Merge pull request #41100 from bruvzg/ctl_text_server_interface

[Complex Text Layouts] Implement TextServer interface.

1 files changed, 1410 insertions, 0 deletions

diff --git a/thirdparty/icu4c/common/loclikely.cpp b/thirdparty/icu4c/common/loclikely.cpp
new file mode 100644
index 0000000000..94a60aba3e
--- /dev/null
+++ b/thirdparty/icu4c/common/loclikely.cpp
@@ -0,0 +1,1410 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+*******************************************************************************
+*
+*   Copyright (C) 1997-2016, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+*******************************************************************************
+*   file name:  loclikely.cpp
+*   encoding:   UTF-8
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 2010feb25
+*   created by: Markus W. Scherer
+*
+*   Code for likely and minimized locale subtags, separated out from other .cpp files
+*   that then do not depend on resource bundle code and likely-subtags data.
+*/
+
+#include "unicode/bytestream.h"
+#include "unicode/utypes.h"
+#include "unicode/locid.h"
+#include "unicode/putil.h"
+#include "unicode/uchar.h"
+#include "unicode/uloc.h"
+#include "unicode/ures.h"
+#include "unicode/uscript.h"
+#include "bytesinkutil.h"
+#include "charstr.h"
+#include "cmemory.h"
+#include "cstring.h"
+#include "ulocimp.h"
+#include "ustr_imp.h"
+
+/**
+ * These are the canonical strings for unknown languages, scripts and regions.
+ **/
+static const char* const unknownLanguage = "und";
+static const char* const unknownScript = "Zzzz";
+static const char* const unknownRegion = "ZZ";
+
+/**
+ * This function looks for the localeID in the likelySubtags resource.
+ *
+ * @param localeID The tag to find.
+ * @param buffer A buffer to hold the matching entry
+ * @param bufferLength The length of the output buffer
+ * @return A pointer to "buffer" if found, or a null pointer if not.
+ */
+static const char*  U_CALLCONV
+findLikelySubtags(const char* localeID,
+                  char* buffer,
+                  int32_t bufferLength,
+                  UErrorCode* err) {
+    const char* result = NULL;
+
+    if (!U_FAILURE(*err)) {
+        int32_t resLen = 0;
+        const UChar* s = NULL;
+        UErrorCode tmpErr = U_ZERO_ERROR;
+        icu::LocalUResourceBundlePointer subtags(ures_openDirect(NULL, "likelySubtags", &tmpErr));
+        if (U_SUCCESS(tmpErr)) {
+            icu::CharString und;
+            if (localeID != NULL) {
+                if (*localeID == '\0') {
+                    localeID = unknownLanguage;
+                } else if (*localeID == '_') {
+                    und.append(unknownLanguage, *err);
+                    und.append(localeID, *err);
+                    if (U_FAILURE(*err)) {
+                        return NULL;
+                    }
+                    localeID = und.data();
+                }
+            }
+            s = ures_getStringByKey(subtags.getAlias(), localeID, &resLen, &tmpErr);
+
+            if (U_FAILURE(tmpErr)) {
+                /*
+                 * If a resource is missing, it's not really an error, it's
+                 * just that we don't have any data for that particular locale ID.
+                 */
+                if (tmpErr != U_MISSING_RESOURCE_ERROR) {
+                    *err = tmpErr;
+                }
+            }
+            else if (resLen >= bufferLength) {
+                /* The buffer should never overflow. */
+                *err = U_INTERNAL_PROGRAM_ERROR;
+            }
+            else {
+                u_UCharsToChars(s, buffer, resLen + 1);
+                if (resLen >= 3 &&
+                    uprv_strnicmp(buffer, unknownLanguage, 3) == 0 &&
+                    (resLen == 3 || buffer[3] == '_')) {
+                    uprv_memmove(buffer, buffer + 3, resLen - 3 + 1);
+                }
+                result = buffer;
+            }
+        } else {
+            *err = tmpErr;
+        }
+    }
+
+    return result;
+}
+
+/**
+ * Append a tag to a buffer, adding the separator if necessary.  The buffer
+ * must be large enough to contain the resulting tag plus any separator
+ * necessary. The tag must not be a zero-length string.
+ *
+ * @param tag The tag to add.
+ * @param tagLength The length of the tag.
+ * @param buffer The output buffer.
+ * @param bufferLength The length of the output buffer.  This is an input/ouput parameter.
+ **/
+static void U_CALLCONV
+appendTag(
+    const char* tag,
+    int32_t tagLength,
+    char* buffer,
+    int32_t* bufferLength,
+    UBool withSeparator) {
+
+    if (withSeparator) {
+        buffer[*bufferLength] = '_';
+        ++(*bufferLength);
+    }
+
+    uprv_memmove(
+        &buffer[*bufferLength],
+        tag,
+        tagLength);
+
+    *bufferLength += tagLength;
+}
+
+/**
+ * Create a tag string from the supplied parameters.  The lang, script and region
+ * parameters may be NULL pointers. If they are, their corresponding length parameters
+ * must be less than or equal to 0.
