Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1793 insertions, 0 deletions

diff --git a/intl/icu/source/common/unicode/uniset.h b/intl/icu/source/common/unicode/uniset.h
new file mode 100644
index 0000000000..84774d9f36
--- /dev/null
+++ b/intl/icu/source/common/unicode/uniset.h
@@ -0,0 +1,1793 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+***************************************************************************
+* Copyright (C) 1999-2016, International Business Machines Corporation
+* and others. All Rights Reserved.
+***************************************************************************
+*   Date        Name        Description
+*   10/20/99    alan        Creation.
+***************************************************************************
+*/
+
+#ifndef UNICODESET_H
+#define UNICODESET_H
+
+#include "unicode/utypes.h"
+
+#if U_SHOW_CPLUSPLUS_API
+
+#include "unicode/ucpmap.h"
+#include "unicode/unifilt.h"
+#include "unicode/unistr.h"
+#include "unicode/uset.h"
+
+/**
+ * \file
+ * \brief C++ API: Unicode Set
+ */
+
+U_NAMESPACE_BEGIN
+
+// Forward Declarations.
+class BMPSet;
+class ParsePosition;
+class RBBIRuleScanner;
+class SymbolTable;
+class UnicodeSetStringSpan;
+class UVector;
+class RuleCharacterIterator;
+
+/**
+ * A mutable set of Unicode characters and multicharacter strings.  Objects of this class
+ * represent <em>character classes</em> used in regular expressions.
+ * A character specifies a subset of Unicode code points.  Legal
+ * code points are U+0000 to U+10FFFF, inclusive.
+ *
+ * <p>The UnicodeSet class is not designed to be subclassed.
+ *
+ * <p><code>UnicodeSet</code> supports two APIs. The first is the
+ * <em>operand</em> API that allows the caller to modify the value of
+ * a <code>UnicodeSet</code> object. It conforms to Java 2's
+ * <code>java.util.Set</code> interface, although
+ * <code>UnicodeSet</code> does not actually implement that
+ * interface. All methods of <code>Set</code> are supported, with the
+ * modification that they take a character range or single character
+ * instead of an <code>Object</code>, and they take a
+ * <code>UnicodeSet</code> instead of a <code>Collection</code>.  The
+ * operand API may be thought of in terms of boolean logic: a boolean
+ * OR is implemented by <code>add</code>, a boolean AND is implemented
+ * by <code>retain</code>, a boolean XOR is implemented by
+ * <code>complement</code> taking an argument, and a boolean NOT is
+ * implemented by <code>complement</code> with no argument.  In terms
+ * of traditional set theory function names, <code>add</code> is a
+ * union, <code>retain</code> is an intersection, <code>remove</code>
+ * is an asymmetric difference, and <code>complement</code> with no
+ * argument is a set complement with respect to the superset range
+ * <code>MIN_VALUE-MAX_VALUE</code>
+ *
+ * <p>The second API is the
+ * <code>applyPattern()</code>/<code>toPattern()</code> API from the
+ * <code>java.text.Format</code>-derived classes.  Unlike the
+ * methods that add characters, add categories, and control the logic
+ * of the set, the method <code>applyPattern()</code> sets all
+ * attributes of a <code>UnicodeSet</code> at once, based on a
+ * string pattern.
+ *
+ * <p><b>Pattern syntax</b></p>
+ *
+ * Patterns are accepted by the constructors and the
+ * <code>applyPattern()</code> methods and returned by the
+ * <code>toPattern()</code> method.  These patterns follow a syntax
+ * similar to that employed by version 8 regular expression character
+ * classes.  Here are some simple examples:
+ *
+ * \htmlonly<blockquote>\endhtmlonly
+ *   <table>
+ *     <tr align="top">
+ *       <td nowrap valign="top" align="left"><code>[]</code></td>
+ *       <td valign="top">No characters</td>
+ *     </tr><tr align="top">
+ *       <td nowrap valign="top" align="left"><code>[a]</code></td>
+ *       <td valign="top">The character 'a'</td>
+ *     </tr><tr align="top">
+ *       <td nowrap valign="top" align="left"><code>[ae]</code></td>
+ *       <td valign="top">The characters 'a' and 'e'</td>
+ *     </tr>
+ *     <tr>
+ *       <td nowrap valign="top" align="left"><code>[a-e]</code></td>
+ *       <td valign="top">The characters 'a' through 'e' inclusive, in Unicode code
+ *       point order</td>
+ *     </tr>
+ *     <tr>
+ *       <td nowrap valign="top" align="left"><code>[\\u4E01]</code></td>
+ *       <td valign="top">The character U+4E01</td>
+ *     </tr>
+ *     <tr>
+ *       <td nowrap valign="top" align="left"><code>[a{ab}{ac}]</code></td>
+ *       <td valign="top">The character 'a' and the multicharacter strings &quot;ab&quot; and
+ *       &quot;ac&quot;</td>
+ *     </tr>
+ *     <tr>
+ *       <td nowrap valign="top" align="left"><code>[\\p{Lu}]</code></td>
+ *       <td valign="top">All characters in the general category Uppercase Letter</td>
+ *     </tr>
+ *   </table>
+ * \htmlonly</blockquote>\endhtmlonly
+ *
+ * Any character may be preceded by a backslash in order to remove any special
+ * meaning.  White space characters, as defined by UCharacter.isWhitespace(), are
+ * ignored, unless they are escaped.
+ *
+ * <p>Property patterns specify a set of characters having a certain
+ * property as defined by the Unicode standard.  Both the POSIX-like
+ * "[:Lu:]" and the Perl-like syntax "\\p{Lu}" are recognized.  For a
+ * complete list of supported property patterns, see the User's Guide
+ * for UnicodeSet at
+ * <a href="https://unicode-org.github.io/icu/userguide/strings/unicodeset">
+ * https://unicode-org.github.io/icu/userguide/strings/unicodeset</a>.
+ * Actual determination of property data is defined by the underlying
+ * Unicode database as implemented by UCharacter.
+ *
+ * <p>Patterns specify individual characters, ranges of characters, and
+ * Unicode property sets.  When elements are concatenated, they
+ * specify their union.  To complement a set, place a '^' immediately
+ * after the opening '['.  Property patterns are inverted by modifying
+ * their delimiters; "[:^foo]" and "\\P{foo}".  In any other location,
+ * '^' has no special meaning.
+ *
+ * <p>Since ICU 70, "[^...]", "[:^foo]", "\\P{foo}", and "[:binaryProperty=No:]"
+ * perform a “code point complement” (all code points minus the original set),
+ * removing all multicharacter strings,
+ * equivalent to <code>.complement().removeAllStrings()</code>.
+ * The complement() API function continues to perform a
+ * symmetric difference with all code points and thus retains all multicharacter strings.
+ *
+ * <p>Ranges are indicated by placing two a '-' between two
+ * characters, as in "a-z".  This specifies the range of all
+ * characters from the left to the right, in Unicode order.  If the
+ * left character is greater than or equal to the
+ * right character it is a syntax error.  If a '-' occurs as the first
+ * character after the opening '[' or '[^', or if it occurs as the
+ * last character before the closing ']', then it is taken as a
+ * literal.  Thus "[a\-b]", "[-ab]", and "[ab-]" all indicate the same
+ * set of three characters, 'a', 'b', and '-'.
+ *
+ * <p>Sets may be intersected using the '&' operator or the asymmetric
+ * set difference may be taken using the '-' operator, for example,
+ * "[[:L:]&[\\u0000-\\u0FFF]]" indicates the set of all Unicode letters
+ * with values less than 4096.  Operators ('&' and '|') have equal
+ * precedence and bind left-to-right.  Thus
+ * "[[:L:]-[a-z]-[\\u0100-\\u01FF]]" is equivalent to
+ * "[[[:L:]-[a-z]]-[\\u0100-\\u01FF]]".  This only really matters for
+ * difference; intersection is commutative.
