Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 881 insertions, 0 deletions

diff --git a/intl/icu/source/i18n/collationruleparser.cpp b/intl/icu/source/i18n/collationruleparser.cpp
new file mode 100644
index 0000000000..4cc25a1f5c
--- /dev/null
+++ b/intl/icu/source/i18n/collationruleparser.cpp
@@ -0,0 +1,881 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+*******************************************************************************
+* Copyright (C) 2013-2015, International Business Machines
+* Corporation and others.  All Rights Reserved.
+*******************************************************************************
+* collationruleparser.cpp
+*
+* (replaced the former ucol_tok.cpp)
+*
+* created on: 2013apr10
+* created by: Markus W. Scherer
+*/
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_COLLATION
+
+#include "unicode/normalizer2.h"
+#include "unicode/parseerr.h"
+#include "unicode/uchar.h"
+#include "unicode/ucol.h"
+#include "unicode/uloc.h"
+#include "unicode/unistr.h"
+#include "unicode/utf16.h"
+#include "charstr.h"
+#include "cmemory.h"
+#include "collation.h"
+#include "collationdata.h"
+#include "collationruleparser.h"
+#include "collationsettings.h"
+#include "collationtailoring.h"
+#include "cstring.h"
+#include "patternprops.h"
+#include "uassert.h"
+#include "uvectr32.h"
+
+U_NAMESPACE_BEGIN
+
+namespace {
+
+static const char16_t BEFORE[] = { 0x5b, 0x62, 0x65, 0x66, 0x6f, 0x72, 0x65, 0 };  // "[before"
+const int32_t BEFORE_LENGTH = 7;
+
+}  // namespace
+
+CollationRuleParser::Sink::~Sink() {}
+
+void
+CollationRuleParser::Sink::suppressContractions(const UnicodeSet &, const char *&, UErrorCode &) {}
+
+void
+CollationRuleParser::Sink::optimize(const UnicodeSet &, const char *&, UErrorCode &) {}
+
+CollationRuleParser::Importer::~Importer() {}
+
+CollationRuleParser::CollationRuleParser(const CollationData *base, UErrorCode &errorCode)
+        : nfd(*Normalizer2::getNFDInstance(errorCode)),
+          nfc(*Normalizer2::getNFCInstance(errorCode)),
+          rules(nullptr), baseData(base), settings(nullptr),
+          parseError(nullptr), errorReason(nullptr),
+          sink(nullptr), importer(nullptr),
+          ruleIndex(0) {
+}
+
+CollationRuleParser::~CollationRuleParser() {
+}
+
+void
+CollationRuleParser::parse(const UnicodeString &ruleString,
+                           CollationSettings &outSettings,
+                           UParseError *outParseError,
+                           UErrorCode &errorCode) {
+    if(U_FAILURE(errorCode)) { return; }
+    settings = &outSettings;
+    parseError = outParseError;
+    if(parseError != nullptr) {
+        parseError->line = 0;
+        parseError->offset = -1;
+        parseError->preContext[0] = 0;
+        parseError->postContext[0] = 0;
+    }
+    errorReason = nullptr;
+    parse(ruleString, errorCode);
+}
+
+void
+CollationRuleParser::parse(const UnicodeString &ruleString, UErrorCode &errorCode) {
+    if(U_FAILURE(errorCode)) { return; }
+    rules = &ruleString;
+    ruleIndex = 0;
+
+    while(ruleIndex < rules->length()) {
+        char16_t c = rules->charAt(ruleIndex);
+        if(PatternProps::isWhiteSpace(c)) {
+            ++ruleIndex;
+            continue;
+        }
+        switch(c) {
+        case 0x26:  // '&'
+            parseRuleChain(errorCode);
+            break;
+        case 0x5b:  // '['
+            parseSetting(errorCode);
+            break;
+        case 0x23:  // '#' starts a comment, until the end of the line
+            ruleIndex = skipComment(ruleIndex + 1);
+            break;
+        case 0x40:  // '@' is equivalent to [backwards 2]
+            settings->setFlag(CollationSettings::BACKWARD_SECONDARY,
+                              UCOL_ON, 0, errorCode);
+            ++ruleIndex;
+            break;
+        case 0x21:  // '!' used to turn on Thai/Lao character reversal
+            // Accept but ignore. The root collator has contractions
+            // that are equivalent to the character reversal, where appropriate.