+ *
+ * If any of the language, script or region parameters are empty, and the alternateTags
+ * parameter is not NULL, it will be parsed for potential language, script and region tags
+ * to be used when constructing the new tag.  If the alternateTags parameter is NULL, or
+ * it contains no language tag, the default tag for the unknown language is used.
+ *
+ * If the length of the new string exceeds the capacity of the output buffer, 
+ * the function copies as many bytes to the output buffer as it can, and returns
+ * the error U_BUFFER_OVERFLOW_ERROR.
+ *
+ * If an illegal argument is provided, the function returns the error
+ * U_ILLEGAL_ARGUMENT_ERROR.
+ *
+ * Note that this function can return the warning U_STRING_NOT_TERMINATED_WARNING if
+ * the tag string fits in the output buffer, but the null terminator doesn't.
+ *
+ * @param lang The language tag to use.
+ * @param langLength The length of the language tag.
+ * @param script The script tag to use.
+ * @param scriptLength The length of the script tag.
+ * @param region The region tag to use.
+ * @param regionLength The length of the region tag.
+ * @param trailing Any trailing data to append to the new tag.
+ * @param trailingLength The length of the trailing data.
+ * @param alternateTags A string containing any alternate tags.
+ * @param sink The output sink receiving the tag string.
+ * @param err A pointer to a UErrorCode for error reporting.
+ **/
+static void U_CALLCONV
+createTagStringWithAlternates(
+    const char* lang,
+    int32_t langLength,
+    const char* script,
+    int32_t scriptLength,
+    const char* region,
+    int32_t regionLength,
+    const char* trailing,
+    int32_t trailingLength,
+    const char* alternateTags,
+    icu::ByteSink& sink,
+    UErrorCode* err) {
+
+    if (U_FAILURE(*err)) {
+        goto error;
+    }
+    else if (langLength >= ULOC_LANG_CAPACITY ||
+             scriptLength >= ULOC_SCRIPT_CAPACITY ||
+             regionLength >= ULOC_COUNTRY_CAPACITY) {
+        goto error;
+    }
+    else {
+        /**
+         * ULOC_FULLNAME_CAPACITY will provide enough capacity
+         * that we can build a string that contains the language,
+         * script and region code without worrying about overrunning
+         * the user-supplied buffer.
+         **/
+        char tagBuffer[ULOC_FULLNAME_CAPACITY];
+        int32_t tagLength = 0;
+        UBool regionAppended = FALSE;
+
+        if (langLength > 0) {
+            appendTag(
+                lang,
+                langLength,
+                tagBuffer,
+                &tagLength,
+                /*withSeparator=*/FALSE);
+        }
+        else if (alternateTags == NULL) {
+            /*
+             * Use the empty string for an unknown language, if
+             * we found no language.
+             */
+        }
+        else {
+            /*
+             * Parse the alternateTags string for the language.
+             */
+            char alternateLang[ULOC_LANG_CAPACITY];
+            int32_t alternateLangLength = sizeof(alternateLang);
+
+            alternateLangLength =
+                uloc_getLanguage(
+                    alternateTags,
+                    alternateLang,
+                    alternateLangLength,
+                    err);
+            if(U_FAILURE(*err) ||
+                alternateLangLength >= ULOC_LANG_CAPACITY) {
+                goto error;
+            }
+            else if (alternateLangLength == 0) {
+                /*
+                 * Use the empty string for an unknown language, if
+                 * we found no language.
+                 */
+            }
+            else {
+                appendTag(
+                    alternateLang,
+                    alternateLangLength,
+                    tagBuffer,
+                    &tagLength,
+                    /*withSeparator=*/FALSE);
+            }
+        }
+
+        if (scriptLength > 0) {
+            appendTag(
+                script,
+                scriptLength,
+                tagBuffer,
+                &tagLength,
+                /*withSeparator=*/TRUE);
+        }
+        else if (alternateTags != NULL) {
+            /*
+             * Parse the alternateTags string for the script.
+             */
+            char alternateScript[ULOC_SCRIPT_CAPACITY];
+
+            const int32_t alternateScriptLength =
+                uloc_getScript(
+                    alternateTags,
+                    alternateScript,
+                    sizeof(alternateScript),
+                    err);
+
+            if (U_FAILURE(*err) ||
+                alternateScriptLength >= ULOC_SCRIPT_CAPACITY) {
+                goto error;
+            }
+            else if (alternateScriptLength > 0) {
+                appendTag(
+                    alternateScript,
+                    alternateScriptLength,
+                    tagBuffer,
+                    &tagLength,
+                    /*withSeparator=*/TRUE);
+            }
+        }
+
+        if (regionLength > 0) {
+            appendTag(
+                region,
+                regionLength,
+                tagBuffer,
+                &tagLength,
+                /*withSeparator=*/TRUE);
+
+            regionAppended = TRUE;
+        }
+        else if (alternateTags != NULL) {
+            /*
+             * Parse the alternateTags string for the region.
