Update charted to 0.4.8 and roll

packages/intl/lib/src/intl/bidi_utils.dart

 // Copyright (c) 2012, 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.
 
 part of intl;
 
-/**
- * Bidi stands for Bi-directional text.
- * According to http://en.wikipedia.org/wiki/Bi-directional_text:
- * Bi-directional text is text containing text in both text directionalities,
- * both right-to-left (RTL) and left-to-right (LTR). It generally involves text
- * containing different types of alphabets, but may also refer to boustrophedon,
- * which is changing text directionality in each row.
- *
- * This file provides some utility classes for determining directionality of
- * text, switching CSS layout from LTR to RTL, and other normalizing utilities
- * needed when switching between RTL and LTR formatting.
- *
- * It defines the TextDirection class which is used to represent directionality
- * of text,
- * In most cases, it is preferable to use bidi_formatter.dart, which provides
- * bidi functionality in the given directional context, instead of using
- * bidi_utils.dart directly.
- */
+/// Bidi stands for Bi-directional text.  According to
+/// http://en.wikipedia.org/wiki/Bi-directional_text: Bi-directional text is
+/// text containing text in both text directionalities, both right-to-left (RTL)
+/// and left-to-right (LTR). It generally involves text containing different
+/// types of alphabets, but may also refer to boustrophedon, which is changing
+/// text directionality in each row.
+///
+/// This file provides some utility classes for determining directionality of
+/// text, switching CSS layout from LTR to RTL, and other normalizing utilities
+/// needed when switching between RTL and LTR formatting.
+///
+/// It defines the TextDirection class which is used to represent directionality
+/// of text,
+/// In most cases, it is preferable to use bidi_formatter.dart, which provides
+/// bidi functionality in the given directional context, instead of using
+/// bidi_utils.dart directly.
 class TextDirection {
   static const LTR = const TextDirection._('LTR', 'ltr');
   static const RTL = const TextDirection._('RTL', 'rtl');
   // If the directionality of the text cannot be determined and we are not using
   // the context direction (or if the context direction is unknown), then the
   // text falls back on the more common ltr direction.
   static const UNKNOWN = const TextDirection._('UNKNOWN', 'ltr');
 
-  /**
-   * Textual representation of the directionality constant. One of
-   * 'LTR', 'RTL', or 'UNKNOWN'.
-   */
+  /// Textual representation of the directionality constant. One of
+  /// 'LTR', 'RTL', or 'UNKNOWN'.
   final String value;
 
-  /** Textual representation of the directionality when used in span tag. */
+  /// Textual representation of the directionality when used in span tag.
   final String spanText;
 
   const TextDirection._(this.value, this.spanText);
 
-  /**
-   * Returns true if [otherDirection] is known to be different from this
-   * direction.
-   */
+  /// Returns true if [otherDirection] is known to be different from this
+  /// direction.
   bool isDirectionChange(TextDirection otherDirection) =>
       otherDirection != TextDirection.UNKNOWN && this != otherDirection;
 }
 
-/**
- * This provides utility methods for working with bidirectional text. All
- * of the methods are static, and are organized into a class primarily to
- * group them together for documentation and discoverability.
- */
+/// This provides utility methods for working with bidirectional text. All
+/// of the methods are static, and are organized into a class primarily to
+/// group them together for documentation and discoverability.
 class Bidi {
-
-  /** Unicode "Left-To-Right Embedding" (LRE) character. */
+  /// Unicode "Left-To-Right Embedding" (LRE) character.
   static const LRE = '\u202A';
 
-  /** Unicode "Right-To-Left Embedding" (RLE) character. */
+  /// Unicode "Right-To-Left Embedding" (RLE) character.
   static const RLE = '\u202B';
 
-  /** Unicode "Pop Directional Formatting" (PDF) character. */
+  /// Unicode "Pop Directional Formatting" (PDF) character.
   static const PDF = '\u202C';
 
-  /** Unicode "Left-To-Right Mark" (LRM) character. */
+  /// Unicode "Left-To-Right Mark" (LRM) character.
   static const LRM = '\u200E';
 
-  /** Unicode "Right-To-Left Mark" (RLM) character. */
+  /// Unicode "Right-To-Left Mark" (RLM) character.
   static const RLM = '\u200F';
 
