1//===--- YAMLParser.cpp - Simple YAML parser ------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements a YAML parser.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Support/YAMLParser.h"
15
16#include "llvm/ADT/ilist.h"
17#include "llvm/ADT/ilist_node.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/ADT/StringExtras.h"
20#include "llvm/ADT/Twine.h"
21#include "llvm/Support/ErrorHandling.h"
22#include "llvm/Support/MemoryBuffer.h"
23#include "llvm/Support/raw_ostream.h"
24#include "llvm/Support/SourceMgr.h"
25
26using namespace llvm;
27using namespace yaml;
28
29enum UnicodeEncodingForm {
30  UEF_UTF32_LE, ///< UTF-32 Little Endian
31  UEF_UTF32_BE, ///< UTF-32 Big Endian
32  UEF_UTF16_LE, ///< UTF-16 Little Endian
33  UEF_UTF16_BE, ///< UTF-16 Big Endian
34  UEF_UTF8,     ///< UTF-8 or ascii.
35  UEF_Unknown   ///< Not a valid Unicode encoding.
36};
37
38/// EncodingInfo - Holds the encoding type and length of the byte order mark if
39///                it exists. Length is in {0, 2, 3, 4}.
40typedef std::pair<UnicodeEncodingForm, unsigned> EncodingInfo;
41
42/// getUnicodeEncoding - Reads up to the first 4 bytes to determine the Unicode
43///                      encoding form of \a Input.
44///
45/// @param Input A string of length 0 or more.
46/// @returns An EncodingInfo indicating the Unicode encoding form of the input
47///          and how long the byte order mark is if one exists.
48static EncodingInfo getUnicodeEncoding(StringRef Input) {
49  if (Input.size() == 0)
50    return std::make_pair(UEF_Unknown, 0);
51
52  switch (uint8_t(Input[0])) {
53  case 0x00:
54    if (Input.size() >= 4) {
55      if (  Input[1] == 0
56         && uint8_t(Input[2]) == 0xFE
57         && uint8_t(Input[3]) == 0xFF)
58        return std::make_pair(UEF_UTF32_BE, 4);
59      if (Input[1] == 0 && Input[2] == 0 && Input[3] != 0)
60        return std::make_pair(UEF_UTF32_BE, 0);
61    }
62
63    if (Input.size() >= 2 && Input[1] != 0)
64      return std::make_pair(UEF_UTF16_BE, 0);
65    return std::make_pair(UEF_Unknown, 0);
66  case 0xFF:
67    if (  Input.size() >= 4
68       && uint8_t(Input[1]) == 0xFE
69       && Input[2] == 0
70       && Input[3] == 0)
71      return std::make_pair(UEF_UTF32_LE, 4);
72
73    if (Input.size() >= 2 && uint8_t(Input[1]) == 0xFE)
74      return std::make_pair(UEF_UTF16_LE, 2);
75    return std::make_pair(UEF_Unknown, 0);
76  case 0xFE:
77    if (Input.size() >= 2 && uint8_t(Input[1]) == 0xFF)
78      return std::make_pair(UEF_UTF16_BE, 2);
79    return std::make_pair(UEF_Unknown, 0);
80  case 0xEF:
81    if (  Input.size() >= 3
82       && uint8_t(Input[1]) == 0xBB
83       && uint8_t(Input[2]) == 0xBF)
84      return std::make_pair(UEF_UTF8, 3);
85    return std::make_pair(UEF_Unknown, 0);
86  }
87
88  // It could still be utf-32 or utf-16.
89  if (Input.size() >= 4 && Input[1] == 0 && Input[2] == 0 && Input[3] == 0)
90    return std::make_pair(UEF_UTF32_LE, 0);
91
92  if (Input.size() >= 2 && Input[1] == 0)
93    return std::make_pair(UEF_UTF16_LE, 0);
94
95  return std::make_pair(UEF_UTF8, 0);
96}
97
98namespace llvm {
99namespace yaml {
100/// Token - A single YAML token.
101struct Token : ilist_node<Token> {
102  enum TokenKind {
103    TK_Error, // Uninitialized token.
104    TK_StreamStart,
105    TK_StreamEnd,
106    TK_VersionDirective,
107    TK_TagDirective,
108    TK_DocumentStart,
109    TK_DocumentEnd,
110    TK_BlockEntry,
111    TK_BlockEnd,
112    TK_BlockSequenceStart,
113    TK_BlockMappingStart,
114    TK_FlowEntry,
115    TK_FlowSequenceStart,
116    TK_FlowSequenceEnd,
117    TK_FlowMappingStart,
118    TK_FlowMappingEnd,
119    TK_Key,
120    TK_Value,
121    TK_Scalar,
122    TK_Alias,
123    TK_Anchor,
124    TK_Tag
125  } Kind;
126
127  /// A string of length 0 or more whose begin() points to the logical location
128  /// of the token in the input.
129  StringRef Range;
130
131  Token() : Kind(TK_Error) {}
132};
133}
134}
135
136namespace llvm {
137template<>
138struct ilist_sentinel_traits<Token> {
139  Token *createSentinel() const {
140    return &Sentinel;
141  }
142  static void destroySentinel(Token*) {}
143
144  Token *provideInitialHead() const { return createSentinel(); }
145  Token *ensureHead(Token*) const { return createSentinel(); }
146  static void noteHead(Token*, Token*) {}
147
148private:
149  mutable Token Sentinel;
150};
151
152template<>
153struct ilist_node_traits<Token> {
154  Token *createNode(const Token &V) {
155    return new (Alloc.Allocate<Token>()) Token(V);
156  }
157  static void deleteNode(Token *V) {}
158
159  void addNodeToList(Token *) {}
160  void removeNodeFromList(Token *) {}
161  void transferNodesFromList(ilist_node_traits &    /*SrcTraits*/,
162                             ilist_iterator<Token> /*first*/,
163                             ilist_iterator<Token> /*last*/) {}
164
165  BumpPtrAllocator Alloc;
166};
167}
168
169typedef ilist<Token> TokenQueueT;
170
171namespace {
172/// @brief This struct is used to track simple keys.
173///
174/// Simple keys are handled by creating an entry in SimpleKeys for each Token
175/// which could legally be the start of a simple key. When peekNext is called,
176/// if the Token To be returned is referenced by a SimpleKey, we continue
177/// tokenizing until that potential simple key has either been found to not be
178/// a simple key (we moved on to the next line or went further than 1024 chars).
179/// Or when we run into a Value, and then insert a Key token (and possibly
180/// others) before the SimpleKey's Tok.
181struct SimpleKey {
182  TokenQueueT::iterator Tok;
183  unsigned Column;
184  unsigned Line;
185  unsigned FlowLevel;
186  bool IsRequired;
187
188  bool operator ==(const SimpleKey &Other) {
189    return Tok == Other.Tok;
190  }
191};
192}
193
194/// @brief The Unicode scalar value of a UTF-8 minimal well-formed code unit
195///        subsequence and the subsequence's length in code units (uint8_t).
196///        A length of 0 represents an error.
197typedef std::pair<uint32_t, unsigned> UTF8Decoded;
198
199static UTF8Decoded decodeUTF8(StringRef Range) {
200  StringRef::iterator Position= Range.begin();
201  StringRef::iterator End = Range.end();
202  // 1 byte: [0x00, 0x7f]
203  // Bit pattern: 0xxxxxxx
204  if ((*Position & 0x80) == 0) {
205     return std::make_pair(*Position, 1);
206  }
207  // 2 bytes: [0x80, 0x7ff]
208  // Bit pattern: 110xxxxx 10xxxxxx
209  if (Position + 1 != End &&
210      ((*Position & 0xE0) == 0xC0) &&
211      ((*(Position + 1) & 0xC0) == 0x80)) {
212    uint32_t codepoint = ((*Position & 0x1F) << 6) |
213                          (*(Position + 1) & 0x3F);
214    if (codepoint >= 0x80)
215      return std::make_pair(codepoint, 2);
216  }
217  // 3 bytes: [0x8000, 0xffff]
218  // Bit pattern: 1110xxxx 10xxxxxx 10xxxxxx
219  if (Position + 2 != End &&
220      ((*Position & 0xF0) == 0xE0) &&
221      ((*(Position + 1) & 0xC0) == 0x80) &&
222      ((*(Position + 2) & 0xC0) == 0x80)) {
223    uint32_t codepoint = ((*Position & 0x0F) << 12) |
224                         ((*(Position + 1) & 0x3F) << 6) |
225                          (*(Position + 2) & 0x3F);
226    // Codepoints between 0xD800 and 0xDFFF are invalid, as
227    // they are high / low surrogate halves used by UTF-16.
228    if (codepoint >= 0x800 &&
229        (codepoint < 0xD800 || codepoint > 0xDFFF))
230      return std::make_pair(codepoint, 3);
231  }
232  // 4 bytes: [0x10000, 0x10FFFF]
233  // Bit pattern: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
234  if (Position + 3 != End &&
235      ((*Position & 0xF8) == 0xF0) &&
236      ((*(Position + 1) & 0xC0) == 0x80) &&
237      ((*(Position + 2) & 0xC0) == 0x80) &&
238      ((*(Position + 3) & 0xC0) == 0x80)) {
239    uint32_t codepoint = ((*Position & 0x07) << 18) |
240                         ((*(Position + 1) & 0x3F) << 12) |
241                         ((*(Position + 2) & 0x3F) << 6) |
242                          (*(Position + 3) & 0x3F);
243    if (codepoint >= 0x10000 && codepoint <= 0x10FFFF)
244      return std::make_pair(codepoint, 4);
245  }
246  return std::make_pair(0, 0);
247}
248
249namespace llvm {
250namespace yaml {
251/// @brief Scans YAML tokens from a MemoryBuffer.