+             */
+            char alternateRegion[ULOC_COUNTRY_CAPACITY];
+
+            const int32_t alternateRegionLength =
+                uloc_getCountry(
+                    alternateTags,
+                    alternateRegion,
+                    sizeof(alternateRegion),
+                    err);
+            if (U_FAILURE(*err) ||
+                alternateRegionLength >= ULOC_COUNTRY_CAPACITY) {
+                goto error;
+            }
+            else if (alternateRegionLength > 0) {
+                appendTag(
+                    alternateRegion,
+                    alternateRegionLength,
+                    tagBuffer,
+                    &tagLength,
+                    /*withSeparator=*/TRUE);
+
+                regionAppended = TRUE;
+            }
+        }
+
+        /**
+         * Copy the partial tag from our internal buffer to the supplied
+         * target.
+         **/
+        sink.Append(tagBuffer, tagLength);
+
+        if (trailingLength > 0) {
+            if (*trailing != '@') {
+                sink.Append("_", 1);
+                if (!regionAppended) {
+                    /* extra separator is required */
+                    sink.Append("_", 1);
+                }
+            }
+
+            /*
+             * Copy the trailing data into the supplied buffer.
+             */
+            sink.Append(trailing, trailingLength);
+        }
+
+        return;
+    }
+
+error:
+
+    /**
+     * An overflow indicates the locale ID passed in
+     * is ill-formed.  If we got here, and there was
+     * no previous error, it's an implicit overflow.
+     **/
+    if (*err ==  U_BUFFER_OVERFLOW_ERROR ||
+        U_SUCCESS(*err)) {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+    }
+}
+
+/**
+ * Create a tag string from the supplied parameters.  The lang, script and region
+ * parameters may be NULL pointers. If they are, their corresponding length parameters
+ * must be less than or equal to 0.  If the lang parameter is an empty string, the
+ * default value for an unknown language is written to the output buffer.
+ *
+ * If the length of the new string exceeds the capacity of the output buffer, 
+ * the function copies as many bytes to the output buffer as it can, and returns
+ * the error U_BUFFER_OVERFLOW_ERROR.
+ *
+ * If an illegal argument is provided, the function returns the error
+ * U_ILLEGAL_ARGUMENT_ERROR.
+ *
+ * @param lang The language tag to use.
+ * @param langLength The length of the language tag.
+ * @param script The script tag to use.
+ * @param scriptLength The length of the script tag.
+ * @param region The region tag to use.
+ * @param regionLength The length of the region tag.
+ * @param trailing Any trailing data to append to the new tag.
+ * @param trailingLength The length of the trailing data.
+ * @param sink The output sink receiving the tag string.
+ * @param err A pointer to a UErrorCode for error reporting.
+ **/
+static void U_CALLCONV
+createTagString(
+    const char* lang,
+    int32_t langLength,
+    const char* script,
+    int32_t scriptLength,
+    const char* region,
+    int32_t regionLength,
+    const char* trailing,
+    int32_t trailingLength,
+    icu::ByteSink& sink,
+    UErrorCode* err)
+{
+    createTagStringWithAlternates(
+                lang,
+                langLength,
+                script,
+                scriptLength,
+                region,
+                regionLength,
+                trailing,
+                trailingLength,
+                NULL,
+                sink,
+                err);
+}
+
+/**
+ * Parse the language, script, and region subtags from a tag string, and copy the
+ * results into the corresponding output parameters. The buffers are null-terminated,
+ * unless overflow occurs.
+ *
+ * The langLength, scriptLength, and regionLength parameters are input/output
+ * parameters, and must contain the capacity of their corresponding buffers on
+ * input.  On output, they will contain the actual length of the buffers, not
+ * including the null terminator.
+ *
+ * If the length of any of the output subtags exceeds the capacity of the corresponding
+ * buffer, the function copies as many bytes to the output buffer as it can, and returns
+ * the error U_BUFFER_OVERFLOW_ERROR.  It will not parse any more subtags once overflow
+ * occurs.
+ *
+ * If an illegal argument is provided, the function returns the error
+ * U_ILLEGAL_ARGUMENT_ERROR.
+ *
+ * @param localeID The locale ID to parse.
+ * @param lang The language tag buffer.
+ * @param langLength The length of the language tag.
+ * @param script The script tag buffer.
+ * @param scriptLength The length of the script tag.
+ * @param region The region tag buffer.
+ * @param regionLength The length of the region tag.
+ * @param err A pointer to a UErrorCode for error reporting.
+ * @return The number of chars of the localeID parameter consumed.
+ **/
+static int32_t U_CALLCONV
+parseTagString(
+    const char* localeID,
+    char* lang,
+    int32_t* langLength,
+    char* script,
+    int32_t* scriptLength,
+    char* region,
+    int32_t* regionLength,
+    UErrorCode* err)
+{
+    const char* position = localeID;
+    int32_t subtagLength = 0;
+
+    if(U_FAILURE(*err) ||
+       localeID == NULL ||
+       lang == NULL ||
+       langLength == NULL ||
+       script == NULL ||
+       scriptLength == NULL ||
+       region == NULL ||
+       regionLength == NULL) {
+        goto error;
+    }
+
+    subtagLength = ulocimp_getLanguage(position, &position, *err).extract(lang, *langLength, *err);
+
+    /*
+     * Note that we explicit consider U_STRING_NOT_TERMINATED_WARNING
+     * to be an error, because it indicates the user-supplied tag is
+     * not well-formed.