-  /** Constant to define the threshold of RTL directionality. */
+  /// Constant to define the threshold of RTL directionality.
   static num _RTL_DETECTION_THRESHOLD = 0.40;
 
-  /**
-   * Practical patterns to identify strong LTR and RTL characters, respectively.
-   * These patterns are not completely correct according to the Unicode
-   * standard. They are simplified for performance and small code size.
-   */
+  /// Practical patterns to identify strong LTR and RTL characters,
+  /// respectively.  These patterns are not completely correct according to the
+  /// Unicode standard. They are simplified for performance and small code size.
   static const String _LTR_CHARS =
       r'A-Za-z\u00C0-\u00D6\u00D8-\u00F6\u00F8-\u02B8\u0300-\u0590'
       r'\u0800-\u1FFF\u2C00-\uFB1C\uFDFE-\uFE6F\uFEFD-\uFFFF';
   static const String _RTL_CHARS = r'\u0591-\u07FF\uFB1D-\uFDFD\uFE70-\uFEFC';
 
-  /**
-   * Returns the input [text] with spaces instead of HTML tags or HTML escapes,
-   * which is helpful for text directionality estimation.
-   * Note: This function should not be used in other contexts.
-   * It does not deal well with many things: comments, script,
-   * elements, style elements, dir attribute,`>` in quoted attribute values,
-   * etc. But it does handle well enough the most common use cases.
-   * Since the worst that can happen as a result of these shortcomings is that
-   * the wrong directionality will be estimated, we have not invested in
-   * improving this.
-   */
+  /// Returns the input [text] with spaces instead of HTML tags or HTML escapes,
+  /// which is helpful for text directionality estimation.
+  /// Note: This function should not be used in other contexts.
+  /// It does not deal well with many things: comments, script,
+  /// elements, style elements, dir attribute,`>` in quoted attribute values,
+  /// etc. But it does handle well enough the most common use cases.
+  /// Since the worst that can happen as a result of these shortcomings is that
+  /// the wrong directionality will be estimated, we have not invested in
+  /// improving this.
   static String stripHtmlIfNeeded(String text) {
     // The regular expression is simplified for an HTML tag (opening or
     // closing) or an HTML escape. We might want to skip over such expressions
     // when estimating the text directionality.
     return text.replaceAll(new RegExp(r'<[^>]*>|&[^;]+;'), ' ');
   }
 
-  /**
-   * Determines if the first character in [text] with strong directionality is
-   * LTR. If [isHtml] is true, the text is HTML or HTML-escaped.
-   */
+  /// Determines if the first character in [text] with strong directionality is
+  /// LTR. If [isHtml] is true, the text is HTML or HTML-escaped.
   static bool startsWithLtr(String text, [isHtml = false]) {
     return new RegExp('^[^$_RTL_CHARS]*[$_LTR_CHARS]')
         .hasMatch(isHtml ? stripHtmlIfNeeded(text) : text);
   }
 
-  /**
-   * Determines if the first character in [text] with strong directionality is
-   * RTL. If [isHtml] is true, the text is HTML or HTML-escaped.
-   */
+  /// Determines if the first character in [text] with strong directionality is
+  /// RTL. If [isHtml] is true, the text is HTML or HTML-escaped.
   static bool startsWithRtl(String text, [isHtml = false]) {
     return new RegExp('^[^$_LTR_CHARS]*[$_RTL_CHARS]')
         .hasMatch(isHtml ? stripHtmlIfNeeded(text) : text);
   }
 
-  /**
-   * Determines if the exit directionality (ie, the last strongly-directional
-   * character in [text] is LTR. If [isHtml] is true, the text is HTML or
-   * HTML-escaped.
-   */
+  /// Determines if the exit directionality (ie, the last strongly-directional
+  /// character in [text] is LTR. If [isHtml] is true, the text is HTML or
+  /// HTML-escaped.
   static bool endsWithLtr(String text, [isHtml = false]) {
     return new RegExp('[$_LTR_CHARS][^$_RTL_CHARS]*\$')
         .hasMatch(isHtml ? stripHtmlIfNeeded(text) : text);
   }
 
