icuSources/common/messagepattern.cpp

   1 /*
   2 *******************************************************************************
   3 *   Copyright (C) 2011-2012, International Business Machines
   4 *   Corporation and others.  All Rights Reserved.
   5 *******************************************************************************
   6 *   file name:  messagepattern.cpp
   7 *   encoding:   US-ASCII
   8 *   tab size:   8 (not used)
   9 *   indentation:4
  10 *
  11 *   created on: 2011mar14
  12 *   created by: Markus W. Scherer
  13 */
  14
  15 #include "unicode/utypes.h"
  16
  17 #if !UCONFIG_NO_FORMATTING
  18
  19 #include "unicode/messagepattern.h"
  20 #include "unicode/unistr.h"
  21 #include "unicode/utf16.h"
  22 #include "cmemory.h"
  23 #include "cstring.h"
  24 #include "messageimpl.h"
  25 #include "patternprops.h"
  26 #include "putilimp.h"
  27 #include "uassert.h"
  28
  29 U_NAMESPACE_BEGIN
  30
  31 // Unicode character/code point constants ---------------------------------- ***
  32
  33 static const UChar u_pound=0x23;
  34 static const UChar u_apos=0x27;
  35 static const UChar u_plus=0x2B;
  36 static const UChar u_comma=0x2C;
  37 static const UChar u_minus=0x2D;
  38 static const UChar u_dot=0x2E;
  39 static const UChar u_colon=0x3A;
  40 static const UChar u_lessThan=0x3C;
  41 static const UChar u_equal=0x3D;
  42 static const UChar u_A=0x41;
  43 static const UChar u_C=0x43;
  44 static const UChar u_D=0x44;
  45 static const UChar u_E=0x45;
  46 static const UChar u_H=0x48;
  47 static const UChar u_I=0x49;
  48 static const UChar u_L=0x4C;
  49 static const UChar u_N=0x4E;
  50 static const UChar u_O=0x4F;
  51 static const UChar u_P=0x50;
  52 static const UChar u_R=0x52;
  53 static const UChar u_S=0x53;
  54 static const UChar u_T=0x54;
  55 static const UChar u_U=0x55;
  56 static const UChar u_Z=0x5A;
  57 static const UChar u_a=0x61;
  58 static const UChar u_c=0x63;
  59 static const UChar u_d=0x64;
  60 static const UChar u_e=0x65;
  61 static const UChar u_f=0x66;
  62 static const UChar u_h=0x68;
  63 static const UChar u_i=0x69;
  64 static const UChar u_l=0x6C;
  65 static const UChar u_n=0x6E;
  66 static const UChar u_o=0x6F;
  67 static const UChar u_p=0x70;
  68 static const UChar u_r=0x72;
  69 static const UChar u_s=0x73;
  70 static const UChar u_t=0x74;
  71 static const UChar u_u=0x75;
  72 static const UChar u_z=0x7A;
  73 static const UChar u_leftCurlyBrace=0x7B;
  74 static const UChar u_pipe=0x7C;
  75 static const UChar u_rightCurlyBrace=0x7D;
  76 static const UChar u_lessOrEqual=0x2264;  // U+2264 is <=
  77
  78 static const UChar kOffsetColon[]={  // "offset:"
  79     u_o, u_f, u_f, u_s, u_e, u_t, u_colon
  80 };
  81
  82 static const UChar kOther[]={  // "other"
  83     u_o, u_t, u_h, u_e, u_r
  84 };
  85
  86 // MessagePatternList ------------------------------------------------------ ***
  87
  88 template<typename T, int32_t stackCapacity>
  89 class MessagePatternList : public UMemory {
  90 public:
  91     MessagePatternList() {}
  92     void copyFrom(const MessagePatternList<T, stackCapacity> &other,
  93                   int32_t length,
  94                   UErrorCode &errorCode);
  95     UBool ensureCapacityForOneMore(int32_t oldLength, UErrorCode &errorCode);
  96     UBool equals(const MessagePatternList<T, stackCapacity> &other, int32_t length) const {
  97         for(int32_t i=0; i<length; ++i) {
  98             if(a[i]!=other.a[i]) { return FALSE; }
  99         }
 100         return TRUE;
 101     }
 102
 103     MaybeStackArray<T, stackCapacity> a;
 104 };
 105
 106 template<typename T, int32_t stackCapacity>
 107 void
 108 MessagePatternList<T, stackCapacity>::copyFrom(
 109         const MessagePatternList<T, stackCapacity> &other,
 110         int32_t length,
 111         UErrorCode &errorCode) {
 112     if(U_SUCCESS(errorCode) && length>0) {
 113         if(length>a.getCapacity() && NULL==a.resize(length)) {
 114             errorCode=U_MEMORY_ALLOCATION_ERROR;
 115             return;
 116         }
 117         uprv_memcpy(a.getAlias(), other.a.getAlias(), length*sizeof(T));
 118     }
 119 }
 120
 121 template<typename T, int32_t stackCapacity>
 122 UBool
 123 MessagePatternList<T, stackCapacity>::ensureCapacityForOneMore(int32_t oldLength, UErrorCode &errorCode) {
 124     if(U_FAILURE(errorCode)) {
 125         return FALSE;
 126     }
 127     if(a.getCapacity()>oldLength || a.resize(2*oldLength, oldLength)!=NULL) {
 128         return TRUE;
 129     }
 130     errorCode=U_MEMORY_ALLOCATION_ERROR;
 131     return FALSE;
 132 }
 133
 134 // MessagePatternList specializations -------------------------------------- ***
 135
 136 class MessagePatternDoubleList : public MessagePatternList<double, 8> {
 137 };
 138
 139 class MessagePatternPartsList : public MessagePatternList<MessagePattern::Part, 32> {
 140 };
 141
 142 // MessagePattern constructors etc. ---------------------------------------- ***
 143
 144 MessagePattern::MessagePattern(UErrorCode &errorCode)
 145         : aposMode(UCONFIG_MSGPAT_DEFAULT_APOSTROPHE_MODE),
 146           partsList(NULL), parts(NULL), partsLength(0),
 147           numericValuesList(NULL), numericValues(NULL), numericValuesLength(0),
 148           hasArgNames(FALSE), hasArgNumbers(FALSE), needsAutoQuoting(FALSE) {
 149     init(errorCode);
 150 }
 151
 152 MessagePattern::MessagePattern(UMessagePatternApostropheMode mode, UErrorCode &errorCode)
 153         : aposMode(mode),
 154           partsList(NULL), parts(NULL), partsLength(0),
 155           numericValuesList(NULL), numericValues(NULL), numericValuesLength(0),
 156           hasArgNames(FALSE), hasArgNumbers(FALSE), needsAutoQuoting(FALSE) {
 157     init(errorCode);
 158 }
 159
 160 MessagePattern::MessagePattern(const UnicodeString &pattern, UParseError *parseError, UErrorCode &errorCode)