+     */
+    if(U_FAILURE(*err)) {
+        goto error;
+    }
+
+    *langLength = subtagLength;
+
+    /*
+     * If no language was present, use the empty string instead.
+     * Otherwise, move past any separator.
+     */
+    if (_isIDSeparator(*position)) {
+        ++position;
+    }
+
+    subtagLength = ulocimp_getScript(position, &position, *err).extract(script, *scriptLength, *err);
+
+    if(U_FAILURE(*err)) {
+        goto error;
+    }
+
+    *scriptLength = subtagLength;
+
+    if (*scriptLength > 0) {
+        if (uprv_strnicmp(script, unknownScript, *scriptLength) == 0) {
+            /**
+             * If the script part is the "unknown" script, then don't return it.
+             **/
+            *scriptLength = 0;
+        }
+
+        /*
+         * Move past any separator.
+         */
+        if (_isIDSeparator(*position)) {
+            ++position;
+        }    
+    }
+
+    subtagLength = ulocimp_getCountry(position, &position, *err).extract(region, *regionLength, *err);
+
+    if(U_FAILURE(*err)) {
+        goto error;
+    }
+
+    *regionLength = subtagLength;
+
+    if (*regionLength > 0) {
+        if (uprv_strnicmp(region, unknownRegion, *regionLength) == 0) {
+            /**
+             * If the region part is the "unknown" region, then don't return it.
+             **/
+            *regionLength = 0;
+        }
+    } else if (*position != 0 && *position != '@') {
+        /* back up over consumed trailing separator */
+        --position;
+    }
+
+exit:
+
+    return (int32_t)(position - localeID);
+
+error:
+
+    /**
+     * If we get here, we have no explicit error, it's the result of an
+     * illegal argument.
+     **/
+    if (!U_FAILURE(*err)) {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+    }
+
+    goto exit;
+}
+
+static UBool U_CALLCONV
+createLikelySubtagsString(
+    const char* lang,
+    int32_t langLength,
+    const char* script,
+    int32_t scriptLength,
+    const char* region,
+    int32_t regionLength,
+    const char* variants,
+    int32_t variantsLength,
+    icu::ByteSink& sink,
+    UErrorCode* err) {
+    /**
+     * ULOC_FULLNAME_CAPACITY will provide enough capacity
+     * that we can build a string that contains the language,
+     * script and region code without worrying about overrunning
+     * the user-supplied buffer.
+     **/
+    char likelySubtagsBuffer[ULOC_FULLNAME_CAPACITY];
+
+    if(U_FAILURE(*err)) {
+        goto error;
+    }
+
+    /**
+     * Try the language with the script and region first.
+     **/
+    if (scriptLength > 0 && regionLength > 0) {
+
+        const char* likelySubtags = NULL;
+
+        icu::CharString tagBuffer;
+        {
+            icu::CharStringByteSink sink(&tagBuffer);
+            createTagString(
+                lang,
+                langLength,
+                script,
+                scriptLength,
+                region,
+                regionLength,
+                NULL,
+                0,
+                sink,
+                err);
+        }
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+
+        likelySubtags =
+            findLikelySubtags(
+                tagBuffer.data(),
+                likelySubtagsBuffer,
+                sizeof(likelySubtagsBuffer),
+                err);
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+
+        if (likelySubtags != NULL) {
+            /* Always use the language tag from the
+               maximal string, since it may be more
+               specific than the one provided. */
+            createTagStringWithAlternates(
+                        NULL,
+                        0,
+                        NULL,
+                        0,
+                        NULL,
+                        0,
+                        variants,
+                        variantsLength,
+                        likelySubtags,
+                        sink,
+                        err);
+            return TRUE;
+        }
+    }
+
+    /**
+     * Try the language with just the script.
+     **/
+    if (scriptLength > 0) {
+
+        const char* likelySubtags = NULL;
+
+        icu::CharString tagBuffer;
+        {
+            icu::CharStringByteSink sink(&tagBuffer);
+            createTagString(
+                lang,
+                langLength,
+                script,
+                scriptLength,
+                NULL,
+                0,
+                NULL,
+                0,
+                sink,
+                err);
+        }
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+
+        likelySubtags =
+            findLikelySubtags(
+                tagBuffer.data(),
+                likelySubtagsBuffer,
+                sizeof(likelySubtagsBuffer),
+                err);
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+
+        if (likelySubtags != NULL) {
+            /* Always use the language tag from the
+               maximal string, since it may be more
+               specific than the one provided. */
+            createTagStringWithAlternates(
+                        NULL,
+                        0,
+                        NULL,
+                        0,
+                        region,
+                        regionLength,
+                        variants,
+                        variantsLength,
+                        likelySubtags,
+                        sink,
+                        err);
+            return TRUE;
+        }
+    }
+
+    /**
+     * Try the language with just the region.
