Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 1678 insertions, 0 deletions

diff --git a/intl/icu/source/i18n/translit.cpp b/intl/icu/source/i18n/translit.cpp
new file mode 100644
index 0000000000..29d38b12c7
--- /dev/null
+++ b/intl/icu/source/i18n/translit.cpp
@@ -0,0 +1,1678 @@
+// © 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
+ *   11/17/99    aliu        Creation.
+ **********************************************************************
+ */
+
+#include "utypeinfo.h"  // for 'typeid' to work
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_TRANSLITERATION
+
+#include "unicode/putil.h"
+#include "unicode/translit.h"
+#include "unicode/locid.h"
+#include "unicode/msgfmt.h"
+#include "unicode/rep.h"
+#include "unicode/resbund.h"
+#include "unicode/unifilt.h"
+#include "unicode/uniset.h"
+#include "unicode/uscript.h"
+#include "unicode/strenum.h"
+#include "unicode/utf16.h"
+#include "cpdtrans.h"
+#include "nultrans.h"
+#include "rbt_data.h"
+#include "rbt_pars.h"
+#include "rbt.h"
+#include "transreg.h"
+#include "name2uni.h"
+#include "nortrans.h"
+#include "remtrans.h"
+#include "titletrn.h"
+#include "tolowtrn.h"
+#include "toupptrn.h"
+#include "uni2name.h"
+#include "brktrans.h"
+#include "esctrn.h"
+#include "unesctrn.h"
+#include "tridpars.h"
+#include "anytrans.h"
+#include "util.h"
+#include "hash.h"
+#include "mutex.h"
+#include "ucln_in.h"
+#include "uassert.h"
+#include "cmemory.h"
+#include "cstring.h"
+#include "uinvchar.h"
+
+static const char16_t TARGET_SEP  = 0x002D; /*-*/
+static const char16_t ID_DELIM    = 0x003B; /*;*/
+static const char16_t VARIANT_SEP = 0x002F; // '/'
+
+/**
+ * Prefix for resource bundle key for the display name for a
+ * transliterator.  The ID is appended to this to form the key.
+ * The resource bundle value should be a String.
+ */
+static const char RB_DISPLAY_NAME_PREFIX[] = "%Translit%%";
+
+/**
+ * Prefix for resource bundle key for the display name for a
+ * transliterator SCRIPT.  The ID is appended to this to form the key.
+ * The resource bundle value should be a String.
+ */
+static const char RB_SCRIPT_DISPLAY_NAME_PREFIX[] = "%Translit%";
+
+/**
+ * Resource bundle key for display name pattern.
+ * The resource bundle value should be a String forming a
+ * MessageFormat pattern, e.g.:
+ * "{0,choice,0#|1#{1} Transliterator|2#{1} to {2} Transliterator}".
+ */
+static const char RB_DISPLAY_NAME_PATTERN[] = "TransliteratorNamePattern";
+
+/**
+ * Resource bundle key for the list of RuleBasedTransliterator IDs.
+ * The resource bundle value should be a String[] with each element
+ * being a valid ID.  The ID will be appended to RB_RULE_BASED_PREFIX
+ * to obtain the class name in which the RB_RULE key will be sought.
+ */
+static const char RB_RULE_BASED_IDS[] = "RuleBasedTransliteratorIDs";
+
+/**
+ * The mutex controlling access to registry object.
+ */
+static icu::UMutex registryMutex;
+
+/**
+ * System transliterator registry; non-null when initialized.
+ */
+static icu::TransliteratorRegistry* registry = 0;
+
+// Macro to check/initialize the registry. ONLY USE WITHIN
+// MUTEX. Avoids function call when registry is initialized.
+#define HAVE_REGISTRY(status) (registry!=0 || initializeRegistry(status))
+
+U_NAMESPACE_BEGIN
+
+UOBJECT_DEFINE_ABSTRACT_RTTI_IMPLEMENTATION(Transliterator)
+
+/**
+ * Return true if the given UTransPosition is valid for text of
+ * the given length.
+ */
+static inline UBool positionIsValid(UTransPosition& index, int32_t len) {
+    return !(index.contextStart < 0 ||
+             index.start < index.contextStart ||
+             index.limit < index.start ||
+             index.contextLimit < index.limit ||
+             len < index.contextLimit);
+}
+
+/**
+ * Default constructor.
+ * @param theID the string identifier for this transliterator
+ * @param theFilter the filter.  Any character for which
+ * <tt>filter.contains()</tt> returns <tt>false</tt> will not be
+ * altered by this transliterator.  If <tt>filter</tt> is
+ * <tt>null</tt> then no filtering is applied.
+ */
+Transliterator::Transliterator(const UnicodeString& theID,
+                               UnicodeFilter* adoptedFilter) :
+    UObject(), ID(theID), filter(adoptedFilter),
+    maximumContextLength(0)
+{
+    // NUL-terminate the ID string, which is a non-aliased copy.
+    ID.append((char16_t)0);
+    ID.truncate(ID.length()-1);
+}
+
+/**
+ * Destructor.
+ */
+Transliterator::~Transliterator() {
+    if (filter) {
+        delete filter;
+    }
+}
+
+/**
+ * Copy constructor.
+ */
+Transliterator::Transliterator(const Transliterator& other) :
+    UObject(other), ID(other.ID), filter(0),
+    maximumContextLength(other.maximumContextLength)
+{
+    // NUL-terminate the ID string, which is a non-aliased copy.
+    ID.append((char16_t)0);
+    ID.truncate(ID.length()-1);
+
+    if (other.filter != 0) {
+        // We own the filter, so we must have our own copy
+        filter = other.filter->clone();
+    }
+}
+
+Transliterator* Transliterator::clone() const {
+    return nullptr;
+}
+
+/**
+ * Assignment operator.
+ */
+Transliterator& Transliterator::operator=(const Transliterator& other) {
+    if (this == &other) { return *this; }  // self-assignment: no-op
+    ID = other.ID;
+    // NUL-terminate the ID string
+    ID.getTerminatedBuffer();
+
+    maximumContextLength = other.maximumContextLength;
+    adoptFilter((other.filter == 0) ? 0 : other.filter->clone());
+    return *this;
+}
+
+/**
+ * Transliterates a segment of a string.  <code>Transliterator</code> API.
+ * @param text the string to be transliterated
+ * @param start the beginning index, inclusive; <code>0 <= start
+ * <= limit</code>.
+ * @param limit the ending index, exclusive; <code>start <= limit
+ * <= text.length()</code>.
+ * @return the new limit index, or -1
+ */
+int32_t Transliterator::transliterate(Replaceable& text,
+                                      int32_t start, int32_t limit) const {
+    if (start < 0 ||
+        limit < start ||
+        text.length() < limit) {
+        return -1;
+    }
+
+    UTransPosition offsets;
+    offsets.contextStart= start;
+    offsets.contextLimit = limit;
+    offsets.start = start;
+    offsets.limit = limit;
+    filteredTransliterate(text, offsets, false, true);
+    return offsets.limit;
+}
+
+/**
+ * Transliterates an entire string in place. Convenience method.
+ * @param text the string to be transliterated
+ */
+void Transliterator::transliterate(Replaceable& text) const {
+    transliterate(text, 0, text.length());
+}
+
+/**
+ * Transliterates the portion of the text buffer that can be
+ * transliterated unambiguosly after new text has been inserted,
+ * typically as a result of a keyboard event.  The new text in
+ * <code>insertion</code> will be inserted into <code>text</code>
+ * at <code>index.contextLimit</code>, advancing
+ * <code>index.contextLimit</code> by <code>insertion.length()</code>.
+ * Then the transliterator will try to transliterate characters of
+ * <code>text</code> between <code>index.start</code> and
+ * <code>index.contextLimit</code>.  Characters before
+ * <code>index.start</code> will not be changed.