252class Scanner {
253public:
254  Scanner(const StringRef Input, SourceMgr &SM);
255
256  /// @brief Parse the next token and return it without popping it.
257  Token &peekNext();
258
259  /// @brief Parse the next token and pop it from the queue.
260  Token getNext();
261
262  void printError(SMLoc Loc, SourceMgr::DiagKind Kind, const Twine &Message,
263                  ArrayRef<SMRange> Ranges = ArrayRef<SMRange>()) {
264    SM.PrintMessage(Loc, Kind, Message, Ranges);
265  }
266
267  void setError(const Twine &Message, StringRef::iterator Position) {
268    if (Current >= End)
269      Current = End - 1;
270
271    // Don't print out more errors after the first one we encounter. The rest
272    // are just the result of the first, and have no meaning.
273    if (!Failed)
274      printError(SMLoc::getFromPointer(Current), SourceMgr::DK_Error, Message);
275    Failed = true;
276  }
277
278  void setError(const Twine &Message) {
279    setError(Message, Current);
280  }
281
282  /// @brief Returns true if an error occurred while parsing.
283  bool failed() {
284    return Failed;
285  }
286
287private:
288  StringRef currentInput() {
289    return StringRef(Current, End - Current);
290  }
291
292  /// @brief Decode a UTF-8 minimal well-formed code unit subsequence starting
293  ///        at \a Position.
294  ///
295  /// If the UTF-8 code units starting at Position do not form a well-formed
296  /// code unit subsequence, then the Unicode scalar value is 0, and the length
297  /// is 0.
298  UTF8Decoded decodeUTF8(StringRef::iterator Position) {
299    return ::decodeUTF8(StringRef(Position, End - Position));
300  }
301
302  // The following functions are based on the gramar rules in the YAML spec. The
303  // style of the function names it meant to closely match how they are written
304  // in the spec. The number within the [] is the number of the grammar rule in
305  // the spec.
306  //
307  // See 4.2 [Production Naming Conventions] for the meaning of the prefixes.
308  //
309  // c-
310  //   A production starting and ending with a special character.
311  // b-
312  //   A production matching a single line break.
313  // nb-
314  //   A production starting and ending with a non-break character.
315  // s-
316  //   A production starting and ending with a white space character.
317  // ns-
318  //   A production starting and ending with a non-space character.
319  // l-
320  //   A production matching complete line(s).
321
322  /// @brief Skip a single nb-char[27] starting at Position.
323  ///
324  /// A nb-char is 0x9 | [0x20-0x7E] | 0x85 | [0xA0-0xD7FF] | [0xE000-0xFEFE]
325  ///                  | [0xFF00-0xFFFD] | [0x10000-0x10FFFF]
326  ///
327  /// @returns The code unit after the nb-char, or Position if it's not an
328  ///          nb-char.
329  StringRef::iterator skip_nb_char(StringRef::iterator Position);
330
331  /// @brief Skip a single b-break[28] starting at Position.
332  ///
333  /// A b-break is 0xD 0xA | 0xD | 0xA
334  ///
335  /// @returns The code unit after the b-break, or Position if it's not a
336  ///          b-break.
337  StringRef::iterator skip_b_break(StringRef::iterator Position);
338
339  /// @brief Skip a single s-white[33] starting at Position.
340  ///
341  /// A s-white is 0x20 | 0x9
342  ///
343  /// @returns The code unit after the s-white, or Position if it's not a
344  ///          s-white.
345  StringRef::iterator skip_s_white(StringRef::iterator Position);
346
347  /// @brief Skip a single ns-char[34] starting at Position.
348  ///
349  /// A ns-char is nb-char - s-white
350  ///
351  /// @returns The code unit after the ns-char, or Position if it's not a
352  ///          ns-char.
353  StringRef::iterator skip_ns_char(StringRef::iterator Position);
354
355  typedef StringRef::iterator (Scanner::*SkipWhileFunc)(StringRef::iterator);
356  /// @brief Skip minimal well-formed code unit subsequences until Func
357  ///        returns its input.
358  ///
359  /// @returns The code unit after the last minimal well-formed code unit
360  ///          subsequence that Func accepted.
361  StringRef::iterator skip_while( SkipWhileFunc Func
362                                , StringRef::iterator Position);
363
364  /// @brief Scan ns-uri-char[39]s starting at Cur.
365  ///
366  /// This updates Cur and Column while scanning.
367  ///
368  /// @returns A StringRef starting at Cur which covers the longest contiguous
369  ///          sequence of ns-uri-char.
370  StringRef scan_ns_uri_char();
371
372  /// @brief Scan ns-plain-one-line[133] starting at \a Cur.
373  StringRef scan_ns_plain_one_line();
374
375  /// @brief Consume a minimal well-formed code unit subsequence starting at
376  ///        \a Cur. Return false if it is not the same Unicode scalar value as
377  ///        \a Expected. This updates \a Column.
378  bool consume(uint32_t Expected);
379
380  /// @brief Skip \a Distance UTF-8 code units. Updates \a Cur and \a Column.
381  void skip(uint32_t Distance);
382
383  /// @brief Return true if the minimal well-formed code unit subsequence at
384  ///        Pos is whitespace or a new line
385  bool isBlankOrBreak(StringRef::iterator Position);
386
387  /// @brief If IsSimpleKeyAllowed, create and push_back a new SimpleKey.
388  void saveSimpleKeyCandidate( TokenQueueT::iterator Tok
389                             , unsigned AtColumn
390                             , bool IsRequired);
391
392  /// @brief Remove simple keys that can no longer be valid simple keys.
393  ///
394  /// Invalid simple keys are not on the current line or are further than 1024
395  /// columns back.
396  void removeStaleSimpleKeyCandidates();
397
398  /// @brief Remove all simple keys on FlowLevel \a Level.
399  void removeSimpleKeyCandidatesOnFlowLevel(unsigned Level);
400
401  /// @brief Unroll indentation in \a Indents back to \a Col. Creates BlockEnd
402  ///        tokens if needed.
403  bool unrollIndent(int ToColumn);
404
405  /// @brief Increase indent to \a Col. Creates \a Kind token at \a InsertPoint
406  ///        if needed.
407  bool rollIndent( int ToColumn
408                 , Token::TokenKind Kind
409                 , TokenQueueT::iterator InsertPoint);
410
411  /// @brief Skip whitespace and comments until the start of the next token.
412  void scanToNextToken();
413
414  /// @brief Must be the first token generated.
415  bool scanStreamStart();
416
417  /// @brief Generate tokens needed to close out the stream.
418  bool scanStreamEnd();
419
420  /// @brief Scan a %BLAH directive.
421  bool scanDirective();
422
423  /// @brief Scan a ... or ---.
424  bool scanDocumentIndicator(bool IsStart);
425
426  /// @brief Scan a [ or { and generate the proper flow collection start token.
427  bool scanFlowCollectionStart(bool IsSequence);
428
429  /// @brief Scan a ] or } and generate the proper flow collection end token.
430  bool scanFlowCollectionEnd(bool IsSequence);
431
432  /// @brief Scan the , that separates entries in a flow collection.
433  bool scanFlowEntry();
434
435  /// @brief Scan the - that starts block sequence entries.
436  bool scanBlockEntry();
437
438  /// @brief Scan an explicit ? indicating a key.
439  bool scanKey();
440
441  /// @brief Scan an explicit : indicating a value.
442  bool scanValue();
443
444  /// @brief Scan a quoted scalar.
445  bool scanFlowScalar(bool IsDoubleQuoted);
446
447  /// @brief Scan an unquoted scalar.
448  bool scanPlainScalar();
449
450  /// @brief Scan an Alias or Anchor starting with * or &.
451  bool scanAliasOrAnchor(bool IsAlias);
452
453  /// @brief Scan a block scalar starting with | or >.
454  bool scanBlockScalar(bool IsLiteral);
455
456  /// @brief Scan a tag of the form !stuff.
457  bool scanTag();
458
459  /// @brief Dispatch to the next scanning function based on \a *Cur.
460  bool fetchMoreTokens();
461
462  /// @brief The SourceMgr used for diagnostics and buffer management.
463  SourceMgr &SM;
464
465  /// @brief The original input.
466  MemoryBuffer *InputBuffer;
467
468  /// @brief The current position of the scanner.
469  StringRef::iterator Current;
470
471  /// @brief The end of the input (one past the last character).
472  StringRef::iterator End;
473
474  /// @brief Current YAML indentation level in spaces.
475  int Indent;
476
477  /// @brief Current column number in Unicode code points.
478  unsigned Column;
479
480  /// @brief Current line number.
481  unsigned Line;
482
483  /// @brief How deep we are in flow style containers. 0 Means at block level.
484  unsigned FlowLevel;
485
486  /// @brief Are we at the start of the stream?
487  bool IsStartOfStream;
488
489  /// @brief Can the next token be the start of a simple key?
490  bool IsSimpleKeyAllowed;
491
492  /// @brief True if an error has occurred.
493  bool Failed;
494
495  /// @brief Queue of tokens. This is required to queue up tokens while looking
496  ///        for the end of a simple key. And for cases where a single character
497  ///        can produce multiple tokens (e.g. BlockEnd).