+            ++ruleIndex;
+            break;
+        default:
+            setParseError("expected a reset or setting or comment", errorCode);
+            break;
+        }
+        if(U_FAILURE(errorCode)) { return; }
+    }
+}
+
+void
+CollationRuleParser::parseRuleChain(UErrorCode &errorCode) {
+    int32_t resetStrength = parseResetAndPosition(errorCode);
+    UBool isFirstRelation = true;
+    for(;;) {
+        int32_t result = parseRelationOperator(errorCode);
+        if(U_FAILURE(errorCode)) { return; }
+        if(result < 0) {
+            if(ruleIndex < rules->length() && rules->charAt(ruleIndex) == 0x23) {
+                // '#' starts a comment, until the end of the line
+                ruleIndex = skipComment(ruleIndex + 1);
+                continue;
+            }
+            if(isFirstRelation) {
+                setParseError("reset not followed by a relation", errorCode);
+            }
+            return;
+        }
+        int32_t strength = result & STRENGTH_MASK;
+        if(resetStrength < UCOL_IDENTICAL) {
+            // reset-before rule chain
+            if(isFirstRelation) {
+                if(strength != resetStrength) {
+                    setParseError("reset-before strength differs from its first relation", errorCode);
+                    return;
+                }
+            } else {
+                if(strength < resetStrength) {
+                    setParseError("reset-before strength followed by a stronger relation", errorCode);
+                    return;
+                }
+            }
+        }
+        int32_t i = ruleIndex + (result >> OFFSET_SHIFT);  // skip over the relation operator
+        if((result & STARRED_FLAG) == 0) {
+            parseRelationStrings(strength, i, errorCode);
+        } else {
+            parseStarredCharacters(strength, i, errorCode);
+        }
+        if(U_FAILURE(errorCode)) { return; }
+        isFirstRelation = false;
+    }
+}
+
+int32_t
+CollationRuleParser::parseResetAndPosition(UErrorCode &errorCode) {
+    if(U_FAILURE(errorCode)) { return UCOL_DEFAULT; }
+    int32_t i = skipWhiteSpace(ruleIndex + 1);
+    int32_t j;
+    char16_t c;
+    int32_t resetStrength;
+    if(rules->compare(i, BEFORE_LENGTH, BEFORE, 0, BEFORE_LENGTH) == 0 &&
+            (j = i + BEFORE_LENGTH) < rules->length() &&
+            PatternProps::isWhiteSpace(rules->charAt(j)) &&
+            ((j = skipWhiteSpace(j + 1)) + 1) < rules->length() &&
+            0x31 <= (c = rules->charAt(j)) && c <= 0x33 &&
+            rules->charAt(j + 1) == 0x5d) {
+        // &[before n] with n=1 or 2 or 3
+        resetStrength = UCOL_PRIMARY + (c - 0x31);
+        i = skipWhiteSpace(j + 2);
+    } else {
+        resetStrength = UCOL_IDENTICAL;
+    }
+    if(i >= rules->length()) {
+        setParseError("reset without position", errorCode);
+        return UCOL_DEFAULT;
+    }
+    UnicodeString str;
+    if(rules->charAt(i) == 0x5b) {  // '['
+        i = parseSpecialPosition(i, str, errorCode);
+    } else {
+        i = parseTailoringString(i, str, errorCode);
+    }
+    sink->addReset(resetStrength, str, errorReason, errorCode);
+    if(U_FAILURE(errorCode)) { setErrorContext(); }
+    ruleIndex = i;
+    return resetStrength;
+}
+
+int32_t
+CollationRuleParser::parseRelationOperator(UErrorCode &errorCode) {
+    if(U_FAILURE(errorCode)) { return UCOL_DEFAULT; }
+    ruleIndex = skipWhiteSpace(ruleIndex);
+    if(ruleIndex >= rules->length()) { return UCOL_DEFAULT; }
+    int32_t strength;
+    int32_t i = ruleIndex;
+    char16_t c = rules->charAt(i++);
+    switch(c) {
+    case 0x3c:  // '<'
+        if(i < rules->length() && rules->charAt(i) == 0x3c) {  // <<
+            ++i;
+            if(i < rules->length() && rules->charAt(i) == 0x3c) {  // <<<
+                ++i;
+                if(i < rules->length() && rules->charAt(i) == 0x3c) {  // <<<<
+                    ++i;
+                    strength = UCOL_QUATERNARY;
+                } else {
+                    strength = UCOL_TERTIARY;
+                }
+            } else {
+                strength = UCOL_SECONDARY;
+            }
+        } else {
+            strength = UCOL_PRIMARY;
+        }
+        if(i < rules->length() && rules->charAt(i) == 0x2a) {  // '*'
+            ++i;
+            strength |= STARRED_FLAG;
+        }
+        break;
+    case 0x3b:  // ';' same as <<
+        strength = UCOL_SECONDARY;
+        break;
+    case 0x2c:  // ',' same as <<<
+        strength = UCOL_TERTIARY;
+        break;
+    case 0x3d:  // '='
+        strength = UCOL_IDENTICAL;
+        if(i < rules->length() && rules->charAt(i) == 0x2a) {  // '*'
+            ++i;
+            strength |= STARRED_FLAG;
+        }
+        break;
+    default:
+        return UCOL_DEFAULT;
+    }
+    return ((i - ruleIndex) << OFFSET_SHIFT) | strength;
+}
+
+void
+CollationRuleParser::parseRelationStrings(int32_t strength, int32_t i, UErrorCode &errorCode) {
+    // Parse
+    //     prefix | str / extension
+    // where prefix and extension are optional.