+ *
+ * <p>Upon return, values in <code>index</code> will be updated.
+ * <code>index.contextStart</code> will be advanced to the first
+ * character that future calls to this method will read.
+ * <code>index.start</code> and <code>index.contextLimit</code> will
+ * be adjusted to delimit the range of text that future calls to
+ * this method may change.
+ *
+ * <p>Typical usage of this method begins with an initial call
+ * with <code>index.contextStart</code> and <code>index.contextLimit</code>
+ * set to indicate the portion of <code>text</code> to be
+ * transliterated, and <code>index.start == index.contextStart</code>.
+ * Thereafter, <code>index</code> can be used without
+ * modification in future calls, provided that all changes to
+ * <code>text</code> are made via this method.
+ *
+ * <p>This method assumes that future calls may be made that will
+ * insert new text into the buffer.  As a result, it only performs
+ * unambiguous transliterations.  After the last call to this
+ * method, there may be untransliterated text that is waiting for
+ * more input to resolve an ambiguity.  In order to perform these
+ * pending transliterations, clients should call {@link
+ * #finishKeyboardTransliteration} after the last call to this
+ * method has been made.
+ * 
+ * @param text the buffer holding transliterated and untransliterated text
+ * @param index an array of three integers.
+ *
+ * <ul><li><code>index.contextStart</code>: the beginning index,
+ * inclusive; <code>0 <= index.contextStart <= index.contextLimit</code>.
+ *
+ * <li><code>index.contextLimit</code>: the ending index, exclusive;
+ * <code>index.contextStart <= index.contextLimit <= text.length()</code>.
+ * <code>insertion</code> is inserted at
+ * <code>index.contextLimit</code>.
+ *
+ * <li><code>index.start</code>: the next character to be
+ * considered for transliteration; <code>index.contextStart <=
+ * index.start <= index.contextLimit</code>.  Characters before
+ * <code>index.start</code> will not be changed by future calls
+ * to this method.</ul>
+ *
+ * @param insertion text to be inserted and possibly
+ * transliterated into the translation buffer at
+ * <code>index.contextLimit</code>.  If <code>null</code> then no text
+ * is inserted.
+ * @see #START
+ * @see #LIMIT
+ * @see #CURSOR
+ * @see #handleTransliterate
+ * @exception IllegalArgumentException if <code>index</code>
+ * is invalid
+ */
+void Transliterator::transliterate(Replaceable& text,
+                                   UTransPosition& index,
+                                   const UnicodeString& insertion,
+                                   UErrorCode &status) const {
+    _transliterate(text, index, &insertion, status);
+}
+
+/**
+ * Transliterates the portion of the text buffer that can be
+ * transliterated unambiguosly after a new character has been
+ * inserted, typically as a result of a keyboard event.  This is a
+ * convenience method; see {@link
+ * #transliterate(Replaceable, int[], String)} for details.
+ * @param text the buffer holding transliterated and
+ * untransliterated text
+ * @param index an array of three integers.  See {@link
+ * #transliterate(Replaceable, int[], String)}.
+ * @param insertion text to be inserted and possibly
+ * transliterated into the translation buffer at
+ * <code>index.contextLimit</code>.
+ * @see #transliterate(Replaceable, int[], String)
+ */
+void Transliterator::transliterate(Replaceable& text,
+                                   UTransPosition& index,
+                                   UChar32 insertion,
+                                   UErrorCode& status) const {
+    UnicodeString str(insertion);
+    _transliterate(text, index, &str, status);
+}
+
+/**
+ * Transliterates the portion of the text buffer that can be
+ * transliterated unambiguosly.  This is a convenience method; see
+ * {@link #transliterate(Replaceable, int[], String)} for
+ * details.
+ * @param text the buffer holding transliterated and
+ * untransliterated text
+ * @param index an array of three integers.  See {@link
+ * #transliterate(Replaceable, int[], String)}.
+ * @see #transliterate(Replaceable, int[], String)
+ */
+void Transliterator::transliterate(Replaceable& text,
+                                   UTransPosition& index,
+                                   UErrorCode& status) const {
+    _transliterate(text, index, 0, status);
+}
+
+/**
+ * Finishes any pending transliterations that were waiting for
+ * more characters.  Clients should call this method as the last
+ * call after a sequence of one or more calls to
+ * <code>transliterate()</code>.
+ * @param text the buffer holding transliterated and
+ * untransliterated text.
+ * @param index the array of indices previously passed to {@link
+ * #transliterate}
+ */
+void Transliterator::finishTransliteration(Replaceable& text,
+                                           UTransPosition& index) const {
+    if (!positionIsValid(index, text.length())) {
+        return;
+    }
+
+    filteredTransliterate(text, index, false, true);
+}
+
+/**
+ * This internal method does keyboard transliteration.  If the
+ * 'insertion' is non-null then we append it to 'text' before
+ * proceeding.  This method calls through to the pure virtual
+ * framework method handleTransliterate() to do the actual
+ * work.
+ */
+void Transliterator::_transliterate(Replaceable& text,
+                                    UTransPosition& index,
+                                    const UnicodeString* insertion,
+                                    UErrorCode &status) const {
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    if (!positionIsValid(index, text.length())) {
+        status = U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+//    int32_t originalStart = index.contextStart;
+    if (insertion != 0) {
+        text.handleReplaceBetween(index.limit, index.limit, *insertion);
+        index.limit += insertion->length();
+        index.contextLimit += insertion->length();
+    }
+
+    if (index.limit > 0 &&
+        U16_IS_LEAD(text.charAt(index.limit - 1))) {
+        // Oops, there is a dangling lead surrogate in the buffer.
+        // This will break most transliterators, since they will
+        // assume it is part of a pair.  Don't transliterate until
+        // more text comes in.
+        return;
+    }
+
+    filteredTransliterate(text, index, true, true);
+
+#if 0
+    // TODO
+    // I CAN'T DO what I'm attempting below now that the Kleene star
+    // operator is supported.  For example, in the rule
+
+    //   ([:Lu:]+) { x } > $1;
+
+    // what is the maximum context length?  getMaximumContextLength()
+    // will return 1, but this is just the length of the ante context
+    // part of the pattern string -- 1 character, which is a standin
+    // for a Quantifier, which contains a StringMatcher, which
+    // contains a UnicodeSet.
+
+    // There is a complicated way to make this work again, and that's
+    // to add a "maximum left context" protocol into the
+    // UnicodeMatcher hierarchy.  At present I'm not convinced this is
+    // worth it.
+
+    // ---
+
+    // The purpose of the code below is to keep the context small
+    // while doing incremental transliteration.  When part of the left
+    // context (between contextStart and start) is no longer needed,
+    // we try to advance contextStart past that portion.  We use the
+    // maximum context length to do so.
+    int32_t newCS = index.start;
+    int32_t n = getMaximumContextLength();
+    while (newCS > originalStart && n-- > 0) {
+        --newCS;
+        newCS -= U16_LENGTH(text.char32At(newCS)) - 1;
+    }
+    index.contextStart = uprv_max(newCS, originalStart);
+#endif
+}
+
+/**
+ * This method breaks up the input text into runs of unfiltered
+ * characters.  It passes each such run to
+ * <subclass>.handleTransliterate().  Subclasses that can handle the
+ * filter logic more efficiently themselves may override this method.
+ *
+ * All transliteration calls in this class go through this method.
+ */
+void Transliterator::filteredTransliterate(Replaceable& text,
+                                           UTransPosition& index,
+                                           UBool incremental,
+                                           UBool rollback) const {
+    // Short circuit path for transliterators with no filter in
+    // non-incremental mode.
