1 //===- YAMLParser.h - Simple YAML parser ------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This is a YAML 1.2 parser.
10 //
11 // See http://www.yaml.org/spec/1.2/spec.html for the full standard.
12 //
13 // This currently does not implement the following:
14 // * Multi-line literal folding.
15 // * Tag resolution.
16 // * UTF-16.
17 // * BOMs anywhere other than the first Unicode scalar value in the file.
18 //
19 // The most important class here is Stream. This represents a YAML stream with
20 // 0, 1, or many documents.
21 //
22 // SourceMgr sm;
23 // StringRef input = getInput();
24 // yaml::Stream stream(input, sm);
25 //
26 // for (yaml::document_iterator di = stream.begin(), de = stream.end();
27 // di != de; ++di) {
28 // yaml::Node *n = di->getRoot();
29 // if (n) {
30 // // Do something with n...
31 // } else
32 // break;
33 // }
34 //
35 //===----------------------------------------------------------------------===//
36
37 #ifndef LLVM_SUPPORT_YAMLPARSER_H
38 #define LLVM_SUPPORT_YAMLPARSER_H
39
40 #include "llvm/ADT/StringRef.h"
41 #include "llvm/Support/Allocator.h"
42 #include "llvm/Support/SMLoc.h"
43 #include <cassert>
44 #include <cstddef>
45 #include <iterator>
46 #include <map>
47 #include <memory>
48 #include <string>
49 #include <system_error>
50
51 namespace llvm {
52
53 class MemoryBufferRef;
54 class SourceMgr;
55 class raw_ostream;
56 class Twine;
57
58 namespace yaml {
59
60 class Document;
61 class document_iterator;
62 class Node;
63 class Scanner;
64 struct Token;
65
66 /// Dump all the tokens in this stream to OS.
67 /// \returns true if there was an error, false otherwise.
68 bool dumpTokens(StringRef Input, raw_ostream &);
69
70 /// Scans all tokens in input without outputting anything. This is used
71 /// for benchmarking the tokenizer.
72 /// \returns true if there was an error, false otherwise.
73 bool scanTokens(StringRef Input);
74
75 /// Escape \a Input for a double quoted scalar; if \p EscapePrintable
76 /// is true, all UTF8 sequences will be escaped, if \p EscapePrintable is
77 /// false, those UTF8 sequences encoding printable unicode scalars will not be
78 /// escaped, but emitted verbatim.
79 std::string escape(StringRef Input, bool EscapePrintable = true);
80
81 /// This class represents a YAML stream potentially containing multiple
82 /// documents.
83 class Stream {
84 public:
85 /// This keeps a reference to the string referenced by \p Input.
86 Stream(StringRef Input, SourceMgr &, bool ShowColors = true,
87 std::error_code *EC = nullptr);
88
89 Stream(MemoryBufferRef InputBuffer, SourceMgr &, bool ShowColors = true,
90 std::error_code *EC = nullptr);
91 ~Stream();
92
93 document_iterator begin();
94 document_iterator end();
95 void skip();
96 bool failed();
97
validate()98 bool validate() {
99 skip();
100 return !failed();
101 }
102
103 void printError(Node *N, const Twine &Msg);
104
105 private:
106 friend class Document;
107
108 std::unique_ptr<Scanner> scanner;
109 std::unique_ptr<Document> CurrentDoc;
110 };
111
112 /// Abstract base class for all Nodes.
113 class Node {
114 virtual void anchor();
115
116 public:
117 enum NodeKind {
118 NK_Null,
119 NK_Scalar,
120 NK_BlockScalar,
121 NK_KeyValue,
122 NK_Mapping,
123 NK_Sequence,
124 NK_Alias
125 };
126
127 Node(unsigned int Type, std::unique_ptr<Document> &, StringRef Anchor,
128 StringRef Tag);
129
130 // It's not safe to copy YAML nodes; the document is streamed and the position
131 // is part of the state.
132 Node(const Node &) = delete;
133 void operator=(const Node &) = delete;
134
135 void *operator new(size_t Size, BumpPtrAllocator &Alloc,
136 size_t Alignment = 16) noexcept {
137 return Alloc.Allocate(Size, Alignment);
138 }
139
delete(void * Ptr,BumpPtrAllocator & Alloc,size_t Size)140 void operator delete(void *Ptr, BumpPtrAllocator &Alloc,
141 size_t Size) noexcept {
142 Alloc.Deallocate(Ptr, Size);
143 }
144
145 void operator delete(void *) noexcept = delete;
146
147 /// Get the value of the anchor attached to this node. If it does not
148 /// have one, getAnchor().size() will be 0.
getAnchor()149 StringRef getAnchor() const { return Anchor; }
150
151 /// Get the tag as it was written in the document. This does not
152 /// perform tag resolution.
getRawTag()153 StringRef getRawTag() const { return Tag; }
154
155 /// Get the verbatium tag for a given Node. This performs tag resoluton
156 /// and substitution.