 161         : aposMode(UCONFIG_MSGPAT_DEFAULT_APOSTROPHE_MODE),
 162           partsList(NULL), parts(NULL), partsLength(0),
 163           numericValuesList(NULL), numericValues(NULL), numericValuesLength(0),
 164           hasArgNames(FALSE), hasArgNumbers(FALSE), needsAutoQuoting(FALSE) {
 165     if(init(errorCode)) {
 166         parse(pattern, parseError, errorCode);
 167     }
 168 }
 169
 170 UBool
 171 MessagePattern::init(UErrorCode &errorCode) {
 172     if(U_FAILURE(errorCode)) {
 173         return FALSE;
 174     }
 175     partsList=new MessagePatternPartsList();
 176     if(partsList==NULL) {
 177         errorCode=U_MEMORY_ALLOCATION_ERROR;
 178         return FALSE;
 179     }
 180     parts=partsList->a.getAlias();
 181     return TRUE;
 182 }
 183
 184 MessagePattern::MessagePattern(const MessagePattern &other)
 185         : UObject(other), aposMode(other.aposMode), msg(other.msg),
 186           partsList(NULL), parts(NULL), partsLength(0),
 187           numericValuesList(NULL), numericValues(NULL), numericValuesLength(0),
 188           hasArgNames(other.hasArgNames), hasArgNumbers(other.hasArgNumbers),
 189           needsAutoQuoting(other.needsAutoQuoting) {
 190     UErrorCode errorCode=U_ZERO_ERROR;
 191     if(!copyStorage(other, errorCode)) {
 192         clear();
 193     }
 194 }
 195
 196 MessagePattern &
 197 MessagePattern::operator=(const MessagePattern &other) {
 198     if(this==&other) {
 199         return *this;
 200     }
 201     aposMode=other.aposMode;
 202     msg=other.msg;
 203     hasArgNames=other.hasArgNames;
 204     hasArgNumbers=other.hasArgNumbers;
 205     needsAutoQuoting=other.needsAutoQuoting;
 206     UErrorCode errorCode=U_ZERO_ERROR;
 207     if(!copyStorage(other, errorCode)) {
 208         clear();
 209     }
 210     return *this;
 211 }
 212
 213 UBool
 214 MessagePattern::copyStorage(const MessagePattern &other, UErrorCode &errorCode) {
 215     if(U_FAILURE(errorCode)) {
 216         return FALSE;
 217     }
 218     parts=NULL;
 219     partsLength=0;
 220     numericValues=NULL;
 221     numericValuesLength=0;
 222     if(partsList==NULL) {
 223         partsList=new MessagePatternPartsList();
 224         if(partsList==NULL) {
 225             errorCode=U_MEMORY_ALLOCATION_ERROR;
 226             return FALSE;
 227         }
 228         parts=partsList->a.getAlias();
 229     }
 230     if(other.partsLength>0) {
 231         partsList->copyFrom(*other.partsList, other.partsLength, errorCode);
 232         if(U_FAILURE(errorCode)) {
 233             return FALSE;
 234         }
 235         parts=partsList->a.getAlias();
 236         partsLength=other.partsLength;
 237     }
 238     if(other.numericValuesLength>0) {
 239         if(numericValuesList==NULL) {
 240             numericValuesList=new MessagePatternDoubleList();
 241             if(numericValuesList==NULL) {
 242                 errorCode=U_MEMORY_ALLOCATION_ERROR;
 243                 return FALSE;
 244             }
 245             numericValues=numericValuesList->a.getAlias();
 246         }
 247         numericValuesList->copyFrom(
 248             *other.numericValuesList, other.numericValuesLength, errorCode);
 249         if(U_FAILURE(errorCode)) {
 250             return FALSE;
 251         }
 252         numericValues=numericValuesList->a.getAlias();
 253         numericValuesLength=other.numericValuesLength;
 254     }
 255     return TRUE;
 256 }
 257
 258 MessagePattern::~MessagePattern() {
 259     delete partsList;
 260     delete numericValuesList;
 261 }
 262
 263 // MessagePattern API ------------------------------------------------------ ***
 264
 265 MessagePattern &
 266 MessagePattern::parse(const UnicodeString &pattern, UParseError *parseError, UErrorCode &errorCode) {
 267     preParse(pattern, parseError, errorCode);
 268     parseMessage(0, 0, 0, UMSGPAT_ARG_TYPE_NONE, parseError, errorCode);
 269     postParse();
 270     return *this;
 271 }
 272
 273 MessagePattern &
 274 MessagePattern::parseChoiceStyle(const UnicodeString &pattern,
 275                                  UParseError *parseError, UErrorCode &errorCode) {
 276     preParse(pattern, parseError, errorCode);
 277     parseChoiceStyle(0, 0, parseError, errorCode);
 278     postParse();
 279     return *this;
 280 }
 281
 282 MessagePattern &
 283 MessagePattern::parsePluralStyle(const UnicodeString &pattern,
 284                                  UParseError *parseError, UErrorCode &errorCode) {
 285     preParse(pattern, parseError, errorCode);
 286     parsePluralOrSelectStyle(UMSGPAT_ARG_TYPE_PLURAL, 0, 0, parseError, errorCode);
 287     postParse();
 288     return *this;
 289 }
 290
 291 MessagePattern &
 292 MessagePattern::parseSelectStyle(const UnicodeString &pattern,
 293                                  UParseError *parseError, UErrorCode &errorCode) {
 294     preParse(pattern, parseError, errorCode);
 295     parsePluralOrSelectStyle(UMSGPAT_ARG_TYPE_SELECT, 0, 0, parseError, errorCode);
 296     postParse();
 297     return *this;
 298 }
 299
 300 void
 301 MessagePattern::clear() {
 302     // Mostly the same as preParse().
 303     msg.remove();
 304     hasArgNames=hasArgNumbers=FALSE;
 305     needsAutoQuoting=FALSE;
 306     partsLength=0;
 307     numericValuesLength=0;
 308 }
 309
 310 UBool
 311 MessagePattern::operator==(const MessagePattern &other) const {
 312     if(this==&other) {
 313         return TRUE;
 314     }
 315     return
 316         aposMode==other.aposMode &&
 317         msg==other.msg &&
 318         // parts.equals(o.parts)
 319         partsLength==other.partsLength &&
 320         (partsLength==0 || partsList->equals(*other.partsList, partsLength));
 321     // No need to compare numericValues if msg and parts are the same.