+    UnicodeString prefix, str, extension;
+    i = parseTailoringString(i, str, errorCode);
+    if(U_FAILURE(errorCode)) { return; }
+    char16_t next = (i < rules->length()) ? rules->charAt(i) : 0;
+    if(next == 0x7c) {  // '|' separates the context prefix from the string.
+        prefix = str;
+        i = parseTailoringString(i + 1, str, errorCode);
+        if(U_FAILURE(errorCode)) { return; }
+        next = (i < rules->length()) ? rules->charAt(i) : 0;
+    }
+    if(next == 0x2f) {  // '/' separates the string from the extension.
+        i = parseTailoringString(i + 1, extension, errorCode);
+    }
+    if(!prefix.isEmpty()) {
+        UChar32 prefix0 = prefix.char32At(0);
+        UChar32 c = str.char32At(0);
+        if(!nfc.hasBoundaryBefore(prefix0) || !nfc.hasBoundaryBefore(c)) {
+            setParseError("in 'prefix|str', prefix and str must each start with an NFC boundary",
+                          errorCode);
+            return;
+        }
+    }
+    sink->addRelation(strength, prefix, str, extension, errorReason, errorCode);
+    if(U_FAILURE(errorCode)) { setErrorContext(); }
+    ruleIndex = i;
+}
+
+void
+CollationRuleParser::parseStarredCharacters(int32_t strength, int32_t i, UErrorCode &errorCode) {
+    UnicodeString empty, raw;
+    i = parseString(skipWhiteSpace(i), raw, errorCode);
+    if(U_FAILURE(errorCode)) { return; }
+    if(raw.isEmpty()) {
+        setParseError("missing starred-relation string", errorCode);
+        return;
+    }
+    UChar32 prev = -1;
+    int32_t j = 0;
+    for(;;) {
+        while(j < raw.length()) {
+            UChar32 c = raw.char32At(j);
+            if(!nfd.isInert(c)) {
+                setParseError("starred-relation string is not all NFD-inert", errorCode);
+                return;
+            }
+            sink->addRelation(strength, empty, UnicodeString(c), empty, errorReason, errorCode);
+            if(U_FAILURE(errorCode)) {
+                setErrorContext();
+                return;
+            }
+            j += U16_LENGTH(c);
+            prev = c;
+        }
+        if(i >= rules->length() || rules->charAt(i) != 0x2d) {  // '-'
+            break;
+        }
+        if(prev < 0) {
+            setParseError("range without start in starred-relation string", errorCode);
+            return;
+        }
+        i = parseString(i + 1, raw, errorCode);
+        if(U_FAILURE(errorCode)) { return; }
+        if(raw.isEmpty()) {
+            setParseError("range without end in starred-relation string", errorCode);
+            return;
+        }
+        UChar32 c = raw.char32At(0);
+        if(c < prev) {
+            setParseError("range start greater than end in starred-relation string", errorCode);
+            return;
+        }
+        // range prev-c
+        UnicodeString s;
+        while(++prev <= c) {
+            if(!nfd.isInert(prev)) {
+                setParseError("starred-relation string range is not all NFD-inert", errorCode);
+                return;
+            }
+            if(U_IS_SURROGATE(prev)) {
+                setParseError("starred-relation string range contains a surrogate", errorCode);
+                return;
+            }
+            if(0xfffd <= prev && prev <= 0xffff) {
+                setParseError("starred-relation string range contains U+FFFD, U+FFFE or U+FFFF", errorCode);
+                return;
+            }
+            s.setTo(prev);
+            sink->addRelation(strength, empty, s, empty, errorReason, errorCode);
+            if(U_FAILURE(errorCode)) {
+                setErrorContext();
+                return;
+            }
+        }
+        prev = -1;
+        j = U16_LENGTH(c);
+    }
+    ruleIndex = skipWhiteSpace(i);
+}
+
+int32_t
+CollationRuleParser::parseTailoringString(int32_t i, UnicodeString &raw, UErrorCode &errorCode) {
+    i = parseString(skipWhiteSpace(i), raw, errorCode);
