Move Bidi functions into methods to make the docs look better

pkg/intl/lib/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.
 
 /**
  * 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,
@@ skipping 10 matching lines @@
  * 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 
+  /**
+   * 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. */
   final String spanText;
 
   const TextDirection._(this.value, this.spanText);
-  
+
   /**
    * Returns true if [otherDirection] is known to be different from this
    * direction.
    */
   bool isDirectionChange(TextDirection otherDirection) {
     return otherDirection != TextDirection.UNKNOWN && this != otherDirection;
   }
 }
 
+/**
+ * This provides a number of utility methods for working with bidirectional
+ * text. #######

[Emily Fortuna, 2012/10/04 18:37:55]

is this a marker for more documentation suggested? (if so, can you make a TODO
instead?)

[Alan Knight, 2012/10/04 19:34:22]

Oops. That was a temporary marker that I should have come back to before
uploading. Removed, and changed the comment.

+ */
+class Bidi {
+
 /** Unicode "Left-To-Right Embedding" (LRE) character. */

[Emily Fortuna, 2012/10/04 18:37:55]

can you fix the indentation of all of these lines now that they're inside of a
class?

[Alan Knight, 2012/10/04 19:34:22]

Done.

-const LRE = '\u202A';
+static const LRE = '\u202A';
 
 /** Unicode "Right-To-Left Embedding" (RLE) character. */
-const RLE = '\u202B';
+static const RLE = '\u202B';
 
 /** Unicode "Pop Directional Formatting" (PDF) character. */
-const PDF = '\u202C';
+static const PDF = '\u202C';
 
 /** Unicode "Left-To-Right Mark" (LRM) character. */
-const LRM = '\u200E';
+static const LRM = '\u200E';
 
 /** Unicode "Right-To-Left Mark" (RLM) character. */
-const RLM = '\u200F';
+static const RLM = '\u200F';
 
 /** Constant to define the threshold of RTL directionality. */
-num _RTL_DETECTION_THRESHOLD = 0.40;
+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.
  */
-const String _LTR_CHARS =
+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';
-const String _RTL_CHARS = r'\u0591-\u07FF\uFB1D-\uFDFD\uFE70-\uFEFC';
+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.
  */
-String stripHtmlIfNeeded(String text) {
-  // The regular expression is simplified for an HTML tag (opening or 
+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(const 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.
  */
-bool startsWithLtr(String text, [isHtml=false]) {
+static bool startsWithLtr(String text, [isHtml=false]) {
   return const 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.
  */
-bool startsWithRtl(String text, [isHtml=false]) {
+static bool startsWithRtl(String text, [isHtml=false]) {
   return const 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.
  */
-bool endsWithLtr(String text, [isHtml=false]) {
+static bool endsWithLtr(String text, [isHtml=false]) {
   return const 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.
  */
-bool endsWithRtl(String text, [isHtml=false]) {
+static bool endsWithRtl(String text, [isHtml=false]) {
   return const 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.
  */
-bool hasAnyLtr(String text, [isHtml=false]) {
+static bool hasAnyLtr(String text, [isHtml=false]) {
   return const 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.
  */
-bool hasAnyRtl(String text, [isHtml=false]) {
+static bool hasAnyRtl(String text, [isHtml=false]) {
   return const 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.
  */
-bool isRtlLanguage(String languageString) {
+static bool isRtlLanguage(String languageString) {
   return const RegExp(r'^(ar|dv|he|iw|fa|nqo|ps|sd|ug|ur|yi|.*[-_]'
       r'(Arab|Hebr|Thaa|Nkoo|Tfng))(?!.*[-_](Latn|Cyrl)($|-|_))'
       r'($|-|_)', ignoreCase : true).hasMatch(languageString);
 }
 
 /**
  * Enforce the [html] snippet in RTL directionality regardless of overall
- * context. If the html piece was enclosed by a tag, the direction will be 
+ * 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).
  */
-String enforceRtlInHtml(String html) {
+static String enforceRtlInHtml(String html) {
   return _enforceInHtmlHelper(html, 'rtl');
 }
 
 /**
  * Enforce RTL on both end of the given [text] using unicode BiDi formatting
  * characters RLE and PDF.
  */
-String enforceRtlInText(String text) {
+static String enforceRtlInText(String text) {
   return '$RLE$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 
+ * 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).
  */
-String enforceLtrInHtml(String html) {
+static String enforceLtrInHtml(String html) {
   return _enforceInHtmlHelper(html, 'ltr');
 }
 