 322 }
 323
 324 int32_t
 325 MessagePattern::hashCode() const {
 326     int32_t hash=(aposMode*37+msg.hashCode())*37+partsLength;
 327     for(int32_t i=0; i<partsLength; ++i) {
 328         hash=hash*37+parts[i].hashCode();
 329     }
 330     return hash;
 331 }
 332
 333 int32_t
 334 MessagePattern::validateArgumentName(const UnicodeString &name) {
 335     if(!PatternProps::isIdentifier(name.getBuffer(), name.length())) {
 336         return UMSGPAT_ARG_NAME_NOT_VALID;
 337     }
 338     return parseArgNumber(name, 0, name.length());
 339 }
 340
 341 UnicodeString
 342 MessagePattern::autoQuoteApostropheDeep() const {
 343     if(!needsAutoQuoting) {
 344         return msg;
 345     }
 346     UnicodeString modified(msg);
 347     // Iterate backward so that the insertion indexes do not change.
 348     int32_t count=countParts();
 349     for(int32_t i=count; i>0;) {
 350         const Part &part=getPart(--i);
 351         if(part.getType()==UMSGPAT_PART_TYPE_INSERT_CHAR) {
 352            modified.insert(part.index, (UChar)part.value);
 353         }
 354     }
 355     return modified;
 356 }
 357
 358 double
 359 MessagePattern::getNumericValue(const Part &part) const {
 360     UMessagePatternPartType type=part.type;
 361     if(type==UMSGPAT_PART_TYPE_ARG_INT) {
 362         return part.value;
 363     } else if(type==UMSGPAT_PART_TYPE_ARG_DOUBLE) {
 364         return numericValues[part.value];
 365     } else {
 366         return UMSGPAT_NO_NUMERIC_VALUE;
 367     }
 368 }
 369
 370 /**
 371   * Returns the "offset:" value of a PluralFormat argument, or 0 if none is specified.
 372   * @param pluralStart the index of the first PluralFormat argument style part. (0..countParts()-1)
 373   * @return the "offset:" value.
 374   * @draft ICU 4.8
 375   */
 376 double
 377 MessagePattern::getPluralOffset(int32_t pluralStart) const {
 378     const Part &part=getPart(pluralStart);
 379     if(Part::hasNumericValue(part.type)) {
 380         return getNumericValue(part);
 381     } else {
 382         return 0;
 383     }
 384 }
 385
 386 // MessagePattern::Part ---------------------------------------------------- ***
 387
 388 UBool
 389 MessagePattern::Part::operator==(const Part &other) const {
 390     if(this==&other) {
 391         return TRUE;
 392     }
 393     return
 394         type==other.type &&
 395         index==other.index &&
 396         length==other.length &&
 397         value==other.value &&
 398         limitPartIndex==other.limitPartIndex;
 399 }
 400
 401 // MessagePattern parser --------------------------------------------------- ***
 402
 403 void
 404 MessagePattern::preParse(const UnicodeString &pattern, UParseError *parseError, UErrorCode &errorCode) {
 405     if(U_FAILURE(errorCode)) {
 406         return;
 407     }
 408     if(parseError!=NULL) {
 409         parseError->line=0;
 410         parseError->offset=0;
 411         parseError->preContext[0]=0;
 412         parseError->postContext[0]=0;
 413     }
 414     msg=pattern;
 415     hasArgNames=hasArgNumbers=FALSE;
 416     needsAutoQuoting=FALSE;
 417     partsLength=0;
 418     numericValuesLength=0;
 419 }
 420
 421 void
 422 MessagePattern::postParse() {
 423     if(partsList!=NULL) {
 424         parts=partsList->a.getAlias();
 425     }
 426     if(numericValuesList!=NULL) {
 427         numericValues=numericValuesList->a.getAlias();
 428     }
 429 }
 430
 431 int32_t
 432 MessagePattern::parseMessage(int32_t index, int32_t msgStartLength,
 433                              int32_t nestingLevel, UMessagePatternArgType parentType,
 434                              UParseError *parseError, UErrorCode &errorCode) {
 435     if(U_FAILURE(errorCode)) {
 436         return 0;
 437     }
 438     if(nestingLevel>Part::MAX_VALUE) {
 439         errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
 440         return 0;
 441     }
 442     int32_t msgStart=partsLength;
 443     addPart(UMSGPAT_PART_TYPE_MSG_START, index, msgStartLength, nestingLevel, errorCode);
 444     index+=msgStartLength;
 445     for(;;) {  // while(index<msg.length()) with U_FAILURE(errorCode) check
 446         if(U_FAILURE(errorCode)) {
 447             return 0;
 448         }
 449         if(index>=msg.length()) {
 450             break;
 451         }
 452         UChar c=msg.charAt(index++);
 453         if(c==u_apos) {
 454             if(index==msg.length()) {
 455                 // The apostrophe is the last character in the pattern.
 456                 // Add a Part for auto-quoting.
 457                 addPart(UMSGPAT_PART_TYPE_INSERT_CHAR, index, 0,
 458                         u_apos, errorCode);  // value=char to be inserted
 459                 needsAutoQuoting=TRUE;
 460             } else {
 461                 c=msg.charAt(index);
 462                 if(c==u_apos) {
 463                     // double apostrophe, skip the second one
 464                     addPart(UMSGPAT_PART_TYPE_SKIP_SYNTAX, index++, 1, 0, errorCode);
 465                 } else if(
 466                     aposMode==UMSGPAT_APOS_DOUBLE_REQUIRED ||
 467                     c==u_leftCurlyBrace || c==u_rightCurlyBrace ||
 468                     (parentType==UMSGPAT_ARG_TYPE_CHOICE && c==u_pipe) ||
 469                     (UMSGPAT_ARG_TYPE_HAS_PLURAL_STYLE(parentType) && c==u_pound)
 470                 ) {
 471                     // skip the quote-starting apostrophe
 472                     addPart(UMSGPAT_PART_TYPE_SKIP_SYNTAX, index-1, 1, 0, errorCode);
 473                     // find the end of the quoted literal text
 474                     for(;;) {
 475                         index=msg.indexOf(u_apos, index+1);
 476                         if(index>=0) {
 477                             if(/*(index+1)<msg.length() &&*/ msg.charAt(index+1)==u_apos) {
 478                                 // double apostrophe inside quoted literal text
 479                                 // still encodes a single apostrophe, skip the second one
 480                                 addPart(UMSGPAT_PART_TYPE_SKIP_SYNTAX, ++index, 1, 0, errorCode);
 481                             } else {
 482                                 // skip the quote-ending apostrophe
 483                                 addPart(UMSGPAT_PART_TYPE_SKIP_SYNTAX, index++, 1, 0, errorCode);
 484                                 break;
 485                             }
 486                         } else {
 487                             // The quoted text reaches to the end of the of the message.