+    if (filter == 0 && !rollback) {
+        handleTransliterate(text, index, incremental);
+        return;
+    }
+
+    //----------------------------------------------------------------------
+    // This method processes text in two groupings:
+    //
+    // RUNS -- A run is a contiguous group of characters which are contained
+    // in the filter for this transliterator (filter.contains(ch) == true).
+    // Text outside of runs may appear as context but it is not modified.
+    // The start and limit Position values are narrowed to each run.
+    //
+    // PASSES (incremental only) -- To make incremental mode work correctly,
+    // each run is broken up into n passes, where n is the length (in code
+    // points) of the run.  Each pass contains the first n characters.  If a
+    // pass is completely transliterated, it is committed, and further passes
+    // include characters after the committed text.  If a pass is blocked,
+    // and does not transliterate completely, then this method rolls back
+    // the changes made during the pass, extends the pass by one code point,
+    // and tries again.
+    //----------------------------------------------------------------------
+    
+    // globalLimit is the limit value for the entire operation.  We
+    // set index.limit to the end of each unfiltered run before
+    // calling handleTransliterate(), so we need to maintain the real
+    // value of index.limit here.  After each transliteration, we
+    // update globalLimit for insertions or deletions that have
+    // happened.
+    int32_t globalLimit = index.limit;
+    
+    // If there is a non-null filter, then break the input text up.  Say the
+    // input text has the form:
+    //   xxxabcxxdefxx
+    // where 'x' represents a filtered character (filter.contains('x') ==
+    // false).  Then we break this up into:
+    //   xxxabc xxdef xx
+    // Each pass through the loop consumes a run of filtered
+    // characters (which are ignored) and a subsequent run of
+    // unfiltered characters (which are transliterated).
+    
+    for (;;) {
+
+        if (filter != nullptr) {
+            // Narrow the range to be transliterated to the first segment
+            // of unfiltered characters at or after index.start.
+
+            // Advance past filtered chars
+            UChar32 c;
+            while (index.start < globalLimit &&
+                   !filter->contains(c=text.char32At(index.start))) {
+                index.start += U16_LENGTH(c);
+            }
+
+            // Find the end of this run of unfiltered chars
+            index.limit = index.start;
+            while (index.limit < globalLimit &&
+                   filter->contains(c=text.char32At(index.limit))) {
+                index.limit += U16_LENGTH(c);
+            }
+        }
+
+        // Check to see if the unfiltered run is empty.  This only
+        // happens at the end of the string when all the remaining
+        // characters are filtered.
+        if (index.limit == index.start) {
+            // assert(index.start == globalLimit);
+            break;
+        }
+
+        // Is this run incremental?  If there is additional
+        // filtered text (if limit < globalLimit) then we pass in
+        // an incremental value of false to force the subclass to
+        // complete the transliteration for this run.
+        UBool isIncrementalRun =
+            (index.limit < globalLimit ? false : incremental);
+        
+        int32_t delta;
+
+        // Implement rollback.  To understand the need for rollback,
+        // consider the following transliterator:
+        //
+        //  "t" is "a > A;"
+        //  "u" is "A > b;"
+        //  "v" is a compound of "t; NFD; u" with a filter [:Ll:]
+        //
+        // Now apply "c" to the input text "a".  The result is "b".  But if
+        // the transliteration is done incrementally, then the NFD holds
+        // things up after "t" has already transformed "a" to "A".  When
+        // finishTransliterate() is called, "A" is _not_ processed because
+        // it gets excluded by the [:Ll:] filter, and the end result is "A"
+        // -- incorrect.  The problem is that the filter is applied to a
+        // partially-transliterated result, when we only want it to apply to
+        // input text.  Although this example hinges on a compound
+        // transliterator containing NFD and a specific filter, it can
+        // actually happen with any transliterator which may do a partial
+        // transformation in incremental mode into characters outside its
+        // filter.
+        //
+        // To handle this, when in incremental mode we supply characters to
+        // handleTransliterate() in several passes.  Each pass adds one more
+        // input character to the input text.  That is, for input "ABCD", we
+        // first try "A", then "AB", then "ABC", and finally "ABCD".  If at
+        // any point we block (upon return, start < limit) then we roll
+        // back.  If at any point we complete the run (upon return start ==
+        // limit) then we commit that run.
+
+        if (rollback && isIncrementalRun) {
+
+            int32_t runStart = index.start;
+            int32_t runLimit = index.limit;
+            int32_t runLength =  runLimit - runStart;
+
+            // Make a rollback copy at the end of the string
+            int32_t rollbackOrigin = text.length();
+            text.copy(runStart, runLimit, rollbackOrigin);
+
+            // Variables reflecting the commitment of completely
+            // transliterated text.  passStart is the runStart, advanced
+            // past committed text.  rollbackStart is the rollbackOrigin,
+            // advanced past rollback text that corresponds to committed
+            // text.
+            int32_t passStart = runStart;
+            int32_t rollbackStart = rollbackOrigin;
+
+            // The limit for each pass; we advance by one code point with
+            // each iteration.
+            int32_t passLimit = index.start;
+
+            // Total length, in 16-bit code units, of uncommitted text.
+            // This is the length to be rolled back.
+            int32_t uncommittedLength = 0;
+
+            // Total delta (change in length) for all passes
+            int32_t totalDelta = 0;
+
+            // PASS MAIN LOOP -- Start with a single character, and extend
+            // the text by one character at a time.  Roll back partial
+            // transliterations and commit complete transliterations.
+            for (;;) {
+                // Length of additional code point, either one or two
+                int32_t charLength = U16_LENGTH(text.char32At(passLimit));
+                passLimit += charLength;
+                if (passLimit > runLimit) {
+                    break;
+                }
+                uncommittedLength += charLength;
+
+                index.limit = passLimit;
+
+                // Delegate to subclass for actual transliteration.  Upon
+                // return, start will be updated to point after the
+                // transliterated text, and limit and contextLimit will be
+                // adjusted for length changes.
+                handleTransliterate(text, index, true);
+
+                delta = index.limit - passLimit; // change in length
+
+                // We failed to completely transliterate this pass.
+                // Roll back the text.  Indices remain unchanged; reset
+                // them where necessary.
+                if (index.start != index.limit) {
+                    // Find the rollbackStart, adjusted for length changes
+                    // and the deletion of partially transliterated text.
+                    int32_t rs = rollbackStart + delta - (index.limit - passStart);
+
+                    // Delete the partially transliterated text
+                    text.handleReplaceBetween(passStart, index.limit, UnicodeString());
+
+                    // Copy the rollback text back
+                    text.copy(rs, rs + uncommittedLength, passStart);
+
+                    // Restore indices to their original values
+                    index.start = passStart;
+                    index.limit = passLimit;
+                    index.contextLimit -= delta;
+                }
+
+                // We did completely transliterate this pass.  Update the
+                // commit indices to record how far we got.  Adjust indices
+                // for length change.
+                else {
+                    // Move the pass indices past the committed text.
+                    passStart = passLimit = index.start;
+
+                    // Adjust the rollbackStart for length changes and move
+                    // it past the committed text.  All characters we've
+                    // processed to this point are committed now, so zero
+                    // out the uncommittedLength.
+                    rollbackStart += delta + uncommittedLength;
+                    uncommittedLength = 0;
+
+                    // Adjust indices for length changes.
+                    runLimit += delta;
+                    totalDelta += delta;
+                }
+            }
+
+            // Adjust overall limit and rollbackOrigin for insertions and
+            // deletions.  Don't need to worry about contextLimit because
+            // handleTransliterate() maintains that.
+            rollbackOrigin += totalDelta;
+            globalLimit += totalDelta;
+
+            // Delete the rollback copy
+            text.handleReplaceBetween(rollbackOrigin, rollbackOrigin + runLength, UnicodeString());
+
+            // Move start past committed text
+            index.start = passStart;
+        }
+
+        else {
+            // Delegate to subclass for actual transliteration.