+ *
+ * <table>
+ * <tr valign=top><td nowrap><code>[a]</code><td>The set containing 'a'
+ * <tr valign=top><td nowrap><code>[a-z]</code><td>The set containing 'a'
+ * through 'z' and all letters in between, in Unicode order
+ * <tr valign=top><td nowrap><code>[^a-z]</code><td>The set containing
+ * all characters but 'a' through 'z',
+ * that is, U+0000 through 'a'-1 and 'z'+1 through U+10FFFF
+ * <tr valign=top><td nowrap><code>[[<em>pat1</em>][<em>pat2</em>]]</code>
+ * <td>The union of sets specified by <em>pat1</em> and <em>pat2</em>
+ * <tr valign=top><td nowrap><code>[[<em>pat1</em>]&[<em>pat2</em>]]</code>
+ * <td>The intersection of sets specified by <em>pat1</em> and <em>pat2</em>
+ * <tr valign=top><td nowrap><code>[[<em>pat1</em>]-[<em>pat2</em>]]</code>
+ * <td>The asymmetric difference of sets specified by <em>pat1</em> and
+ * <em>pat2</em>
+ * <tr valign=top><td nowrap><code>[:Lu:] or \\p{Lu}</code>
+ * <td>The set of characters having the specified
+ * Unicode property; in
+ * this case, Unicode uppercase letters
+ * <tr valign=top><td nowrap><code>[:^Lu:] or \\P{Lu}</code>
+ * <td>The set of characters <em>not</em> having the given
+ * Unicode property
+ * </table>
+ *
+ * <p><b>Formal syntax</b></p>
+ *
+ * \htmlonly<blockquote>\endhtmlonly
+ *   <table>
+ *     <tr align="top">
+ *       <td nowrap valign="top" align="right"><code>pattern :=&nbsp; </code></td>
+ *       <td valign="top"><code>('[' '^'? item* ']') |
+ *       property</code></td>
+ *     </tr>
+ *     <tr align="top">
+ *       <td nowrap valign="top" align="right"><code>item :=&nbsp; </code></td>
+ *       <td valign="top"><code>char | (char '-' char) | pattern-expr<br>
+ *       </code></td>
+ *     </tr>
+ *     <tr align="top">
+ *       <td nowrap valign="top" align="right"><code>pattern-expr :=&nbsp; </code></td>
+ *       <td valign="top"><code>pattern | pattern-expr pattern |
+ *       pattern-expr op pattern<br>
+ *       </code></td>
+ *     </tr>
+ *     <tr align="top">
+ *       <td nowrap valign="top" align="right"><code>op :=&nbsp; </code></td>
+ *       <td valign="top"><code>'&amp;' | '-'<br>
+ *       </code></td>
+ *     </tr>
+ *     <tr align="top">
+ *       <td nowrap valign="top" align="right"><code>special :=&nbsp; </code></td>
+ *       <td valign="top"><code>'[' | ']' | '-'<br>
+ *       </code></td>
+ *     </tr>
+ *     <tr align="top">
+ *       <td nowrap valign="top" align="right"><code>char :=&nbsp; </code></td>
+ *       <td valign="top"><em>any character that is not</em><code> special<br>
+ *       | ('\' </code><em>any character</em><code>)<br>
+ *       | ('\\u' hex hex hex hex)<br>
+ *       </code></td>
+ *     </tr>
+ *     <tr align="top">
+ *       <td nowrap valign="top" align="right"><code>hex :=&nbsp; </code></td>
+ *       <td valign="top"><code>'0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' |<br>
+ *       &nbsp;&nbsp;&nbsp;&nbsp;'A' | 'B' | 'C' | 'D' | 'E' | 'F' | 'a' | 'b' | 'c' | 'd' | 'e' | 'f'</code></td>
+ *     </tr>
+ *     <tr>
+ *       <td nowrap valign="top" align="right"><code>property :=&nbsp; </code></td>
+ *       <td valign="top"><em>a Unicode property set pattern</em></td>
+ *     </tr>
+ *   </table>
+ *   <br>
+ *   <table border="1">
+ *     <tr>
+ *       <td>Legend: <table>
+ *         <tr>
+ *           <td nowrap valign="top"><code>a := b</code></td>
+ *           <td width="20" valign="top">&nbsp; </td>
+ *           <td valign="top"><code>a</code> may be replaced by <code>b</code> </td>
+ *         </tr>
+ *         <tr>
+ *           <td nowrap valign="top"><code>a?</code></td>
+ *           <td valign="top"></td>
+ *           <td valign="top">zero or one instance of <code>a</code><br>
+ *           </td>
+ *         </tr>
+ *         <tr>
+ *           <td nowrap valign="top"><code>a*</code></td>
+ *           <td valign="top"></td>
+ *           <td valign="top">one or more instances of <code>a</code><br>
+ *           </td>
+ *         </tr>
+ *         <tr>
+ *           <td nowrap valign="top"><code>a | b</code></td>
+ *           <td valign="top"></td>
+ *           <td valign="top">either <code>a</code> or <code>b</code><br>
+ *           </td>
+ *         </tr>
+ *         <tr>
+ *           <td nowrap valign="top"><code>'a'</code></td>
+ *           <td valign="top"></td>
+ *           <td valign="top">the literal string between the quotes </td>
+ *         </tr>
+ *       </table>
+ *       </td>
+ *     </tr>
+ *   </table>
+ * \htmlonly</blockquote>\endhtmlonly
+ * 
+ * <p>Note:
+ *  - Most UnicodeSet methods do not take a UErrorCode parameter because
+ *   there are usually very few opportunities for failure other than a shortage
+ *   of memory, error codes in low-level C++ string methods would be inconvenient,
+ *   and the error code as the last parameter (ICU convention) would prevent
+ *   the use of default parameter values.
+ *   Instead, such methods set the UnicodeSet into a "bogus" state
+ *   (see isBogus()) if an error occurs.
+ *
+ * @author Alan Liu
+ * @stable ICU 2.0
+ */
+class U_COMMON_API UnicodeSet final : public UnicodeFilter {
+private:
+    /**
+     * Enough for sets with few ranges.
+     * For example, White_Space has 10 ranges, list length 21.
+     */
+    static constexpr int32_t INITIAL_CAPACITY = 25;
+    // fFlags constant
+    static constexpr uint8_t kIsBogus = 1;  // This set is bogus (i.e. not valid)
+
+    UChar32* list = stackList; // MUST be terminated with HIGH
+    int32_t capacity = INITIAL_CAPACITY; // capacity of list
+    int32_t len = 1; // length of list used; 1 <= len <= capacity
+    uint8_t fFlags = 0;         // Bit flag (see constants above)
+
+    BMPSet *bmpSet = nullptr; // The set is frozen iff either bmpSet or stringSpan is not nullptr.
+    UChar32* buffer = nullptr; // internal buffer, may be nullptr
+    int32_t bufferCapacity = 0; // capacity of buffer
+
+    /**
+     * The pattern representation of this set.  This may not be the
+     * most economical pattern.  It is the pattern supplied to
+     * applyPattern(), with variables substituted and whitespace
+     * removed.  For sets constructed without applyPattern(), or
+     * modified using the non-pattern API, this string will be empty,
+     * indicating that toPattern() must generate a pattern
+     * representation from the inversion list.
+     */
+    char16_t *pat = nullptr;
+    int32_t patLen = 0;
+
+    UVector* strings = nullptr; // maintained in sorted order
+    UnicodeSetStringSpan *stringSpan = nullptr;
+
+    /**
+     * Initial list array.
+     * Avoids some heap allocations, and list is never nullptr.
+     * Increases the object size a bit.
+     */
+    UChar32 stackList[INITIAL_CAPACITY];
+
+public:
+    /**
+     * Determine if this object contains a valid set.
+     * A bogus set has no value. It is different from an empty set.
+     * It can be used to indicate that no set value is available.
+     *
+     * @return true if the set is bogus/invalid, false otherwise
+     * @see setToBogus()
+     * @stable ICU 4.0
+     */
+    inline UBool isBogus(void) const;
+
+    /**
+     * Make this UnicodeSet object invalid.
+     * The string will test true with isBogus().
+     *
+     * A bogus set has no value. It is different from an empty set.
+     * It can be used to indicate that no set value is available.
+     *
+     * This utility function is used throughout the UnicodeSet
+     * implementation to indicate that a UnicodeSet operation failed,
+     * and may be used in other functions,
+     * especially but not exclusively when such functions do not
+     * take a UErrorCode for simplicity.
+     *
+     * @see isBogus()
+     * @stable ICU 4.0
+     */
+    void setToBogus();
+
+public:
+
+    enum {
+        /**
+         * Minimum value that can be stored in a UnicodeSet.
+         * @stable ICU 2.4
+         */
+        MIN_VALUE = 0,
+
+        /**
+         * Maximum value that can be stored in a UnicodeSet.
+         * @stable ICU 2.4
+         */
+        MAX_VALUE = 0x10ffff
+    };
+
+    //----------------------------------------------------------------
+    // Constructors &c
+    //----------------------------------------------------------------
+
+public:
+
+    /**
+     * Constructs an empty set.