-  /**
-   * Determines if the exit directionality (ie, the last strongly-directional
-   * character in [text] is RTL. If [isHtml] is true, the text is HTML or
-   * HTML-escaped.
-   */
+  /// Determines if the exit directionality (ie, the last strongly-directional
+  /// character in [text] is RTL. If [isHtml] is true, the text is HTML or
+  /// HTML-escaped.
   static bool endsWithRtl(String text, [isHtml = false]) {
     return new RegExp('[$_RTL_CHARS][^$_LTR_CHARS]*\$')
         .hasMatch(isHtml ? stripHtmlIfNeeded(text) : text);
   }
 
-  /**
-   * Determines if the given [text] has any LTR characters in it.
-   * If [isHtml] is true, the text is HTML or HTML-escaped.
-   */
+  /// Determines if the given [text] has any LTR characters in it.
+  /// If [isHtml] is true, the text is HTML or HTML-escaped.
   static bool hasAnyLtr(String text, [isHtml = false]) {
     return new RegExp(r'[' '$_LTR_CHARS' r']')
         .hasMatch(isHtml ? stripHtmlIfNeeded(text) : text);
   }
 
-  /**
-   * Determines if the given [text] has any RTL characters in it.
-   * If [isHtml] is true, the text is HTML or HTML-escaped.
-   */
+  /// Determines if the given [text] has any RTL characters in it.
+  /// If [isHtml] is true, the text is HTML or HTML-escaped.
   static bool hasAnyRtl(String text, [isHtml = false]) {
     return new RegExp(r'[' '$_RTL_CHARS' r']')
         .hasMatch(isHtml ? stripHtmlIfNeeded(text) : text);
   }
 
-  /**
-   * Check if a BCP 47 / III [languageString] indicates an RTL language.
-   *
-   * i.e. either:
-   * - a language code explicitly specifying one of the right-to-left scripts,
-   *   e.g. "az-Arab", or
-   * - a language code specifying one of the languages normally written in a
-   *   right-to-left script, e.g. "fa" (Farsi), except ones explicitly
-   *   specifying Latin or Cyrillic script (which are the usual LTR
-   *   alternatives).
-   *
-   * The list of right-to-left scripts appears in the 100-199 range in
-   * http://www.unicode.org/iso15924/iso15924-num.html, of which Arabic and
-   * Hebrew are by far the most widely used. We also recognize Thaana, N'Ko, and
-   * Tifinagh, which also have significant modern usage. The rest (Syriac,
-   * Samaritan, Mandaic, etc.) seem to have extremely limited or no modern usage
-   * and are not recognized.
-   * The languages usually written in a right-to-left script are taken as those
-   * with Suppress-Script: Hebr|Arab|Thaa|Nkoo|Tfng  in
-   * http://www.iana.org/assignments/language-subtag-registry,
-   * as well as Sindhi (sd) and Uyghur (ug).
-   * The presence of other subtags of the language code, e.g. regions like EG
-   * (Egypt), is ignored.
-   */
-  static bool isRtlLanguage(String languageString) {
-    return new RegExp(r'^(ar|dv|he|iw|fa|nqo|ps|sd|ug|ur|yi|.*[-_]'
-        r'(Arab|Hebr|Thaa|Nkoo|Tfng))(?!.*[-_](Latn|Cyrl)($|-|_))'
-        r'($|-|_)', caseSensitive: false).hasMatch(languageString);
+  static final _rtlLocaleRegex = new RegExp(
+      r'^(ar|dv|he|iw|fa|nqo|ps|sd|ug|ur|yi|.*[-_]'
+      r'(Arab|Hebr|Thaa|Nkoo|Tfng))(?!.*[-_](Latn|Cyrl)($|-|_))'
+      r'($|-|_)',
+      caseSensitive: false);
+
+  static String _lastLocaleCheckedForRtl;
+  static bool _lastRtlCheck;
+
+  /// Check if a BCP 47 / III [languageString] indicates an RTL language.
+  ///
+  /// i.e. either:
+  /// - a language code explicitly specifying one of the right-to-left scripts,
+  ///   e.g. "az-Arab", or
+  /// - a language code specifying one of the languages normally written in a
+  ///   right-to-left script, e.g. "fa" (Farsi), except ones explicitly
+  ///   specifying Latin or Cyrillic script (which are the usual LTR
+  ///   alternatives).
+  ///
+  /// The list of right-to-left scripts appears in the 100-199 range in
+  /// http://www.unicode.org/iso15924/iso15924-num.html, of which Arabic and
+  /// Hebrew are by far the most widely used. We also recognize Thaana, N'Ko,
+  /// and Tifinagh, which also have significant modern usage. The rest (Syriac,
+  /// Samaritan, Mandaic, etc.) seem to have extremely limited or no modern
+  /// usage and are not recognized.  The languages usually written in a
+  /// right-to-left script are taken as those with Suppress-Script:
+  /// Hebr|Arab|Thaa|Nkoo|Tfng in
+  /// http://www.iana.org/assignments/language-subtag-registry, as well as
+  /// Sindhi (sd) and Uyghur (ug).  The presence of other subtags of the
+  /// language code, e.g. regions like EG (Egypt), is ignored.
+  static bool isRtlLanguage([String languageString]) {
+    var language = languageString ?? Intl.getCurrentLocale();
+    if (_lastLocaleCheckedForRtl != language) {
+      _lastLocaleCheckedForRtl = language;
+      _lastRtlCheck = _rtlLocaleRegex.hasMatch(language);
+    }
+    return _lastRtlCheck;
   }
 