+            int32_t limit = index.limit;
+            handleTransliterate(text, index, isIncrementalRun);
+            delta = index.limit - limit; // change in length
+
+            // In a properly written transliterator, start == limit after
+            // handleTransliterate() returns when incremental is false.
+            // Catch cases where the subclass doesn't do this, and throw
+            // an exception.  (Just pinning start to limit is a bad idea,
+            // because what's probably happening is that the subclass
+            // isn't transliterating all the way to the end, and it should
+            // in non-incremental mode.)
+            if (!incremental && index.start != index.limit) {
+                // We can't throw an exception, so just fudge things
+                index.start = index.limit;
+            }
+
+            // Adjust overall limit for insertions/deletions.  Don't need
+            // to worry about contextLimit because handleTransliterate()
+            // maintains that.
+            globalLimit += delta;
+        }
+
+        if (filter == nullptr || isIncrementalRun) {
+            break;
+        }
+
+        // If we did completely transliterate this
+        // run, then repeat with the next unfiltered run.
+    }
+
+    // Start is valid where it is.  Limit needs to be put back where
+    // it was, modulo adjustments for deletions/insertions.
+    index.limit = globalLimit;
+}
+
+void Transliterator::filteredTransliterate(Replaceable& text,
+                                           UTransPosition& index,
+                                           UBool incremental) const {
+    filteredTransliterate(text, index, incremental, false);
+}
+
+/**
+ * Method for subclasses to use to set the maximum context length.
+ * @see #getMaximumContextLength
+ */
+void Transliterator::setMaximumContextLength(int32_t maxContextLength) {
+    maximumContextLength = maxContextLength;
+}
+
+/**
+ * Returns a programmatic identifier for this transliterator.
+ * If this identifier is passed to <code>getInstance()</code>, it
+ * will return this object, if it has been registered.
+ * @see #registerInstance
+ * @see #getAvailableIDs
+ */
+const UnicodeString& Transliterator::getID() const {
+    return ID;
+}
+
+/**
+ * Returns a name for this transliterator that is appropriate for
+ * display to the user in the default locale.  See {@link
+ * #getDisplayName(Locale)} for details.
+ */
+UnicodeString& U_EXPORT2 Transliterator::getDisplayName(const UnicodeString& ID,
+                                              UnicodeString& result) {
+    return getDisplayName(ID, Locale::getDefault(), result);
+}
+
+/**
+ * Returns a name for this transliterator that is appropriate for
+ * display to the user in the given locale.  This name is taken
+ * from the locale resource data in the standard manner of the
+ * <code>java.text</code> package.
+ *
+ * <p>If no localized names exist in the system resource bundles,
+ * a name is synthesized using a localized
+ * <code>MessageFormat</code> pattern from the resource data.  The
+ * arguments to this pattern are an integer followed by one or two
+ * strings.  The integer is the number of strings, either 1 or 2.
+ * The strings are formed by splitting the ID for this
+ * transliterator at the first TARGET_SEP.  If there is no TARGET_SEP, then the
+ * entire ID forms the only string.
+ * @param inLocale the Locale in which the display name should be
+ * localized.
+ * @see java.text.MessageFormat
+ */
+UnicodeString& U_EXPORT2 Transliterator::getDisplayName(const UnicodeString& id,
+                                              const Locale& inLocale,
+                                              UnicodeString& result) {
+    UErrorCode status = U_ZERO_ERROR;
+
+    ResourceBundle bundle(U_ICUDATA_TRANSLIT, inLocale, status);
+
+    // Suspend checking status until later...
+
+    result.truncate(0);
+
+    // Normalize the ID
+    UnicodeString source, target, variant;
+    UBool sawSource;
+    TransliteratorIDParser::IDtoSTV(id, source, target, variant, sawSource);
+    if (target.length() < 1) {
+        // No target; malformed id
+        return result;
+    }
+    if (variant.length() > 0) { // Change "Foo" to "/Foo"
+        variant.insert(0, VARIANT_SEP);
+    }
+    UnicodeString ID(source);
+    ID.append(TARGET_SEP).append(target).append(variant);
+
+    // build the char* key
+    if (uprv_isInvariantUString(ID.getBuffer(), ID.length())) {
+        char key[200];
+        uprv_strcpy(key, RB_DISPLAY_NAME_PREFIX);
+        int32_t length=(int32_t)uprv_strlen(RB_DISPLAY_NAME_PREFIX);
+        ID.extract(0, (int32_t)(sizeof(key)-length), key+length, (int32_t)(sizeof(key)-length), US_INV);
+
+        // Try to retrieve a UnicodeString from the bundle.
+        UnicodeString resString = bundle.getStringEx(key, status);
+
+        if (U_SUCCESS(status) && resString.length() != 0) {
+            return result = resString; // [sic] assign & return
+        }
+
+#if !UCONFIG_NO_FORMATTING
+        // We have failed to get a name from the locale data.  This is
+        // typical, since most transliterators will not have localized
+        // name data.  The next step is to retrieve the MessageFormat
+        // pattern from the locale data and to use it to synthesize the
+        // name from the ID.
+
+        status = U_ZERO_ERROR;
+        resString = bundle.getStringEx(RB_DISPLAY_NAME_PATTERN, status);
+
+        if (U_SUCCESS(status) && resString.length() != 0) {
+            MessageFormat msg(resString, inLocale, status);
+            // Suspend checking status until later...
+
+            // We pass either 2 or 3 Formattable objects to msg.
+            Formattable args[3];
+            int32_t nargs;
+            args[0].setLong(2); // # of args to follow
+            args[1].setString(source);
+            args[2].setString(target);
+            nargs = 3;
+
+            // Use display names for the scripts, if they exist
+            UnicodeString s;
+            length=(int32_t)uprv_strlen(RB_SCRIPT_DISPLAY_NAME_PREFIX);
+            for (int j=1; j<=2; ++j) {
+                status = U_ZERO_ERROR;
+                uprv_strcpy(key, RB_SCRIPT_DISPLAY_NAME_PREFIX);
+                args[j].getString(s);
+                if (uprv_isInvariantUString(s.getBuffer(), s.length())) {
+                    s.extract(0, sizeof(key)-length-1, key+length, (int32_t)sizeof(key)-length-1, US_INV);
+
+                    resString = bundle.getStringEx(key, status);
+
+                    if (U_SUCCESS(status)) {
+                        args[j] = resString;
+                    }
+                }
+            }
+
+            status = U_ZERO_ERROR;
+            FieldPosition pos; // ignored by msg
+            msg.format(args, nargs, result, pos, status);
+            if (U_SUCCESS(status)) {
+                result.append(variant);
+                return result;
+            }
+        }
+#endif
+    }
+
+    // We should not reach this point unless there is something
+    // wrong with the build or the RB_DISPLAY_NAME_PATTERN has
+    // been deleted from the root RB_LOCALE_ELEMENTS resource.
+    result = ID;
+    return result;
+}
+
+/**
+ * Returns the filter used by this transliterator, or <tt>null</tt>
+ * if this transliterator uses no filter.  Caller musn't delete
+ * the result!
+ */
+const UnicodeFilter* Transliterator::getFilter() const {
+    return filter;
+}
+
+/**
+ * Returns the filter used by this transliterator, or
+ * <tt>nullptr</tt> if this transliterator uses no filter.  The
+ * caller must eventually delete the result.  After this call,
+ * this transliterator's filter is set to <tt>nullptr</tt>.
+ */
+UnicodeFilter* Transliterator::orphanFilter() {
+    UnicodeFilter *result = filter;
+    filter = nullptr;
+    return result;
+}
+
+/**
+ * Changes the filter used by this transliterator.  If the filter
+ * is set to <tt>null</tt> then no filtering will occur.