 488                             index=msg.length();
 489                             // Add a Part for auto-quoting.
 490                             addPart(UMSGPAT_PART_TYPE_INSERT_CHAR, index, 0,
 491                                     u_apos, errorCode);  // value=char to be inserted
 492                             needsAutoQuoting=TRUE;
 493                             break;
 494                         }
 495                     }
 496                 } else {
 497                     // Interpret the apostrophe as literal text.
 498                     // Add a Part for auto-quoting.
 499                     addPart(UMSGPAT_PART_TYPE_INSERT_CHAR, index, 0,
 500                             u_apos, errorCode);  // value=char to be inserted
 501                     needsAutoQuoting=TRUE;
 502                 }
 503             }
 504         } else if(UMSGPAT_ARG_TYPE_HAS_PLURAL_STYLE(parentType) && c==u_pound) {
 505             // The unquoted # in a plural message fragment will be replaced
 506             // with the (number-offset).
 507             addPart(UMSGPAT_PART_TYPE_REPLACE_NUMBER, index-1, 1, 0, errorCode);
 508         } else if(c==u_leftCurlyBrace) {
 509             index=parseArg(index-1, 1, nestingLevel, parseError, errorCode);
 510         } else if((nestingLevel>0 && c==u_rightCurlyBrace) ||
 511                   (parentType==UMSGPAT_ARG_TYPE_CHOICE && c==u_pipe)) {
 512             // Finish the message before the terminator.
 513             // In a choice style, report the "}" substring only for the following ARG_LIMIT,
 514             // not for this MSG_LIMIT.
 515             int32_t limitLength=(parentType==UMSGPAT_ARG_TYPE_CHOICE && c==u_rightCurlyBrace) ? 0 : 1;
 516             addLimitPart(msgStart, UMSGPAT_PART_TYPE_MSG_LIMIT, index-1, limitLength,
 517                          nestingLevel, errorCode);
 518             if(parentType==UMSGPAT_ARG_TYPE_CHOICE) {
 519                 // Let the choice style parser see the '}' or '|'.
 520                 return index-1;
 521             } else {
 522                 // continue parsing after the '}'
 523                 return index;
 524             }
 525         }  // else: c is part of literal text
 526     }
 527     if(nestingLevel>0 && !inTopLevelChoiceMessage(nestingLevel, parentType)) {
 528         setParseError(parseError, 0);  // Unmatched '{' braces in message.
 529         errorCode=U_UNMATCHED_BRACES;
 530         return 0;
 531     }
 532     addLimitPart(msgStart, UMSGPAT_PART_TYPE_MSG_LIMIT, index, 0, nestingLevel, errorCode);
 533     return index;
 534 }
 535
 536 int32_t
 537 MessagePattern::parseArg(int32_t index, int32_t argStartLength, int32_t nestingLevel,
 538                          UParseError *parseError, UErrorCode &errorCode) {
 539     int32_t argStart=partsLength;
 540     UMessagePatternArgType argType=UMSGPAT_ARG_TYPE_NONE;
 541     addPart(UMSGPAT_PART_TYPE_ARG_START, index, argStartLength, argType, errorCode);
 542     if(U_FAILURE(errorCode)) {
 543         return 0;
 544     }
 545     int32_t nameIndex=index=skipWhiteSpace(index+argStartLength);
 546     if(index==msg.length()) {
 547         setParseError(parseError, 0);  // Unmatched '{' braces in message.
 548         errorCode=U_UNMATCHED_BRACES;
 549         return 0;
 550     }
 551     // parse argument name or number
 552     index=skipIdentifier(index);
 553     int32_t number=parseArgNumber(nameIndex, index);
 554     if(number>=0) {
 555         int32_t length=index-nameIndex;
 556         if(length>Part::MAX_LENGTH || number>Part::MAX_VALUE) {
 557             setParseError(parseError, nameIndex);  // Argument number too large.
 558             errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
 559             return 0;
 560         }
 561         hasArgNumbers=TRUE;
 562         addPart(UMSGPAT_PART_TYPE_ARG_NUMBER, nameIndex, length, number, errorCode);
 563     } else if(number==UMSGPAT_ARG_NAME_NOT_NUMBER) {
 564         int32_t length=index-nameIndex;
 565         if(length>Part::MAX_LENGTH) {
 566             setParseError(parseError, nameIndex);  // Argument name too long.
 567             errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
 568             return 0;
 569         }
 570         hasArgNames=TRUE;
 571         addPart(UMSGPAT_PART_TYPE_ARG_NAME, nameIndex, length, 0, errorCode);
 572     } else {  // number<-1 (ARG_NAME_NOT_VALID)
 573         setParseError(parseError, nameIndex);  // Bad argument syntax.
 574         errorCode=U_PATTERN_SYNTAX_ERROR;
 575         return 0;
 576     }
 577     index=skipWhiteSpace(index);
 578     if(index==msg.length()) {
 579         setParseError(parseError, 0);  // Unmatched '{' braces in message.
 580         errorCode=U_UNMATCHED_BRACES;
 581         return 0;
 582     }
 583     UChar c=msg.charAt(index);
 584     if(c==u_rightCurlyBrace) {
 585         // all done
 586     } else if(c!=u_comma) {
 587         setParseError(parseError, nameIndex);  // Bad argument syntax.
 588         errorCode=U_PATTERN_SYNTAX_ERROR;
 589         return 0;
 590     } else /* ',' */ {
 591         // parse argument type: case-sensitive a-zA-Z
 592         int32_t typeIndex=index=skipWhiteSpace(index+1);
 593         while(index<msg.length() && isArgTypeChar(msg.charAt(index))) {
 594             ++index;
 595         }
 596         int32_t length=index-typeIndex;
 597         index=skipWhiteSpace(index);
 598         if(index==msg.length()) {
 599             setParseError(parseError, 0);  // Unmatched '{' braces in message.
 600             errorCode=U_UNMATCHED_BRACES;
 601             return 0;
 602         }
 603         if(length==0 || ((c=msg.charAt(index))!=u_comma && c!=u_rightCurlyBrace)) {
 604             setParseError(parseError, nameIndex);  // Bad argument syntax.
 605             errorCode=U_PATTERN_SYNTAX_ERROR;
 606             return 0;
 607         }
 608         if(length>Part::MAX_LENGTH) {
 609             setParseError(parseError, nameIndex);  // Argument type name too long.