-  /**
-   * Enforce the [html] snippet in RTL directionality regardless of overall
-   * context. If the html piece was enclosed by a tag, the direction will be
-   * applied to existing tag, otherwise a span tag will be added as wrapper.
-   * For this reason, if html snippet start with with tag, this tag must enclose
-   * the whole piece. If the tag already has a direction specified, this new one
-   * will override existing one in behavior (should work on Chrome, FF, and IE
-   * since this was ported directly from the Closure version).
-   */
+  /// Enforce the [html] snippet in RTL directionality regardless of overall
+  /// context. If the html piece was enclosed by a tag, the direction will be
+  /// applied to existing tag, otherwise a span tag will be added as wrapper.
+  /// For this reason, if html snippet start with with tag, this tag must
+  /// enclose the whole piece. If the tag already has a direction specified,
+  /// this new one will override existing one in behavior (should work on
+  /// Chrome, FF, and IE since this was ported directly from the Closure
+  /// version).
   static String enforceRtlInHtml(String html) =>
       _enforceInHtmlHelper(html, 'rtl');
 
-  /**
-   * Enforce RTL on both end of the given [text] using unicode BiDi formatting
-   * characters RLE and PDF.
-   */
+  /// Enforce RTL on both end of the given [text] using unicode BiDi formatting
+  /// characters RLE and PDF.
   static String enforceRtlInText(String text) => '$RLE$text$PDF';
 
-  /**
-   * Enforce the [html] snippet in LTR directionality regardless of overall
-   * context. If the html piece was enclosed by a tag, the direction will be
-   * applied to existing tag, otherwise a span tag will be added as wrapper.
-   * For this reason, if html snippet start with with tag, this tag must enclose
-   * the whole piece. If the tag already has a direction specified, this new one
-   * will override existing one in behavior (tested on FF and IE).
-   */
+  /// Enforce the [html] snippet in LTR directionality regardless of overall
+  /// context. If the html piece was enclosed by a tag, the direction will be
+  /// applied to existing tag, otherwise a span tag will be added as wrapper.
+  /// For this reason, if html snippet start with with tag, this tag must
+  /// enclose the whole piece. If the tag already has a direction specified,
+  /// this new one will override existing one in behavior (tested on FF and IE).
   static String enforceLtrInHtml(String html) =>
       _enforceInHtmlHelper(html, 'ltr');
 
-  /**
-   * Enforce LTR on both end of the given [text] using unicode BiDi formatting
-   * characters LRE and PDF.
-   */
+  /// Enforce LTR on both end of the given [text] using unicode BiDi formatting
+  /// characters LRE and PDF.
   static String enforceLtrInText(String text) => '$LRE$text$PDF';
 