+    if(U_SUCCESS(errorCode) && raw.isEmpty()) {
+        setParseError("missing relation string", errorCode);
+    }
+    return skipWhiteSpace(i);
+}
+
+int32_t
+CollationRuleParser::parseString(int32_t i, UnicodeString &raw, UErrorCode &errorCode) {
+    if(U_FAILURE(errorCode)) { return i; }
+    raw.remove();
+    while(i < rules->length()) {
+        UChar32 c = rules->charAt(i++);
+        if(isSyntaxChar(c)) {
+            if(c == 0x27) {  // apostrophe
+                if(i < rules->length() && rules->charAt(i) == 0x27) {
+                    // Double apostrophe, encodes a single one.
+                    raw.append((char16_t)0x27);
+                    ++i;
+                    continue;
+                }
+                // Quote literal text until the next single apostrophe.
+                for(;;) {
+                    if(i == rules->length()) {
+                        setParseError("quoted literal text missing terminating apostrophe", errorCode);
+                        return i;
+                    }
+                    c = rules->charAt(i++);
+                    if(c == 0x27) {
+                        if(i < rules->length() && rules->charAt(i) == 0x27) {
+                            // Double apostrophe inside quoted literal text,
+                            // still encodes a single apostrophe.
+                            ++i;
+                        } else {
+                            break;
+                        }
+                    }
+                    raw.append((char16_t)c);
+                }
+            } else if(c == 0x5c) {  // backslash
+                if(i == rules->length()) {
+                    setParseError("backslash escape at the end of the rule string", errorCode);
+                    return i;
+                }
+                c = rules->char32At(i);
+                raw.append(c);
+                i += U16_LENGTH(c);
+            } else {
+                // Any other syntax character terminates a string.
+                --i;
+                break;
+            }
+        } else if(PatternProps::isWhiteSpace(c)) {
+            // Unquoted white space terminates a string.
+            --i;
+            break;
+        } else {
+            raw.append((char16_t)c);
+        }
+    }
+    for(int32_t j = 0; j < raw.length();) {
+        UChar32 c = raw.char32At(j);
+        if(U_IS_SURROGATE(c)) {
+            setParseError("string contains an unpaired surrogate", errorCode);
+            return i;
+        }
+        if(0xfffd <= c && c <= 0xffff) {
+            setParseError("string contains U+FFFD, U+FFFE or U+FFFF", errorCode);
+            return i;
+        }
+        j += U16_LENGTH(c);
+    }
+    return i;
+}
+
+namespace {
+
+static const char *const positions[] = {
+    "first tertiary ignorable",
+    "last tertiary ignorable",
+    "first secondary ignorable",
+    "last secondary ignorable",
+    "first primary ignorable",
+    "last primary ignorable",
+    "first variable",
+    "last variable",
+    "first regular",
+    "last regular",
+    "first implicit",
+    "last implicit",
+    "first trailing",
+    "last trailing"
+};
+
+}  // namespace
+
+int32_t
+CollationRuleParser::parseSpecialPosition(int32_t i, UnicodeString &str, UErrorCode &errorCode) {
+    if(U_FAILURE(errorCode)) { return 0; }
+    UnicodeString raw;
+    int32_t j = readWords(i + 1, raw);
+    if(j > i && rules->charAt(j) == 0x5d && !raw.isEmpty()) {  // words end with ]
+        ++j;
+        for(int32_t pos = 0; pos < UPRV_LENGTHOF(positions); ++pos) {
+            if(raw == UnicodeString(positions[pos], -1, US_INV)) {
+                str.setTo((char16_t)POS_LEAD).append((char16_t)(POS_BASE + pos));
+                return j;
+            }
+        }
+        if(raw == UNICODE_STRING_SIMPLE("top")) {