+ *
+ * <p>Callers must take care if a transliterator is in use by
+ * multiple threads.  The filter should not be changed by one
+ * thread while another thread may be transliterating.
+ */
+void Transliterator::adoptFilter(UnicodeFilter* filterToAdopt) {
+    delete filter;
+    filter = filterToAdopt;
+}
+
+/**
+ * Returns this transliterator's inverse.  See the class
+ * documentation for details.  This implementation simply inverts
+ * the two entities in the ID and attempts to retrieve the
+ * resulting transliterator.  That is, if <code>getID()</code>
+ * returns "A-B", then this method will return the result of
+ * <code>getInstance("B-A")</code>, or <code>null</code> if that
+ * call fails.
+ *
+ * <p>This method does not take filtering into account.  The
+ * returned transliterator will have no filter.
+ *
+ * <p>Subclasses with knowledge of their inverse may wish to
+ * override this method.
+ *
+ * @return a transliterator that is an inverse, not necessarily
+ * exact, of this transliterator, or <code>null</code> if no such
+ * transliterator is registered.
+ * @see #registerInstance
+ */
+Transliterator* Transliterator::createInverse(UErrorCode& status) const {
+    UParseError parseError;
+    return Transliterator::createInstance(ID, UTRANS_REVERSE,parseError,status);
+}
+
+Transliterator* U_EXPORT2
+Transliterator::createInstance(const UnicodeString& ID,
+                                UTransDirection dir,
+                                UErrorCode& status)
+{
+    UParseError parseError;
+    return createInstance(ID, dir, parseError, status);
+}
+
+/**
+ * Returns a <code>Transliterator</code> object given its ID.
+ * The ID must be either a system transliterator ID or a ID registered
+ * using <code>registerInstance()</code>.
+ *
+ * @param ID a valid ID, as enumerated by <code>getAvailableIDs()</code>
+ * @return A <code>Transliterator</code> object with the given ID
+ * @see #registerInstance
+ * @see #getAvailableIDs
+ * @see #getID
+ */
+Transliterator* U_EXPORT2
+Transliterator::createInstance(const UnicodeString& ID,
+                                UTransDirection dir,
+                                UParseError& parseError,
+                                UErrorCode& status)
+{
+    if (U_FAILURE(status)) {
+        return 0;
+    }
+
+    UnicodeString canonID;
+    UVector list(status);
+    if (U_FAILURE(status)) {
+        return nullptr;
+    }
+
+    UnicodeSet* globalFilter = nullptr;
+    // TODO add code for parseError...currently unused, but
+    // later may be used by parsing code...
+    if (!TransliteratorIDParser::parseCompoundID(ID, dir, canonID, list, globalFilter)) {
+        status = U_INVALID_ID;
+        delete globalFilter;
+        return nullptr;
+    }
+    LocalPointer<UnicodeSet> lpGlobalFilter(globalFilter);
+    
+    TransliteratorIDParser::instantiateList(list, status);
+    if (U_FAILURE(status)) {
+        return nullptr;
+    }
+    
+    U_ASSERT(list.size() > 0);
+    Transliterator* t = nullptr;
+    
+    if (list.size() > 1 || canonID.indexOf(ID_DELIM) >= 0) {
+        // [NOTE: If it's a compoundID, we instantiate a CompoundTransliterator even if it only
+        // has one child transliterator.  This is so that toRules() will return the right thing
+        // (without any inactive ID), but our main ID still comes out correct.  That is, if we
+        // instantiate "(Lower);Latin-Greek;", we want the rules to come out as "::Latin-Greek;"
+        // even though the ID is "(Lower);Latin-Greek;".
+        t = new CompoundTransliterator(list, parseError, status);
+    }
+    else {
+        t = (Transliterator*)list.elementAt(0);
+    }
+    // Check null pointer
+    if (t != nullptr) {
+        t->setID(canonID);
+        if (lpGlobalFilter.isValid()) {
+            t->adoptFilter(lpGlobalFilter.orphan());
+        }
+    }
+    else if (U_SUCCESS(status)) {
+        status = U_MEMORY_ALLOCATION_ERROR;
+    }
+    return t;
+}
+
+/**
+ * Create a transliterator from a basic ID.  This is an ID
+ * containing only the forward direction source, target, and
+ * variant.
+ * @param id a basic ID of the form S-T or S-T/V.
+ * @return a newly created Transliterator or null if the ID is
+ * invalid.
+ */
+Transliterator* Transliterator::createBasicInstance(const UnicodeString& id,
+                                                    const UnicodeString* canon) {
+    UParseError pe;
+    UErrorCode ec = U_ZERO_ERROR;
+    TransliteratorAlias* alias = 0;
+    Transliterator* t = 0;
+
+    umtx_lock(&registryMutex);
+    if (HAVE_REGISTRY(ec)) {
+        t = registry->get(id, alias, ec);
+    }
+    umtx_unlock(&registryMutex);
+
+    if (U_FAILURE(ec)) {
+        delete t;
+        delete alias;
+        return 0;
+    }
+
+    // We may have not gotten a transliterator:  Because we can't
+    // instantiate a transliterator from inside TransliteratorRegistry::
+    // get() (that would deadlock), we sometimes pass back an alias.  This
+    // contains the data we need to finish the instantiation outside the
+    // registry mutex.  The alias may, in turn, generate another alias, so
+    // we handle aliases in a loop.  The max times through the loop is two.
+    // [alan]
+    while (alias != 0) {
+        U_ASSERT(t==0);
+        // Rule-based aliases are handled with TransliteratorAlias::
+        // parse(), followed by TransliteratorRegistry::reget().
+        // Other aliases are handled with TransliteratorAlias::create().
+        if (alias->isRuleBased()) {
+            // Step 1. parse
+            TransliteratorParser parser(ec);
+            alias->parse(parser, pe, ec);
+            delete alias;
+            alias = 0;
+
+            // Step 2. reget
+            umtx_lock(&registryMutex);
+            if (HAVE_REGISTRY(ec)) {
+                t = registry->reget(id, parser, alias, ec);
+            }
+            umtx_unlock(&registryMutex);
+
+            // Step 3. Loop back around!
+        } else {
+            t = alias->create(pe, ec);
+            delete alias;
+            alias = 0;
+            break;
+        }
+        if (U_FAILURE(ec)) {
+            delete t;
+            delete alias;
+            t = nullptr;
+            break;
+        }
+    }
+
+    if (t != nullptr && canon != nullptr) {
+        t->setID(*canon);
+    }
+
+    return t;
+}
+
+/**
+ * Returns a <code>Transliterator</code> object constructed from
+ * the given rule string.  This will be a RuleBasedTransliterator,
+ * if the rule string contains only rules, or a
+ * CompoundTransliterator, if it contains ID blocks, or a
+ * NullTransliterator, if it contains ID blocks which parse as
+ * empty for the given direction.
+ */
+Transliterator* U_EXPORT2
+Transliterator::createFromRules(const UnicodeString& ID,
+                                const UnicodeString& rules,
+                                UTransDirection dir,
+                                UParseError& parseError,
+                                UErrorCode& status)
+{
+    Transliterator* t = nullptr;
+
+    TransliteratorParser parser(status);
+    parser.parse(rules, dir, parseError, status);
+
+    if (U_FAILURE(status)) {
+        return 0;
+    }
+
+    // NOTE: The logic here matches that in TransliteratorRegistry.