 610             errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
 611             return 0;
 612         }
 613         argType=UMSGPAT_ARG_TYPE_SIMPLE;
 614         if(length==6) {
 615             // case-insensitive comparisons for complex-type names
 616             if(isChoice(typeIndex)) {
 617                 argType=UMSGPAT_ARG_TYPE_CHOICE;
 618             } else if(isPlural(typeIndex)) {
 619                 argType=UMSGPAT_ARG_TYPE_PLURAL;
 620             } else if(isSelect(typeIndex)) {
 621                 argType=UMSGPAT_ARG_TYPE_SELECT;
 622             }
 623         } else if(length==13) {
 624             if(isSelect(typeIndex) && isOrdinal(typeIndex+6)) {
 625                 argType=UMSGPAT_ARG_TYPE_SELECTORDINAL;
 626             }
 627         }
 628         // change the ARG_START type from NONE to argType
 629         partsList->a[argStart].value=(int16_t)argType;
 630         if(argType==UMSGPAT_ARG_TYPE_SIMPLE) {
 631             addPart(UMSGPAT_PART_TYPE_ARG_TYPE, typeIndex, length, 0, errorCode);
 632         }
 633         // look for an argument style (pattern)
 634         if(c==u_rightCurlyBrace) {
 635             if(argType!=UMSGPAT_ARG_TYPE_SIMPLE) {
 636                 setParseError(parseError, nameIndex);  // No style field for complex argument.
 637                 errorCode=U_PATTERN_SYNTAX_ERROR;
 638                 return 0;
 639             }
 640         } else /* ',' */ {
 641             ++index;
 642             if(argType==UMSGPAT_ARG_TYPE_SIMPLE) {
 643                 index=parseSimpleStyle(index, parseError, errorCode);
 644             } else if(argType==UMSGPAT_ARG_TYPE_CHOICE) {
 645                 index=parseChoiceStyle(index, nestingLevel, parseError, errorCode);
 646             } else {
 647                 index=parsePluralOrSelectStyle(argType, index, nestingLevel, parseError, errorCode);
 648             }
 649         }
 650     }
 651     // Argument parsing stopped on the '}'.
 652     addLimitPart(argStart, UMSGPAT_PART_TYPE_ARG_LIMIT, index, 1, argType, errorCode);
 653     return index+1;
 654 }
 655
 656 int32_t
 657 MessagePattern::parseSimpleStyle(int32_t index, UParseError *parseError, UErrorCode &errorCode) {
 658     if(U_FAILURE(errorCode)) {
 659         return 0;
 660     }
 661     int32_t start=index;
 662     int32_t nestedBraces=0;
 663     while(index<msg.length()) {
 664         UChar c=msg.charAt(index++);
 665         if(c==u_apos) {
 666             // Treat apostrophe as quoting but include it in the style part.
 667             // Find the end of the quoted literal text.
 668             index=msg.indexOf(u_apos, index);
 669             if(index<0) {
 670                 // Quoted literal argument style text reaches to the end of the message.
 671                 setParseError(parseError, start);
 672                 errorCode=U_PATTERN_SYNTAX_ERROR;
 673                 return 0;
 674             }
 675             // skip the quote-ending apostrophe
 676             ++index;
 677         } else if(c==u_leftCurlyBrace) {
 678             ++nestedBraces;
 679         } else if(c==u_rightCurlyBrace) {
 680             if(nestedBraces>0) {
 681                 --nestedBraces;
 682             } else {
 683                 int32_t length=--index-start;
 684                 if(length>Part::MAX_LENGTH) {
 685                     setParseError(parseError, start);  // Argument style text too long.
 686                     errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
 687                     return 0;
 688                 }
 689                 addPart(UMSGPAT_PART_TYPE_ARG_STYLE, start, length, 0, errorCode);
 690                 return index;
 691             }
 692         }  // c is part of literal text
 693     }
 694     setParseError(parseError, 0);  // Unmatched '{' braces in message.
 695     errorCode=U_UNMATCHED_BRACES;
 696     return 0;
 697 }
 698
 699 int32_t
 700 MessagePattern::parseChoiceStyle(int32_t index, int32_t nestingLevel,
 701                                  UParseError *parseError, UErrorCode &errorCode) {
 702     if(U_FAILURE(errorCode)) {
 703         return 0;
 704     }
 705     int32_t start=index;
 706     index=skipWhiteSpace(index);
 707     if(index==msg.length() || msg.charAt(index)==u_rightCurlyBrace) {
 708         setParseError(parseError, 0);  // Missing choice argument pattern.
 709         errorCode=U_PATTERN_SYNTAX_ERROR;
 710         return 0;
 711     }
 712     for(;;) {
 713         // The choice argument style contains |-separated (number, separator, message) triples.
 714         // Parse the number.
 715         int32_t numberIndex=index;
 716         index=skipDouble(index);
 717         int32_t length=index-numberIndex;
 718         if(length==0) {
 719             setParseError(parseError, start);  // Bad choice pattern syntax.
 720             errorCode=U_PATTERN_SYNTAX_ERROR;
 721             return 0;
 722         }
 723         if(length>Part::MAX_LENGTH) {
 724             setParseError(parseError, numberIndex);  // Choice number too long.
 725             errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
 726             return 0;
 727         }
 728         parseDouble(numberIndex, index, TRUE, parseError, errorCode);  // adds ARG_INT or ARG_DOUBLE
 729         if(U_FAILURE(errorCode)) {
 730             return 0;
 731         }
 732         // Parse the separator.
 733         index=skipWhiteSpace(index);
 734         if(index==msg.length()) {
 735             setParseError(parseError, start);  // Bad choice pattern syntax.
 736             errorCode=U_PATTERN_SYNTAX_ERROR;
 737             return 0;
 738         }
 739         UChar c=msg.charAt(index);
 740         if(!(c==u_pound || c==u_lessThan || c==u_lessOrEqual)) {  // U+2264 is <=
 741             setParseError(parseError, start);  // Expected choice separator (#<\u2264) instead of c.
 742             errorCode=U_PATTERN_SYNTAX_ERROR;
 743             return 0;
 744         }
 745         addPart(UMSGPAT_PART_TYPE_ARG_SELECTOR, index, 1, 0, errorCode);
 746         // Parse the message fragment.
 747         index=parseMessage(++index, 0, nestingLevel+1, UMSGPAT_ARG_TYPE_CHOICE, parseError, errorCode);
 748         if(U_FAILURE(errorCode)) {
 749             return 0;
 750         }
 751         // parseMessage(..., CHOICE) returns the index of the terminator, or msg.length().
 752         if(index==msg.length()) {
 753             return index;
 754         }
 755         if(msg.charAt(index)==u_rightCurlyBrace) {
 756             if(!inMessageFormatPattern(nestingLevel)) {
 757                 setParseError(parseError, start);  // Bad choice pattern syntax.