+            str.setTo((char16_t)POS_LEAD).append((char16_t)(POS_BASE + LAST_REGULAR));
+            return j;
+        }
+        if(raw == UNICODE_STRING_SIMPLE("variable top")) {
+            str.setTo((char16_t)POS_LEAD).append((char16_t)(POS_BASE + LAST_VARIABLE));
+            return j;
+        }
+    }
+    setParseError("not a valid special reset position", errorCode);
+    return i;
+}
+
+void
+CollationRuleParser::parseSetting(UErrorCode &errorCode) {
+    if(U_FAILURE(errorCode)) { return; }
+    UnicodeString raw;
+    int32_t i = ruleIndex + 1;
+    int32_t j = readWords(i, raw);
+    if(j <= i || raw.isEmpty()) {
+        setParseError("expected a setting/option at '['", errorCode);
+    }
+    if(rules->charAt(j) == 0x5d) {  // words end with ]
+        ++j;
+        if(raw.startsWith(UNICODE_STRING_SIMPLE("reorder")) &&
+                (raw.length() == 7 || raw.charAt(7) == 0x20)) {
+            parseReordering(raw, errorCode);
+            ruleIndex = j;
+            return;
+        }
+        if(raw == UNICODE_STRING_SIMPLE("backwards 2")) {
+            settings->setFlag(CollationSettings::BACKWARD_SECONDARY,
+                              UCOL_ON, 0, errorCode);
+            ruleIndex = j;
+            return;
+        }
+        UnicodeString v;
+        int32_t valueIndex = raw.lastIndexOf((char16_t)0x20);
+        if(valueIndex >= 0) {
+            v.setTo(raw, valueIndex + 1);
+            raw.truncate(valueIndex);
+        }
+        if(raw == UNICODE_STRING_SIMPLE("strength") && v.length() == 1) {
+            int32_t value = UCOL_DEFAULT;
+            char16_t c = v.charAt(0);
+            if(0x31 <= c && c <= 0x34) {  // 1..4
+                value = UCOL_PRIMARY + (c - 0x31);
+            } else if(c == 0x49) {  // 'I'
+                value = UCOL_IDENTICAL;
+            }
+            if(value != UCOL_DEFAULT) {
+                settings->setStrength(value, 0, errorCode);
+                ruleIndex = j;
+                return;
+            }
+        } else if(raw == UNICODE_STRING_SIMPLE("alternate")) {
+            UColAttributeValue value = UCOL_DEFAULT;
+            if(v == UNICODE_STRING_SIMPLE("non-ignorable")) {
+                value = UCOL_NON_IGNORABLE;
+            } else if(v == UNICODE_STRING_SIMPLE("shifted")) {
+                value = UCOL_SHIFTED;
+            }
+            if(value != UCOL_DEFAULT) {
+                settings->setAlternateHandling(value, 0, errorCode);
+                ruleIndex = j;
+                return;
+            }
+        } else if(raw == UNICODE_STRING_SIMPLE("maxVariable")) {
+            int32_t value = UCOL_DEFAULT;
+            if(v == UNICODE_STRING_SIMPLE("space")) {
+                value = CollationSettings::MAX_VAR_SPACE;
+            } else if(v == UNICODE_STRING_SIMPLE("punct")) {
+                value = CollationSettings::MAX_VAR_PUNCT;
+            } else if(v == UNICODE_STRING_SIMPLE("symbol")) {
+                value = CollationSettings::MAX_VAR_SYMBOL;
+            } else if(v == UNICODE_STRING_SIMPLE("currency")) {
+                value = CollationSettings::MAX_VAR_CURRENCY;
+            }
+            if(value != UCOL_DEFAULT) {
+                settings->setMaxVariable(value, 0, errorCode);
+                settings->variableTop = baseData->getLastPrimaryForGroup(
+                    UCOL_REORDER_CODE_FIRST + value);
+                U_ASSERT(settings->variableTop != 0);
+                ruleIndex = j;
+                return;
+            }
+        } else if(raw == UNICODE_STRING_SIMPLE("caseFirst")) {
+            UColAttributeValue value = UCOL_DEFAULT;
+            if(v == UNICODE_STRING_SIMPLE("off")) {
+                value = UCOL_OFF;
+            } else if(v == UNICODE_STRING_SIMPLE("lower")) {
+                value = UCOL_LOWER_FIRST;
+            } else if(v == UNICODE_STRING_SIMPLE("upper")) {
+                value = UCOL_UPPER_FIRST;