+     * @stable ICU 2.0
+     */
+    UnicodeSet();
+
+    /**
+     * Constructs a set containing the given range. If <code>end <
+     * start</code> then an empty set is created.
+     *
+     * @param start first character, inclusive, of range
+     * @param end last character, inclusive, of range
+     * @stable ICU 2.4
+     */
+    UnicodeSet(UChar32 start, UChar32 end);
+
+#ifndef U_HIDE_INTERNAL_API
+    /**
+     * @internal
+     */
+    enum ESerialization {
+      kSerialized  /* result of serialize() */
+    };
+
+    /**
+     * Constructs a set from the output of serialize().
+     *
+     * @param buffer the 16 bit array
+     * @param bufferLen the original length returned from serialize()
+     * @param serialization the value 'kSerialized'
+     * @param status error code
+     *
+     * @internal
+     */
+    UnicodeSet(const uint16_t buffer[], int32_t bufferLen,
+               ESerialization serialization, UErrorCode &status);
+#endif  /* U_HIDE_INTERNAL_API */
+
+    /**
+     * Constructs a set from the given pattern.  See the class
+     * description for the syntax of the pattern language.
+     * @param pattern a string specifying what characters are in the set
+     * @param status returns <code>U_ILLEGAL_ARGUMENT_ERROR</code> if the pattern
+     * contains a syntax error.
+     * @stable ICU 2.0
+     */
+    UnicodeSet(const UnicodeString& pattern,
+               UErrorCode& status);
+
+#ifndef U_HIDE_INTERNAL_API
+    /**
+     * Constructs a set from the given pattern.  See the class
+     * description for the syntax of the pattern language.
+     * @param pattern a string specifying what characters are in the set
+     * @param options bitmask for options to apply to the pattern.
+     * Valid options are USET_IGNORE_SPACE and
+     * at most one of USET_CASE_INSENSITIVE, USET_ADD_CASE_MAPPINGS, USET_SIMPLE_CASE_INSENSITIVE.
+     * These case options are mutually exclusive.
+     * @param symbols a symbol table mapping variable names to values
+     * and stand-in characters to UnicodeSets; may be nullptr
+     * @param status returns <code>U_ILLEGAL_ARGUMENT_ERROR</code> if the pattern
+     * contains a syntax error.
+     * @internal
+     */
+    UnicodeSet(const UnicodeString& pattern,
+               uint32_t options,
+               const SymbolTable* symbols,
+               UErrorCode& status);
+#endif  /* U_HIDE_INTERNAL_API */
+
+    /**
+     * Constructs a set from the given pattern.  See the class description
+     * for the syntax of the pattern language.
+     * @param pattern a string specifying what characters are in the set
+     * @param pos on input, the position in pattern at which to start parsing.
+     * On output, the position after the last character parsed.
+     * @param options bitmask for options to apply to the pattern.
+     * Valid options are USET_IGNORE_SPACE and
+     * at most one of USET_CASE_INSENSITIVE, USET_ADD_CASE_MAPPINGS, USET_SIMPLE_CASE_INSENSITIVE.
+     * These case options are mutually exclusive.
+     * @param symbols a symbol table mapping variable names to values
+     * and stand-in characters to UnicodeSets; may be nullptr
+     * @param status input-output error code
+     * @stable ICU 2.8
+     */
+    UnicodeSet(const UnicodeString& pattern, ParsePosition& pos,
+               uint32_t options,
+               const SymbolTable* symbols,
+               UErrorCode& status);
+
+    /**
+     * Constructs a set that is identical to the given UnicodeSet.
+     * @stable ICU 2.0
+     */
+    UnicodeSet(const UnicodeSet& o);
+
+    /**
+     * Destructs the set.
+     * @stable ICU 2.0
+     */
+    virtual ~UnicodeSet();
+
+    /**
+     * Assigns this object to be a copy of another.
+     * A frozen set will not be modified.
+     * @stable ICU 2.0
+     */
+    UnicodeSet& operator=(const UnicodeSet& o);
+
+    /**
+     * Compares the specified object with this set for equality.  Returns
+     * <tt>true</tt> if the two sets
+     * have the same size, and every member of the specified set is
+     * contained in this set (or equivalently, every member of this set is
+     * contained in the specified set).
+     *
+     * @param o set to be compared for equality with this set.
+     * @return <tt>true</tt> if the specified set is equal to this set.
+     * @stable ICU 2.0
+     */
+    virtual bool operator==(const UnicodeSet& o) const;
+
+    /**
+     * Compares the specified object with this set for equality.  Returns
+     * <tt>true</tt> if the specified set is not equal to this set.
+     * @stable ICU 2.0
+     */
+    inline bool operator!=(const UnicodeSet& o) const;
+
+    /**
+     * Returns a copy of this object.  All UnicodeFunctor objects have
+     * to support cloning in order to allow classes using
+     * UnicodeFunctors, such as Transliterator, to implement cloning.
+     * If this set is frozen, then the clone will be frozen as well.
+     * Use cloneAsThawed() for a mutable clone of a frozen set.
+     * @see cloneAsThawed
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet* clone() const override;
+
+    /**
+     * Returns the hash code value for this set.
+     *
+     * @return the hash code value for this set.
+     * @see Object#hashCode()
+     * @stable ICU 2.0
+     */
+    virtual int32_t hashCode(void) const;
+
+    /**
+     * Get a UnicodeSet pointer from a USet
+     *
+     * @param uset a USet (the ICU plain C type for UnicodeSet)
+     * @return the corresponding UnicodeSet pointer.
+     *
+     * @stable ICU 4.2
+     */
+    inline static UnicodeSet *fromUSet(USet *uset);
+
+    /**
+     * Get a UnicodeSet pointer from a const USet
+     *
+     * @param uset a const USet (the ICU plain C type for UnicodeSet)
+     * @return the corresponding UnicodeSet pointer.
+     *
+     * @stable ICU 4.2
+     */
+    inline static const UnicodeSet *fromUSet(const USet *uset);
+    
+    /**
+     * Produce a USet * pointer for this UnicodeSet.
+     * USet is the plain C type for UnicodeSet
+     *
+     * @return a USet pointer for this UnicodeSet
+     * @stable ICU 4.2
+     */
+    inline USet *toUSet();
+
+
+    /**
+     * Produce a const USet * pointer for this UnicodeSet.
+     * USet is the plain C type for UnicodeSet
+     *
+     * @return a const USet pointer for this UnicodeSet
+     * @stable ICU 4.2
+     */
+    inline const USet * toUSet() const;
+
+
+    //----------------------------------------------------------------
+    // Freezable API
+    //----------------------------------------------------------------
+
+    /**
+     * Determines whether the set has been frozen (made immutable) or not.
+     * See the ICU4J Freezable interface for details.
+     * @return true/false for whether the set has been frozen
+     * @see freeze
+     * @see cloneAsThawed
+     * @stable ICU 3.8
+     */
+    inline UBool isFrozen() const;
+
+    /**
+     * Freeze the set (make it immutable).
+     * Once frozen, it cannot be unfrozen and is therefore thread-safe
+     * until it is deleted.
+     * See the ICU4J Freezable interface for details.
+     * Freezing the set may also make some operations faster, for example
+     * contains() and span().
+     * A frozen set will not be modified. (It remains frozen.)
+     * @return this set.
+     * @see isFrozen
+     * @see cloneAsThawed
+     * @stable ICU 3.8
+     */
+    UnicodeSet *freeze();
+
+    /**
+     * Clone the set and make the clone mutable.
+     * See the ICU4J Freezable interface for details.
+     * @return the mutable clone
+     * @see freeze
+     * @see isFrozen
+     * @stable ICU 3.8
+     */
+    UnicodeSet *cloneAsThawed() const;
+
+    //----------------------------------------------------------------
+    // Public API
+    //----------------------------------------------------------------
+
+    /**
+     * Make this object represent the range `start - end`.
+     * If `start > end` then this object is set to an empty range.
+     * A frozen set will not be modified.
+     *
+     * @param start first character in the set, inclusive
+     * @param end last character in the set, inclusive
+     * @stable ICU 2.4
+     */
+    UnicodeSet& set(UChar32 start, UChar32 end);
+
+    /**
+     * Return true if the given position, in the given pattern, appears
+     * to be the start of a UnicodeSet pattern.
+     * @stable ICU 2.4
+     */
+    static UBool resemblesPattern(const UnicodeString& pattern,
+                                  int32_t pos);
+
+    /**
+     * Modifies this set to represent the set specified by the given
+     * pattern, ignoring Unicode Pattern_White_Space characters.
+     * See the class description for the syntax of the pattern language.