498  TokenQueueT TokenQueue;
499
500  /// @brief Indentation levels.
501  SmallVector<int, 4> Indents;
502
503  /// @brief Potential simple keys.
504  SmallVector<SimpleKey, 4> SimpleKeys;
505};
506
507} // end namespace yaml
508} // end namespace llvm
509
510/// encodeUTF8 - Encode \a UnicodeScalarValue in UTF-8 and append it to result.
511static void encodeUTF8( uint32_t UnicodeScalarValue
512                      , SmallVectorImpl<char> &Result) {
513  if (UnicodeScalarValue <= 0x7F) {
514    Result.push_back(UnicodeScalarValue & 0x7F);
515  } else if (UnicodeScalarValue <= 0x7FF) {
516    uint8_t FirstByte = 0xC0 | ((UnicodeScalarValue & 0x7C0) >> 6);
517    uint8_t SecondByte = 0x80 | (UnicodeScalarValue & 0x3F);
518    Result.push_back(FirstByte);
519    Result.push_back(SecondByte);
520  } else if (UnicodeScalarValue <= 0xFFFF) {
521    uint8_t FirstByte = 0xE0 | ((UnicodeScalarValue & 0xF000) >> 12);
522    uint8_t SecondByte = 0x80 | ((UnicodeScalarValue & 0xFC0) >> 6);
523    uint8_t ThirdByte = 0x80 | (UnicodeScalarValue & 0x3F);
524    Result.push_back(FirstByte);
525    Result.push_back(SecondByte);
526    Result.push_back(ThirdByte);
527  } else if (UnicodeScalarValue <= 0x10FFFF) {
528    uint8_t FirstByte = 0xF0 | ((UnicodeScalarValue & 0x1F0000) >> 18);
529    uint8_t SecondByte = 0x80 | ((UnicodeScalarValue & 0x3F000) >> 12);
530    uint8_t ThirdByte = 0x80 | ((UnicodeScalarValue & 0xFC0) >> 6);
531    uint8_t FourthByte = 0x80 | (UnicodeScalarValue & 0x3F);
532    Result.push_back(FirstByte);
533    Result.push_back(SecondByte);
534    Result.push_back(ThirdByte);
535    Result.push_back(FourthByte);
536  }
537}
538
539bool yaml::dumpTokens(StringRef Input, raw_ostream &OS) {
540  SourceMgr SM;
541  Scanner scanner(Input, SM);
542  while (true) {
543    Token T = scanner.getNext();
544    switch (T.Kind) {
545    case Token::TK_StreamStart:
546      OS << "Stream-Start: ";
547      break;
548    case Token::TK_StreamEnd:
549      OS << "Stream-End: ";
550      break;
551    case Token::TK_VersionDirective:
552      OS << "Version-Directive: ";
553      break;
554    case Token::TK_TagDirective:
555      OS << "Tag-Directive: ";
556      break;
557    case Token::TK_DocumentStart:
558      OS << "Document-Start: ";
559      break;
560    case Token::TK_DocumentEnd:
561      OS << "Document-End: ";
562      break;
563    case Token::TK_BlockEntry:
564      OS << "Block-Entry: ";
565      break;
566    case Token::TK_BlockEnd:
567      OS << "Block-End: ";
568      break;
569    case Token::TK_BlockSequenceStart:
570      OS << "Block-Sequence-Start: ";
571      break;
572    case Token::TK_BlockMappingStart:
573      OS << "Block-Mapping-Start: ";
574      break;
575    case Token::TK_FlowEntry:
576      OS << "Flow-Entry: ";
577      break;
578    case Token::TK_FlowSequenceStart:
579      OS << "Flow-Sequence-Start: ";
580      break;
581    case Token::TK_FlowSequenceEnd:
582      OS << "Flow-Sequence-End: ";
583      break;
584    case Token::TK_FlowMappingStart:
585      OS << "Flow-Mapping-Start: ";
586      break;
587    case Token::TK_FlowMappingEnd:
588      OS << "Flow-Mapping-End: ";
589      break;
590    case Token::TK_Key:
591      OS << "Key: ";
592      break;
593    case Token::TK_Value:
594      OS << "Value: ";
595      break;
596    case Token::TK_Scalar:
597      OS << "Scalar: ";
598      break;
599    case Token::TK_Alias:
600      OS << "Alias: ";
601      break;
602    case Token::TK_Anchor:
603      OS << "Anchor: ";
604      break;
605    case Token::TK_Tag:
606      OS << "Tag: ";
607      break;
608    case Token::TK_Error:
609      break;
610    }
611    OS << T.Range << "\n";
612    if (T.Kind == Token::TK_StreamEnd)
613      break;
614    else if (T.Kind == Token::TK_Error)
615      return false;
616  }
617  return true;
618}
619
620bool yaml::scanTokens(StringRef Input) {
621  llvm::SourceMgr SM;
622  llvm::yaml::Scanner scanner(Input, SM);
623  for (;;) {
624    llvm::yaml::Token T = scanner.getNext();
625    if (T.Kind == Token::TK_StreamEnd)
626      break;
627    else if (T.Kind == Token::TK_Error)
628      return false;
629  }
630  return true;
631}
632
633std::string yaml::escape(StringRef Input) {
634  std::string EscapedInput;
635  for (StringRef::iterator i = Input.begin(), e = Input.end(); i != e; ++i) {
636    if (*i == '\\')
637      EscapedInput += "\\\\";
638    else if (*i == '"')
639      EscapedInput += "\\\"";
640    else if (*i == 0)
641      EscapedInput += "\\0";
642    else if (*i == 0x07)
643      EscapedInput += "\\a";
644    else if (*i == 0x08)
645      EscapedInput += "\\b";
646    else if (*i == 0x09)
647      EscapedInput += "\\t";
648    else if (*i == 0x0A)
649      EscapedInput += "\\n";
650    else if (*i == 0x0B)
651      EscapedInput += "\\v";
652    else if (*i == 0x0C)
653      EscapedInput += "\\f";
654    else if (*i == 0x0D)
655      EscapedInput += "\\r";
656    else if (*i == 0x1B)
657      EscapedInput += "\\e";
658    else if ((unsigned char)*i < 0x20) { // Control characters not handled above.
659      std::string HexStr = utohexstr(*i);
660      EscapedInput += "\\x" + std::string(2 - HexStr.size(), '0') + HexStr;
661    } else if (*i & 0x80) { // UTF-8 multiple code unit subsequence.
662      UTF8Decoded UnicodeScalarValue
663        = decodeUTF8(StringRef(i, Input.end() - i));
664      if (UnicodeScalarValue.second == 0) {
665        // Found invalid char.
666        SmallString<4> Val;
667        encodeUTF8(0xFFFD, Val);
668        EscapedInput.insert(EscapedInput.end(), Val.begin(), Val.end());
669        // FIXME: Error reporting.
670        return EscapedInput;
671      }
672      if (UnicodeScalarValue.first == 0x85)
673        EscapedInput += "\\N";
674      else if (UnicodeScalarValue.first == 0xA0)
675        EscapedInput += "\\_";
676      else if (UnicodeScalarValue.first == 0x2028)
677        EscapedInput += "\\L";
678      else if (UnicodeScalarValue.first == 0x2029)
679        EscapedInput += "\\P";
680      else {
681        std::string HexStr = utohexstr(UnicodeScalarValue.first);
682        if (HexStr.size() <= 2)
683          EscapedInput += "\\x" + std::string(2 - HexStr.size(), '0') + HexStr;
684        else if (HexStr.size() <= 4)
685          EscapedInput += "\\u" + std::string(4 - HexStr.size(), '0') + HexStr;
686        else if (HexStr.size() <= 8)
687          EscapedInput += "\\U" + std::string(8 - HexStr.size(), '0') + HexStr;
688      }
689      i += UnicodeScalarValue.second - 1;
690    } else
691      EscapedInput.push_back(*i);
692  }
693  return EscapedInput;
694}
695
696Scanner::Scanner(StringRef Input, SourceMgr &sm)
697  : SM(sm)
698  , Indent(-1)
699  , Column(0)
700  , Line(0)
701  , FlowLevel(0)
702  , IsStartOfStream(true)
703  , IsSimpleKeyAllowed(true)
704  , Failed(false) {
705  InputBuffer = MemoryBuffer::getMemBuffer(Input, "YAML");
706  SM.AddNewSourceBuffer(InputBuffer, SMLoc());
707  Current = InputBuffer->getBufferStart();
708  End = InputBuffer->getBufferEnd();
709}
710
711Token &Scanner::peekNext() {
712  // If the current token is a possible simple key, keep parsing until we
713  // can confirm.
714  bool NeedMore = false;
715  while (true) {
716    if (TokenQueue.empty() || NeedMore) {
717      if (!fetchMoreTokens()) {
718        TokenQueue.clear();
719        TokenQueue.push_back(Token());
720        return TokenQueue.front();
721      }
722    }
723    assert(!TokenQueue.empty() &&
724            "fetchMoreTokens lied about getting tokens!");
725
726    removeStaleSimpleKeyCandidates();
727    SimpleKey SK;
728    SK.Tok = TokenQueue.front();
729    if (std::find(SimpleKeys.begin(), SimpleKeys.end(), SK)
730        == SimpleKeys.end())
731      break;
732    else
733      NeedMore = true;
734  }
735  return TokenQueue.front();
736}
737
738Token Scanner::getNext() {
739  Token Ret = peekNext();
740  // TokenQueue can be empty if there was an error getting the next token.