+            }
+            if(value != UCOL_DEFAULT) {
+                settings->setCaseFirst(value, 0, errorCode);
+                ruleIndex = j;
+                return;
+            }
+        } else if(raw == UNICODE_STRING_SIMPLE("caseLevel")) {
+            UColAttributeValue value = getOnOffValue(v);
+            if(value != UCOL_DEFAULT) {
+                settings->setFlag(CollationSettings::CASE_LEVEL, value, 0, errorCode);
+                ruleIndex = j;
+                return;
+            }
+        } else if(raw == UNICODE_STRING_SIMPLE("normalization")) {
+            UColAttributeValue value = getOnOffValue(v);
+            if(value != UCOL_DEFAULT) {
+                settings->setFlag(CollationSettings::CHECK_FCD, value, 0, errorCode);
+                ruleIndex = j;
+                return;
+            }
+        } else if(raw == UNICODE_STRING_SIMPLE("numericOrdering")) {
+            UColAttributeValue value = getOnOffValue(v);
+            if(value != UCOL_DEFAULT) {
+                settings->setFlag(CollationSettings::NUMERIC, value, 0, errorCode);
+                ruleIndex = j;
+                return;
+            }
+        } else if(raw == UNICODE_STRING_SIMPLE("hiraganaQ")) {
+            UColAttributeValue value = getOnOffValue(v);
+            if(value != UCOL_DEFAULT) {
+                if(value == UCOL_ON) {
+                    setParseError("[hiraganaQ on] is not supported", errorCode);
+                }
+                ruleIndex = j;
+                return;
+            }
+        } else if(raw == UNICODE_STRING_SIMPLE("import")) {
+            CharString lang;
+            lang.appendInvariantChars(v, errorCode);
+            if(errorCode == U_MEMORY_ALLOCATION_ERROR) { return; }
+            // BCP 47 language tag -> ICU locale ID
+            char localeID[ULOC_FULLNAME_CAPACITY];
+            int32_t parsedLength;
+            int32_t length = uloc_forLanguageTag(lang.data(), localeID, ULOC_FULLNAME_CAPACITY,
+                                                 &parsedLength, &errorCode);
+            if(U_FAILURE(errorCode) ||
+                    parsedLength != lang.length() || length >= ULOC_FULLNAME_CAPACITY) {
+                errorCode = U_ZERO_ERROR;
+                setParseError("expected language tag in [import langTag]", errorCode);
+                return;
+            }
+            // localeID minus all keywords
+            char baseID[ULOC_FULLNAME_CAPACITY];
+            length = uloc_getBaseName(localeID, baseID, ULOC_FULLNAME_CAPACITY, &errorCode);
+            if(U_FAILURE(errorCode) || length >= ULOC_KEYWORDS_CAPACITY) {
+                errorCode = U_ZERO_ERROR;
+                setParseError("expected language tag in [import langTag]", errorCode);
+                return;
+            }
+            if(length == 0) {
+                uprv_strcpy(baseID, "root");
+            } else if(*baseID == '_') {
+                uprv_memmove(baseID + 3, baseID, length + 1);
+                uprv_memcpy(baseID, "und", 3);
+            }
+            // @collation=type, or length=0 if not specified
+            char collationType[ULOC_KEYWORDS_CAPACITY];
+            length = uloc_getKeywordValue(localeID, "collation",
+                                          collationType, ULOC_KEYWORDS_CAPACITY,
+                                          &errorCode);
+            if(U_FAILURE(errorCode) || length >= ULOC_KEYWORDS_CAPACITY) {
+                errorCode = U_ZERO_ERROR;
+                setParseError("expected language tag in [import langTag]", errorCode);
+                return;
+            }
+            if(importer == nullptr) {
+                setParseError("[import langTag] is not supported", errorCode);
+            } else {
+                UnicodeString importedRules;
+                importer->getRules(baseID, length > 0 ? collationType : "standard",
