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diff --git a/intl/icu/source/i18n/uitercollationiterator.h b/intl/icu/source/i18n/uitercollationiterator.h
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+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+*******************************************************************************
+* Copyright (C) 2012-2016, International Business Machines
+* Corporation and others.  All Rights Reserved.
+*******************************************************************************
+* uitercollationiterator.h
+*
+* created on: 2012sep23 (from utf16collationiterator.h)
+* created by: Markus W. Scherer
+*/
+
+#ifndef __UITERCOLLATIONITERATOR_H__
+#define __UITERCOLLATIONITERATOR_H__
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_COLLATION
+
+#include "unicode/uiter.h"
+#include "cmemory.h"
+#include "collation.h"
+#include "collationdata.h"
+#include "collationiterator.h"
+#include "normalizer2impl.h"
+
+U_NAMESPACE_BEGIN
+
+/**
+ * UCharIterator-based collation element and character iterator.
+ * Handles normalized text inline, with length or NUL-terminated.
+ * Unnormalized text is handled by a subclass.
+ */
+class U_I18N_API UIterCollationIterator : public CollationIterator {
+public:
+    UIterCollationIterator(const CollationData *d, UBool numeric, UCharIterator &ui)
+            : CollationIterator(d, numeric), iter(ui) {}
+
+    virtual ~UIterCollationIterator();
+
+    virtual void resetToOffset(int32_t newOffset) override;
+
+    virtual int32_t getOffset() const override;
+
+    virtual UChar32 nextCodePoint(UErrorCode &errorCode) override;
+
+    virtual UChar32 previousCodePoint(UErrorCode &errorCode) override;
+
+protected:
+    virtual uint32_t handleNextCE32(UChar32 &c, UErrorCode &errorCode) override;
+
+    virtual char16_t handleGetTrailSurrogate() override;
+
+    virtual void forwardNumCodePoints(int32_t num, UErrorCode &errorCode) override;
+
+    virtual void backwardNumCodePoints(int32_t num, UErrorCode &errorCode) override;
+
+    UCharIterator &iter;
+};
+
+/**
+ * Incrementally checks the input text for FCD and normalizes where necessary.
+ */
+class U_I18N_API FCDUIterCollationIterator : public UIterCollationIterator {
+public:
+    FCDUIterCollationIterator(const CollationData *data, UBool numeric, UCharIterator &ui, int32_t startIndex)
+            : UIterCollationIterator(data, numeric, ui),
+              state(ITER_CHECK_FWD), start(startIndex),
+              nfcImpl(data->nfcImpl) {}
+
+    virtual ~FCDUIterCollationIterator();
+
+    virtual void resetToOffset(int32_t newOffset) override;
+
+    virtual int32_t getOffset() const override;
+
+    virtual UChar32 nextCodePoint(UErrorCode &errorCode) override;
+
+    virtual UChar32 previousCodePoint(UErrorCode &errorCode) override;
+
+protected:
+    virtual uint32_t handleNextCE32(UChar32 &c, UErrorCode &errorCode) override;
+
+    virtual char16_t handleGetTrailSurrogate() override;
+
+
+    virtual void forwardNumCodePoints(int32_t num, UErrorCode &errorCode) override;
+
+    virtual void backwardNumCodePoints(int32_t num, UErrorCode &errorCode) override;
+
+private:
+    /**
+     * Switches to forward checking if possible.
+     */
+    void switchToForward();
+
+    /**
+     * Extends the FCD text segment forward or normalizes around pos.
+     * @return true if success
+     */
+    UBool nextSegment(UErrorCode &errorCode);
+
+    /**
+     * Switches to backward checking.
+     */
+    void switchToBackward();
+
+    /**
+     * Extends the FCD text segment backward or normalizes around pos.
+     * @return true if success
+     */
+    UBool previousSegment(UErrorCode &errorCode);
+
+    UBool normalize(const UnicodeString &s, UErrorCode &errorCode);
+
+    enum State {
+        /**
+         * The input text [start..(iter index)[ passes the FCD check.
+         * Moving forward checks incrementally.
+         * pos & limit are undefined.
+         */
+        ITER_CHECK_FWD,
+        /**
+         * The input text [(iter index)..limit[ passes the FCD check.
+         * Moving backward checks incrementally.
+         * start & pos are undefined.
+         */
+        ITER_CHECK_BWD,
+        /**
+         * The input text [start..limit[ passes the FCD check.
+         * pos tracks the current text index.
+         */
+        ITER_IN_FCD_SEGMENT,
+        /**
+         * The input text [start..limit[ failed the FCD check and was normalized.
+         * pos tracks the current index in the normalized string.
+         * The text iterator is at the limit index.
+         */
+        IN_NORM_ITER_AT_LIMIT,
+        /**
+         * The input text [start..limit[ failed the FCD check and was normalized.
+         * pos tracks the current index in the normalized string.
+         * The text iterator is at the start index.
+         */
+        IN_NORM_ITER_AT_START
+    };
+
+    State state;
+
+    int32_t start;
+    int32_t pos;
+    int32_t limit;
+
+    const Normalizer2Impl &nfcImpl;
+    UnicodeString normalized;
+};
+
+U_NAMESPACE_END
+
+#endif  // !UCONFIG_NO_COLLATION
+#endif  // __UITERCOLLATIONITERATOR_H__