741  if (!TokenQueue.empty())
742    TokenQueue.pop_front();
743
744  // There cannot be any referenced Token's if the TokenQueue is empty. So do a
745  // quick deallocation of them all.
746  if (TokenQueue.empty()) {
747    TokenQueue.Alloc.Reset();
748  }
749
750  return Ret;
751}
752
753StringRef::iterator Scanner::skip_nb_char(StringRef::iterator Position) {
754  if (Position == End)
755    return Position;
756  // Check 7 bit c-printable - b-char.
757  if (   *Position == 0x09
758      || (*Position >= 0x20 && *Position <= 0x7E))
759    return Position + 1;
760
761  // Check for valid UTF-8.
762  if (uint8_t(*Position) & 0x80) {
763    UTF8Decoded u8d = decodeUTF8(Position);
764    if (   u8d.second != 0
765        && u8d.first != 0xFEFF
766        && ( u8d.first == 0x85
767          || ( u8d.first >= 0xA0
768            && u8d.first <= 0xD7FF)
769          || ( u8d.first >= 0xE000
770            && u8d.first <= 0xFFFD)
771          || ( u8d.first >= 0x10000
772            && u8d.first <= 0x10FFFF)))
773      return Position + u8d.second;
774  }
775  return Position;
776}
777
778StringRef::iterator Scanner::skip_b_break(StringRef::iterator Position) {
779  if (Position == End)
780    return Position;
781  if (*Position == 0x0D) {
782    if (Position + 1 != End && *(Position + 1) == 0x0A)
783      return Position + 2;
784    return Position + 1;
785  }
786
787  if (*Position == 0x0A)
788    return Position + 1;
789  return Position;
790}
791
792
793StringRef::iterator Scanner::skip_s_white(StringRef::iterator Position) {
794  if (Position == End)
795    return Position;
796  if (*Position == ' ' || *Position == '\t')
797    return Position + 1;
798  return Position;
799}
800
801StringRef::iterator Scanner::skip_ns_char(StringRef::iterator Position) {
802  if (Position == End)
803    return Position;
804  if (*Position == ' ' || *Position == '\t')
805    return Position;
806  return skip_nb_char(Position);
807}
808
809StringRef::iterator Scanner::skip_while( SkipWhileFunc Func
810                                       , StringRef::iterator Position) {
811  while (true) {
812    StringRef::iterator i = (this->*Func)(Position);
813    if (i == Position)
814      break;
815    Position = i;
816  }
817  return Position;
818}
819
820static bool is_ns_hex_digit(const char C) {
821  return    (C >= '0' && C <= '9')
822         || (C >= 'a' && C <= 'z')
823         || (C >= 'A' && C <= 'Z');
824}
825
826static bool is_ns_word_char(const char C) {
827  return    C == '-'
828         || (C >= 'a' && C <= 'z')
829         || (C >= 'A' && C <= 'Z');
830}
831
832StringRef Scanner::scan_ns_uri_char() {
833  StringRef::iterator Start = Current;
834  while (true) {
835    if (Current == End)
836      break;
837    if ((   *Current == '%'
838          && Current + 2 < End
839          && is_ns_hex_digit(*(Current + 1))
840          && is_ns_hex_digit(*(Current + 2)))
841        || is_ns_word_char(*Current)
842        || StringRef(Current, 1).find_first_of("#;/?:@&=+$,_.!~*'()[]")
843          != StringRef::npos) {
844      ++Current;
845      ++Column;
846    } else
847      break;
848  }
849  return StringRef(Start, Current - Start);
850}
851
852StringRef Scanner::scan_ns_plain_one_line() {
853  StringRef::iterator start = Current;
854  // The first character must already be verified.
855  ++Current;
856  while (true) {
857    if (Current == End) {
858      break;
859    } else if (*Current == ':') {
860      // Check if the next character is a ns-char.
861      if (Current + 1 == End)
862        break;
863      StringRef::iterator i = skip_ns_char(Current + 1);
864      if (Current + 1 != i) {
865        Current = i;
866        Column += 2; // Consume both the ':' and ns-char.
867      } else
868        break;
869    } else if (*Current == '#') {
870      // Check if the previous character was a ns-char.
871      // The & 0x80 check is to check for the trailing byte of a utf-8
872      if (*(Current - 1) & 0x80 || skip_ns_char(Current - 1) == Current) {
873        ++Current;
874        ++Column;
875      } else
876        break;
877    } else {
878      StringRef::iterator i = skip_nb_char(Current);
879      if (i == Current)
880        break;
881      Current = i;
882      ++Column;
883    }
884  }
885  return StringRef(start, Current - start);
886}
887
888bool Scanner::consume(uint32_t Expected) {
889  if (Expected >= 0x80)
890    report_fatal_error("Not dealing with this yet");
891  if (Current == End)
892    return false;
893  if (uint8_t(*Current) >= 0x80)
894    report_fatal_error("Not dealing with this yet");
895  if (uint8_t(*Current) == Expected) {
896    ++Current;
897    ++Column;
898    return true;
899  }
900  return false;
901}
902
903void Scanner::skip(uint32_t Distance) {
904  Current += Distance;
905  Column += Distance;
906}
907
908bool Scanner::isBlankOrBreak(StringRef::iterator Position) {
909  if (Position == End)
910    return false;
911  if (   *Position == ' ' || *Position == '\t'
912      || *Position == '\r' || *Position == '\n')
913    return true;
914  return false;
915}
916
917void Scanner::saveSimpleKeyCandidate( TokenQueueT::iterator Tok
918                                    , unsigned AtColumn
919                                    , bool IsRequired) {
920  if (IsSimpleKeyAllowed) {
921    SimpleKey SK;
922    SK.Tok = Tok;
923    SK.Line = Line;
924    SK.Column = AtColumn;
925    SK.IsRequired = IsRequired;
926    SK.FlowLevel = FlowLevel;
927    SimpleKeys.push_back(SK);
928  }
929}
930
931void Scanner::removeStaleSimpleKeyCandidates() {
932  for (SmallVectorImpl<SimpleKey>::iterator i = SimpleKeys.begin();
933                                            i != SimpleKeys.end();) {
934    if (i->Line != Line || i->Column + 1024 < Column) {
935      if (i->IsRequired)
936        setError( "Could not find expected : for simple key"
937                , i->Tok->Range.begin());
938      i = SimpleKeys.erase(i);
939    } else
940      ++i;
941  }
942}
943
944void Scanner::removeSimpleKeyCandidatesOnFlowLevel(unsigned Level) {
945  if (!SimpleKeys.empty() && (SimpleKeys.end() - 1)->FlowLevel == Level)
946    SimpleKeys.pop_back();
947}
948
949bool Scanner::unrollIndent(int ToColumn) {
950  Token T;
951  // Indentation is ignored in flow.
952  if (FlowLevel != 0)
953    return true;
954
955  while (Indent > ToColumn) {
956    T.Kind = Token::TK_BlockEnd;
957    T.Range = StringRef(Current, 1);
958    TokenQueue.push_back(T);
959    Indent = Indents.pop_back_val();
960  }
961
962  return true;
963}
964
965bool Scanner::rollIndent( int ToColumn
966                        , Token::TokenKind Kind
967                        , TokenQueueT::iterator InsertPoint) {
968  if (FlowLevel)
969    return true;
970  if (Indent < ToColumn) {
971    Indents.push_back(Indent);
972    Indent = ToColumn;
973
974    Token T;
975    T.Kind = Kind;
976    T.Range = StringRef(Current, 0);
977    TokenQueue.insert(InsertPoint, T);
978  }
979  return true;
980}
981
982void Scanner::scanToNextToken() {
983  while (true) {
984    while (*Current == ' ' || *Current == '\t') {
985      skip(1);
986    }
987
988    // Skip comment.
989    if (*Current == '#') {
990      while (true) {
991        // This may skip more than one byte, thus Column is only incremented
992        // for code points.
993        StringRef::iterator i = skip_nb_char(Current);
994        if (i == Current)
995          break;
996        Current = i;
997        ++Column;
998      }
999    }
1000
1001    // Skip EOL.
1002    StringRef::iterator i = skip_b_break(Current);
1003    if (i == Current)
1004      break;
1005    Current = i;
1006    ++Line;
1007    Column = 0;
1008    // New lines may start a simple key.
1009    if (!FlowLevel)
1010      IsSimpleKeyAllowed = true;
1011  }
1012}
1013
1014bool Scanner::scanStreamStart() {
1015  IsStartOfStream = false;
1016
1017  EncodingInfo EI = getUnicodeEncoding(currentInput());
1018
1019  Token T;
1020  T.Kind = Token::TK_StreamStart;
1021  T.Range = StringRef(Current, EI.second);
1022  TokenQueue.push_back(T);
1023  Current += EI.second;
1024  return true;
1025}
1026
1027bool Scanner::scanStreamEnd() {
1028  // Force an ending new line if one isn't present.
1029  if (Column != 0) {
1030    Column = 0;
1031    ++Line;
1032  }
1033
1034  unrollIndent(-1);
1035  SimpleKeys.clear();
1036  IsSimpleKeyAllowed = false;
1037
1038  Token T;
1039  T.Kind = Token::TK_StreamEnd;
1040  T.Range = StringRef(Current, 0);
1041  TokenQueue.push_back(T);
1042  return true;
1043}
1044
1045bool Scanner::scanDirective() {
1046  // Reset the indentation level.