+     **/
+    if (regionLength > 0) {
+
+        const char* likelySubtags = NULL;
+
+        icu::CharString tagBuffer;
+        {
+            icu::CharStringByteSink sink(&tagBuffer);
+            createTagString(
+                lang,
+                langLength,
+                NULL,
+                0,
+                region,
+                regionLength,
+                NULL,
+                0,
+                sink,
+                err);
+        }
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+
+        likelySubtags =
+            findLikelySubtags(
+                tagBuffer.data(),
+                likelySubtagsBuffer,
+                sizeof(likelySubtagsBuffer),
+                err);
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+
+        if (likelySubtags != NULL) {
+            /* Always use the language tag from the
+               maximal string, since it may be more
+               specific than the one provided. */
+            createTagStringWithAlternates(
+                        NULL,
+                        0,
+                        script,
+                        scriptLength,
+                        NULL,
+                        0,
+                        variants,
+                        variantsLength,
+                        likelySubtags,
+                        sink,
+                        err);
+            return TRUE;
+        }
+    }
+
+    /**
+     * Finally, try just the language.
+     **/
+    {
+        const char* likelySubtags = NULL;
+
+        icu::CharString tagBuffer;
+        {
+            icu::CharStringByteSink sink(&tagBuffer);
+            createTagString(
+                lang,
+                langLength,
+                NULL,
+                0,
+                NULL,
+                0,
+                NULL,
+                0,
+                sink,
+                err);
+        }
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+
+        likelySubtags =
+            findLikelySubtags(
+                tagBuffer.data(),
+                likelySubtagsBuffer,
+                sizeof(likelySubtagsBuffer),
+                err);
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+
+        if (likelySubtags != NULL) {
+            /* Always use the language tag from the
+               maximal string, since it may be more
+               specific than the one provided. */
+            createTagStringWithAlternates(
+                        NULL,
+                        0,
+                        script,
+                        scriptLength,
+                        region,
+                        regionLength,
+                        variants,
+                        variantsLength,
+                        likelySubtags,
+                        sink,
+                        err);
+            return TRUE;
+        }
+    }
+
+    return FALSE;
+
+error:
+
+    if (!U_FAILURE(*err)) {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+    }
+
+    return FALSE;
+}
+
+#define CHECK_TRAILING_VARIANT_SIZE(trailing, trailingLength) UPRV_BLOCK_MACRO_BEGIN { \
+    int32_t count = 0; \
+    int32_t i; \
+    for (i = 0; i < trailingLength; i++) { \
+        if (trailing[i] == '-' || trailing[i] == '_') { \
+            count = 0; \
+            if (count > 8) { \
+                goto error; \
+            } \
+        } else if (trailing[i] == '@') { \
+            break; \
+        } else if (count > 8) { \
+            goto error; \
+        } else { \
+            count++; \
+        } \
+    } \
+} UPRV_BLOCK_MACRO_END
+
+static UBool
+_uloc_addLikelySubtags(const char* localeID,
+                       icu::ByteSink& sink,
+                       UErrorCode* err) {
+    char lang[ULOC_LANG_CAPACITY];
+    int32_t langLength = sizeof(lang);
+    char script[ULOC_SCRIPT_CAPACITY];
+    int32_t scriptLength = sizeof(script);
+    char region[ULOC_COUNTRY_CAPACITY];
+    int32_t regionLength = sizeof(region);
+    const char* trailing = "";
+    int32_t trailingLength = 0;
+    int32_t trailingIndex = 0;
+    UBool success = FALSE;
+
+    if(U_FAILURE(*err)) {
+        goto error;
+    }
+    if (localeID == NULL) {
+        goto error;
+    }
+
+    trailingIndex = parseTagString(
+        localeID,
+        lang,
+        &langLength,
+        script,
+        &scriptLength,
+        region,
+        &regionLength,
+        err);
+    if(U_FAILURE(*err)) {
+        /* Overflow indicates an illegal argument error */
+        if (*err == U_BUFFER_OVERFLOW_ERROR) {
+            *err = U_ILLEGAL_ARGUMENT_ERROR;
+        }
+
+        goto error;
+    }
+
+    /* Find the length of the trailing portion. */
+    while (_isIDSeparator(localeID[trailingIndex])) {
+        trailingIndex++;
+    }
+    trailing = &localeID[trailingIndex];
+    trailingLength = (int32_t)uprv_strlen(trailing);
+
+    CHECK_TRAILING_VARIANT_SIZE(trailing, trailingLength);
+
+    success =
+        createLikelySubtagsString(
+            lang,
+            langLength,
+            script,
+            scriptLength,
+            region,
+            regionLength,
+            trailing,
+            trailingLength,
+            sink,
+            err);
+
+    if (!success) {
+        const int32_t localIDLength = (int32_t)uprv_strlen(localeID);
+
+        /*
+         * If we get here, we need to return localeID.
+         */
+        sink.Append(localeID, localIDLength);
+    }
+
+    return success;
+
+error:
+
+    if (!U_FAILURE(*err)) {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+    }
+    return FALSE;
+}
+
+// Add likely subtags to the sink
+// return true if the value in the sink is produced by a match during the lookup
+// return false if the value in the sink is the same as input because there are
+// no match after the lookup.