 /**
  * Enforce LTR on both end of the given [text] using unicode BiDi formatting
  * characters LRE and PDF.
  */
-String enforceLtrInText(String text) {
+static String enforceLtrInText(String text) {
   return '$LRE$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 
+ * 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).
  */
-String _enforceInHtmlHelper(String html, String direction) {
+static String _enforceInHtmlHelper(String html, String direction) {
   if (html.startsWith('<')) {
     StringBuffer buffer = new StringBuffer();
     var startIndex = 0;
     Match match = const RegExp('<\\w+').firstMatch(html);
     if (match != null) {
       buffer.add(html.substring(
           startIndex, match.end())).add(' dir=$direction');
       startIndex = match.end();
     }
     return buffer.add(html.substring(startIndex)).toString();
   }
   // '\n' is important for FF so that it won't incorrectly merge span groups.
   return '\n<span dir=$direction>$html</span>';
 }
 
 /**
- * Apply bracket guard to [str] using html span tag. This is to address the 
+ * 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.
  */
-String guardBracketInHtml(String str, [bool isRtlContext]) {
+static String guardBracketInHtml(String str, [bool isRtlContext]) {
   var useRtl = isRtlContext == null ? hasAnyRtl(str) : isRtlContext;
-  RegExp matchingBrackets = 
+  RegExp matchingBrackets =
       const 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 
+ * 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.
  */
-String guardBracketInText(String str, [bool isRtlContext]) {
+static String guardBracketInText(String str, [bool isRtlContext]) {
   var useRtl = isRtlContext == null ? hasAnyRtl(str) : isRtlContext;
   var mark = useRtl ? RLM : LRM;
   return _guardBracketHelper(str,
       const 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, 
+ * be inserted [before] the match and/or [after]. For example,
  * `_guardBracketHelper('firetruck', const RegExp('truck'), 'hydrant', '!')`
  * would return 'firehydrant!'.
  */
 // TODO(efortuna): Get rid of this once this is implemented in Dart.
 // See Issue 2979.
-String _guardBracketHelper(String str, RegExp regexp, [String before,
+static String _guardBracketHelper(String str, RegExp regexp, [String before,
     String after]) {
   StringBuffer buffer = new StringBuffer();
   var startIndex = 0;
   Iterable matches = regexp.allMatches(str);
   for (Match match in matches) {
     buffer.add(str.substring(startIndex, match.start())).add(before);
     buffer.add(str.substring(match.start(), match.end())).add(after);
     startIndex = match.end();
   }
   return buffer.add(str.substring(startIndex)).toString();
 }
 
 /**
  * Estimates the directionality of [text] using the best known
- * general-purpose method (using relative word counts). A 
+ * 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.
  */
-TextDirection estimateDirectionOfText(String text, [bool isHtml=false]) {
+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(const RegExp(r'\s+'))) {
     if (startsWithRtl(token)) {
       rtlCount++;
       total++;
@@ skipping 15 matching lines @@
     return TextDirection.RTL;
   } else {
     return TextDirection.LTR;
   }
 }
 
 /**
  * Find the first index in [str] of the first closing parenthesis that does
  * not match an opening parenthesis.
  */
-int _unmatchedParenIndex(String str) {
+static int _unmatchedParenIndex(String str) {
   int sum = 0;
   int index = 0;
   while (sum >= 0 || index > str.length) {
     int char = str.charCodeAt(index);
     if (char == '('.charCodeAt(0)) sum++;
     else if (char == ')'.charCodeAt(0)) sum--;
     index++;
   }
   return index;
 }
 
 /**
  * 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.
  */
-String normalizeHebrewQuote(String str) {
+static String normalizeHebrewQuote(String str) {
   StringBuffer buf = new StringBuffer();
   if (str.length > 0) {
     buf.add(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) == '"'
         && const RegExp('[\u0591-\u05f2]').hasMatch(str.substring(i-1, i))) {
       buf.add('\u05f4');
     } else if (str.substring(i, i+1) == "'"
         && const RegExp('[\u0591-\u05f2]').hasMatch(str.substring(i-1, i))) {
       buf.add('\u05f3');
     } else {
       buf.add(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.
  */
-bool detectRtlDirectionality(String str, [bool isHtml]) {
+static bool detectRtlDirectionality(String str, [bool isHtml]) {
   return estimateDirectionOfText(str, isHtml) == TextDirection.RTL;
 }
+

[Emily Fortuna, 2012/10/04 18:37:55]

You're going to love this... delete this extra line, please.

[Alan Knight, 2012/10/04 19:34:22]

Done.

+}