1047  unrollIndent(-1);
1048  SimpleKeys.clear();
1049  IsSimpleKeyAllowed = false;
1050
1051  StringRef::iterator Start = Current;
1052  consume('%');
1053  StringRef::iterator NameStart = Current;
1054  Current = skip_while(&Scanner::skip_ns_char, Current);
1055  StringRef Name(NameStart, Current - NameStart);
1056  Current = skip_while(&Scanner::skip_s_white, Current);
1057
1058  if (Name == "YAML") {
1059    Current = skip_while(&Scanner::skip_ns_char, Current);
1060    Token T;
1061    T.Kind = Token::TK_VersionDirective;
1062    T.Range = StringRef(Start, Current - Start);
1063    TokenQueue.push_back(T);
1064    return true;
1065  }
1066  return false;
1067}
1068
1069bool Scanner::scanDocumentIndicator(bool IsStart) {
1070  unrollIndent(-1);
1071  SimpleKeys.clear();
1072  IsSimpleKeyAllowed = false;
1073
1074  Token T;
1075  T.Kind = IsStart ? Token::TK_DocumentStart : Token::TK_DocumentEnd;
1076  T.Range = StringRef(Current, 3);
1077  skip(3);
1078  TokenQueue.push_back(T);
1079  return true;
1080}
1081
1082bool Scanner::scanFlowCollectionStart(bool IsSequence) {
1083  Token T;
1084  T.Kind = IsSequence ? Token::TK_FlowSequenceStart
1085                      : Token::TK_FlowMappingStart;
1086  T.Range = StringRef(Current, 1);
1087  skip(1);
1088  TokenQueue.push_back(T);
1089
1090  // [ and { may begin a simple key.
1091  saveSimpleKeyCandidate(TokenQueue.back(), Column - 1, false);
1092
1093  // And may also be followed by a simple key.
1094  IsSimpleKeyAllowed = true;
1095  ++FlowLevel;
1096  return true;
1097}
1098
1099bool Scanner::scanFlowCollectionEnd(bool IsSequence) {
1100  removeSimpleKeyCandidatesOnFlowLevel(FlowLevel);
1101  IsSimpleKeyAllowed = false;
1102  Token T;
1103  T.Kind = IsSequence ? Token::TK_FlowSequenceEnd
1104                      : Token::TK_FlowMappingEnd;
1105  T.Range = StringRef(Current, 1);
1106  skip(1);
1107  TokenQueue.push_back(T);
1108  if (FlowLevel)
1109    --FlowLevel;
1110  return true;
1111}
1112
1113bool Scanner::scanFlowEntry() {
1114  removeSimpleKeyCandidatesOnFlowLevel(FlowLevel);
1115  IsSimpleKeyAllowed = true;
1116  Token T;
1117  T.Kind = Token::TK_FlowEntry;
1118  T.Range = StringRef(Current, 1);
1119  skip(1);
1120  TokenQueue.push_back(T);
1121  return true;
1122}
1123
1124bool Scanner::scanBlockEntry() {
1125  rollIndent(Column, Token::TK_BlockSequenceStart, TokenQueue.end());
1126  removeSimpleKeyCandidatesOnFlowLevel(FlowLevel);
1127  IsSimpleKeyAllowed = true;
1128  Token T;
1129  T.Kind = Token::TK_BlockEntry;
1130  T.Range = StringRef(Current, 1);
1131  skip(1);
1132  TokenQueue.push_back(T);
1133  return true;
1134}
1135
1136bool Scanner::scanKey() {
1137  if (!FlowLevel)
1138    rollIndent(Column, Token::TK_BlockMappingStart, TokenQueue.end());
1139
1140  removeSimpleKeyCandidatesOnFlowLevel(FlowLevel);
1141  IsSimpleKeyAllowed = !FlowLevel;
1142
1143  Token T;
1144  T.Kind = Token::TK_Key;
1145  T.Range = StringRef(Current, 1);
1146  skip(1);
1147  TokenQueue.push_back(T);
1148  return true;
1149}
1150
1151bool Scanner::scanValue() {
1152  // If the previous token could have been a simple key, insert the key token
1153  // into the token queue.
1154  if (!SimpleKeys.empty()) {
1155    SimpleKey SK = SimpleKeys.pop_back_val();
1156    Token T;
1157    T.Kind = Token::TK_Key;
1158    T.Range = SK.Tok->Range;
1159    TokenQueueT::iterator i, e;
1160    for (i = TokenQueue.begin(), e = TokenQueue.end(); i != e; ++i) {
1161      if (i == SK.Tok)
1162        break;
1163    }
1164    assert(i != e && "SimpleKey not in token queue!");
1165    i = TokenQueue.insert(i, T);
1166
1167    // We may also need to add a Block-Mapping-Start token.
1168    rollIndent(SK.Column, Token::TK_BlockMappingStart, i);
1169
1170    IsSimpleKeyAllowed = false;
1171  } else {
1172    if (!FlowLevel)
1173      rollIndent(Column, Token::TK_BlockMappingStart, TokenQueue.end());
1174    IsSimpleKeyAllowed = !FlowLevel;
1175  }
1176
1177  Token T;
1178  T.Kind = Token::TK_Value;
1179  T.Range = StringRef(Current, 1);
1180  skip(1);
1181  TokenQueue.push_back(T);
1182  return true;
1183}
1184
1185// Forbidding inlining improves performance by roughly 20%.
1186// FIXME: Remove once llvm optimizes this to the faster version without hints.
1187LLVM_ATTRIBUTE_NOINLINE static bool
1188wasEscaped(StringRef::iterator First, StringRef::iterator Position);
1189
1190// Returns whether a character at 'Position' was escaped with a leading '\'.
1191// 'First' specifies the position of the first character in the string.
1192static bool wasEscaped(StringRef::iterator First,
1193                       StringRef::iterator Position) {
1194  assert(Position - 1 >= First);
1195  StringRef::iterator I = Position - 1;
1196  // We calculate the number of consecutive '\'s before the current position
1197  // by iterating backwards through our string.
1198  while (I >= First && *I == '\\') --I;
1199  // (Position - 1 - I) now contains the number of '\'s before the current
1200  // position. If it is odd, the character at 'Position' was escaped.
1201  return (Position - 1 - I) % 2 == 1;
1202}
1203
1204bool Scanner::scanFlowScalar(bool IsDoubleQuoted) {
1205  StringRef::iterator Start = Current;
1206  unsigned ColStart = Column;
1207  if (IsDoubleQuoted) {
1208    do {
1209      ++Current;
1210      while (Current != End && *Current != '"')
1211        ++Current;
1212      // Repeat until the previous character was not a '\' or was an escaped
1213      // backslash.
1214    } while (   Current != End
1215             && *(Current - 1) == '\\'
1216             && wasEscaped(Start + 1, Current));
1217  } else {
1218    skip(1);
1219    while (true) {
1220      // Skip a ' followed by another '.
1221      if (Current + 1 < End && *Current == '\'' && *(Current + 1) == '\'') {
1222        skip(2);
1223        continue;
1224      } else if (*Current == '\'')
1225        break;
1226      StringRef::iterator i = skip_nb_char(Current);
1227      if (i == Current) {
1228        i = skip_b_break(Current);
1229        if (i == Current)
1230          break;
1231        Current = i;
1232        Column = 0;
1233        ++Line;
1234      } else {
1235        if (i == End)
1236          break;
1237        Current = i;
1238        ++Column;
1239      }
1240    }
1241  }
1242  skip(1); // Skip ending quote.
1243  Token T;
1244  T.Kind = Token::TK_Scalar;
1245  T.Range = StringRef(Start, Current - Start);
1246  TokenQueue.push_back(T);
1247
1248  saveSimpleKeyCandidate(TokenQueue.back(), ColStart, false);
1249
1250  IsSimpleKeyAllowed = false;
1251
1252  return true;
1253}
1254
1255bool Scanner::scanPlainScalar() {
1256  StringRef::iterator Start = Current;
1257  unsigned ColStart = Column;
1258  unsigned LeadingBlanks = 0;
1259  assert(Indent >= -1 && "Indent must be >= -1 !");
1260  unsigned indent = static_cast<unsigned>(Indent + 1);
1261  while (true) {
1262    if (*Current == '#')
1263      break;
1264
1265    while (!isBlankOrBreak(Current)) {
1266      if (  FlowLevel && *Current == ':'
1267          && !(isBlankOrBreak(Current + 1) || *(Current + 1) == ',')) {
1268        setError("Found unexpected ':' while scanning a plain scalar", Current);
1269        return false;
1270      }
1271
1272      // Check for the end of the plain scalar.
1273      if (  (*Current == ':' && isBlankOrBreak(Current + 1))
1274          || (  FlowLevel
1275          && (StringRef(Current, 1).find_first_of(",:?[]{}")
1276              != StringRef::npos)))
1277        break;
1278
1279      StringRef::iterator i = skip_nb_char(Current);
1280      if (i == Current)
1281        break;
1282      Current = i;
1283      ++Column;
1284    }
1285
1286    // Are we at the end?
1287    if (!isBlankOrBreak(Current))
1288      break;
1289
1290    // Eat blanks.