+     * A frozen set will not be modified.
+     * @param pattern a string specifying what characters are in the set
+     * @param status returns <code>U_ILLEGAL_ARGUMENT_ERROR</code> if the pattern
+     * contains a syntax error.
+     * <em> Empties the set passed before applying the pattern.</em>
+     * @return a reference to this
+     * @stable ICU 2.0
+     */
+    UnicodeSet& applyPattern(const UnicodeString& pattern,
+                             UErrorCode& status);
+
+#ifndef U_HIDE_INTERNAL_API
+    /**
+     * Modifies this set to represent the set specified by the given
+     * pattern, optionally ignoring Unicode Pattern_White_Space characters.
+     * See the class description for the syntax of the pattern language.
+     * A frozen set will not be modified.
+     * @param pattern a string specifying what characters are in the set
+     * @param options bitmask for options to apply to the pattern.
+     * Valid options are USET_IGNORE_SPACE and
+     * at most one of USET_CASE_INSENSITIVE, USET_ADD_CASE_MAPPINGS, USET_SIMPLE_CASE_INSENSITIVE.
+     * These case options are mutually exclusive.
+     * @param symbols a symbol table mapping variable names to
+     * values and stand-ins to UnicodeSets; may be nullptr
+     * @param status returns <code>U_ILLEGAL_ARGUMENT_ERROR</code> if the pattern
+     * contains a syntax error.
+     *<em> Empties the set passed before applying the pattern.</em>
+     * @return a reference to this
+     * @internal
+     */
+    UnicodeSet& applyPattern(const UnicodeString& pattern,
+                             uint32_t options,
+                             const SymbolTable* symbols,
+                             UErrorCode& status);
+#endif  /* U_HIDE_INTERNAL_API */
+
+    /**
+     * Parses the given pattern, starting at the given position.  The
+     * character at pattern.charAt(pos.getIndex()) must be '[', or the
+     * parse fails.  Parsing continues until the corresponding closing
+     * ']'.  If a syntax error is encountered between the opening and
+     * closing brace, the parse fails.  Upon return from a successful
+     * parse, the ParsePosition is updated to point to the character
+     * following the closing ']', and a StringBuffer containing a
+     * pairs list for the parsed pattern is returned.  This method calls
+     * itself recursively to parse embedded subpatterns.
+     *<em> Empties the set passed before applying the pattern.</em>
+     * A frozen set will not be modified.
+     *
+     * @param pattern the string containing the pattern to be parsed.
+     * The portion of the string from pos.getIndex(), which must be a
+     * '[', to the corresponding closing ']', is parsed.
+     * @param pos upon entry, the position at which to being parsing.
+     * The character at pattern.charAt(pos.getIndex()) must be a '['.
+     * Upon return from a successful parse, pos.getIndex() is either
+     * the character after the closing ']' of the parsed pattern, or
+     * pattern.length() if the closing ']' is the last character of
+     * the pattern string.
+     * @param options bitmask for options to apply to the pattern.
+     * Valid options are USET_IGNORE_SPACE and
+     * at most one of USET_CASE_INSENSITIVE, USET_ADD_CASE_MAPPINGS, USET_SIMPLE_CASE_INSENSITIVE.
+     * These case options are mutually exclusive.
+     * @param symbols a symbol table mapping variable names to
+     * values and stand-ins to UnicodeSets; may be nullptr
+     * @param status returns <code>U_ILLEGAL_ARGUMENT_ERROR</code> if the pattern
+     * contains a syntax error.
+     * @return a reference to this
+     * @stable ICU 2.8
+     */
+    UnicodeSet& applyPattern(const UnicodeString& pattern,
+                             ParsePosition& pos,
+                             uint32_t options,
+                             const SymbolTable* symbols,
+                             UErrorCode& status);
+
+    /**
+     * Returns a string representation of this set.  If the result of
+     * calling this function is passed to a UnicodeSet constructor, it
+     * will produce another set that is equal to this one.
+     * A frozen set will not be modified.
+     * @param result the string to receive the rules.  Previous
+     * contents will be deleted.
+     * @param escapeUnprintable if true then convert unprintable
+     * character to their hex escape representations, \\uxxxx or
+     * \\Uxxxxxxxx.  Unprintable characters are those other than
+     * U+000A, U+0020..U+007E.
+     * @stable ICU 2.0
+     */
+    virtual UnicodeString& toPattern(UnicodeString& result,
+                                     UBool escapeUnprintable = false) const override;
+
+    /**
+     * Modifies this set to contain those code points which have the given value
+     * for the given binary or enumerated property, as returned by
+     * u_getIntPropertyValue.  Prior contents of this set are lost.
+     * A frozen set will not be modified.
+     *
+     * @param prop a property in the range UCHAR_BIN_START..UCHAR_BIN_LIMIT-1
+     * or UCHAR_INT_START..UCHAR_INT_LIMIT-1
+     * or UCHAR_MASK_START..UCHAR_MASK_LIMIT-1.
+     *
+     * @param value a value in the range u_getIntPropertyMinValue(prop)..
+     * u_getIntPropertyMaxValue(prop), with one exception.  If prop is
+     * UCHAR_GENERAL_CATEGORY_MASK, then value should not be a UCharCategory, but
+     * rather a mask value produced by U_GET_GC_MASK().  This allows grouped
+     * categories such as [:L:] to be represented.
+     *
+     * @param ec error code input/output parameter
+     *
+     * @return a reference to this set
+     *
+     * @stable ICU 2.4
+     */
+    UnicodeSet& applyIntPropertyValue(UProperty prop,
+                                      int32_t value,
+                                      UErrorCode& ec);
+
+    /**
+     * Modifies this set to contain those code points which have the
+     * given value for the given property.  Prior contents of this
+     * set are lost.
+     * A frozen set will not be modified.
+     *
+     * @param prop a property alias, either short or long.  The name is matched
+     * loosely.  See PropertyAliases.txt for names and a description of loose
+     * matching.  If the value string is empty, then this string is interpreted
+     * as either a General_Category value alias, a Script value alias, a binary
+     * property alias, or a special ID.  Special IDs are matched loosely and
+     * correspond to the following sets:
+     *
+     * "ANY" = [\\u0000-\\U0010FFFF],
+     * "ASCII" = [\\u0000-\\u007F],
+     * "Assigned" = [:^Cn:].
+     *
+     * @param value a value alias, either short or long.  The name is matched
+     * loosely.  See PropertyValueAliases.txt for names and a description of
+     * loose matching.  In addition to aliases listed, numeric values and
+     * canonical combining classes may be expressed numerically, e.g., ("nv",
+     * "0.5") or ("ccc", "220").  The value string may also be empty.
+     *
+     * @param ec error code input/output parameter
+     *
+     * @return a reference to this set
+     *
+     * @stable ICU 2.4
+     */
+    UnicodeSet& applyPropertyAlias(const UnicodeString& prop,
+                                   const UnicodeString& value,
+                                   UErrorCode& ec);
+
+    /**
+     * Returns the number of elements in this set (its cardinality).
+     * Note than the elements of a set may include both individual
+     * codepoints and strings.
+     *
+     * This is slower than getRangeCount() because
+     * it counts the code points of all ranges.
+     *
+     * @return the number of elements in this set (its cardinality).
+     * @stable ICU 2.0
+     * @see getRangeCount
+     */
+    virtual int32_t size(void) const;
+
+    /**
+     * Returns <tt>true</tt> if this set contains no elements.
+     *
+     * @return <tt>true</tt> if this set contains no elements.
+     * @stable ICU 2.0
+     */
+    virtual UBool isEmpty(void) const;
+
+    /**
+     * @return true if this set contains multi-character strings or the empty string.
+     * @stable ICU 70
+     */
+    UBool hasStrings() const;
+
+    /**
+     * Returns true if this set contains the given character.
+     * This function works faster with a frozen set.
+     * @param c character to be checked for containment
+     * @return true if the test condition is met
+     * @stable ICU 2.0
+     */
+    virtual UBool contains(UChar32 c) const override;
+
+    /**
+     * Returns true if this set contains every character
+     * of the given range.
+     * @param start first character, inclusive, of the range
+     * @param end last character, inclusive, of the range
+     * @return true if the test condition is met
+     * @stable ICU 2.0
+     */
+    virtual UBool contains(UChar32 start, UChar32 end) const;
+
+    /**
+     * Returns <tt>true</tt> if this set contains the given
+     * multicharacter string.
+     * @param s string to be checked for containment
+     * @return <tt>true</tt> if this set contains the specified string
+     * @stable ICU 2.4
+     */
+    UBool contains(const UnicodeString& s) const;
+
+    /**
+     * Returns true if this set contains all the characters and strings
+     * of the given set.