+    if (parser.idBlockVector.size() == 0 && parser.dataVector.size() == 0) {
+        t = new NullTransliterator();
+    }
+    else if (parser.idBlockVector.size() == 0 && parser.dataVector.size() == 1) {
+        t = new RuleBasedTransliterator(ID, (TransliterationRuleData*)parser.dataVector.orphanElementAt(0), true);
+    }
+    else if (parser.idBlockVector.size() == 1 && parser.dataVector.size() == 0) {
+        // idBlock, no data -- this is an alias.  The ID has
+        // been munged from reverse into forward mode, if
+        // necessary, so instantiate the ID in the forward
+        // direction.
+        if (parser.compoundFilter != nullptr) {
+            UnicodeString filterPattern;
+            parser.compoundFilter->toPattern(filterPattern, false);
+            t = createInstance(filterPattern + UnicodeString(ID_DELIM)
+                    + *((UnicodeString*)parser.idBlockVector.elementAt(0)), UTRANS_FORWARD, parseError, status);
+        }
+        else
+            t = createInstance(*((UnicodeString*)parser.idBlockVector.elementAt(0)), UTRANS_FORWARD, parseError, status);
+
+
+        if (t != nullptr) {
+            t->setID(ID);
+        }
+    }
+    else {
+        UVector transliterators(status);
+        // TODO ICU-21701 missing U_FAILURE check here.
+        //      Error and nullptr checking through this whole block looks suspect.
+        int32_t passNumber = 1;
+
+        int32_t limit = parser.idBlockVector.size();
+        if (parser.dataVector.size() > limit)
+            limit = parser.dataVector.size();
+
+        for (int32_t i = 0; i < limit; i++) {
+            if (i < parser.idBlockVector.size()) {
+                UnicodeString* idBlock = (UnicodeString*)parser.idBlockVector.elementAt(i);
+                if (!idBlock->isEmpty()) {
+                    Transliterator* temp = createInstance(*idBlock, UTRANS_FORWARD, parseError, status);
+                    if (U_FAILURE(status)) {
+                        delete temp;
+                        return nullptr;
+                    }
+                    if (temp != nullptr && typeid(*temp) != typeid(NullTransliterator)) {
+                        transliterators.addElement(temp, status);
+                        if (U_FAILURE(status)) {
+                            delete temp;
+                            return nullptr;
+                        }
+                    } else {
+                        delete temp;
+                    }
+                }
+            }
+            if (!parser.dataVector.isEmpty()) {
+                TransliterationRuleData* data = (TransliterationRuleData*)parser.dataVector.orphanElementAt(0);
+                // TODO: Should passNumber be turned into a decimal-string representation (1 -> "1")?
+                RuleBasedTransliterator* temprbt = new RuleBasedTransliterator(UnicodeString(CompoundTransliterator::PASS_STRING) + UnicodeString(passNumber++),
+                        data, true);
+                // Check if nullptr before adding it to transliterators to avoid future usage of nullptr pointer.
+                if (temprbt == nullptr) {
+                    if (U_SUCCESS(status)) {
+                        status = U_MEMORY_ALLOCATION_ERROR;
+                    }
+                    return t;
+                }
+                transliterators.addElement(temprbt, status);
+                if (U_FAILURE(status)) {
+                    delete temprbt;
+                    return t;
+                }
+                // TODO: ICU-21701 the transliterators vector will leak its contents if anything goes wrong.
+                //       Under normal operation, the CompoundTransliterator constructor adopts the
+                //       the contents of the vector.
+            }
+        }
+
+        t = new CompoundTransliterator(transliterators, passNumber - 1, parseError, status);
+        // Null pointer check
+        if (t != nullptr) {
+            t->setID(ID);
+            t->adoptFilter(parser.orphanCompoundFilter());
+        }
+    }
+    if (U_SUCCESS(status) && t == nullptr) {
+        status = U_MEMORY_ALLOCATION_ERROR;
+    }
+    return t;
+}
+
+UnicodeString& Transliterator::toRules(UnicodeString& rulesSource,
+                                       UBool escapeUnprintable) const {
+    // The base class implementation of toRules munges the ID into
+    // the correct format.  That is: foo => ::foo
+    if (escapeUnprintable) {
+        rulesSource.truncate(0);
+        UnicodeString id = getID();
+        for (int32_t i=0; i<id.length();) {
+            UChar32 c = id.char32At(i);
+            if (!ICU_Utility::escapeUnprintable(rulesSource, c)) {
+                rulesSource.append(c);
+            }
+            i += U16_LENGTH(c);
+        }
+    } else {
+        rulesSource = getID();
+    }
+    // KEEP in sync with rbt_pars
+    rulesSource.insert(0, UNICODE_STRING_SIMPLE("::"));
+    rulesSource.append(ID_DELIM);
+    return rulesSource;
+}
+
+int32_t Transliterator::countElements() const {
+    const CompoundTransliterator* ct = dynamic_cast<const CompoundTransliterator*>(this);
+    return ct != nullptr ? ct->getCount() : 0;
+}
+
+const Transliterator& Transliterator::getElement(int32_t index, UErrorCode& ec) const {
+    if (U_FAILURE(ec)) {
+        return *this;
+    }
+    const CompoundTransliterator* cpd = dynamic_cast<const CompoundTransliterator*>(this);
+    int32_t n = (cpd == nullptr) ? 1 : cpd->getCount();
+    if (index < 0 || index >= n) {
+        ec = U_INDEX_OUTOFBOUNDS_ERROR;
+        return *this;
+    } else {
+        return (n == 1) ? *this : cpd->getTransliterator(index);
+    }
+}
+
+UnicodeSet& Transliterator::getSourceSet(UnicodeSet& result) const {
+    handleGetSourceSet(result);
+    if (filter != nullptr) {
+        UnicodeSet* filterSet = dynamic_cast<UnicodeSet*>(filter);
+        UBool deleteFilterSet = false;
+        // Most, but not all filters will be UnicodeSets.  Optimize for
+        // the high-runner case.
+        if (filterSet == nullptr) {
+            filterSet = new UnicodeSet();
+            // Check null pointer
+            if (filterSet == nullptr) {
+                return result;
+            }
+            deleteFilterSet = true;
+            filter->addMatchSetTo(*filterSet);
+        }
+        result.retainAll(*filterSet);
+        if (deleteFilterSet) {
+            delete filterSet;
+        }
+    }
+    return result;
+}
+
+void Transliterator::handleGetSourceSet(UnicodeSet& result) const {
+    result.clear();
+}
+
+UnicodeSet& Transliterator::getTargetSet(UnicodeSet& result) const {
+    return result.clear();
+}
+
+// For public consumption
+void U_EXPORT2 Transliterator::registerFactory(const UnicodeString& id,
+                                     Transliterator::Factory factory,
+                                     Transliterator::Token context) {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    if (HAVE_REGISTRY(ec)) {
+        _registerFactory(id, factory, context);
+    }
+}
+
+// To be called only by Transliterator subclasses that are called
+// to register themselves by initializeRegistry().
+void Transliterator::_registerFactory(const UnicodeString& id,
+                                      Transliterator::Factory factory,
+                                      Transliterator::Token context) {
+    UErrorCode ec = U_ZERO_ERROR;
+    registry->put(id, factory, context, true, ec);
+}
+
+// To be called only by Transliterator subclasses that are called
+// to register themselves by initializeRegistry().
+void Transliterator::_registerSpecialInverse(const UnicodeString& target,
+                                             const UnicodeString& inverseTarget,
+                                             UBool bidirectional) {
+    UErrorCode status = U_ZERO_ERROR;
+    TransliteratorIDParser::registerSpecialInverse(target, inverseTarget, bidirectional, status);
+}
+
+/**
+ * Registers a instance <tt>obj</tt> of a subclass of
+ * <code>Transliterator</code> with the system.  This object must
+ * implement the <tt>clone()</tt> method.  When
+ * <tt>getInstance()</tt> is called with an ID string that is
+ * equal to <tt>obj.getID()</tt>, then <tt>obj.clone()</tt> is
+ * returned.