+                                   importedRules, errorReason, errorCode);
+                if(U_FAILURE(errorCode)) {
+                    if(errorReason == nullptr) {
+                        errorReason = "[import langTag] failed";
+                    }
+                    setErrorContext();
+                    return;
+                }
+                const UnicodeString *outerRules = rules;
+                int32_t outerRuleIndex = ruleIndex;
+                parse(importedRules, errorCode);
+                if(U_FAILURE(errorCode)) {
+                    if(parseError != nullptr) {
+                        parseError->offset = outerRuleIndex;
+                    }
+                }
+                rules = outerRules;
+                ruleIndex = j;
+            }
+            return;
+        }
+    } else if(rules->charAt(j) == 0x5b) {  // words end with [
+        UnicodeSet set;
+        j = parseUnicodeSet(j, set, errorCode);
+        if(U_FAILURE(errorCode)) { return; }
+        if(raw == UNICODE_STRING_SIMPLE("optimize")) {
+            sink->optimize(set, errorReason, errorCode);
+            if(U_FAILURE(errorCode)) { setErrorContext(); }
+            ruleIndex = j;
+            return;
+        } else if(raw == UNICODE_STRING_SIMPLE("suppressContractions")) {
+            sink->suppressContractions(set, errorReason, errorCode);
+            if(U_FAILURE(errorCode)) { setErrorContext(); }
+            ruleIndex = j;
+            return;
+        }
+    }
+    setParseError("not a valid setting/option", errorCode);
+}
+
+void
+CollationRuleParser::parseReordering(const UnicodeString &raw, UErrorCode &errorCode) {
+    if(U_FAILURE(errorCode)) { return; }
+    int32_t i = 7;  // after "reorder"
+    if(i == raw.length()) {
+        // empty [reorder] with no codes
+        settings->resetReordering();
+        return;
+    }
+    // Parse the codes in [reorder aa bb cc].
+    UVector32 reorderCodes(errorCode);
+    if(U_FAILURE(errorCode)) { return; }
+    CharString word;
+    while(i < raw.length()) {
+        ++i;  // skip the word-separating space
+        int32_t limit = raw.indexOf((char16_t)0x20, i);
+        if(limit < 0) { limit = raw.length(); }
+        word.clear().appendInvariantChars(raw.tempSubStringBetween(i, limit), errorCode);
+        if(U_FAILURE(errorCode)) { return; }
+        int32_t code = getReorderCode(word.data());
+        if(code < 0) {
+            setParseError("unknown script or reorder code", errorCode);
+            return;
+        }
+        reorderCodes.addElement(code, errorCode);
+        if(U_FAILURE(errorCode)) { return; }
+        i = limit;
+    }
+    settings->setReordering(*baseData, reorderCodes.getBuffer(), reorderCodes.size(), errorCode);
+}
+
+static const char *const gSpecialReorderCodes[] = {
+    "space", "punct", "symbol", "currency", "digit"
+};
+
+int32_t
+CollationRuleParser::getReorderCode(const char *word) {
+    for(int32_t i = 0; i < UPRV_LENGTHOF(gSpecialReorderCodes); ++i) {
+        if(uprv_stricmp(word, gSpecialReorderCodes[i]) == 0) {
+            return UCOL_REORDER_CODE_FIRST + i;
+        }
+    }
+    int32_t script = u_getPropertyValueEnum(UCHAR_SCRIPT, word);
+    if(script >= 0) {
+        return script;
+    }
+    if(uprv_stricmp(word, "others") == 0) {
+        return UCOL_REORDER_CODE_OTHERS;  // same as Zzzz = USCRIPT_UNKNOWN
+    }
+    return -1;
+}
+
+UColAttributeValue
+CollationRuleParser::getOnOffValue(const UnicodeString &s) {
+    if(s == UNICODE_STRING_SIMPLE("on")) {
+        return UCOL_ON;
+    } else if(s == UNICODE_STRING_SIMPLE("off")) {
+        return UCOL_OFF;
+    } else {
+        return UCOL_DEFAULT;
+    }
+}
+
+int32_t
+CollationRuleParser::parseUnicodeSet(int32_t i, UnicodeSet &set, UErrorCode &errorCode) {
+    // Collect a UnicodeSet pattern between a balanced pair of [brackets].