+     * @param c set to be checked for containment
+     * @return true if the test condition is met
+     * @stable ICU 2.4
+     */
+    virtual UBool containsAll(const UnicodeSet& c) const;
+
+    /**
+     * Returns true if this set contains all the characters
+     * of the given string.
+     * @param s string containing characters to be checked for containment
+     * @return true if the test condition is met
+     * @stable ICU 2.4
+     */
+    UBool containsAll(const UnicodeString& s) const;
+
+    /**
+     * Returns true if this set contains none of the characters
+     * of the given range.
+     * @param start first character, inclusive, of the range
+     * @param end last character, inclusive, of the range
+     * @return true if the test condition is met
+     * @stable ICU 2.4
+     */
+    UBool containsNone(UChar32 start, UChar32 end) const;
+
+    /**
+     * Returns true if this set contains none of the characters and strings
+     * of the given set.
+     * @param c set to be checked for containment
+     * @return true if the test condition is met
+     * @stable ICU 2.4
+     */
+    UBool containsNone(const UnicodeSet& c) const;
+
+    /**
+     * Returns true if this set contains none of the characters
+     * of the given string.
+     * @param s string containing characters to be checked for containment
+     * @return true if the test condition is met
+     * @stable ICU 2.4
+     */
+    UBool containsNone(const UnicodeString& s) const;
+
+    /**
+     * Returns true if this set contains one or more of the characters
+     * in the given range.
+     * @param start first character, inclusive, of the range
+     * @param end last character, inclusive, of the range
+     * @return true if the condition is met
+     * @stable ICU 2.4
+     */
+    inline UBool containsSome(UChar32 start, UChar32 end) const;
+
+    /**
+     * Returns true if this set contains one or more of the characters
+     * and strings of the given set.
+     * @param s The set to be checked for containment
+     * @return true if the condition is met
+     * @stable ICU 2.4
+     */
+    inline UBool containsSome(const UnicodeSet& s) const;
+
+    /**
+     * Returns true if this set contains one or more of the characters
+     * of the given string.
+     * @param s string containing characters to be checked for containment
+     * @return true if the condition is met
+     * @stable ICU 2.4
+     */
+    inline UBool containsSome(const UnicodeString& s) const;
+
+    /**
+     * Returns the length of the initial substring of the input string which
+     * consists only of characters and strings that are contained in this set
+     * (USET_SPAN_CONTAINED, USET_SPAN_SIMPLE),
+     * or only of characters and strings that are not contained
+     * in this set (USET_SPAN_NOT_CONTAINED).
+     * See USetSpanCondition for details.
+     * Similar to the strspn() C library function.
+     * Unpaired surrogates are treated according to contains() of their surrogate code points.
+     * This function works faster with a frozen set and with a non-negative string length argument.
+     * @param s start of the string
+     * @param length of the string; can be -1 for NUL-terminated
+     * @param spanCondition specifies the containment condition
+     * @return the length of the initial substring according to the spanCondition;
+     *         0 if the start of the string does not fit the spanCondition
+     * @stable ICU 3.8
+     * @see USetSpanCondition
+     */
+    int32_t span(const char16_t *s, int32_t length, USetSpanCondition spanCondition) const;
+
+    /**
+     * Returns the end of the substring of the input string according to the USetSpanCondition.
+     * Same as <code>start+span(s.getBuffer()+start, s.length()-start, spanCondition)</code>
+     * after pinning start to 0<=start<=s.length().
+     * @param s the string
+     * @param start the start index in the string for the span operation
+     * @param spanCondition specifies the containment condition
+     * @return the exclusive end of the substring according to the spanCondition;
+     *         the substring s.tempSubStringBetween(start, end) fulfills the spanCondition
+     * @stable ICU 4.4
+     * @see USetSpanCondition
+     */
+    inline int32_t span(const UnicodeString &s, int32_t start, USetSpanCondition spanCondition) const;
+
+    /**
+     * Returns the start of the trailing substring of the input string which
+     * consists only of characters and strings that are contained in this set
+     * (USET_SPAN_CONTAINED, USET_SPAN_SIMPLE),
+     * or only of characters and strings that are not contained
+     * in this set (USET_SPAN_NOT_CONTAINED).
+     * See USetSpanCondition for details.
+     * Unpaired surrogates are treated according to contains() of their surrogate code points.
+     * This function works faster with a frozen set and with a non-negative string length argument.
+     * @param s start of the string
+     * @param length of the string; can be -1 for NUL-terminated
+     * @param spanCondition specifies the containment condition
+     * @return the start of the trailing substring according to the spanCondition;
+     *         the string length if the end of the string does not fit the spanCondition
+     * @stable ICU 3.8
+     * @see USetSpanCondition
+     */
+    int32_t spanBack(const char16_t *s, int32_t length, USetSpanCondition spanCondition) const;
+
+    /**
+     * Returns the start of the substring of the input string according to the USetSpanCondition.
+     * Same as <code>spanBack(s.getBuffer(), limit, spanCondition)</code>
+     * after pinning limit to 0<=end<=s.length().
+     * @param s the string
+     * @param limit the exclusive-end index in the string for the span operation
+     *              (use s.length() or INT32_MAX for spanning back from the end of the string)
+     * @param spanCondition specifies the containment condition
+     * @return the start of the substring according to the spanCondition;
+     *         the substring s.tempSubStringBetween(start, limit) fulfills the spanCondition
+     * @stable ICU 4.4
+     * @see USetSpanCondition
+     */
+    inline int32_t spanBack(const UnicodeString &s, int32_t limit, USetSpanCondition spanCondition) const;
+
+    /**
+     * Returns the length of the initial substring of the input string which
+     * consists only of characters and strings that are contained in this set
+     * (USET_SPAN_CONTAINED, USET_SPAN_SIMPLE),
+     * or only of characters and strings that are not contained
+     * in this set (USET_SPAN_NOT_CONTAINED).
+     * See USetSpanCondition for details.
+     * Similar to the strspn() C library function.
+     * Malformed byte sequences are treated according to contains(0xfffd).
+     * This function works faster with a frozen set and with a non-negative string length argument.
+     * @param s start of the string (UTF-8)
+     * @param length of the string; can be -1 for NUL-terminated
+     * @param spanCondition specifies the containment condition
+     * @return the length of the initial substring according to the spanCondition;
+     *         0 if the start of the string does not fit the spanCondition
+     * @stable ICU 3.8
+     * @see USetSpanCondition
+     */
+    int32_t spanUTF8(const char *s, int32_t length, USetSpanCondition spanCondition) const;
+
+    /**
+     * Returns the start of the trailing substring of the input string which
+     * consists only of characters and strings that are contained in this set
+     * (USET_SPAN_CONTAINED, USET_SPAN_SIMPLE),
+     * or only of characters and strings that are not contained
+     * in this set (USET_SPAN_NOT_CONTAINED).
+     * See USetSpanCondition for details.
+     * Malformed byte sequences are treated according to contains(0xfffd).
+     * This function works faster with a frozen set and with a non-negative string length argument.
+     * @param s start of the string (UTF-8)
+     * @param length of the string; can be -1 for NUL-terminated
+     * @param spanCondition specifies the containment condition
+     * @return the start of the trailing substring according to the spanCondition;
+     *         the string length if the end of the string does not fit the spanCondition
+     * @stable ICU 3.8
+     * @see USetSpanCondition
+     */
+    int32_t spanBackUTF8(const char *s, int32_t length, USetSpanCondition spanCondition) const;
+
+    /**
+     * Implement UnicodeMatcher::matches()
+     * @stable ICU 2.4
+     */
+    virtual UMatchDegree matches(const Replaceable& text,
+                         int32_t& offset,
+                         int32_t limit,
+                         UBool incremental) override;
+
+private:
+    /**
+     * Returns the longest match for s in text at the given position.
+     * If limit > start then match forward from start+1 to limit
+     * matching all characters except s.charAt(0).  If limit < start,
+     * go backward starting from start-1 matching all characters
+     * except s.charAt(s.length()-1).  This method assumes that the
+     * first character, text.charAt(start), matches s, so it does not
+     * check it.
+     * @param text the text to match
+     * @param start the first character to match.  In the forward
+     * direction, text.charAt(start) is matched against s.charAt(0).
+     * In the reverse direction, it is matched against
+     * s.charAt(s.length()-1).
+     * @param limit the limit offset for matching, either last+1 in
+     * the forward direction, or last-1 in the reverse direction,
+     * where last is the index of the last character to match.