+ *
+ * @param obj an instance of subclass of
+ * <code>Transliterator</code> that defines <tt>clone()</tt>
+ * @see #getInstance
+ * @see #unregister
+ */
+void U_EXPORT2 Transliterator::registerInstance(Transliterator* adoptedPrototype) {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    if (HAVE_REGISTRY(ec)) {
+        _registerInstance(adoptedPrototype);
+    }
+}
+
+void Transliterator::_registerInstance(Transliterator* adoptedPrototype) {
+    UErrorCode ec = U_ZERO_ERROR;
+    registry->put(adoptedPrototype, true, ec);
+}
+
+void U_EXPORT2 Transliterator::registerAlias(const UnicodeString& aliasID,
+                                             const UnicodeString& realID) {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    if (HAVE_REGISTRY(ec)) {
+        _registerAlias(aliasID, realID);
+    }
+}
+
+void Transliterator::_registerAlias(const UnicodeString& aliasID,
+                                    const UnicodeString& realID) {
+    UErrorCode ec = U_ZERO_ERROR;
+    registry->put(aliasID, realID, false, true, ec);
+}
+
+/**
+ * Unregisters a transliterator or class.  This may be either
+ * a system transliterator or a user transliterator or class.
+ * 
+ * @param ID the ID of the transliterator or class
+ * @see #registerInstance
+
+ */
+void U_EXPORT2 Transliterator::unregister(const UnicodeString& ID) {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    if (HAVE_REGISTRY(ec)) {
+        registry->remove(ID);
+    }
+}
+
+/**
+ * == OBSOLETE - remove in ICU 3.4 ==
+ * Return the number of IDs currently registered with the system.
+ * To retrieve the actual IDs, call getAvailableID(i) with
+ * i from 0 to countAvailableIDs() - 1.
+ */
+int32_t U_EXPORT2 Transliterator::countAvailableIDs() {
+    int32_t retVal = 0;
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    if (HAVE_REGISTRY(ec)) {
+        retVal = registry->countAvailableIDs();
+    }
+    return retVal;
+}
+
+/**
+ * == OBSOLETE - remove in ICU 3.4 ==
+ * Return the index-th available ID.  index must be between 0
+ * and countAvailableIDs() - 1, inclusive.  If index is out of
+ * range, the result of getAvailableID(0) is returned.
+ */
+const UnicodeString& U_EXPORT2 Transliterator::getAvailableID(int32_t index) {
+    const UnicodeString* result = nullptr;
+    umtx_lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    if (HAVE_REGISTRY(ec)) {
+        result = &registry->getAvailableID(index);
+    }
+    umtx_unlock(&registryMutex);
+    U_ASSERT(result != nullptr); // fail if no registry
+    return *result;
+}
+
+StringEnumeration* U_EXPORT2 Transliterator::getAvailableIDs(UErrorCode& ec) {
+    if (U_FAILURE(ec)) return nullptr;
+    StringEnumeration* result = nullptr;
+    umtx_lock(&registryMutex);
+    if (HAVE_REGISTRY(ec)) {
+        result = registry->getAvailableIDs();
+    }
+    umtx_unlock(&registryMutex);
+    if (result == nullptr) {
+        ec = U_INTERNAL_TRANSLITERATOR_ERROR;
+    }
+    return result;
+}
+
+int32_t U_EXPORT2 Transliterator::countAvailableSources() {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    return HAVE_REGISTRY(ec) ? _countAvailableSources() : 0;
+}
+
+UnicodeString& U_EXPORT2 Transliterator::getAvailableSource(int32_t index,
+                                                  UnicodeString& result) {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    if (HAVE_REGISTRY(ec)) {
+        _getAvailableSource(index, result);
+    }
+    return result;
+}
+
+int32_t U_EXPORT2 Transliterator::countAvailableTargets(const UnicodeString& source) {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    return HAVE_REGISTRY(ec) ? _countAvailableTargets(source) : 0;
+}
+
+UnicodeString& U_EXPORT2 Transliterator::getAvailableTarget(int32_t index,
+                                                  const UnicodeString& source,
+                                                  UnicodeString& result) {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    if (HAVE_REGISTRY(ec)) {
+        _getAvailableTarget(index, source, result);
+    }
+    return result;
+}
+
+int32_t U_EXPORT2 Transliterator::countAvailableVariants(const UnicodeString& source,
+                                               const UnicodeString& target) {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    return HAVE_REGISTRY(ec) ? _countAvailableVariants(source, target) : 0;
+}
+
+UnicodeString& U_EXPORT2 Transliterator::getAvailableVariant(int32_t index,
+                                                   const UnicodeString& source,
+                                                   const UnicodeString& target,
+                                                   UnicodeString& result) {
+    Mutex lock(&registryMutex);
+    UErrorCode ec = U_ZERO_ERROR;
+    if (HAVE_REGISTRY(ec)) {
+        _getAvailableVariant(index, source, target, result);
+    }
+    return result;
+}
+
+int32_t Transliterator::_countAvailableSources() {
+    return registry->countAvailableSources();
+}
+
+UnicodeString& Transliterator::_getAvailableSource(int32_t index,
+                                                  UnicodeString& result) {
+    return registry->getAvailableSource(index, result);
+}
+
+int32_t Transliterator::_countAvailableTargets(const UnicodeString& source) {
+    return registry->countAvailableTargets(source);
+}
+
+UnicodeString& Transliterator::_getAvailableTarget(int32_t index,
+                                                  const UnicodeString& source,
+                                                  UnicodeString& result) {
+    return registry->getAvailableTarget(index, source, result);
+}
+
+int32_t Transliterator::_countAvailableVariants(const UnicodeString& source,
+                                               const UnicodeString& target) {
+    return registry->countAvailableVariants(source, target);
+}
+
+UnicodeString& Transliterator::_getAvailableVariant(int32_t index,
+                                                   const UnicodeString& source,
+                                                   const UnicodeString& target,
+                                                   UnicodeString& result) {
+    return registry->getAvailableVariant(index, source, target, result);
+}
+
+#ifdef U_USE_DEPRECATED_TRANSLITERATOR_API
+
+/**
+ * Method for subclasses to use to obtain a character in the given
+ * string, with filtering.
+ * @deprecated the new architecture provides filtering at the top
+ * level.  This method will be removed Dec 31 2001.
+ */
+char16_t Transliterator::filteredCharAt(const Replaceable& text, int32_t i) const {
+    char16_t c;
+    const UnicodeFilter* localFilter = getFilter();
+    return (localFilter == 0) ? text.charAt(i) :
+        (localFilter->contains(c = text.charAt(i)) ? c : (char16_t)0xFFFE);
+}
+
+#endif
+
+/**
+ * If the registry is initialized, return true.  If not, initialize it
+ * and return true.  If the registry cannot be initialized, return
+ * false (rare).
+ *
+ * IMPORTANT: Upon entry, registryMutex must be LOCKED.  The entire
+ * initialization is done with the lock held.  There is NO REASON to
+ * unlock, since no other thread that is waiting on the registryMutex
+ * cannot itself proceed until the registry is initialized.
+ */
+UBool Transliterator::initializeRegistry(UErrorCode &status) {
+    if (registry != 0) {
+        return true;
+    }
+
+    registry = new TransliteratorRegistry(status);
+    if (registry == 0 || U_FAILURE(status)) {
+        delete registry;
+        registry = 0;
+        return false; // can't create registry, no recovery
+    }
+
+    /* The following code parses the index table located in
+     * icu/data/translit/root.txt.  The index is an n x 4 table
+     * that follows this format:
+     *  <id>{
+     *      file{
+     *          resource{"<resource>"}
+     *          direction{"<direction>"}
+     *      }
+     *  }
+     *  <id>{
+     *      internal{
+     *          resource{"<resource>"}
+     *          direction{"<direction"}
+     *       }
+     *  }
+     *  <id>{
+     *      alias{"<getInstanceArg"}
+     *  }
+     * <id> is the ID of the system transliterator being defined.  These
+     * are public IDs enumerated by Transliterator.getAvailableIDs(),
+     * unless the second field is "internal".