 758                 errorCode=U_PATTERN_SYNTAX_ERROR;
 759                 return 0;
 760             }
 761             return index;
 762         }  // else the terminator is '|'
 763         index=skipWhiteSpace(index+1);
 764     }
 765 }
 766
 767 int32_t
 768 MessagePattern::parsePluralOrSelectStyle(UMessagePatternArgType argType,
 769                                          int32_t index, int32_t nestingLevel,
 770                                          UParseError *parseError, UErrorCode &errorCode) {
 771     if(U_FAILURE(errorCode)) {
 772         return 0;
 773     }
 774     int32_t start=index;
 775     UBool isEmpty=TRUE;
 776     UBool hasOther=FALSE;
 777     for(;;) {
 778         // First, collect the selector looking for a small set of terminators.
 779         // It would be a little faster to consider the syntax of each possible
 780         // token right here, but that makes the code too complicated.
 781         index=skipWhiteSpace(index);
 782         UBool eos=index==msg.length();
 783         if(eos || msg.charAt(index)==u_rightCurlyBrace) {
 784             if(eos==inMessageFormatPattern(nestingLevel)) {
 785                 setParseError(parseError, start);  // Bad plural/select pattern syntax.
 786                 errorCode=U_PATTERN_SYNTAX_ERROR;
 787                 return 0;
 788             }
 789             if(!hasOther) {
 790                 setParseError(parseError, 0);  // Missing 'other' keyword in plural/select pattern.
 791                 errorCode=U_DEFAULT_KEYWORD_MISSING;
 792                 return 0;
 793             }
 794             return index;
 795         }
 796         int32_t selectorIndex=index;
 797         if(UMSGPAT_ARG_TYPE_HAS_PLURAL_STYLE(argType) && msg.charAt(selectorIndex)==u_equal) {
 798             // explicit-value plural selector: =double
 799             index=skipDouble(index+1);
 800             int32_t length=index-selectorIndex;
 801             if(length==1) {
 802                 setParseError(parseError, start);  // Bad plural/select pattern syntax.
 803                 errorCode=U_PATTERN_SYNTAX_ERROR;
 804                 return 0;
 805             }
 806             if(length>Part::MAX_LENGTH) {
 807                 setParseError(parseError, selectorIndex);  // Argument selector too long.
 808                 errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
 809                 return 0;
 810             }
 811             addPart(UMSGPAT_PART_TYPE_ARG_SELECTOR, selectorIndex, length, 0, errorCode);
 812             parseDouble(selectorIndex+1, index, FALSE,
 813                         parseError, errorCode);  // adds ARG_INT or ARG_DOUBLE
 814         } else {
 815             index=skipIdentifier(index);
 816             int32_t length=index-selectorIndex;
 817             if(length==0) {
 818                 setParseError(parseError, start);  // Bad plural/select pattern syntax.
 819                 errorCode=U_PATTERN_SYNTAX_ERROR;
 820                 return 0;
 821             }
 822             // Note: The ':' in "offset:" is just beyond the skipIdentifier() range.
 823             if( UMSGPAT_ARG_TYPE_HAS_PLURAL_STYLE(argType) && length==6 && index<msg.length() &&
 824                 0==msg.compare(selectorIndex, 7, kOffsetColon, 0, 7)
 825             ) {
 826                 // plural offset, not a selector
 827                 if(!isEmpty) {
 828                     // Plural argument 'offset:' (if present) must precede key-message pairs.
 829                     setParseError(parseError, start);
 830                     errorCode=U_PATTERN_SYNTAX_ERROR;
 831                     return 0;
 832                 }
 833                 // allow whitespace between offset: and its value
 834                 int32_t valueIndex=skipWhiteSpace(index+1);  // The ':' is at index.
 835                 index=skipDouble(valueIndex);
 836                 if(index==valueIndex) {
 837                     setParseError(parseError, start);  // Missing value for plural 'offset:'.
 838                     errorCode=U_PATTERN_SYNTAX_ERROR;
 839                     return 0;
 840                 }
 841                 if((index-valueIndex)>Part::MAX_LENGTH) {
 842                     setParseError(parseError, valueIndex);  // Plural offset value too long.
 843                     errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
 844                     return 0;
 845                 }
 846                 parseDouble(valueIndex, index, FALSE,
 847                             parseError, errorCode);  // adds ARG_INT or ARG_DOUBLE
 848                 if(U_FAILURE(errorCode)) {
 849                     return 0;
 850                 }
 851                 isEmpty=FALSE;
 852                 continue;  // no message fragment after the offset
 853             } else {
 854                 // normal selector word
 855                 if(length>Part::MAX_LENGTH) {
 856                     setParseError(parseError, selectorIndex);  // Argument selector too long.
 857                     errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
 858                     return 0;
 859                 }
 860                 addPart(UMSGPAT_PART_TYPE_ARG_SELECTOR, selectorIndex, length, 0, errorCode);
 861                 if(0==msg.compare(selectorIndex, length, kOther, 0, 5)) {
 862                     hasOther=TRUE;
 863                 }
 864             }
 865         }
 866         if(U_FAILURE(errorCode)) {
 867             return 0;
 868         }
 869
 870         // parse the message fragment following the selector
 871         index=skipWhiteSpace(index);
 872         if(index==msg.length() || msg.charAt(index)!=u_leftCurlyBrace) {
 873             setParseError(parseError, selectorIndex);  // No message fragment after plural/select selector.
 874             errorCode=U_PATTERN_SYNTAX_ERROR;
 875             return 0;
 876         }
 877         index=parseMessage(index, 1, nestingLevel+1, argType, parseError, errorCode);
 878         if(U_FAILURE(errorCode)) {
 879             return 0;
 880         }
 881         isEmpty=FALSE;
 882     }
 883 }
 884
 885 int32_t
 886 MessagePattern::parseArgNumber(const UnicodeString &s, int32_t start, int32_t limit) {
 887     // If the identifier contains only ASCII digits, then it is an argument _number_
 888     // and must not have leading zeros (except "0" itself).
 889     // Otherwise it is an argument _name_.
 890     if(start>=limit) {
 891         return UMSGPAT_ARG_NAME_NOT_VALID;
 892     }
 893     int32_t number;
 894     // Defer numeric errors until we know there are only digits.
 895     UBool badNumber;
 896     UChar c=s.charAt(start++);
 897     if(c==0x30) {
 898         if(start==limit) {
 899             return 0;
 900         } else {
 901             number=0;
 902             badNumber=TRUE;  // leading zero
 903         }
 904     } else if(0x31<=c && c<=0x39) {
 905         number=c-0x30;
 906         badNumber=FALSE;
 907     } else {
 908         return UMSGPAT_ARG_NAME_NOT_NUMBER;
 909     }
 910     while(start<limit) {
 911         c=s.charAt(start++);
 912         if(0x30<=c && c<=0x39) {
 913             if(number>=INT32_MAX/10) {
 914                 badNumber=TRUE;  // overflow
 915             }
 916             number=number*10+(c-0x30);
 917         } else {
 918             return UMSGPAT_ARG_NAME_NOT_NUMBER;
 919         }
 920     }
 921     // There are only ASCII digits.