+     * @param s
+     * @return If part of s matches up to the limit, return |limit -
+     * start|.  If all of s matches before reaching the limit, return
+     * s.length().  If there is a mismatch between s and text, return
+     * 0
+     */
+    static int32_t matchRest(const Replaceable& text,
+                             int32_t start, int32_t limit,
+                             const UnicodeString& s);
+
+    /**
+     * Returns the smallest value i such that c < list[i].  Caller
+     * must ensure that c is a legal value or this method will enter
+     * an infinite loop.  This method performs a binary search.
+     * @param c a character in the range MIN_VALUE..MAX_VALUE
+     * inclusive
+     * @return the smallest integer i in the range 0..len-1,
+     * inclusive, such that c < list[i]
+     */
+    int32_t findCodePoint(UChar32 c) const;
+
+public:
+
+    /**
+     * Implementation of UnicodeMatcher API.  Union the set of all
+     * characters that may be matched by this object into the given
+     * set.
+     * @param toUnionTo the set into which to union the source characters
+     * @stable ICU 2.4
+     */
+    virtual void addMatchSetTo(UnicodeSet& toUnionTo) const override;
+
+    /**
+     * Returns the index of the given character within this set, where
+     * the set is ordered by ascending code point.  If the character
+     * is not in this set, return -1.  The inverse of this method is
+     * <code>charAt()</code>.
+     * @return an index from 0..size()-1, or -1
+     * @stable ICU 2.4
+     */
+    int32_t indexOf(UChar32 c) const;
+
+    /**
+     * Returns the character at the given index within this set, where
+     * the set is ordered by ascending code point.  If the index is
+     * out of range for characters, returns (UChar32)-1.
+     * The inverse of this method is <code>indexOf()</code>.
+     *
+     * For iteration, this is slower than UnicodeSetIterator or
+     * getRangeCount()/getRangeStart()/getRangeEnd(),
+     * because for each call it skips linearly over <code>index</code>
+     * characters in the ranges.
+     *
+     * @param index an index from 0..size()-1
+     * @return the character at the given index, or (UChar32)-1.
+     * @stable ICU 2.4
+     */
+    UChar32 charAt(int32_t index) const;
+
+    /**
+     * Adds the specified range to this set if it is not already
+     * present.  If this set already contains the specified range,
+     * the call leaves this set unchanged.  If <code>start > end</code>
+     * then an empty range is added, leaving the set unchanged.
+     * This is equivalent to a boolean logic OR, or a set UNION.
+     * A frozen set will not be modified.
+     *
+     * @param start first character, inclusive, of range to be added
+     * to this set.
+     * @param end last character, inclusive, of range to be added
+     * to this set.
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet& add(UChar32 start, UChar32 end);
+
+    /**
+     * Adds the specified character to this set if it is not already
+     * present.  If this set already contains the specified character,
+     * the call leaves this set unchanged.
+     * A frozen set will not be modified.
+     *
+     * @param c the character (code point)
+     * @return this object, for chaining
+     * @stable ICU 2.0
+     */
+    UnicodeSet& add(UChar32 c);
+
+    /**
+     * Adds the specified multicharacter to this set if it is not already
+     * present.  If this set already contains the multicharacter,
+     * the call leaves this set unchanged.
+     * Thus "ch" => {"ch"}
+     * A frozen set will not be modified.
+     *
+     * @param s the source string
+     * @return this object, for chaining
+     * @stable ICU 2.4
+     */
+    UnicodeSet& add(const UnicodeString& s);
+
+ private:
+    /**
+     * @return a code point IF the string consists of a single one.
+     * otherwise returns -1.
+     * @param s string to test
+     */
+    static int32_t getSingleCP(const UnicodeString& s);
+
+    void _add(const UnicodeString& s);
+
+ public:
+    /**
+     * Adds each of the characters in this string to the set. Note: "ch" => {"c", "h"}
+     * If this set already contains any particular character, it has no effect on that character.
+     * A frozen set will not be modified.
+     * @param s the source string
+     * @return this object, for chaining
+     * @stable ICU 2.4
+     */
+    UnicodeSet& addAll(const UnicodeString& s);
+
+    /**
+     * Retains EACH of the characters in this string. Note: "ch" == {"c", "h"}
+     * A frozen set will not be modified.
+     * @param s the source string
+     * @return this object, for chaining
+     * @stable ICU 2.4
+     */
+    UnicodeSet& retainAll(const UnicodeString& s);
+
+    /**
+     * Complement EACH of the characters in this string. Note: "ch" == {"c", "h"}
+     * A frozen set will not be modified.
+     * @param s the source string
+     * @return this object, for chaining
+     * @stable ICU 2.4
+     */
+    UnicodeSet& complementAll(const UnicodeString& s);
+
+    /**
+     * Remove EACH of the characters in this string. Note: "ch" == {"c", "h"}
+     * A frozen set will not be modified.
+     * @param s the source string
+     * @return this object, for chaining
+     * @stable ICU 2.4
+     */
+    UnicodeSet& removeAll(const UnicodeString& s);
+
+    /**
+     * Makes a set from a multicharacter string. Thus "ch" => {"ch"}
+     *
+     * @param s the source string
+     * @return a newly created set containing the given string.
+     * The caller owns the return object and is responsible for deleting it.
+     * @stable ICU 2.4
+     */
+    static UnicodeSet* U_EXPORT2 createFrom(const UnicodeString& s);
+
+
+    /**
+     * Makes a set from each of the characters in the string. Thus "ch" => {"c", "h"}
+     * @param s the source string
+     * @return a newly created set containing the given characters
+     * The caller owns the return object and is responsible for deleting it.
+     * @stable ICU 2.4
+     */
+    static UnicodeSet* U_EXPORT2 createFromAll(const UnicodeString& s);
+
+    /**
+     * Retain only the elements in this set that are contained in the
+     * specified range.  If <code>start > end</code> then an empty range is
+     * retained, leaving the set empty.  This is equivalent to
+     * a boolean logic AND, or a set INTERSECTION.
+     * A frozen set will not be modified.
+     *
+     * @param start first character, inclusive, of range
+     * @param end last character, inclusive, of range
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet& retain(UChar32 start, UChar32 end);
+
+
+    /**
+     * Retain the specified character from this set if it is present.
+     * A frozen set will not be modified.
+     *
+     * @param c the character (code point)
+     * @return this object, for chaining
+     * @stable ICU 2.0
+     */
+    UnicodeSet& retain(UChar32 c);
+
+    /**
+     * Retains only the specified string from this set if it is present.
+     * Upon return this set will be empty if it did not contain s, or
+     * will only contain s if it did contain s.
+     * A frozen set will not be modified.
+     *
+     * @param s the source string
+     * @return this object, for chaining
+     * @stable ICU 69
+     */
+    UnicodeSet& retain(const UnicodeString &s);
+
+    /**
+     * Removes the specified range from this set if it is present.
+     * The set will not contain the specified range once the call
+     * returns.  If <code>start > end</code> then an empty range is
+     * removed, leaving the set unchanged.
+     * A frozen set will not be modified.
+     *
+     * @param start first character, inclusive, of range to be removed
+     * from this set.
+     * @param end last character, inclusive, of range to be removed
+     * from this set.
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet& remove(UChar32 start, UChar32 end);
+
+    /**
+     * Removes the specified character from this set if it is present.
+     * The set will not contain the specified range once the call
+     * returns.
+     * A frozen set will not be modified.
+     *
+     * @param c the character (code point)
+     * @return this object, for chaining
+     * @stable ICU 2.0
+     */
+    UnicodeSet& remove(UChar32 c);
+
+    /**
+     * Removes the specified string from this set if it is present.
+     * The set will not contain the specified character once the call
+     * returns.
+     * A frozen set will not be modified.
+     * @param s the source string
+     * @return this object, for chaining
+     * @stable ICU 2.4
+     */
+    UnicodeSet& remove(const UnicodeString& s);
+
+    /**
+     * This is equivalent to
+     * <code>complement(MIN_VALUE, MAX_VALUE)</code>.
+     *
+     * <strong>Note:</strong> This performs a symmetric difference with all code points
+     * <em>and thus retains all multicharacter strings</em>.
+     * In order to achieve a “code point complement” (all code points minus this set),
+     * the easiest is to <code>.complement().removeAllStrings()</code>.
+     *
+     * A frozen set will not be modified.
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet& complement();
+
+    /**
+     * Complements the specified range in this set.  Any character in
+     * the range will be removed if it is in this set, or will be
+     * added if it is not in this set.  If <code>start > end</code>
+     * then an empty range is complemented, leaving the set unchanged.