+     * 
+     * <resource> is a ResourceReader resource name.  Currently these refer
+     * to file names under com/ibm/text/resources.  This string is passed
+     * directly to ResourceReader, together with <encoding>.
+     * 
+     * <direction> is either "FORWARD" or "REVERSE".
+     * 
+     * <getInstanceArg> is a string to be passed directly to
+     * Transliterator.getInstance().  The returned Transliterator object
+     * then has its ID changed to <id> and is returned.
+     *
+     * The extra blank field on "alias" lines is to make the array square.
+     */
+    //static const char translit_index[] = "translit_index";
+
+    UErrorCode lstatus = U_ZERO_ERROR;
+    UResourceBundle *bundle, *transIDs, *colBund;
+    bundle = ures_open(U_ICUDATA_TRANSLIT, nullptr/*open default locale*/, &lstatus);
+    transIDs = ures_getByKey(bundle, RB_RULE_BASED_IDS, 0, &lstatus);
+    const UnicodeString T_PART = UNICODE_STRING_SIMPLE("-t-");
+
+    int32_t row, maxRows;
+    if (lstatus == U_MEMORY_ALLOCATION_ERROR) {
+        delete registry;
+        registry = nullptr;
+        status = U_MEMORY_ALLOCATION_ERROR;
+        return false;
+    }
+    if (U_SUCCESS(lstatus)) {
+        maxRows = ures_getSize(transIDs);
+        for (row = 0; row < maxRows; row++) {
+            colBund = ures_getByIndex(transIDs, row, 0, &lstatus);
+            if (U_SUCCESS(lstatus)) {
+                UnicodeString id(ures_getKey(colBund), -1, US_INV);
+                if(id.indexOf(T_PART) != -1) {
+                    ures_close(colBund);
+                    continue;
+                }
+                UResourceBundle* res = ures_getNextResource(colBund, nullptr, &lstatus);
+                const char* typeStr = ures_getKey(res);
+                char16_t type;
+                u_charsToUChars(typeStr, &type, 1);
+
+                if (U_SUCCESS(lstatus)) {
+                    int32_t len = 0;
+                    const char16_t *resString;
+                    switch (type) {
+                    case 0x66: // 'f'
+                    case 0x69: // 'i'
+                        // 'file' or 'internal';
+                        // row[2]=resource, row[3]=direction
+                        {
+                            
+                            resString = ures_getStringByKey(res, "resource", &len, &lstatus);
+                            UBool visible = (type == 0x0066 /*f*/);
+                            UTransDirection dir = 
+                                (ures_getUnicodeStringByKey(res, "direction", &lstatus).charAt(0) ==
+                                 0x0046 /*F*/) ?
+                                UTRANS_FORWARD : UTRANS_REVERSE;
+                            registry->put(id, UnicodeString(true, resString, len), dir, true, visible, lstatus);
+                        }
+                        break;
+                    case 0x61: // 'a'
+                        // 'alias'; row[2]=createInstance argument
+                        resString = ures_getString(res, &len, &lstatus);
+                        registry->put(id, UnicodeString(true, resString, len), true, true, lstatus);
+                        break;
+                    }
+                }
+                ures_close(res);
+            }
+            ures_close(colBund);
+        }
+    }
+
+    ures_close(transIDs);
+    ures_close(bundle);
+
+    // Manually add prototypes that the system knows about to the
+    // cache.  This is how new non-rule-based transliterators are
+    // added to the system.
+    
+    // This is to allow for null pointer check
+    NullTransliterator* tempNullTranslit = new NullTransliterator();
+    LowercaseTransliterator* tempLowercaseTranslit = new LowercaseTransliterator();
+    UppercaseTransliterator* tempUppercaseTranslit = new UppercaseTransliterator();
+    TitlecaseTransliterator* tempTitlecaseTranslit = new TitlecaseTransliterator();
+    UnicodeNameTransliterator* tempUnicodeTranslit = new UnicodeNameTransliterator();
+    NameUnicodeTransliterator* tempNameUnicodeTranslit = new NameUnicodeTransliterator();
+#if !UCONFIG_NO_BREAK_ITERATION
+     // TODO: could or should these transliterators be referenced polymorphically once constructed?
+     BreakTransliterator* tempBreakTranslit         = new BreakTransliterator();
+#endif
+    // Check for null pointers
+    if (tempNullTranslit == nullptr || tempLowercaseTranslit == nullptr || tempUppercaseTranslit == nullptr ||
+        tempTitlecaseTranslit == nullptr || tempUnicodeTranslit == nullptr || 
+#if !UCONFIG_NO_BREAK_ITERATION
+        tempBreakTranslit == nullptr ||
+#endif
+        tempNameUnicodeTranslit == nullptr )
+    {
+        delete tempNullTranslit;
+        delete tempLowercaseTranslit;
+        delete tempUppercaseTranslit;
+        delete tempTitlecaseTranslit;
+        delete tempUnicodeTranslit;
+        delete tempNameUnicodeTranslit;
+#if !UCONFIG_NO_BREAK_ITERATION
+        delete tempBreakTranslit;
+#endif
+        // Since there was an error, remove registry
+        delete registry;
+        registry = nullptr;
+
+        status = U_MEMORY_ALLOCATION_ERROR;
+        return 0;
+    }
+
+    registry->put(tempNullTranslit, true, status);
+    registry->put(tempLowercaseTranslit, true, status);
+    registry->put(tempUppercaseTranslit, true, status);
+    registry->put(tempTitlecaseTranslit, true, status);
+    registry->put(tempUnicodeTranslit, true, status);
+    registry->put(tempNameUnicodeTranslit, true, status);
+#if !UCONFIG_NO_BREAK_ITERATION
+    registry->put(tempBreakTranslit, false, status);   // false means invisible.
+#endif
+
+    RemoveTransliterator::registerIDs(); // Must be within mutex
+    EscapeTransliterator::registerIDs();
+    UnescapeTransliterator::registerIDs();
+    NormalizationTransliterator::registerIDs();
+    AnyTransliterator::registerIDs();
+
+    _registerSpecialInverse(UNICODE_STRING_SIMPLE("Null"),
+                            UNICODE_STRING_SIMPLE("Null"), false);
+    _registerSpecialInverse(UNICODE_STRING_SIMPLE("Upper"),
+                            UNICODE_STRING_SIMPLE("Lower"), true);
+    _registerSpecialInverse(UNICODE_STRING_SIMPLE("Title"),
+                            UNICODE_STRING_SIMPLE("Lower"), false);
+
+    ucln_i18n_registerCleanup(UCLN_I18N_TRANSLITERATOR, utrans_transliterator_cleanup);
+
+    return true;
+}
+
+U_NAMESPACE_END
+
+// Defined in transreg.h:
+
+/**
+ * Release all static memory held by transliterator.  This will
+ * necessarily invalidate any rule-based transliterators held by the
+ * user, because RBTs hold pointers to common data objects.
+ */
+U_CFUNC UBool utrans_transliterator_cleanup() {
+    U_NAMESPACE_USE
+    TransliteratorIDParser::cleanup();
+    if (registry) {
+        delete registry;
+        registry = nullptr;
+    }
+    return true;
+}
+
+#endif /* #if !UCONFIG_NO_TRANSLITERATION */
+
+//eof