 922     if(badNumber) {
 923         return UMSGPAT_ARG_NAME_NOT_VALID;
 924     } else {
 925         return number;
 926     }
 927 }
 928
 929 void
 930 MessagePattern::parseDouble(int32_t start, int32_t limit, UBool allowInfinity,
 931                             UParseError *parseError, UErrorCode &errorCode) {
 932     if(U_FAILURE(errorCode)) {
 933         return;
 934     }
 935     U_ASSERT(start<limit);
 936     // fake loop for easy exit and single throw statement
 937     for(;;) { /*loop doesn't iterate*/
 938         // fast path for small integers and infinity
 939         int32_t value=0;
 940         int32_t isNegative=0;  // not boolean so that we can easily add it to value
 941         int32_t index=start;
 942         UChar c=msg.charAt(index++);
 943         if(c==u_minus) {
 944             isNegative=1;
 945             if(index==limit) {
 946                 break;  // no number
 947             }
 948             c=msg.charAt(index++);
 949         } else if(c==u_plus) {
 950             if(index==limit) {
 951                 break;  // no number
 952             }
 953             c=msg.charAt(index++);
 954         }
 955         if(c==0x221e) {  // infinity
 956             if(allowInfinity && index==limit) {
 957                 double infinity=uprv_getInfinity();
 958                 addArgDoublePart(
 959                     isNegative!=0 ? -infinity : infinity,
 960                     start, limit-start, errorCode);
 961                 return;
 962             } else {
 963                 break;
 964             }
 965         }
 966         // try to parse the number as a small integer but fall back to a double
 967         while('0'<=c && c<='9') {
 968             value=value*10+(c-'0');
 969             if(value>(Part::MAX_VALUE+isNegative)) {
 970                 break;  // not a small-enough integer
 971             }
 972             if(index==limit) {
 973                 addPart(UMSGPAT_PART_TYPE_ARG_INT, start, limit-start,
 974                         isNegative!=0 ? -value : value, errorCode);
 975                 return;
 976             }
 977             c=msg.charAt(index++);
 978         }
 979         // Let Double.parseDouble() throw a NumberFormatException.
 980         char numberChars[128];
 981         int32_t capacity=(int32_t)sizeof(numberChars);
 982         int32_t length=limit-start;
 983         if(length>=capacity) {
 984             break;  // number too long
 985         }
 986         msg.extract(start, length, numberChars, capacity, US_INV);
 987         if((int32_t)uprv_strlen(numberChars)<length) {
 988             break;  // contains non-invariant character that was turned into NUL
 989         }
 990         char *end;
 991         double numericValue=uprv_strtod(numberChars, &end);
 992         if(end!=(numberChars+length)) {
 993             break;  // parsing error
 994         }
 995         addArgDoublePart(numericValue, start, length, errorCode);
 996         return;
 997     }
 998     setParseError(parseError, start /*, limit*/);  // Bad syntax for numeric value.
 999     errorCode=U_PATTERN_SYNTAX_ERROR;
1000     return;
1001 }
1002
1003 int32_t
1004 MessagePattern::skipWhiteSpace(int32_t index) {
1005     const UChar *s=msg.getBuffer();
1006     int32_t msgLength=msg.length();
1007     const UChar *t=PatternProps::skipWhiteSpace(s+index, msgLength-index);
1008     return (int32_t)(t-s);
1009 }
1010
1011 int32_t
1012 MessagePattern::skipIdentifier(int32_t index) {
1013     const UChar *s=msg.getBuffer();
1014     int32_t msgLength=msg.length();
1015     const UChar *t=PatternProps::skipIdentifier(s+index, msgLength-index);
1016     return (int32_t)(t-s);
1017 }
1018
1019 int32_t
1020 MessagePattern::skipDouble(int32_t index) {
1021     int32_t msgLength=msg.length();
1022     while(index<msgLength) {
1023         UChar c=msg.charAt(index);
1024         // U+221E: Allow the infinity symbol, for ChoiceFormat patterns.
1025         if((c<0x30 && c!=u_plus && c!=u_minus && c!=u_dot) || (c>0x39 && c!=u_e && c!=u_E && c!=0x221e)) {
1026             break;
1027         }
1028         ++index;
1029     }
1030     return index;
1031 }
1032
1033 UBool
1034 MessagePattern::isArgTypeChar(UChar32 c) {
1035     return (u_a<=c && c<=u_z) || (u_A<=c && c<=u_Z);
1036 }
1037
1038 UBool
1039 MessagePattern::isChoice(int32_t index) {
1040     UChar c;
1041     return
1042         ((c=msg.charAt(index++))==u_c || c==u_C) &&
1043         ((c=msg.charAt(index++))==u_h || c==u_H) &&
1044         ((c=msg.charAt(index++))==u_o || c==u_O) &&
1045         ((c=msg.charAt(index++))==u_i || c==u_I) &&
1046         ((c=msg.charAt(index++))==u_c || c==u_C) &&
1047         ((c=msg.charAt(index))==u_e || c==u_E);
1048 }
1049
1050 UBool
1051 MessagePattern::isPlural(int32_t index) {
1052     UChar c;
1053     return
1054         ((c=msg.charAt(index++))==u_p || c==u_P) &&
1055         ((c=msg.charAt(index++))==u_l || c==u_L) &&
1056         ((c=msg.charAt(index++))==u_u || c==u_U) &&
1057         ((c=msg.charAt(index++))==u_r || c==u_R) &&
1058         ((c=msg.charAt(index++))==u_a || c==u_A) &&
1059         ((c=msg.charAt(index))==u_l || c==u_L);
1060 }
1061
1062 UBool
1063 MessagePattern::isSelect(int32_t index) {
1064     UChar c;
1065     return
1066         ((c=msg.charAt(index++))==u_s || c==u_S) &&
1067         ((c=msg.charAt(index++))==u_e || c==u_E) &&
1068         ((c=msg.charAt(index++))==u_l || c==u_L) &&
1069         ((c=msg.charAt(index++))==u_e || c==u_E) &&
1070         ((c=msg.charAt(index++))==u_c || c==u_C) &&
1071         ((c=msg.charAt(index))==u_t || c==u_T);
1072 }
1073
1074 UBool
1075 MessagePattern::isOrdinal(int32_t index) {
1076     UChar c;
1077     return
1078         ((c=msg.charAt(index++))==u_o || c==u_O) &&
1079         ((c=msg.charAt(index++))==u_r || c==u_R) &&
1080         ((c=msg.charAt(index++))==u_d || c==u_D) &&
1081         ((c=msg.charAt(index++))==u_i || c==u_I) &&