+     * This is equivalent to a boolean logic XOR.
+     * A frozen set will not be modified.
+     *
+     * @param start first character, inclusive, of range
+     * @param end last character, inclusive, of range
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet& complement(UChar32 start, UChar32 end);
+
+    /**
+     * Complements the specified character in this set.  The character
+     * will be removed if it is in this set, or will be added if it is
+     * not in this set.
+     * A frozen set will not be modified.
+     *
+     * @param c the character (code point)
+     * @return this object, for chaining
+     * @stable ICU 2.0
+     */
+    UnicodeSet& complement(UChar32 c);
+
+    /**
+     * Complement the specified string in this set.
+     * The string will be removed if it is in this set, or will be added if it is not in this set.
+     * A frozen set will not be modified.
+     *
+     * @param s the string to complement
+     * @return this object, for chaining
+     * @stable ICU 2.4
+     */
+    UnicodeSet& complement(const UnicodeString& s);
+
+    /**
+     * Adds all of the elements in the specified set to this set if
+     * they're not already present.  This operation effectively
+     * modifies this set so that its value is the <i>union</i> of the two
+     * sets.  The behavior of this operation is unspecified if the specified
+     * collection is modified while the operation is in progress.
+     * A frozen set will not be modified.
+     *
+     * @param c set whose elements are to be added to this set.
+     * @see #add(UChar32, UChar32)
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet& addAll(const UnicodeSet& c);
+
+    /**
+     * Retains only the elements in this set that are contained in the
+     * specified set.  In other words, removes from this set all of
+     * its elements that are not contained in the specified set.  This
+     * operation effectively modifies this set so that its value is
+     * the <i>intersection</i> of the two sets.
+     * A frozen set will not be modified.
+     *
+     * @param c set that defines which elements this set will retain.
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet& retainAll(const UnicodeSet& c);
+
+    /**
+     * Removes from this set all of its elements that are contained in the
+     * specified set.  This operation effectively modifies this
+     * set so that its value is the <i>asymmetric set difference</i> of
+     * the two sets.
+     * A frozen set will not be modified.
+     *
+     * @param c set that defines which elements will be removed from
+     *          this set.
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet& removeAll(const UnicodeSet& c);
+
+    /**
+     * Complements in this set all elements contained in the specified
+     * set.  Any character in the other set will be removed if it is
+     * in this set, or will be added if it is not in this set.
+     * A frozen set will not be modified.
+     *
+     * @param c set that defines which elements will be xor'ed from
+     *          this set.
+     * @stable ICU 2.4
+     */
+    virtual UnicodeSet& complementAll(const UnicodeSet& c);
+
+    /**
+     * Removes all of the elements from this set.  This set will be
+     * empty after this call returns.
+     * A frozen set will not be modified.
+     * @stable ICU 2.0
+     */
+    virtual UnicodeSet& clear(void);
+
+    /**
+     * Close this set over the given attribute.  For the attribute
+     * USET_CASE_INSENSITIVE, the result is to modify this set so that:
+     *
+     * 1. For each character or string 'a' in this set, all strings or
+     * characters 'b' such that foldCase(a) == foldCase(b) are added
+     * to this set.
+     *
+     * 2. For each string 'e' in the resulting set, if e !=
+     * foldCase(e), 'e' will be removed.
+     *
+     * Example: [aq\\u00DF{Bc}{bC}{Fi}] => [aAqQ\\u00DF\\uFB01{ss}{bc}{fi}]
+     *
+     * (Here foldCase(x) refers to the operation u_strFoldCase, and a
+     * == b denotes that the contents are the same, not pointer
+     * comparison.)
+     *
+     * A frozen set will not be modified.
+     *
+     * @param attribute bitmask for attributes to close over.
+     * Valid options:
+     * At most one of USET_CASE_INSENSITIVE, USET_ADD_CASE_MAPPINGS, USET_SIMPLE_CASE_INSENSITIVE.
+     * These case options are mutually exclusive.
+     * Unrelated options bits are ignored.
+     * @return a reference to this set.
+     * @stable ICU 4.2
+     */
+    UnicodeSet& closeOver(int32_t attribute);
+
+    /**
+     * Remove all strings from this set.
+     *
+     * @return a reference to this set.
+     * @stable ICU 4.2
+     */
+    virtual UnicodeSet &removeAllStrings();
+
+    /**
+     * Iteration method that returns the number of ranges contained in
+     * this set.
+     * @see #getRangeStart
+     * @see #getRangeEnd
+     * @stable ICU 2.4
+     */
+    virtual int32_t getRangeCount(void) const;
+
+    /**
+     * Iteration method that returns the first character in the
+     * specified range of this set.
+     * @see #getRangeCount
+     * @see #getRangeEnd
+     * @stable ICU 2.4
+     */
+    virtual UChar32 getRangeStart(int32_t index) const;
+
+    /**
+     * Iteration method that returns the last character in the
+     * specified range of this set.
+     * @see #getRangeStart
+     * @see #getRangeEnd
+     * @stable ICU 2.4
+     */
+    virtual UChar32 getRangeEnd(int32_t index) const;
+
+    /**
+     * Serializes this set into an array of 16-bit integers.  Serialization
+     * (currently) only records the characters in the set; multicharacter
+     * strings are ignored.
+     *
+     * The array has following format (each line is one 16-bit
+     * integer):
+     *
+     *  length     = (n+2*m) | (m!=0?0x8000:0)
+     *  bmpLength  = n; present if m!=0
+     *  bmp[0]
+     *  bmp[1]
+     *  ...
+     *  bmp[n-1]
+     *  supp-high[0]
+     *  supp-low[0]
+     *  supp-high[1]
+     *  supp-low[1]
+     *  ...
+     *  supp-high[m-1]
+     *  supp-low[m-1]
+     *
+     * The array starts with a header.  After the header are n bmp
+     * code points, then m supplementary code points.  Either n or m
+     * or both may be zero.  n+2*m is always <= 0x7FFF.
+     *
+     * If there are no supplementary characters (if m==0) then the
+     * header is one 16-bit integer, 'length', with value n.
+     *
+     * If there are supplementary characters (if m!=0) then the header
+     * is two 16-bit integers.  The first, 'length', has value
+     * (n+2*m)|0x8000.  The second, 'bmpLength', has value n.
+     *
+     * After the header the code points are stored in ascending order.
+     * Supplementary code points are stored as most significant 16
+     * bits followed by least significant 16 bits.
+     *
+     * @param dest pointer to buffer of destCapacity 16-bit integers.
+     * May be nullptr only if destCapacity is zero.
+     * @param destCapacity size of dest, or zero.  Must not be negative.
+     * @param ec error code.  Will be set to U_INDEX_OUTOFBOUNDS_ERROR
+     * if n+2*m > 0x7FFF.  Will be set to U_BUFFER_OVERFLOW_ERROR if
+     * n+2*m+(m!=0?2:1) > destCapacity.
+     * @return the total length of the serialized format, including
+     * the header, that is, n+2*m+(m!=0?2:1), or 0 on error other
+     * than U_BUFFER_OVERFLOW_ERROR.
+     * @stable ICU 2.4
+     */
+    int32_t serialize(uint16_t *dest, int32_t destCapacity, UErrorCode& ec) const;
+
+    /**
+     * Reallocate this objects internal structures to take up the least
+     * possible space, without changing this object's value.
+     * A frozen set will not be modified.
+     * @stable ICU 2.4
+     */
+    virtual UnicodeSet& compact();
+
+    /**
+     * Return the class ID for this class.  This is useful only for
+     * comparing to a return value from getDynamicClassID().  For example:
+     * <pre>
+     * .      Base* polymorphic_pointer = createPolymorphicObject();
+     * .      if (polymorphic_pointer->getDynamicClassID() ==
+     * .          Derived::getStaticClassID()) ...
+     * </pre>
+     * @return          The class ID for all objects of this class.
+     * @stable ICU 2.0
+     */
+    static UClassID U_EXPORT2 getStaticClassID(void);
+
+    /**
+     * Implement UnicodeFunctor API.
+     *
+     * @return The class ID for this object. All objects of a given
+     * class have the same class ID.  Objects of other classes have
+     * different class IDs.
+     * @stable ICU 2.4
+     */
+    virtual UClassID getDynamicClassID(void) const override;
+
+private:
+
+    // Private API for the USet API
+
+    friend class USetAccess;
+
+    const UnicodeString* getString(int32_t index) const;
+
+    //----------------------------------------------------------------
+    // RuleBasedTransliterator support
+    //----------------------------------------------------------------
+
+private:
+
+    /**
+     * Returns <tt>true</tt> if this set contains any character whose low byte
+     * is the given value.  This is used by <tt>RuleBasedTransliterator</tt> for
+     * indexing.