1291    StringRef::iterator Tmp = Current;
1292    while (isBlankOrBreak(Tmp)) {
1293      StringRef::iterator i = skip_s_white(Tmp);
1294      if (i != Tmp) {
1295        if (LeadingBlanks && (Column < indent) && *Tmp == '\t') {
1296          setError("Found invalid tab character in indentation", Tmp);
1297          return false;
1298        }
1299        Tmp = i;
1300        ++Column;
1301      } else {
1302        i = skip_b_break(Tmp);
1303        if (!LeadingBlanks)
1304          LeadingBlanks = 1;
1305        Tmp = i;
1306        Column = 0;
1307        ++Line;
1308      }
1309    }
1310
1311    if (!FlowLevel && Column < indent)
1312      break;
1313
1314    Current = Tmp;
1315  }
1316  if (Start == Current) {
1317    setError("Got empty plain scalar", Start);
1318    return false;
1319  }
1320  Token T;
1321  T.Kind = Token::TK_Scalar;
1322  T.Range = StringRef(Start, Current - Start);
1323  TokenQueue.push_back(T);
1324
1325  // Plain scalars can be simple keys.
1326  saveSimpleKeyCandidate(TokenQueue.back(), ColStart, false);
1327
1328  IsSimpleKeyAllowed = false;
1329
1330  return true;
1331}
1332
1333bool Scanner::scanAliasOrAnchor(bool IsAlias) {
1334  StringRef::iterator Start = Current;
1335  unsigned ColStart = Column;
1336  skip(1);
1337  while(true) {
1338    if (   *Current == '[' || *Current == ']'
1339        || *Current == '{' || *Current == '}'
1340        || *Current == ','
1341        || *Current == ':')
1342      break;
1343    StringRef::iterator i = skip_ns_char(Current);
1344    if (i == Current)
1345      break;
1346    Current = i;
1347    ++Column;
1348  }
1349
1350  if (Start == Current) {
1351    setError("Got empty alias or anchor", Start);
1352    return false;
1353  }
1354
1355  Token T;
1356  T.Kind = IsAlias ? Token::TK_Alias : Token::TK_Anchor;
1357  T.Range = StringRef(Start, Current - Start);
1358  TokenQueue.push_back(T);
1359
1360  // Alias and anchors can be simple keys.
1361  saveSimpleKeyCandidate(TokenQueue.back(), ColStart, false);
1362
1363  IsSimpleKeyAllowed = false;
1364
1365  return true;
1366}
1367
1368bool Scanner::scanBlockScalar(bool IsLiteral) {
1369  StringRef::iterator Start = Current;
1370  skip(1); // Eat | or >
1371  while(true) {
1372    StringRef::iterator i = skip_nb_char(Current);
1373    if (i == Current) {
1374      if (Column == 0)
1375        break;
1376      i = skip_b_break(Current);
1377      if (i != Current) {
1378        // We got a line break.
1379        Column = 0;
1380        ++Line;
1381        Current = i;
1382        continue;
1383      } else {
1384        // There was an error, which should already have been printed out.
1385        return false;
1386      }
1387    }
1388    Current = i;
1389    ++Column;
1390  }
1391
1392  if (Start == Current) {
1393    setError("Got empty block scalar", Start);
1394    return false;
1395  }
1396
1397  Token T;
1398  T.Kind = Token::TK_Scalar;
1399  T.Range = StringRef(Start, Current - Start);
1400  TokenQueue.push_back(T);
1401  return true;
1402}
1403
1404bool Scanner::scanTag() {
1405  StringRef::iterator Start = Current;
1406  unsigned ColStart = Column;
1407  skip(1); // Eat !.
1408  if (Current == End || isBlankOrBreak(Current)); // An empty tag.
1409  else if (*Current == '<') {
1410    skip(1);
1411    scan_ns_uri_char();
1412    if (!consume('>'))
1413      return false;
1414  } else {
1415    // FIXME: Actually parse the c-ns-shorthand-tag rule.
1416    Current = skip_while(&Scanner::skip_ns_char, Current);
1417  }
1418
1419  Token T;
1420  T.Kind = Token::TK_Tag;
1421  T.Range = StringRef(Start, Current - Start);
1422  TokenQueue.push_back(T);
1423
1424  // Tags can be simple keys.
1425  saveSimpleKeyCandidate(TokenQueue.back(), ColStart, false);
1426
1427  IsSimpleKeyAllowed = false;
1428
1429  return true;
1430}
1431
1432bool Scanner::fetchMoreTokens() {
1433  if (IsStartOfStream)
1434    return scanStreamStart();
1435
1436  scanToNextToken();
1437
1438  if (Current == End)
1439    return scanStreamEnd();
1440
1441  removeStaleSimpleKeyCandidates();
1442
1443  unrollIndent(Column);
1444
1445  if (Column == 0 && *Current == '%')
1446    return scanDirective();
1447
1448  if (Column == 0 && Current + 4 <= End
1449      && *Current == '-'
1450      && *(Current + 1) == '-'
1451      && *(Current + 2) == '-'
1452      && (Current + 3 == End || isBlankOrBreak(Current + 3)))
1453    return scanDocumentIndicator(true);
1454
1455  if (Column == 0 && Current + 4 <= End
1456      && *Current == '.'
1457      && *(Current + 1) == '.'
1458      && *(Current + 2) == '.'
1459      && (Current + 3 == End || isBlankOrBreak(Current + 3)))
1460    return scanDocumentIndicator(false);
1461
1462  if (*Current == '[')
1463    return scanFlowCollectionStart(true);
1464
1465  if (*Current == '{')
1466    return scanFlowCollectionStart(false);
1467
1468  if (*Current == ']')
1469    return scanFlowCollectionEnd(true);
1470
1471  if (*Current == '}')
1472    return scanFlowCollectionEnd(false);
1473
1474  if (*Current == ',')
1475    return scanFlowEntry();
1476
1477  if (*Current == '-' && isBlankOrBreak(Current + 1))
1478    return scanBlockEntry();
1479
1480  if (*Current == '?' && (FlowLevel || isBlankOrBreak(Current + 1)))
1481    return scanKey();
1482
1483  if (*Current == ':' && (FlowLevel || isBlankOrBreak(Current + 1)))
1484    return scanValue();
1485
1486  if (*Current == '*')
1487    return scanAliasOrAnchor(true);
1488
1489  if (*Current == '&')
1490    return scanAliasOrAnchor(false);
1491
1492  if (*Current == '!')
1493    return scanTag();
1494
1495  if (*Current == '|' && !FlowLevel)
1496    return scanBlockScalar(true);
1497
1498  if (*Current == '>' && !FlowLevel)
1499    return scanBlockScalar(false);
1500
1501  if (*Current == '\'')
1502    return scanFlowScalar(false);
1503
1504  if (*Current == '"')
1505    return scanFlowScalar(true);
1506
1507  // Get a plain scalar.
1508  StringRef FirstChar(Current, 1);
1509  if (!(isBlankOrBreak(Current)
1510        || FirstChar.find_first_of("-?:,[]{}#&*!|>'\"%@`") != StringRef::npos)
1511      || (*Current == '-' && !isBlankOrBreak(Current + 1))
1512      || (!FlowLevel && (*Current == '?' || *Current == ':')
1513          && isBlankOrBreak(Current + 1))
1514      || (!FlowLevel && *Current == ':'
1515                      && Current + 2 < End
1516                      && *(Current + 1) == ':'
1517                      && !isBlankOrBreak(Current + 2)))
1518    return scanPlainScalar();
1519
1520  setError("Unrecognized character while tokenizing.");
1521  return false;
1522}
1523
1524Stream::Stream(StringRef Input, SourceMgr &SM)
1525  : scanner(new Scanner(Input, SM))
1526  , CurrentDoc(0) {}
1527
1528Stream::~Stream() {}
1529
1530bool Stream::failed() { return scanner->failed(); }
1531
1532void Stream::printError(Node *N, const Twine &Msg) {
1533  SmallVector<SMRange, 1> Ranges;
1534  Ranges.push_back(N->getSourceRange());
1535  scanner->printError( N->getSourceRange().Start
1536                     , SourceMgr::DK_Error
1537                     , Msg
1538                     , Ranges);
1539}
1540
1541void Stream::handleYAMLDirective(const Token &t) {
1542  // TODO: Ensure version is 1.x.
1543}
1544
1545document_iterator Stream::begin() {
1546  if (CurrentDoc)
1547    report_fatal_error("Can only iterate over the stream once");
1548
1549  // Skip Stream-Start.
1550  scanner->getNext();
1551
1552  CurrentDoc.reset(new Document(*this));
1553  return document_iterator(CurrentDoc);
1554}
1555
1556document_iterator Stream::end() {
1557  return document_iterator();
1558}
1559
1560void Stream::skip() {
1561  for (document_iterator i = begin(), e = end(); i != e; ++i)
1562    i->skip();
1563}
1564
1565Node::Node(unsigned int Type, OwningPtr<Document> &D, StringRef A)
1566  : Doc(D)
1567  , TypeID(Type)
1568  , Anchor(A) {
1569  SMLoc Start = SMLoc::getFromPointer(peekNext().Range.begin());
1570  SourceRange = SMRange(Start, Start);
1571}
1572
1573Token &Node::peekNext() {
1574  return Doc->peekNext();
1575}
1576
1577Token Node::getNext() {
1578  return Doc->getNext();
1579}
1580
1581Node *Node::parseBlockNode() {
1582  return Doc->parseBlockNode();
1583}
1584
1585BumpPtrAllocator &Node::getAllocator() {
1586  return Doc->NodeAllocator;
1587}
1588
1589void Node::setError(const Twine &Msg, Token &Tok) const {
1590  Doc->setError(Msg, Tok);
1591}
1592
1593bool Node::failed() const {
1594  return Doc->failed();
1595}
1596
1597
1598
1599StringRef ScalarNode::getValue(SmallVectorImpl<char> &Storage) const {
1600  // TODO: Handle newlines properly. We need to remove leading whitespace.