1082         ((c=msg.charAt(index++))==u_n || c==u_N) &&
1083         ((c=msg.charAt(index++))==u_a || c==u_A) &&
1084         ((c=msg.charAt(index))==u_l || c==u_L);
1085 }
1086
1087 UBool
1088 MessagePattern::inMessageFormatPattern(int32_t nestingLevel) {
1089     return nestingLevel>0 || partsList->a[0].type==UMSGPAT_PART_TYPE_MSG_START;
1090 }
1091
1092 UBool
1093 MessagePattern::inTopLevelChoiceMessage(int32_t nestingLevel, UMessagePatternArgType parentType) {
1094     return
1095         nestingLevel==1 &&
1096         parentType==UMSGPAT_ARG_TYPE_CHOICE &&
1097         partsList->a[0].type!=UMSGPAT_PART_TYPE_MSG_START;
1098 }
1099
1100 void
1101 MessagePattern::addPart(UMessagePatternPartType type, int32_t index, int32_t length,
1102                         int32_t value, UErrorCode &errorCode) {
1103     if(partsList->ensureCapacityForOneMore(partsLength, errorCode)) {
1104         Part &part=partsList->a[partsLength++];
1105         part.type=type;
1106         part.index=index;
1107         part.length=(uint16_t)length;
1108         part.value=(int16_t)value;
1109         part.limitPartIndex=0;
1110     }
1111 }
1112
1113 void
1114 MessagePattern::addLimitPart(int32_t start,
1115                              UMessagePatternPartType type, int32_t index, int32_t length,
1116                              int32_t value, UErrorCode &errorCode) {
1117     partsList->a[start].limitPartIndex=partsLength;
1118     addPart(type, index, length, value, errorCode);
1119 }
1120
1121 void
1122 MessagePattern::addArgDoublePart(double numericValue, int32_t start, int32_t length,
1123                                  UErrorCode &errorCode) {
1124     if(U_FAILURE(errorCode)) {
1125         return;
1126     }
1127     int32_t numericIndex=numericValuesLength;
1128     if(numericValuesList==NULL) {
1129         numericValuesList=new MessagePatternDoubleList();
1130         if(numericValuesList==NULL) {
1131             errorCode=U_MEMORY_ALLOCATION_ERROR;
1132             return;
1133         }
1134     } else if(!numericValuesList->ensureCapacityForOneMore(numericValuesLength, errorCode)) {
1135         return;
1136     } else {
1137         if(numericIndex>Part::MAX_VALUE) {
1138             errorCode=U_INDEX_OUTOFBOUNDS_ERROR;
1139             return;
1140         }
1141     }
1142     numericValuesList->a[numericValuesLength++]=numericValue;
1143     addPart(UMSGPAT_PART_TYPE_ARG_DOUBLE, start, length, numericIndex, errorCode);
1144 }
1145
1146 void
1147 MessagePattern::setParseError(UParseError *parseError, int32_t index) {
1148     if(parseError==NULL) {
1149         return;
1150     }
1151     parseError->offset=index;
1152
1153     // Set preContext to some of msg before index.
1154     // Avoid splitting a surrogate pair.
1155     int32_t length=index;
1156     if(length>=U_PARSE_CONTEXT_LEN) {
1157         length=U_PARSE_CONTEXT_LEN-1;
1158         if(length>0 && U16_IS_TRAIL(msg[index-length])) {
1159             --length;
1160         }
1161     }
1162     msg.extract(index-length, length, parseError->preContext);
1163     parseError->preContext[length]=0;
1164
1165     // Set postContext to some of msg starting at index.
1166     length=msg.length()-index;
1167     if(length>=U_PARSE_CONTEXT_LEN) {
1168         length=U_PARSE_CONTEXT_LEN-1;
1169         if(length>0 && U16_IS_LEAD(msg[index+length-1])) {
1170             --length;
1171         }
1172     }
1173     msg.extract(index, length, parseError->postContext);
1174     parseError->postContext[length]=0;
1175 }
1176
1177 // MessageImpl ------------------------------------------------------------- ***
1178
1179 void
1180 MessageImpl::appendReducedApostrophes(const UnicodeString &s, int32_t start, int32_t limit,
1181                                       UnicodeString &sb) {
1182     int32_t doubleApos=-1;
1183     for(;;) {
1184         int32_t i=s.indexOf(u_apos, start);
1185         if(i<0 || i>=limit) {
1186             sb.append(s, start, limit-start);
1187             break;
1188         }
1189         if(i==doubleApos) {
1190             // Double apostrophe at start-1 and start==i, append one.
1191             sb.append(u_apos);
1192             ++start;
1193             doubleApos=-1;
1194         } else {
1195             // Append text between apostrophes and skip this one.
1196             sb.append(s, start, i-start);
1197             doubleApos=start=i+1;
1198         }
1199     }
1200 }
1201
1202 // Ported from second half of ICU4J SelectFormat.format(String).
1203 UnicodeString &
1204 MessageImpl::appendSubMessageWithoutSkipSyntax(const MessagePattern &msgPattern,
1205                                                int32_t msgStart,
1206                                                UnicodeString &result) {
1207     const UnicodeString &msgString=msgPattern.getPatternString();
1208     int32_t prevIndex=msgPattern.getPart(msgStart).getLimit();
1209     for(int32_t i=msgStart;;) {
1210         const MessagePattern::Part &part=msgPattern.getPart(++i);
1211         UMessagePatternPartType type=part.getType();
1212         int32_t index=part.getIndex();
1213         if(type==UMSGPAT_PART_TYPE_MSG_LIMIT) {
1214             return result.append(msgString, prevIndex, index-prevIndex);
1215         } else if(type==UMSGPAT_PART_TYPE_SKIP_SYNTAX) {
1216             result.append(msgString, prevIndex, index-prevIndex);
1217             prevIndex=part.getLimit();
1218         } else if(type==UMSGPAT_PART_TYPE_ARG_START) {
1219             result.append(msgString, prevIndex, index-prevIndex);
1220             prevIndex=index;
1221             i=msgPattern.getLimitPartIndex(i);
1222             index=msgPattern.getPart(i).getLimit();
1223             appendReducedApostrophes(msgString, prevIndex, index, result);
1224             prevIndex=index;
1225         }
1226     }
1227 }
1228
1229 U_NAMESPACE_END
1230
1231 #endif  // !UCONFIG_NO_FORMATTING