Update tables to Unicode 16.0.0.

Add license file change check.
(Since the license file changed this time,
and it's something that one should check if it happens.)

Some clean-up.
Documents that the BG9c rule from Unicode 15.10 is not supported.
(That would require more bits of information per character,
information that the current table builder does not have,
and a correspondingly larger state machine.)

Author: lrhn

pkgs/characters/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.4.0
+
+* Updated to use Unicode 16.0.0.
+
 ## 1.3.1
 
 * Fixed README rendering on pub.dev and API docs.

pkgs/characters/README.md

@@ -11,6 +11,12 @@ the individual characters of a string,
 and a way to navigate back and forth between them
 using a [`CharacterRange`][CharacterRange].
 
+Based on Unicode <!-- unicode-version -->version 16.0.0<!-- /unicode-version -->.
+
+This package is not script-aware, and does not currently support the rule for
+Indic Conjunct Breaks introduced in Unicode 15.10.0
+([GB9c](https://www.unicode.org/reports/tr29/tr29-43.html#GB9c)).
+
 ## Unicode characters and representations
 
 There is no such thing as plain text.

pkgs/characters/lib/src/characters.dart

@@ -19,7 +19,7 @@ import "characters_impl.dart";
 /// which allows iterating the independent characters in both directions,
 /// but which also provides ways to select other ranges of characters
 /// in different ways.
-abstract class Characters implements Iterable<String> {
+abstract interface class Characters implements Iterable<String> {
   /// An empty [Characters] containing no characters.
   static const Characters empty = StringCharacters("");
 
@@ -272,7 +272,7 @@ abstract class Characters implements Iterable<String> {
 
   /// Replaces the first occurrence of [pattern] with [replacement].
   ///
-  /// Returns a new [Characters] where the first occurence of the
+  /// Returns a new [Characters] where the first occurrence of the
   /// [pattern] character sequence, if any, is replaced by [replacement].
   ///
   /// Returns the current characters if there is no occurrence of [pattern].
@@ -304,7 +304,7 @@ abstract class Characters implements Iterable<String> {
 /// The range may even be empty, but that will still correspond to a position
 /// where both start and end happen to be the same position.
 ///
-/// The source sequence can be separated into the *preceeding* characters,
+/// The source sequence can be separated into the *preceding* characters,
 /// those before the range, the range itself, and the *following* characters,
 /// those after the range.
 ///
@@ -318,11 +318,11 @@ abstract class Characters implements Iterable<String> {
 /// Operations starting with `collapse` reduces the current range to
 /// a sub-range of itself.
 /// Operations starting with `expand` increase the current range
-/// by moving/ the end postion to a later position
+/// by moving the end position to a later position
 /// or the start position to an earlier position,
 /// and operations starting with `drop` reduce the current range
 /// by moving the start to a later position or the end to an earlier position,
-/// therebyt dropping characters from one or both ends from the current range.
+/// thereby dropping characters from one or both ends from the current range.
 ///
 ///
 /// The character range implements [Iterator]
@@ -479,7 +479,7 @@ abstract class CharacterRange implements Iterator<String> {
   /// Returns `true` if the range is modified and `false` if not.
   bool moveBackTo(Characters target);
 
-  /// Moves to the range after the previous occurence of [target].
+  /// Moves to the range after the previous occurrence of [target].
   ///
   /// If there is an occurrence of [target] in the characters preceding
   /// the current range,
@@ -506,7 +506,7 @@ abstract class CharacterRange implements Iterator<String> {
   /// the current range, and `false` if not.
   bool expandNext([int count = 1]);
 
-  /// Expands the range to include the next occurence of [target].
+  /// Expands the range to include the next occurrence of [target].
   ///
   /// If there is an occurrence of [target] in the characters following
   /// the current range, the end of the the range is moved to just after
@@ -554,7 +554,7 @@ abstract class CharacterRange implements Iterator<String> {
   /// the current range, and `false` if not.
   bool expandBack([int count = 1]);
 
-  /// Expands the range to include the previous occurence of [target].
+  /// Expands the range to include the previous occurrence of [target].
   ///
   /// If there is an occurrence of [target] in the characters preceding
   /// the current range, the stat of the the range is moved to just before
@@ -579,7 +579,7 @@ abstract class CharacterRange implements Iterator<String> {
   /// Returns `true` if there is an occurrence of [target] and `false` if not.
   bool expandBackUntil(Characters target);
 
-  /// Expands the range with the preceding characters satisffying [test].
+  /// Expands the range with the preceding characters satisfying [test].
   ///
   /// Iterates back through the characters preceding the current range
   /// and includes them into the range until finding a character that
@@ -661,7 +661,7 @@ abstract class CharacterRange implements Iterator<String> {
   /// first occurrence of [target].
   ///
   /// If there are no occurrences of [target] in the range,
-  /// all characteres in the range are removed,
+  /// all characters in the range are removed,
   /// which gives the same effect as [collapseToEnd].
   ///
   /// Returns `true` if there is an occurrence of [target] and `false` if not.
@@ -713,7 +713,7 @@ abstract class CharacterRange implements Iterator<String> {
   /// last occurrence of [target].
   ///
   /// If there are no occurrences of [target] in the range,
-  /// all characteres in the range are removed,
+  /// all characters in the range are removed,
   /// which gives the same effect as [collapseToStart].
   ///
   /// Returns `true` if there is an occurrence of [target] and `false` if not.

pkgs/characters/lib/src/characters_impl.dart

@@ -10,7 +10,7 @@ import 'grapheme_clusters/table.dart';
 /// The grapheme clusters of a string.
 ///
 /// Backed by a single string.
-class StringCharacters extends Iterable<String> implements Characters {
+final class StringCharacters extends Iterable<String> implements Characters {
   @override
   final String string;