-  /**
-   * Enforce the [html] snippet in the desired [direction] regardless of overall
-   * context. If the html piece was enclosed by a tag, the direction will be
-   * applied to existing tag, otherwise a span tag will be added as wrapper.
-   * For this reason, if html snippet start with with tag, this tag must enclose
-   * the whole piece. If the tag already has a direction specified, this new one
-   * will override existing one in behavior (tested on FF and IE).
-   */
+  /// Enforce the [html] snippet in the desired [direction] regardless of
+  /// overall context. If the html piece was enclosed by a tag, the direction
+  /// will be applied to existing tag, otherwise a span tag will be added as
+  /// wrapper.  For this reason, if html snippet start with with tag, this tag
+  /// must enclose the whole piece. If the tag already has a direction
+  /// specified, this new one will override existing one in behavior (tested on
+  /// FF and IE).
   static String _enforceInHtmlHelper(String html, String direction) {
     if (html.startsWith('<')) {
       StringBuffer buffer = new StringBuffer();
       var startIndex = 0;
       Match match = new RegExp('<\\w+').firstMatch(html);
       if (match != null) {
         buffer
           ..write(html.substring(startIndex, match.end))
           ..write(' dir=$direction');
         startIndex = match.end;
       }
       return (buffer..write(html.substring(startIndex))).toString();
     }
     // '\n' is important for FF so that it won't incorrectly merge span groups.
     return '\n<span dir=$direction>$html</span>';
   }
 
-  /**
-   * Apply bracket guard to [str] using html span tag. This is to address the
-   * problem of messy bracket display that frequently happens in RTL layout.
-   * If [isRtlContext] is true, then we explicitly want to wrap in a span of RTL
-   * directionality, regardless of the estimated directionality.
-   */
+  /// Apply bracket guard to [str] using html span tag. This is to address the
+  /// problem of messy bracket display that frequently happens in RTL layout.
+  /// If [isRtlContext] is true, then we explicitly want to wrap in a span of
+  /// RTL directionality, regardless of the estimated directionality.
   static String guardBracketInHtml(String str, [bool isRtlContext]) {
     var useRtl = isRtlContext == null ? hasAnyRtl(str) : isRtlContext;
     RegExp matchingBrackets =
         new RegExp(r'(\(.*?\)+)|(\[.*?\]+)|(\{.*?\}+)|(&lt;.*?(&gt;)+)');
     return _guardBracketHelper(str, matchingBrackets,
         '<span dir=${useRtl? "rtl" : "ltr"}>', '</span>');
   }
 
-  /**
-   * Apply bracket guard to [str] using LRM and RLM. This is to address the
-   * problem of messy bracket display that frequently happens in RTL layout.
-   * This version works for both plain text and html, but in some cases is not
-   * as good as guardBracketInHtml.
-   * If [isRtlContext] is true, then we explicitly want to wrap in a span of RTL
-   * directionality, regardless of the estimated directionality.
-   */
+  /// Apply bracket guard to [str] using LRM and RLM. This is to address the
+  /// problem of messy bracket display that frequently happens in RTL layout.
+  /// This version works for both plain text and html, but in some cases is not
+  /// as good as guardBracketInHtml. If [isRtlContext] is true, then we
+  /// explicitly want to wrap in a span of RTL directionality, regardless of the
+  /// estimated directionality.
   static String guardBracketInText(String str, [bool isRtlContext]) {
     var useRtl = isRtlContext == null ? hasAnyRtl(str) : isRtlContext;
     var mark = useRtl ? RLM : LRM;
     return _guardBracketHelper(str,
         new RegExp(r'(\(.*?\)+)|(\[.*?\]+)|(\{.*?\}+)|(<.*?>+)'), mark, mark);
   }
 
-  /**
-   * (Mostly) reimplements the $& functionality of "replace" in JavaScript.
-   * Given a [str] and the [regexp] to match with, optionally supply a string to
-   * be inserted [before] the match and/or [after]. For example,
-   * `_guardBracketHelper('firetruck', new RegExp('truck'), 'hydrant', '!')`
-   * would return 'firehydrant!'.
-   */
-  // TODO(efortuna): Get rid of this once this is implemented in Dart.
-  // See Issue 2979.
+  /// (Mostly) reimplements the $& functionality of "replace" in JavaScript.
+  /// Given a [str] and the [regexp] to match with, optionally supply a string
+  /// to be inserted [before] the match and/or [after]. For example,
+  /// `_guardBracketHelper('firetruck', new RegExp('truck'), 'hydrant', '!')`
+  /// would return 'firehydrant!'.  // TODO(efortuna): Get rid of this once this
+  /// is implemented in Dart.  // See Issue 2979.
   static String _guardBracketHelper(String str, RegExp regexp,
       [String before, String after]) {
     var buffer = new StringBuffer();
     var startIndex = 0;
     regexp.allMatches(str).forEach((match) {
       buffer
         ..write(str.substring(startIndex, match.start))
         ..write(before)
         ..write(str.substring(match.start, match.end))
         ..write(after);
       startIndex = match.end;
     });
     return (buffer..write(str.substring(startIndex))).toString();
   }
 