1601  if (Value[0] == '"') { // Double quoted.
1602    // Pull off the leading and trailing "s.
1603    StringRef UnquotedValue = Value.substr(1, Value.size() - 2);
1604    // Search for characters that would require unescaping the value.
1605    StringRef::size_type i = UnquotedValue.find_first_of("\\\r\n");
1606    if (i != StringRef::npos)
1607      return unescapeDoubleQuoted(UnquotedValue, i, Storage);
1608    return UnquotedValue;
1609  } else if (Value[0] == '\'') { // Single quoted.
1610    // Pull off the leading and trailing 's.
1611    StringRef UnquotedValue = Value.substr(1, Value.size() - 2);
1612    StringRef::size_type i = UnquotedValue.find('\'');
1613    if (i != StringRef::npos) {
1614      // We're going to need Storage.
1615      Storage.clear();
1616      Storage.reserve(UnquotedValue.size());
1617      for (; i != StringRef::npos; i = UnquotedValue.find('\'')) {
1618        StringRef Valid(UnquotedValue.begin(), i);
1619        Storage.insert(Storage.end(), Valid.begin(), Valid.end());
1620        Storage.push_back('\'');
1621        UnquotedValue = UnquotedValue.substr(i + 2);
1622      }
1623      Storage.insert(Storage.end(), UnquotedValue.begin(), UnquotedValue.end());
1624      return StringRef(Storage.begin(), Storage.size());
1625    }
1626    return UnquotedValue;
1627  }
1628  // Plain or block.
1629  return Value.rtrim(" ");
1630}
1631
1632StringRef ScalarNode::unescapeDoubleQuoted( StringRef UnquotedValue
1633                                          , StringRef::size_type i
1634                                          , SmallVectorImpl<char> &Storage)
1635                                          const {
1636  // Use Storage to build proper value.
1637  Storage.clear();
1638  Storage.reserve(UnquotedValue.size());
1639  for (; i != StringRef::npos; i = UnquotedValue.find_first_of("\\\r\n")) {
1640    // Insert all previous chars into Storage.
1641    StringRef Valid(UnquotedValue.begin(), i);
1642    Storage.insert(Storage.end(), Valid.begin(), Valid.end());
1643    // Chop off inserted chars.
1644    UnquotedValue = UnquotedValue.substr(i);
1645
1646    assert(!UnquotedValue.empty() && "Can't be empty!");
1647
1648    // Parse escape or line break.
1649    switch (UnquotedValue[0]) {
1650    case '\r':
1651    case '\n':
1652      Storage.push_back('\n');
1653      if (   UnquotedValue.size() > 1
1654          && (UnquotedValue[1] == '\r' || UnquotedValue[1] == '\n'))
1655        UnquotedValue = UnquotedValue.substr(1);
1656      UnquotedValue = UnquotedValue.substr(1);
1657      break;
1658    default:
1659      if (UnquotedValue.size() == 1)
1660        // TODO: Report error.
1661        break;
1662      UnquotedValue = UnquotedValue.substr(1);
1663      switch (UnquotedValue[0]) {
1664      default: {
1665          Token T;
1666          T.Range = StringRef(UnquotedValue.begin(), 1);
1667          setError("Unrecognized escape code!", T);
1668          return "";
1669        }
1670      case '\r':
1671      case '\n':
1672        // Remove the new line.
1673        if (   UnquotedValue.size() > 1
1674            && (UnquotedValue[1] == '\r' || UnquotedValue[1] == '\n'))
1675          UnquotedValue = UnquotedValue.substr(1);
1676        // If this was just a single byte newline, it will get skipped
1677        // below.
1678        break;
1679      case '0':
1680        Storage.push_back(0x00);
1681        break;
1682      case 'a':
1683        Storage.push_back(0x07);
1684        break;
1685      case 'b':
1686        Storage.push_back(0x08);
1687        break;
1688      case 't':
1689      case 0x09:
1690        Storage.push_back(0x09);
1691        break;
1692      case 'n':
1693        Storage.push_back(0x0A);
1694        break;
1695      case 'v':
1696        Storage.push_back(0x0B);
1697        break;
1698      case 'f':
1699        Storage.push_back(0x0C);
1700        break;
1701      case 'r':
1702        Storage.push_back(0x0D);
1703        break;
1704      case 'e':
1705        Storage.push_back(0x1B);
1706        break;
1707      case ' ':
1708        Storage.push_back(0x20);
1709        break;
1710      case '"':
1711        Storage.push_back(0x22);
1712        break;
1713      case '/':
1714        Storage.push_back(0x2F);
1715        break;
1716      case '\\':
1717        Storage.push_back(0x5C);
1718        break;
1719      case 'N':
1720        encodeUTF8(0x85, Storage);
1721        break;
1722      case '_':
1723        encodeUTF8(0xA0, Storage);
1724        break;
1725      case 'L':
1726        encodeUTF8(0x2028, Storage);
1727        break;
1728      case 'P':
1729        encodeUTF8(0x2029, Storage);
1730        break;
1731      case 'x': {
1732          if (UnquotedValue.size() < 3)
1733            // TODO: Report error.
1734            break;
1735          unsigned int UnicodeScalarValue;
1736          if (UnquotedValue.substr(1, 2).getAsInteger(16, UnicodeScalarValue))
1737            // TODO: Report error.
1738            UnicodeScalarValue = 0xFFFD;
1739          encodeUTF8(UnicodeScalarValue, Storage);
1740          UnquotedValue = UnquotedValue.substr(2);
1741          break;
1742        }
1743      case 'u': {
1744          if (UnquotedValue.size() < 5)
1745            // TODO: Report error.
1746            break;
1747          unsigned int UnicodeScalarValue;
1748          if (UnquotedValue.substr(1, 4).getAsInteger(16, UnicodeScalarValue))
1749            // TODO: Report error.
1750            UnicodeScalarValue = 0xFFFD;
1751          encodeUTF8(UnicodeScalarValue, Storage);
1752          UnquotedValue = UnquotedValue.substr(4);
1753          break;
1754        }
1755      case 'U': {
1756          if (UnquotedValue.size() < 9)
1757            // TODO: Report error.
1758            break;
1759          unsigned int UnicodeScalarValue;
1760          if (UnquotedValue.substr(1, 8).getAsInteger(16, UnicodeScalarValue))
1761            // TODO: Report error.
1762            UnicodeScalarValue = 0xFFFD;
1763          encodeUTF8(UnicodeScalarValue, Storage);
1764          UnquotedValue = UnquotedValue.substr(8);
1765          break;
1766        }
1767      }
1768      UnquotedValue = UnquotedValue.substr(1);
1769    }
1770  }
1771  Storage.insert(Storage.end(), UnquotedValue.begin(), UnquotedValue.end());
1772  return StringRef(Storage.begin(), Storage.size());
1773}
1774
1775Node *KeyValueNode::getKey() {
1776  if (Key)
1777    return Key;
1778  // Handle implicit null keys.
1779  {
1780    Token &t = peekNext();
1781    if (   t.Kind == Token::TK_BlockEnd
1782        || t.Kind == Token::TK_Value
1783        || t.Kind == Token::TK_Error) {
1784      return Key = new (getAllocator()) NullNode(Doc);
1785    }
1786    if (t.Kind == Token::TK_Key)
1787      getNext(); // skip TK_Key.
1788  }
1789
1790  // Handle explicit null keys.
1791  Token &t = peekNext();
1792  if (t.Kind == Token::TK_BlockEnd || t.Kind == Token::TK_Value) {
1793    return Key = new (getAllocator()) NullNode(Doc);
1794  }
1795
1796  // We've got a normal key.
1797  return Key = parseBlockNode();
1798}
1799
1800Node *KeyValueNode::getValue() {
1801  if (Value)
1802    return Value;
1803  getKey()->skip();
1804  if (failed())
1805    return Value = new (getAllocator()) NullNode(Doc);
1806
1807  // Handle implicit null values.
1808  {
1809    Token &t = peekNext();
1810    if (   t.Kind == Token::TK_BlockEnd
1811        || t.Kind == Token::TK_FlowMappingEnd
1812        || t.Kind == Token::TK_Key
1813        || t.Kind == Token::TK_FlowEntry
1814        || t.Kind == Token::TK_Error) {
1815      return Value = new (getAllocator()) NullNode(Doc);
1816    }
1817
1818    if (t.Kind != Token::TK_Value) {
1819      setError("Unexpected token in Key Value.", t);
1820      return Value = new (getAllocator()) NullNode(Doc);
1821    }
1822    getNext(); // skip TK_Value.
1823  }
1824
1825  // Handle explicit null values.
1826  Token &t = peekNext();
1827  if (t.Kind == Token::TK_BlockEnd || t.Kind == Token::TK_Key) {
1828    return Value = new (getAllocator()) NullNode(Doc);
1829  }
1830
1831  // We got a normal value.
1832  return Value = parseBlockNode();
1833}
1834
1835void MappingNode::increment() {
1836  if (failed()) {
1837    IsAtEnd = true;
1838    CurrentEntry = 0;
1839    return;
1840  }
1841  if (CurrentEntry) {
1842    CurrentEntry->skip();
1843    if (Type == MT_Inline) {
1844      IsAtEnd = true;
1845      CurrentEntry = 0;
1846      return;
1847    }
1848  }
1849  Token T = peekNext();
1850  if (T.Kind == Token::TK_Key || T.Kind == Token::TK_Scalar) {
1851    // KeyValueNode eats the TK_Key. That way it can detect null keys.