+static UBool _ulocimp_addLikelySubtags(const char*, icu::ByteSink&, UErrorCode*);
+
+static void
+_uloc_minimizeSubtags(const char* localeID,
+                      icu::ByteSink& sink,
+                      UErrorCode* err) {
+    icu::CharString maximizedTagBuffer;
+
+    char lang[ULOC_LANG_CAPACITY];
+    int32_t langLength = sizeof(lang);
+    char script[ULOC_SCRIPT_CAPACITY];
+    int32_t scriptLength = sizeof(script);
+    char region[ULOC_COUNTRY_CAPACITY];
+    int32_t regionLength = sizeof(region);
+    const char* trailing = "";
+    int32_t trailingLength = 0;
+    int32_t trailingIndex = 0;
+    UBool successGetMax = FALSE;
+
+    if(U_FAILURE(*err)) {
+        goto error;
+    }
+    else if (localeID == NULL) {
+        goto error;
+    }
+
+    trailingIndex =
+        parseTagString(
+            localeID,
+            lang,
+            &langLength,
+            script,
+            &scriptLength,
+            region,
+            &regionLength,
+            err);
+    if(U_FAILURE(*err)) {
+
+        /* Overflow indicates an illegal argument error */
+        if (*err == U_BUFFER_OVERFLOW_ERROR) {
+            *err = U_ILLEGAL_ARGUMENT_ERROR;
+        }
+
+        goto error;
+    }
+
+    /* Find the spot where the variants or the keywords begin, if any. */
+    while (_isIDSeparator(localeID[trailingIndex])) {
+        trailingIndex++;
+    }
+    trailing = &localeID[trailingIndex];
+    trailingLength = (int32_t)uprv_strlen(trailing);
+
+    CHECK_TRAILING_VARIANT_SIZE(trailing, trailingLength);
+
+    {
+        icu::CharString base;
+        {
+            icu::CharStringByteSink baseSink(&base);
+            createTagString(
+                lang,
+                langLength,
+                script,
+                scriptLength,
+                region,
+                regionLength,
+                NULL,
+                0,
+                baseSink,
+                err);
+        }
+
+        /**
+         * First, we need to first get the maximization
+         * from AddLikelySubtags.
+         **/
+        {
+            icu::CharStringByteSink maxSink(&maximizedTagBuffer);
+            successGetMax = _ulocimp_addLikelySubtags(base.data(), maxSink, err);
+        }
+    }
+
+    if(U_FAILURE(*err)) {
+        goto error;
+    }
+
+    if (!successGetMax) {
+        /**
+         * If we got here, return the locale ID parameter unchanged.
+         **/
+        const int32_t localeIDLength = (int32_t)uprv_strlen(localeID);
+        sink.Append(localeID, localeIDLength);
+        return;
+    }
+
+    // In the following, the lang, script, region are referring to those in
+    // the maximizedTagBuffer, not the one in the localeID.
+    langLength = sizeof(lang);
+    scriptLength = sizeof(script);
+    regionLength = sizeof(region);
+    parseTagString(
+        maximizedTagBuffer.data(),
+        lang,
+        &langLength,
+        script,
+        &scriptLength,
+        region,
+        &regionLength,
+        err);
+    if(U_FAILURE(*err)) {
+        goto error;
+    }
+
+    /**
+     * Start first with just the language.
+     **/
+    {
+        icu::CharString tagBuffer;
+        {
+            icu::CharStringByteSink tagSink(&tagBuffer);
+            createLikelySubtagsString(
+                lang,
+                langLength,
+                NULL,
+                0,
+                NULL,
+                0,
+                NULL,
+                0,
+                tagSink,
+                err);
+        }
+
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+        else if (!tagBuffer.isEmpty() &&
+                 uprv_strnicmp(
+                    maximizedTagBuffer.data(),
+                    tagBuffer.data(),
+                    tagBuffer.length()) == 0) {
+
+            createTagString(
+                        lang,
+                        langLength,
+                        NULL,
+                        0,
+                        NULL,
+                        0,
+                        trailing,
+                        trailingLength,
+                        sink,
+                        err);
+            return;
+        }
+    }
+
+    /**
+     * Next, try the language and region.
+     **/
+    if (regionLength > 0) {
+
+        icu::CharString tagBuffer;
+        {
+            icu::CharStringByteSink tagSink(&tagBuffer);
+            createLikelySubtagsString(
+                lang,
+                langLength,
+                NULL,
+                0,
+                region,
+                regionLength,
+                NULL,
+                0,
+                tagSink,
+                err);
+        }
+
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+        else if (!tagBuffer.isEmpty() &&
+                 uprv_strnicmp(
+                    maximizedTagBuffer.data(),
+                    tagBuffer.data(),
+                    tagBuffer.length()) == 0) {
+
+            createTagString(
+                        lang,
+                        langLength,
+                        NULL,
+                        0,
+                        region,
+                        regionLength,
+                        trailing,
+                        trailingLength,
+                        sink,
+                        err);
+            return;
+        }
+    }
+
+    /**
+     * Finally, try the language and script.  This is our last chance,
+     * since trying with all three subtags would only yield the
+     * maximal version that we already have.