+     */
+    virtual UBool matchesIndexValue(uint8_t v) const override;
+
+private:
+    friend class RBBIRuleScanner;
+
+    //----------------------------------------------------------------
+    // Implementation: Clone as thawed (see ICU4J Freezable)
+    //----------------------------------------------------------------
+
+    UnicodeSet(const UnicodeSet& o, UBool /* asThawed */);
+    UnicodeSet& copyFrom(const UnicodeSet& o, UBool asThawed);
+
+    //----------------------------------------------------------------
+    // Implementation: Pattern parsing
+    //----------------------------------------------------------------
+
+    void applyPatternIgnoreSpace(const UnicodeString& pattern,
+                                 ParsePosition& pos,
+                                 const SymbolTable* symbols,
+                                 UErrorCode& status);
+
+    void applyPattern(RuleCharacterIterator& chars,
+                      const SymbolTable* symbols,
+                      UnicodeString& rebuiltPat,
+                      uint32_t options,
+                      UnicodeSet& (UnicodeSet::*caseClosure)(int32_t attribute),
+                      int32_t depth,
+                      UErrorCode& ec);
+
+    void closeOverCaseInsensitive(bool simple);
+    void closeOverAddCaseMappings();
+
+    //----------------------------------------------------------------
+    // Implementation: Utility methods
+    //----------------------------------------------------------------
+
+    static int32_t nextCapacity(int32_t minCapacity);
+
+    bool ensureCapacity(int32_t newLen);
+
+    bool ensureBufferCapacity(int32_t newLen);
+
+    void swapBuffers(void);
+
+    UBool allocateStrings(UErrorCode &status);
+    int32_t stringsSize() const;
+    UBool stringsContains(const UnicodeString &s) const;
+
+    UnicodeString& _toPattern(UnicodeString& result,
+                              UBool escapeUnprintable) const;
+
+    UnicodeString& _generatePattern(UnicodeString& result,
+                                    UBool escapeUnprintable) const;
+
+    static void _appendToPat(UnicodeString& buf, const UnicodeString& s, UBool escapeUnprintable);
+
+    static void _appendToPat(UnicodeString& buf, UChar32 c, UBool escapeUnprintable);
+
+    static void _appendToPat(UnicodeString &result, UChar32 start, UChar32 end,
+                             UBool escapeUnprintable);
+
+    //----------------------------------------------------------------
+    // Implementation: Fundamental operators
+    //----------------------------------------------------------------
+
+    void exclusiveOr(const UChar32* other, int32_t otherLen, int8_t polarity);
+
+    void add(const UChar32* other, int32_t otherLen, int8_t polarity);
+
+    void retain(const UChar32* other, int32_t otherLen, int8_t polarity);
+
+    /**
+     * Return true if the given position, in the given pattern, appears
+     * to be the start of a property set pattern [:foo:], \\p{foo}, or
+     * \\P{foo}, or \\N{name}.
+     */
+    static UBool resemblesPropertyPattern(const UnicodeString& pattern,
+                                          int32_t pos);
+
+    static UBool resemblesPropertyPattern(RuleCharacterIterator& chars,
+                                          int32_t iterOpts);
+
+    /**
+     * Parse the given property pattern at the given parse position
+     * and set this UnicodeSet to the result.
+     *
+     * The original design document is out of date, but still useful.
+     * Ignore the property and value names:
+     * https://htmlpreview.github.io/?https://github.com/unicode-org/icu-docs/blob/main/design/unicodeset_properties.html
+     *
+     * Recognized syntax:
+     *
+     * [:foo:] [:^foo:] - white space not allowed within "[:" or ":]"
+     * \\p{foo} \\P{foo}  - white space not allowed within "\\p" or "\\P"
+     * \\N{name}         - white space not allowed within "\\N"
+     *
+     * Other than the above restrictions, Unicode Pattern_White_Space characters are ignored.
+     * Case is ignored except in "\\p" and "\\P" and "\\N".  In 'name' leading
+     * and trailing space is deleted, and internal runs of whitespace
+     * are collapsed to a single space.
+     *
+     * We support binary properties, enumerated properties, and the
+     * following non-enumerated properties:
+     *
+     *  Numeric_Value
+     *  Name
+     *  Unicode_1_Name
+     *
+     * @param pattern the pattern string
+     * @param ppos on entry, the position at which to begin parsing.
+     * This should be one of the locations marked '^':
+     *
+     *   [:blah:]     \\p{blah}     \\P{blah}     \\N{name}
+     *   ^       %    ^       %    ^       %    ^       %
+     *
+     * On return, the position after the last character parsed, that is,
+     * the locations marked '%'.  If the parse fails, ppos is returned
+     * unchanged.
+     * @param ec status
+     * @return a reference to this.
+     */
+    UnicodeSet& applyPropertyPattern(const UnicodeString& pattern,
+                                     ParsePosition& ppos,
+                                     UErrorCode &ec);
+
+    void applyPropertyPattern(RuleCharacterIterator& chars,
+                              UnicodeString& rebuiltPat,
+                              UErrorCode& ec);
+
+    /**
+     * A filter that returns true if the given code point should be
+     * included in the UnicodeSet being constructed.
+     */
+    typedef UBool (*Filter)(UChar32 codePoint, void* context);
+
+    /**
+     * Given a filter, set this UnicodeSet to the code points
+     * contained by that filter.  The filter MUST be
+     * property-conformant.  That is, if it returns value v for one
+     * code point, then it must return v for all affiliated code
+     * points, as defined by the inclusions list.  See
+     * getInclusions().
+     * src is a UPropertySource value.
+     */
+    void applyFilter(Filter filter,
+                     void* context,
+                     const UnicodeSet* inclusions,
+                     UErrorCode &status);
+
+    /**
+     * Set the new pattern to cache.
+     */
+    void setPattern(const UnicodeString& newPat) {
+        setPattern(newPat.getBuffer(), newPat.length());
+    }
+    void setPattern(const char16_t *newPat, int32_t newPatLen);
+    /**
+     * Release existing cached pattern.
+     */
+    void releasePattern();
+
+    friend class UnicodeSetIterator;
+};
+
+
+
+inline bool UnicodeSet::operator!=(const UnicodeSet& o) const {
+    return !operator==(o);
+}
+
+inline UBool UnicodeSet::isFrozen() const {
+    return (UBool)(bmpSet!=nullptr || stringSpan!=nullptr);
+}
+
+inline UBool UnicodeSet::containsSome(UChar32 start, UChar32 end) const {
+    return !containsNone(start, end);
+}
+
+inline UBool UnicodeSet::containsSome(const UnicodeSet& s) const {
+    return !containsNone(s);
+}
+
+inline UBool UnicodeSet::containsSome(const UnicodeString& s) const {
+    return !containsNone(s);
+}
+
+inline UBool UnicodeSet::isBogus() const {
+    return (UBool)(fFlags & kIsBogus);
+}
+
+inline UnicodeSet *UnicodeSet::fromUSet(USet *uset) {
+    return reinterpret_cast<UnicodeSet *>(uset);
+}
+
+inline const UnicodeSet *UnicodeSet::fromUSet(const USet *uset) {
+    return reinterpret_cast<const UnicodeSet *>(uset);
+}
+
+inline USet *UnicodeSet::toUSet() {
+    return reinterpret_cast<USet *>(this);
+}
+
+inline const USet *UnicodeSet::toUSet() const {
+    return reinterpret_cast<const USet *>(this);
+}
+
+inline int32_t UnicodeSet::span(const UnicodeString &s, int32_t start, USetSpanCondition spanCondition) const {
+    int32_t sLength=s.length();
+    if(start<0) {
+        start=0;
+    } else if(start>sLength) {
+        start=sLength;
+    }
+    return start+span(s.getBuffer()+start, sLength-start, spanCondition);
+}
+
+inline int32_t UnicodeSet::spanBack(const UnicodeString &s, int32_t limit, USetSpanCondition spanCondition) const {
+    int32_t sLength=s.length();
+    if(limit<0) {
+        limit=0;
+    } else if(limit>sLength) {
+        limit=sLength;
+    }
+    return spanBack(s.getBuffer(), limit, spanCondition);
+}
+
+U_NAMESPACE_END
+
+#endif /* U_SHOW_CPLUSPLUS_API */
+
+#endif