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diff --git a/intl/icu/source/common/unisetspan.h b/intl/icu/source/common/unisetspan.h
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+++ b/intl/icu/source/common/unisetspan.h
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+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+******************************************************************************
+*
+*   Copyright (C) 2007, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+******************************************************************************
+*   file name:  unisetspan.h
+*   encoding:   UTF-8
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 2007mar01
+*   created by: Markus W. Scherer
+*/
+
+#ifndef __UNISETSPAN_H__
+#define __UNISETSPAN_H__
+
+#include "unicode/utypes.h"
+#include "unicode/uniset.h"
+
+U_NAMESPACE_BEGIN
+
+/*
+ * Implement span() etc. for a set with strings.
+ * Avoid recursion because of its exponential complexity.
+ * Instead, try multiple paths at once and track them with an IndexList.
+ */
+class UnicodeSetStringSpan : public UMemory {
+public:
+    /*
+     * Which span() variant will be used?
+     * The object is either built for one variant and used once,
+     * or built for all and may be used many times.
+     */
+    enum {
+        FWD             = 0x20,
+        BACK            = 0x10,
+        UTF16           = 8,
+        UTF8            = 4,
+        CONTAINED       = 2,
+        NOT_CONTAINED   = 1,
+
+        ALL             = 0x3f,
+
+        FWD_UTF16_CONTAINED     = FWD  | UTF16 |     CONTAINED,
+        FWD_UTF16_NOT_CONTAINED = FWD  | UTF16 | NOT_CONTAINED,
+        FWD_UTF8_CONTAINED      = FWD  | UTF8  |     CONTAINED,
+        FWD_UTF8_NOT_CONTAINED  = FWD  | UTF8  | NOT_CONTAINED,
+        BACK_UTF16_CONTAINED    = BACK | UTF16 |     CONTAINED,
+        BACK_UTF16_NOT_CONTAINED= BACK | UTF16 | NOT_CONTAINED,
+        BACK_UTF8_CONTAINED     = BACK | UTF8  |     CONTAINED,
+        BACK_UTF8_NOT_CONTAINED = BACK | UTF8  | NOT_CONTAINED
+    };
+
+    UnicodeSetStringSpan(const UnicodeSet &set, const UVector &setStrings, uint32_t which);
+
+    // Copy constructor. Assumes which==ALL for a frozen set.
+    UnicodeSetStringSpan(const UnicodeSetStringSpan &otherStringSpan, const UVector &newParentSetStrings);
+
+    ~UnicodeSetStringSpan();
+
+    /*
+     * Do the strings need to be checked in span() etc.?
+     * @return true if strings need to be checked (call span() here),
+     *         false if not (use a BMPSet for best performance).
+     */
+    inline UBool needsStringSpanUTF16();
+    inline UBool needsStringSpanUTF8();
+
+    // For fast UnicodeSet::contains(c).
+    inline UBool contains(UChar32 c) const;
+
+    int32_t span(const char16_t *s, int32_t length, USetSpanCondition spanCondition) const;
+
+    int32_t spanBack(const char16_t *s, int32_t length, USetSpanCondition spanCondition) const;
+
+    int32_t spanUTF8(const uint8_t *s, int32_t length, USetSpanCondition spanCondition) const;
+
+    int32_t spanBackUTF8(const uint8_t *s, int32_t length, USetSpanCondition spanCondition) const;
+
+private:
+    // Special spanLength byte values.
+    enum {
+        // The spanLength is >=0xfe.
+        LONG_SPAN=0xfe,
+        // All code points in the string are contained in the parent set.
+        ALL_CP_CONTAINED=0xff
+    };
+
+    // Add a starting or ending string character to the spanNotSet
+    // so that a character span ends before any string.
+    void addToSpanNotSet(UChar32 c);
+
+    int32_t spanNot(const char16_t *s, int32_t length) const;
+    int32_t spanNotBack(const char16_t *s, int32_t length) const;
+    int32_t spanNotUTF8(const uint8_t *s, int32_t length) const;
+    int32_t spanNotBackUTF8(const uint8_t *s, int32_t length) const;
+
+    // Set for span(). Same as parent but without strings.
+    UnicodeSet spanSet;
+
+    // Set for span(not contained).
+    // Same as spanSet, plus characters that start or end strings.
+    UnicodeSet *pSpanNotSet;
+
+    // The strings of the parent set.
+    const UVector &strings;
+
+    // Pointer to the UTF-8 string lengths.
+    // Also pointer to further allocated storage for meta data and
+    // UTF-8 string contents as necessary.
+    int32_t *utf8Lengths;
+
+    // Pointer to the part of the (utf8Lengths) memory block that stores
+    // the lengths of span(), spanBack() etc. for each string.
+    uint8_t *spanLengths;
+
+    // Pointer to the part of the (utf8Lengths) memory block that stores
+    // the UTF-8 versions of the parent set's strings.
+    uint8_t *utf8;
+
+    // Number of bytes for all UTF-8 versions of strings together.
+    int32_t utf8Length;
+
+    // Maximum lengths of relevant strings.
+    int32_t maxLength16;
+    int32_t maxLength8;
+
+    // Set up for all variants of span()?
+    UBool all;
+
+    // Memory for small numbers and lengths of strings.
+    // For example, for 8 strings:
+    // 8 UTF-8 lengths, 8*4 bytes span lengths, 8*2 3-byte UTF-8 characters
+    // = 112 bytes = int32_t[28].
+    int32_t staticLengths[32];
+};
+
+UBool UnicodeSetStringSpan::needsStringSpanUTF16() {
+    return (UBool)(maxLength16!=0);
+}
+
+UBool UnicodeSetStringSpan::needsStringSpanUTF8() {
+    return (UBool)(maxLength8!=0);
+}
+
+UBool UnicodeSetStringSpan::contains(UChar32 c) const {
+    return spanSet.contains(c);
+}
+
+U_NAMESPACE_END
+
+#endif