+    int32_t level = 0;
+    int32_t j = i;
+    for(;;) {
+        if(j == rules->length()) {
+            setParseError("unbalanced UnicodeSet pattern brackets", errorCode);
+            return j;
+        }
+        char16_t c = rules->charAt(j++);
+        if(c == 0x5b) {  // '['
+            ++level;
+        } else if(c == 0x5d) {  // ']'
+            if(--level == 0) { break; }
+        }
+    }
+    set.applyPattern(rules->tempSubStringBetween(i, j), errorCode);
+    if(U_FAILURE(errorCode)) {
+        errorCode = U_ZERO_ERROR;
+        setParseError("not a valid UnicodeSet pattern", errorCode);
+        return j;
+    }
+    j = skipWhiteSpace(j);
+    if(j == rules->length() || rules->charAt(j) != 0x5d) {
+        setParseError("missing option-terminating ']' after UnicodeSet pattern", errorCode);
+        return j;
+    }
+    return ++j;
+}
+
+int32_t
+CollationRuleParser::readWords(int32_t i, UnicodeString &raw) const {
+    static const char16_t sp = 0x20;
+    raw.remove();
+    i = skipWhiteSpace(i);
+    for(;;) {
+        if(i >= rules->length()) { return 0; }
+        char16_t c = rules->charAt(i);
+        if(isSyntaxChar(c) && c != 0x2d && c != 0x5f) {  // syntax except -_
+            if(raw.isEmpty()) { return i; }
+            if(raw.endsWith(&sp, 1)) {  // remove trailing space
+                raw.truncate(raw.length() - 1);
+            }
+            return i;
+        }
+        if(PatternProps::isWhiteSpace(c)) {
+            raw.append(sp);
+            i = skipWhiteSpace(i + 1);
+        } else {
+            raw.append(c);
+            ++i;
+        }
+    }
+}
+
+int32_t
+CollationRuleParser::skipComment(int32_t i) const {
+    // skip to past the newline
+    while(i < rules->length()) {
+        char16_t c = rules->charAt(i++);
+        // LF or FF or CR or NEL or LS or PS
+        if(c == 0xa || c == 0xc || c == 0xd || c == 0x85 || c == 0x2028 || c == 0x2029) {
+            // Unicode Newline Guidelines: "A readline function should stop at NLF, LS, FF, or PS."
+            // NLF (new line function) = CR or LF or CR+LF or NEL.
+            // No need to collect all of CR+LF because a following LF will be ignored anyway.
+            break;
+        }
+    }
+    return i;
+}
+
+void
+CollationRuleParser::setParseError(const char *reason, UErrorCode &errorCode) {
+    if(U_FAILURE(errorCode)) { return; }
+    // Error code consistent with the old parser (from ca. 2001),
+    // rather than U_PARSE_ERROR;
+    errorCode = U_INVALID_FORMAT_ERROR;
+    errorReason = reason;
+    if(parseError != nullptr) { setErrorContext(); }
+}
+
+void
+CollationRuleParser::setErrorContext() {
+    if(parseError == nullptr) { return; }
+
+    // Note: This relies on the calling code maintaining the ruleIndex
+    // at a position that is useful for debugging.
+    // For example, at the beginning of a reset or relation etc.
+    parseError->offset = ruleIndex;
+    parseError->line = 0;  // We are not counting line numbers.
+
+    // before ruleIndex
+    int32_t start = ruleIndex - (U_PARSE_CONTEXT_LEN - 1);
+    if(start < 0) {
+        start = 0;
+    } else if(start > 0 && U16_IS_TRAIL(rules->charAt(start))) {
+        ++start;
+    }
+    int32_t length = ruleIndex - start;
+    rules->extract(start, length, parseError->preContext);
+    parseError->preContext[length] = 0;
+
+    // starting from ruleIndex
+    length = rules->length() - ruleIndex;
+    if(length >= U_PARSE_CONTEXT_LEN) {
+        length = U_PARSE_CONTEXT_LEN - 1;
+        if(U16_IS_LEAD(rules->charAt(ruleIndex + length - 1))) {
+            --length;
+        }
+    }
+    rules->extract(ruleIndex, length, parseError->postContext);
+    parseError->postContext[length] = 0;
+}
+
+UBool
+CollationRuleParser::isSyntaxChar(UChar32 c) {
+    return 0x21 <= c && c <= 0x7e &&
+            (c <= 0x2f || (0x3a <= c && c <= 0x40) ||
+            (0x5b <= c && c <= 0x60) || (0x7b <= c));
+}
+
+int32_t
+CollationRuleParser::skipWhiteSpace(int32_t i) const {
+    while(i < rules->length() && PatternProps::isWhiteSpace(rules->charAt(i))) {
+        ++i;
+    }
+    return i;
+}
+
+U_NAMESPACE_END
+
+#endif  // !UCONFIG_NO_COLLATION