157 std::string getVerbatimTag() const;
158
getSourceRange()159 SMRange getSourceRange() const { return SourceRange; }
setSourceRange(SMRange SR)160 void setSourceRange(SMRange SR) { SourceRange = SR; }
161
162 // These functions forward to Document and Scanner.
163 Token &peekNext();
164 Token getNext();
165 Node *parseBlockNode();
166 BumpPtrAllocator &getAllocator();
167 void setError(const Twine &Message, Token &Location) const;
168 bool failed() const;
169
skip()170 virtual void skip() {}
171
getType()172 unsigned int getType() const { return TypeID; }
173
174 protected:
175 std::unique_ptr<Document> &Doc;
176 SMRange SourceRange;
177
178 ~Node() = default;
179
180 private:
181 unsigned int TypeID;
182 StringRef Anchor;
183 /// The tag as typed in the document.
184 StringRef Tag;
185 };
186
187 /// A null value.
188 ///
189 /// Example:
190 /// !!null null
191 class NullNode final : public Node {
192 void anchor() override;
193
194 public:
NullNode(std::unique_ptr<Document> & D)195 NullNode(std::unique_ptr<Document> &D)
196 : Node(NK_Null, D, StringRef(), StringRef()) {}
197
classof(const Node * N)198 static bool classof(const Node *N) { return N->getType() == NK_Null; }
199 };
200
201 /// A scalar node is an opaque datum that can be presented as a
202 /// series of zero or more Unicode scalar values.
203 ///
204 /// Example:
205 /// Adena
206 class ScalarNode final : public Node {
207 void anchor() override;
208
209 public:
ScalarNode(std::unique_ptr<Document> & D,StringRef Anchor,StringRef Tag,StringRef Val)210 ScalarNode(std::unique_ptr<Document> &D, StringRef Anchor, StringRef Tag,
211 StringRef Val)
212 : Node(NK_Scalar, D, Anchor, Tag), Value(Val) {
213 SMLoc Start = SMLoc::getFromPointer(Val.begin());
214 SMLoc End = SMLoc::getFromPointer(Val.end());
215 SourceRange = SMRange(Start, End);
216 }
217
218 // Return Value without any escaping or folding or other fun YAML stuff. This
219 // is the exact bytes that are contained in the file (after conversion to
220 // utf8).
getRawValue()221 StringRef getRawValue() const { return Value; }
222
223 /// Gets the value of this node as a StringRef.
224 ///
225 /// \param Storage is used to store the content of the returned StringRef iff
226 /// it requires any modification from how it appeared in the source.
227 /// This happens with escaped characters and multi-line literals.
228 StringRef getValue(SmallVectorImpl<char> &Storage) const;
229
classof(const Node * N)230 static bool classof(const Node *N) {
231 return N->getType() == NK_Scalar;
232 }
233
234 private:
235 StringRef Value;
236
237 StringRef unescapeDoubleQuoted(StringRef UnquotedValue,
238 StringRef::size_type Start,
239 SmallVectorImpl<char> &Storage) const;
240 };
241
242 /// A block scalar node is an opaque datum that can be presented as a
243 /// series of zero or more Unicode scalar values.
244 ///
245 /// Example:
246 /// |
247 /// Hello
248 /// World
249 class BlockScalarNode final : public Node {
250 void anchor() override;
251
252 public:
BlockScalarNode(std::unique_ptr<Document> & D,StringRef Anchor,StringRef Tag,StringRef Value,StringRef RawVal)253 BlockScalarNode(std::unique_ptr<Document> &D, StringRef Anchor, StringRef Tag,
254 StringRef Value, StringRef RawVal)
255 : Node(NK_BlockScalar, D, Anchor, Tag), Value(Value) {
256 SMLoc Start = SMLoc::getFromPointer(RawVal.begin());
257 SMLoc End = SMLoc::getFromPointer(RawVal.end());
258 SourceRange = SMRange(Start, End);
259 }
260
261 /// Gets the value of this node as a StringRef.
getValue()262 StringRef getValue() const { return Value; }
263
classof(const Node * N)264 static bool classof(const Node *N) {
265 return N->getType() == NK_BlockScalar;
266 }
267
268 private:
269 StringRef Value;
270 };
271
272 /// A key and value pair. While not technically a Node under the YAML
273 /// representation graph, it is easier to treat them this way.
274 ///
275 /// TODO: Consider making this not a child of Node.