-  /**
-   * Estimates the directionality of [text] using the best known
-   * general-purpose method (using relative word counts). A
-   * TextDirection.UNKNOWN return value indicates completely neutral input.
-   * [isHtml] is true if [text] HTML or HTML-escaped.
-   *
-   * If the number of RTL words is above a certain percentage of the total
-   * number of strongly directional words, returns RTL.
-   * Otherwise, if any words are strongly or weakly LTR, returns LTR.
-   * Otherwise, returns UNKNOWN, which is used to mean `neutral`.
-   * Numbers and URLs are counted as weakly LTR.
-   */
+  /// Estimates the directionality of [text] using the best known
+  /// general-purpose method (using relative word counts). A
+  /// TextDirection.UNKNOWN return value indicates completely neutral input.
+  /// [isHtml] is true if [text] HTML or HTML-escaped.
+  ///
+  /// If the number of RTL words is above a certain percentage of the total
+  /// number of strongly directional words, returns RTL.
+  /// Otherwise, if any words are strongly or weakly LTR, returns LTR.
+  /// Otherwise, returns UNKNOWN, which is used to mean `neutral`.
+  /// Numbers and URLs are counted as weakly LTR.
   static TextDirection estimateDirectionOfText(String text,
       {bool isHtml: false}) {
     text = isHtml ? stripHtmlIfNeeded(text) : text;
     var rtlCount = 0;
     var total = 0;
     var hasWeaklyLtr = false;
     // Split a string into 'words' for directionality estimation based on
     // relative word counts.
     for (String token in text.split(new RegExp(r'\s+'))) {
       if (startsWithRtl(token)) {
@@ skipping 13 matching lines @@
 
     if (total == 0) {
       return hasWeaklyLtr ? TextDirection.LTR : TextDirection.UNKNOWN;
     } else if (rtlCount > _RTL_DETECTION_THRESHOLD * total) {
       return TextDirection.RTL;
     } else {
       return TextDirection.LTR;
     }
   }
 
-  /**
-   * Replace the double and single quote directly after a Hebrew character in
-   * [str] with GERESH and GERSHAYIM. This is most likely the user's intention.
-   */
+  /// Replace the double and single quote directly after a Hebrew character in
+  /// [str] with GERESH and GERSHAYIM. This is most likely the user's intention.
   static String normalizeHebrewQuote(String str) {
     StringBuffer buf = new StringBuffer();
     if (str.length > 0) {
       buf.write(str.substring(0, 1));
     }
     // Start at 1 because we're looking for the patterns [\u0591-\u05f2])" or
     // [\u0591-\u05f2]'.
     for (int i = 1; i < str.length; i++) {
       if (str.substring(i, i + 1) == '"' &&
           new RegExp('[\u0591-\u05f2]').hasMatch(str.substring(i - 1, i))) {
         buf.write('\u05f4');
       } else if (str.substring(i, i + 1) == "'" &&
           new RegExp('[\u0591-\u05f2]').hasMatch(str.substring(i - 1, i))) {
         buf.write('\u05f3');
       } else {
         buf.write(str.substring(i, i + 1));
       }
     }
     return buf.toString();
   }
 
-  /**
-   * Check the estimated directionality of [str], return true if the piece of
-   * text should be laid out in RTL direction. If [isHtml] is true, the string
-   * is HTML or HTML-escaped.
-   */
+  /// Check the estimated directionality of [str], return true if the piece of
+  /// text should be laid out in RTL direction. If [isHtml] is true, the string
+  /// is HTML or HTML-escaped.
   static bool detectRtlDirectionality(String str, {bool isHtml: false}) =>
       estimateDirectionOfText(str, isHtml: isHtml) == TextDirection.RTL;
 }