str == null) return null;
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final p = new _GridTemplateParser._internal(str);
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final result = p._maybeEatString();
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p._eatEnd();
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return result;
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}
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// => <string>+ | 'none'
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GridTemplate _parseTemplate() {
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if (_maybeEat('none')) {
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return null;
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}
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final rows = new List<String>();
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String row;
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while ((row = _maybeEatString()) != null) {
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rows.add(row);
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}
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if (rows.length == 0) {
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_error('expected at least one cell, or "none"');
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}
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return new GridTemplate(rows);
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}
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}
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/** Parses a grid-row or grid-column */
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class _GridItemParser extends _Parser {
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_GridItemParser._internal(String src) : super(src);
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/** Parses the grid-rows and grid-columns CSS properties into object form. */
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static _GridLocation parse(String cell, GridTrackList list) {
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if (cell == null) return null;
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final p = new _GridItemParser._internal(cell);
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final result = p._parseTrack(list);
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p._eatEnd();
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return result;
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}
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// [ [ <integer> | <string> | 'start' | 'end' ]
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// [ <integer> | <string> | 'start' | 'end' ]? ]
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// | 'auto'
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_GridLocation _parseTrack(GridTrackList list) {
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if (_maybeEat('auto')) {
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return null;
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}
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int start = _maybeParseLine(list);
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if (start == null) {
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_error('expected row/column number or name');
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}
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int end = _maybeParseLine(list);
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int span = null;
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if (end != null) {
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span = end - start;
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if (span <= 0) {
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_error('expected row/column span to be a positive integer');
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}
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}
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return new _GridLocation(start, span);
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}
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// [ <integer> | <string> | 'start' | 'end' ]
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int _maybeParseLine(GridTrackList list) {
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if (_maybeEat('start')) {
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return 1;
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} else if (_maybeEat('end')) {
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// The end is exclusive and 1-based, so return one past the size of the
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// track list.
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// TODO(jmesserly): this won't interact properly with implicit
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// rows/columns. Instead it will snap to the number of tracks at the point
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// where it is evaluated.
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return list.tracks.length + 1;
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}
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String name = _maybeEatString();
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if (name == null) {
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return _maybeEatInt();
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} else {
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int edge = list.lineNames[name];
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if (edge == null) {
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_error('row/column name "$name" not found in the parent\'s '
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+ ' grid-row/grid-columns properties');
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}
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return edge;
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}
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}
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}
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/**
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* Parses grid-rows and grid-column properties, see:
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* [http://dev.w3.org/csswg/css3-grid-align/#grid-columns-and-rows-properties]
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* This is kept as a recursive descent parser for simplicity.
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*/
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// TODO(jmesserly): implement missing features from the spec. Mainly around
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// CSS units, support for all escape sequences, etc.
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class _GridTrackParser extends _Parser {
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final List<GridTrack> _tracks;
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final Map<String, int> _lineNames;
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_GridTrackParser._internal(String src)
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: super(src),
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_tracks = new List<GridTrack>(),
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_lineNames = new Map<String, int>();
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/** Parses the grid-rows and grid-columns CSS properties into object form. */
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static GridTrackList parse(String str) {
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if (str == null) return null;
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final p = new _GridTrackParser._internal(str);
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final result = p._parseTrackList();
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p._eatEnd();
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return result;
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}
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/**
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* Parses the grid-row-sizing and grid-column-sizing CSS properties into
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* object form.
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*/
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static TrackSizing parseTrackSizing(String str) {
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if (str == null) str = 'auto';
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final p = new _GridTrackParser._internal(str);
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final result = p._parseTrackMinmax();
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p._eatEnd();
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return result;
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}
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// <track-list> => [ [ <string> ]* <track-group> [ <string> ]* ]+ | 'none'
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GridTrackList _parseTrackList() {
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if (_maybeEat('none')) {
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return null;
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}
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_parseTrackListHelper();
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return new GridTrackList(_tracks, _lineNames);
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}
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/** Code shared by _parseTrackList and _parseTrackGroup */
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void _parseTrackListHelper([List<GridTrack> resultTracks = null]) {
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_maybeEatWhitespace();
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while (!endOfInput) {
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String name;
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while ((name = _maybeEatString()) != null) {
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_lineNames[name] = _tracks.length + 1; // should be 1-based
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}
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_maybeEatWhitespace();
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if (endOfInput) {
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return;
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}
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if (resultTracks != null) {
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if (_peekChar() == R_PAREN) {
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return;
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}
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resultTracks.add(new GridTrack(_parseTrackMinmax()));
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} else {
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_parseTrackGroup();
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}
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_maybeEatWhitespace();
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}
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}
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// <track-group> => [ '(' [ [ <string> ]* <track-minmax> [ <string> ]* ]+ ')'
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// [ '[' <positive-number> ']' ]? ]
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// | <track-minmax>
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void _parseTrackGroup() {
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if (_maybeEat('(')) {
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final tracks = new List<GridTrack>();
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_parseTrackListHelper(tracks);
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_eat(')');
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if (_maybeEat('[')) {
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num expand = _eatInt();
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_eat(']');
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if (expand <= 0) {
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_error('expected positive number');
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}
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// Repeat the track definition (but not the names) the specified number
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// of times. See:
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// http://dev.w3.org/csswg/css3-grid-align/#grid-repeating-columns-and-rows
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for (int i = 0; i < expand; i++) {
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for (GridTrack t in tracks) {
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_tracks.add(t.clone());
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}
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}
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}
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} else {
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_tracks.add(new GridTrack(_parseTrackMinmax()));
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}
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}
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// <track-minmax> => 'minmax(' <track-breadth> ',' <track-breadth> ')'
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// | 'auto' | <track-breadth>
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TrackSizing _parseTrackMinmax() {
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if (_maybeEat('auto') || _maybeEat('fit-content')) {
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return const TrackSizing.auto();
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}
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if (_maybeEat('minmax(')) {
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final min = _parseTrackBreadth();
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_eat(',');
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final max = _parseTrackBreadth();
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_eat(')');
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return new TrackSizing(min, max);
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} else {
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final breadth = _parseTrackBreadth();
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return new TrackSizing(breadth, breadth);
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}
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}
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// <track-breadth> => <length> | <percentage> | <fraction>
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// | 'min-content' | 'max-content'
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SizingFunction _parseTrackBreadth() {
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if (_maybeEat('min-content')) {
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return const MinContentSizing();
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} else if (_maybeEat('max-content')) {
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return const MaxContentSizing();
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}
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num value = _eatDouble();
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String units;
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if (_maybeEat('%')) {
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units = '%';
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} else {
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units = _eatWord();
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}
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if (units == 'fr') {
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return new FractionSizing(value);
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} else {
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return new FixedSizing(value, units);
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}
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}
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}
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/**
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* Exception thrown because the grid style properties had incorrect values.
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*/
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class SyntaxErrorException implements Exception {
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final String _message;
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final int _offset;
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final String _source;
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const SyntaxErrorException(this._message, this._source, this._offset);
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String toString() {
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String location;
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if (_offset < _source.length) {
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location = 'location: ' + _source.substringToEnd(_offset);
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} else {
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location = 'end of input';
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}
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return 'SyntaxErrorException: $_message at $location';
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}
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}
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