1852    CurrentEntry = new (getAllocator()) KeyValueNode(Doc);
1853  } else if (Type == MT_Block) {
1854    switch (T.Kind) {
1855    case Token::TK_BlockEnd:
1856      getNext();
1857      IsAtEnd = true;
1858      CurrentEntry = 0;
1859      break;
1860    default:
1861      setError("Unexpected token. Expected Key or Block End", T);
1862    case Token::TK_Error:
1863      IsAtEnd = true;
1864      CurrentEntry = 0;
1865    }
1866  } else {
1867    switch (T.Kind) {
1868    case Token::TK_FlowEntry:
1869      // Eat the flow entry and recurse.
1870      getNext();
1871      return increment();
1872    case Token::TK_FlowMappingEnd:
1873      getNext();
1874    case Token::TK_Error:
1875      // Set this to end iterator.
1876      IsAtEnd = true;
1877      CurrentEntry = 0;
1878      break;
1879    default:
1880      setError( "Unexpected token. Expected Key, Flow Entry, or Flow "
1881                "Mapping End."
1882              , T);
1883      IsAtEnd = true;
1884      CurrentEntry = 0;
1885    }
1886  }
1887}
1888
1889void SequenceNode::increment() {
1890  if (failed()) {
1891    IsAtEnd = true;
1892    CurrentEntry = 0;
1893    return;
1894  }
1895  if (CurrentEntry)
1896    CurrentEntry->skip();
1897  Token T = peekNext();
1898  if (SeqType == ST_Block) {
1899    switch (T.Kind) {
1900    case Token::TK_BlockEntry:
1901      getNext();
1902      CurrentEntry = parseBlockNode();
1903      if (CurrentEntry == 0) { // An error occurred.
1904        IsAtEnd = true;
1905        CurrentEntry = 0;
1906      }
1907      break;
1908    case Token::TK_BlockEnd:
1909      getNext();
1910      IsAtEnd = true;
1911      CurrentEntry = 0;
1912      break;
1913    default:
1914      setError( "Unexpected token. Expected Block Entry or Block End."
1915              , T);
1916    case Token::TK_Error:
1917      IsAtEnd = true;
1918      CurrentEntry = 0;
1919    }
1920  } else if (SeqType == ST_Indentless) {
1921    switch (T.Kind) {
1922    case Token::TK_BlockEntry:
1923      getNext();
1924      CurrentEntry = parseBlockNode();
1925      if (CurrentEntry == 0) { // An error occurred.
1926        IsAtEnd = true;
1927        CurrentEntry = 0;
1928      }
1929      break;
1930    default:
1931    case Token::TK_Error:
1932      IsAtEnd = true;
1933      CurrentEntry = 0;
1934    }
1935  } else if (SeqType == ST_Flow) {
1936    switch (T.Kind) {
1937    case Token::TK_FlowEntry:
1938      // Eat the flow entry and recurse.
1939      getNext();
1940      WasPreviousTokenFlowEntry = true;
1941      return increment();
1942    case Token::TK_FlowSequenceEnd:
1943      getNext();
1944    case Token::TK_Error:
1945      // Set this to end iterator.
1946      IsAtEnd = true;
1947      CurrentEntry = 0;
1948      break;
1949    case Token::TK_StreamEnd:
1950    case Token::TK_DocumentEnd:
1951    case Token::TK_DocumentStart:
1952      setError("Could not find closing ]!", T);
1953      // Set this to end iterator.
1954      IsAtEnd = true;
1955      CurrentEntry = 0;
1956      break;
1957    default:
1958      if (!WasPreviousTokenFlowEntry) {
1959        setError("Expected , between entries!", T);
1960        IsAtEnd = true;
1961        CurrentEntry = 0;
1962        break;
1963      }
1964      // Otherwise it must be a flow entry.
1965      CurrentEntry = parseBlockNode();
1966      if (!CurrentEntry) {
1967        IsAtEnd = true;
1968      }
1969      WasPreviousTokenFlowEntry = false;
1970      break;
1971    }
1972  }
1973}
1974
1975Document::Document(Stream &S) : stream(S), Root(0) {
1976  if (parseDirectives())
1977    expectToken(Token::TK_DocumentStart);
1978  Token &T = peekNext();
1979  if (T.Kind == Token::TK_DocumentStart)
1980    getNext();
1981}
1982
1983bool Document::skip()  {
1984  if (stream.scanner->failed())
1985    return false;
1986  if (!Root)
1987    getRoot();
1988  Root->skip();
1989  Token &T = peekNext();
1990  if (T.Kind == Token::TK_StreamEnd)
1991    return false;
1992  if (T.Kind == Token::TK_DocumentEnd) {
1993    getNext();
1994    return skip();
1995  }
1996  return true;
1997}
1998
1999Token &Document::peekNext() {
2000  return stream.scanner->peekNext();
2001}
2002
2003Token Document::getNext() {
2004  return stream.scanner->getNext();
2005}
2006
2007void Document::setError(const Twine &Message, Token &Location) const {
2008  stream.scanner->setError(Message, Location.Range.begin());
2009}
2010
2011bool Document::failed() const {
2012  return stream.scanner->failed();
2013}
2014
2015Node *Document::parseBlockNode() {
2016  Token T = peekNext();
2017  // Handle properties.
2018  Token AnchorInfo;
2019parse_property:
2020  switch (T.Kind) {
2021  case Token::TK_Alias:
2022    getNext();
2023    return new (NodeAllocator) AliasNode(stream.CurrentDoc, T.Range.substr(1));
2024  case Token::TK_Anchor:
2025    if (AnchorInfo.Kind == Token::TK_Anchor) {
2026      setError("Already encountered an anchor for this node!", T);
2027      return 0;
2028    }
2029    AnchorInfo = getNext(); // Consume TK_Anchor.
2030    T = peekNext();
2031    goto parse_property;
2032  case Token::TK_Tag:
2033    getNext(); // Skip TK_Tag.
2034    T = peekNext();
2035    goto parse_property;
2036  default:
2037    break;
2038  }
2039
2040  switch (T.Kind) {
2041  case Token::TK_BlockEntry:
2042    // We got an unindented BlockEntry sequence. This is not terminated with
2043    // a BlockEnd.
2044    // Don't eat the TK_BlockEntry, SequenceNode needs it.
2045    return new (NodeAllocator) SequenceNode( stream.CurrentDoc
2046                                           , AnchorInfo.Range.substr(1)
2047                                           , SequenceNode::ST_Indentless);
2048  case Token::TK_BlockSequenceStart:
2049    getNext();
2050    return new (NodeAllocator)
2051      SequenceNode( stream.CurrentDoc
2052                  , AnchorInfo.Range.substr(1)
2053                  , SequenceNode::ST_Block);
2054  case Token::TK_BlockMappingStart:
2055    getNext();
2056    return new (NodeAllocator)
2057      MappingNode( stream.CurrentDoc
2058                 , AnchorInfo.Range.substr(1)
2059                 , MappingNode::MT_Block);
2060  case Token::TK_FlowSequenceStart:
2061    getNext();
2062    return new (NodeAllocator)
2063      SequenceNode( stream.CurrentDoc
2064                  , AnchorInfo.Range.substr(1)
2065                  , SequenceNode::ST_Flow);
2066  case Token::TK_FlowMappingStart:
2067    getNext();
2068    return new (NodeAllocator)
2069      MappingNode( stream.CurrentDoc
2070                 , AnchorInfo.Range.substr(1)
2071                 , MappingNode::MT_Flow);
2072  case Token::TK_Scalar:
2073    getNext();
2074    return new (NodeAllocator)
2075      ScalarNode( stream.CurrentDoc
2076                , AnchorInfo.Range.substr(1)
2077                , T.Range);
2078  case Token::TK_Key:
2079    // Don't eat the TK_Key, KeyValueNode expects it.
2080    return new (NodeAllocator)
2081      MappingNode( stream.CurrentDoc
2082                 , AnchorInfo.Range.substr(1)
2083                 , MappingNode::MT_Inline);
2084  case Token::TK_DocumentStart:
2085  case Token::TK_DocumentEnd:
2086  case Token::TK_StreamEnd:
2087  default:
2088    // TODO: Properly handle tags. "[!!str ]" should resolve to !!str "", not
2089    //       !!null null.
2090    return new (NodeAllocator) NullNode(stream.CurrentDoc);
2091  case Token::TK_Error:
2092    return 0;
2093  }
2094  llvm_unreachable("Control flow shouldn't reach here.");
2095  return 0;
2096}
2097
2098bool Document::parseDirectives() {
2099  bool isDirective = false;
2100  while (true) {
2101    Token T = peekNext();
2102    if (T.Kind == Token::TK_TagDirective) {
2103      handleTagDirective(getNext());
2104      isDirective = true;
2105    } else if (T.Kind == Token::TK_VersionDirective) {
2106      stream.handleYAMLDirective(getNext());
2107      isDirective = true;
2108    } else
2109      break;
2110  }
2111  return isDirective;
2112}
2113
2114bool Document::expectToken(int TK) {
2115  Token T = getNext();
2116  if (T.Kind != TK) {
2117    setError("Unexpected token", T);
2118    return false;
2119  }
2120  return true;
2121}
2122