+     **/
+    if (scriptLength > 0) {
+        icu::CharString tagBuffer;
+        {
+            icu::CharStringByteSink tagSink(&tagBuffer);
+            createLikelySubtagsString(
+                lang,
+                langLength,
+                script,
+                scriptLength,
+                NULL,
+                0,
+                NULL,
+                0,
+                tagSink,
+                err);
+        }
+
+        if(U_FAILURE(*err)) {
+            goto error;
+        }
+        else if (!tagBuffer.isEmpty() &&
+                 uprv_strnicmp(
+                    maximizedTagBuffer.data(),
+                    tagBuffer.data(),
+                    tagBuffer.length()) == 0) {
+
+            createTagString(
+                        lang,
+                        langLength,
+                        script,
+                        scriptLength,
+                        NULL,
+                        0,
+                        trailing,
+                        trailingLength,
+                        sink,
+                        err);
+            return;
+        }
+    }
+
+    {
+        /**
+         * If we got here, return the max + trail.
+         **/
+        createTagString(
+                    lang,
+                    langLength,
+                    script,
+                    scriptLength,
+                    region,
+                    regionLength,
+                    trailing,
+                    trailingLength,
+                    sink,
+                    err);
+        return;
+    }
+
+error:
+
+    if (!U_FAILURE(*err)) {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+    }
+}
+
+static UBool
+do_canonicalize(const char*    localeID,
+         char* buffer,
+         int32_t bufferCapacity,
+         UErrorCode* err)
+{
+    uloc_canonicalize(
+        localeID,
+        buffer,
+        bufferCapacity,
+        err);
+
+    if (*err == U_STRING_NOT_TERMINATED_WARNING ||
+        *err == U_BUFFER_OVERFLOW_ERROR) {
+        *err = U_ILLEGAL_ARGUMENT_ERROR;
+
+        return FALSE;
+    }
+    else if (U_FAILURE(*err)) {
+
+        return FALSE;
+    }
+    else {
+        return TRUE;
+    }
+}
+
+U_CAPI int32_t U_EXPORT2
+uloc_addLikelySubtags(const char* localeID,
+                      char* maximizedLocaleID,
+                      int32_t maximizedLocaleIDCapacity,
+                      UErrorCode* status) {
+    if (U_FAILURE(*status)) {
+        return 0;
+    }
+
+    icu::CheckedArrayByteSink sink(
+            maximizedLocaleID, maximizedLocaleIDCapacity);
+
+    ulocimp_addLikelySubtags(localeID, sink, status);
+    int32_t reslen = sink.NumberOfBytesAppended();
+
+    if (U_FAILURE(*status)) {
+        return sink.Overflowed() ? reslen : -1;
+    }
+
+    if (sink.Overflowed()) {
+        *status = U_BUFFER_OVERFLOW_ERROR;
+    } else {
+        u_terminateChars(
+                maximizedLocaleID, maximizedLocaleIDCapacity, reslen, status);
+    }
+
+    return reslen;
+}
+
+static UBool
+_ulocimp_addLikelySubtags(const char* localeID,
+                          icu::ByteSink& sink,
+                          UErrorCode* status) {
+    char localeBuffer[ULOC_FULLNAME_CAPACITY];
+
+    if (do_canonicalize(localeID, localeBuffer, sizeof localeBuffer, status)) {
+        return _uloc_addLikelySubtags(localeBuffer, sink, status);
+    }
+    return FALSE;
+}
+
+U_CAPI void U_EXPORT2
+ulocimp_addLikelySubtags(const char* localeID,
+                         icu::ByteSink& sink,
+                         UErrorCode* status) {
+    _ulocimp_addLikelySubtags(localeID, sink, status);
+}
+
+U_CAPI int32_t U_EXPORT2
+uloc_minimizeSubtags(const char* localeID,
+                     char* minimizedLocaleID,
+                     int32_t minimizedLocaleIDCapacity,
+                     UErrorCode* status) {
+    if (U_FAILURE(*status)) {
+        return 0;
+    }
+
+    icu::CheckedArrayByteSink sink(
+            minimizedLocaleID, minimizedLocaleIDCapacity);
+
+    ulocimp_minimizeSubtags(localeID, sink, status);
+    int32_t reslen = sink.NumberOfBytesAppended();
+
+    if (U_FAILURE(*status)) {
+        return sink.Overflowed() ? reslen : -1;
+    }
+
+    if (sink.Overflowed()) {
+        *status = U_BUFFER_OVERFLOW_ERROR;
+    } else {
+        u_terminateChars(
+                minimizedLocaleID, minimizedLocaleIDCapacity, reslen, status);
+    }
+
+    return reslen;
+}
+
+U_CAPI void U_EXPORT2
+ulocimp_minimizeSubtags(const char* localeID,
+                        icu::ByteSink& sink,
+                        UErrorCode* status) {
+    char localeBuffer[ULOC_FULLNAME_CAPACITY];
+
+    if (do_canonicalize(localeID, localeBuffer, sizeof localeBuffer, status)) {
+        _uloc_minimizeSubtags(localeBuffer, sink, status);
+    }
+}
+
+// Pairs of (language subtag, + or -) for finding out fast if common languages
+// are LTR (minus) or RTL (plus).
+static const char LANG_DIR_STRING[] =
+        "root-en-es-pt-zh-ja-ko-de-fr-it-ar+he+fa+ru-nl-pl-th-tr-";
+
+// Implemented here because this calls ulocimp_addLikelySubtags().
+U_CAPI UBool U_EXPORT2
+uloc_isRightToLeft(const char *locale) {
+    UErrorCode errorCode = U_ZERO_ERROR;
+    char script[8];
+    int32_t scriptLength = uloc_getScript(locale, script, UPRV_LENGTHOF(script), &errorCode);
+    if (U_FAILURE(errorCode) || errorCode == U_STRING_NOT_TERMINATED_WARNING ||
+            scriptLength == 0) {
+        // Fastpath: We know the likely scripts and their writing direction
+        // for some common languages.
+        errorCode = U_ZERO_ERROR;
+        char lang[8];
+        int32_t langLength = uloc_getLanguage(locale, lang, UPRV_LENGTHOF(lang), &errorCode);
+        if (U_FAILURE(errorCode) || errorCode == U_STRING_NOT_TERMINATED_WARNING) {
+            return FALSE;
+        }
+        if (langLength > 0) {
+            const char* langPtr = uprv_strstr(LANG_DIR_STRING, lang);
+            if (langPtr != NULL) {
+                switch (langPtr[langLength]) {
+                case '-': return FALSE;
+                case '+': return TRUE;
+                default: break;  // partial match of a longer code
+                }
+            }
+        }
+        // Otherwise, find the likely script.
+        errorCode = U_ZERO_ERROR;
+        icu::CharString likely;
+        {
+            icu::CharStringByteSink sink(&likely);
+            ulocimp_addLikelySubtags(locale, sink, &errorCode);
+        }
+        if (U_FAILURE(errorCode) || errorCode == U_STRING_NOT_TERMINATED_WARNING) {
+            return FALSE;
+        }
+        scriptLength = uloc_getScript(likely.data(), script, UPRV_LENGTHOF(script), &errorCode);
+        if (U_FAILURE(errorCode) || errorCode == U_STRING_NOT_TERMINATED_WARNING ||
+                scriptLength == 0) {
+            return FALSE;
+        }
+    }
+    UScriptCode scriptCode = (UScriptCode)u_getPropertyValueEnum(UCHAR_SCRIPT, script);
+    return uscript_isRightToLeft(scriptCode);
+}
+
+U_NAMESPACE_BEGIN
+
+UBool
+Locale::isRightToLeft() const {
+    return uloc_isRightToLeft(getBaseName());
+}
+
+U_NAMESPACE_END
+
+// The following must at least allow for rg key value (6) plus terminator (1).
+#define ULOC_RG_BUFLEN 8
+
+U_CAPI int32_t U_EXPORT2
+ulocimp_getRegionForSupplementalData(const char *localeID, UBool inferRegion,
+                                     char *region, int32_t regionCapacity, UErrorCode* status) {
+    if (U_FAILURE(*status)) {
+        return 0;
+    }
+    char rgBuf[ULOC_RG_BUFLEN];
+    UErrorCode rgStatus = U_ZERO_ERROR;
+
+    // First check for rg keyword value
+    int32_t rgLen = uloc_getKeywordValue(localeID, "rg", rgBuf, ULOC_RG_BUFLEN, &rgStatus);
+    if (U_FAILURE(rgStatus) || rgLen != 6) {
+        rgLen = 0;
+    } else {
+        // rgBuf guaranteed to be zero terminated here, with text len 6
+        char *rgPtr = rgBuf;
+        for (; *rgPtr!= 0; rgPtr++) {
+            *rgPtr = uprv_toupper(*rgPtr);
+        }
+        rgLen = (uprv_strcmp(rgBuf+2, "ZZZZ") == 0)? 2: 0;
+    }
+
+    if (rgLen == 0) {
+        // No valid rg keyword value, try for unicode_region_subtag
+        rgLen = uloc_getCountry(localeID, rgBuf, ULOC_RG_BUFLEN, status);
+        if (U_FAILURE(*status)) {
+            rgLen = 0;
+        } else if (rgLen == 0 && inferRegion) {
+            // no unicode_region_subtag but inferRegion TRUE, try likely subtags
+            rgStatus = U_ZERO_ERROR;
+            icu::CharString locBuf;
+            {
+                icu::CharStringByteSink sink(&locBuf);
+                ulocimp_addLikelySubtags(localeID, sink, &rgStatus);
+            }
+            if (U_SUCCESS(rgStatus)) {
+                rgLen = uloc_getCountry(locBuf.data(), rgBuf, ULOC_RG_BUFLEN, status);
+                if (U_FAILURE(*status)) {
+                    rgLen = 0;
+                }
+            }
+        }
+    }
+
+    rgBuf[rgLen] = 0;
+    uprv_strncpy(region, rgBuf, regionCapacity);
+    return u_terminateChars(region, regionCapacity, rgLen, status);
+}
+