276 ///
277 /// Example:
278 /// Section: .text
279 class KeyValueNode final : public Node {
280 void anchor() override;
281
282 public:
KeyValueNode(std::unique_ptr<Document> & D)283 KeyValueNode(std::unique_ptr<Document> &D)
284 : Node(NK_KeyValue, D, StringRef(), StringRef()) {}
285
286 /// Parse and return the key.
287 ///
288 /// This may be called multiple times.
289 ///
290 /// \returns The key, or nullptr if failed() == true.
291 Node *getKey();
292
293 /// Parse and return the value.
294 ///
295 /// This may be called multiple times.
296 ///
297 /// \returns The value, or nullptr if failed() == true.
298 Node *getValue();
299
skip()300 void skip() override {
301 if (Node *Key = getKey()) {
302 Key->skip();
303 if (Node *Val = getValue())
304 Val->skip();
305 }
306 }
307
classof(const Node * N)308 static bool classof(const Node *N) {
309 return N->getType() == NK_KeyValue;
310 }
311
312 private:
313 Node *Key = nullptr;
314 Node *Value = nullptr;
315 };
316
317 /// This is an iterator abstraction over YAML collections shared by both
318 /// sequences and maps.
319 ///
320 /// BaseT must have a ValueT* member named CurrentEntry and a member function
321 /// increment() which must set CurrentEntry to 0 to create an end iterator.
322 template <class BaseT, class ValueT>
323 class basic_collection_iterator
324 : public std::iterator<std::input_iterator_tag, ValueT> {
325 public:
326 basic_collection_iterator() = default;
basic_collection_iterator(BaseT * B)327 basic_collection_iterator(BaseT *B) : Base(B) {}
328
329 ValueT *operator->() const {
330 assert(Base && Base->CurrentEntry && "Attempted to access end iterator!");
331 return Base->CurrentEntry;
332 }
333
334 ValueT &operator*() const {
335 assert(Base && Base->CurrentEntry &&
336 "Attempted to dereference end iterator!");
337 return *Base->CurrentEntry;
338 }
339
340 operator ValueT *() const {
341 assert(Base && Base->CurrentEntry && "Attempted to access end iterator!");
342 return Base->CurrentEntry;
343 }
344
345 /// Note on EqualityComparable:
346 ///
347 /// The iterator is not re-entrant,
348 /// it is meant to be used for parsing YAML on-demand
349 /// Once iteration started - it can point only to one entry at a time
350 /// hence Base.CurrentEntry and Other.Base.CurrentEntry are equal
351 /// iff Base and Other.Base are equal.
352 bool operator==(const basic_collection_iterator &Other) const {
353 if (Base && (Base == Other.Base)) {
354 assert((Base->CurrentEntry == Other.Base->CurrentEntry)
355 && "Equal Bases expected to point to equal Entries");
356 }
357
358 return Base == Other.Base;
359 }
360
361 bool operator!=(const basic_collection_iterator &Other) const {
362 return !(Base == Other.Base);
363 }
364
365 basic_collection_iterator &operator++() {
366 assert(Base && "Attempted to advance iterator past end!");
367 Base->increment();
368 // Create an end iterator.
369 if (!Base->CurrentEntry)
370 Base = nullptr;
371 return *this;
372 }
373
374 private:
375 BaseT *Base = nullptr;
376 };
377
378 // The following two templates are used for both MappingNode and Sequence Node.
379 template <class CollectionType>
begin(CollectionType & C)380 typename CollectionType::iterator begin(CollectionType &C) {
381 assert(C.IsAtBeginning && "You may only iterate over a collection once!");
382 C.IsAtBeginning = false;
383 typename CollectionType::iterator ret(&C);
384 ++ret;
385 return ret;
386 }
387
skip(CollectionType & C)388 template <class CollectionType> void skip(CollectionType &C) {
389 // TODO: support skipping from the middle of a parsed collection ;/
390 assert((C.IsAtBeginning || C.IsAtEnd) && "Cannot skip mid parse!");
391 if (C.IsAtBeginning)
392 for (typename CollectionType::iterator i = begin(C), e = C.end(); i != e;
393 ++i)
394 i->skip();
395 }
396
397 /// Represents a YAML map created from either a block map for a flow map.
398 ///
399 /// This parses the YAML stream as increment() is called.
400 ///
401 /// Example:
402 /// Name: _main
403 /// Scope: Global
404 class MappingNode final : public Node {
405 void anchor() override;
406
407 public:
408 enum MappingType {
409 MT_Block,
410 MT_Flow,
411 MT_Inline ///< An inline mapping node is used for "[key: value]".
412 };
413
MappingNode(std::unique_ptr<Document> & D,StringRef Anchor,StringRef Tag,MappingType MT)414 MappingNode(std::unique_ptr<Document> &D, StringRef Anchor, StringRef Tag,
415 MappingType MT)
416 : Node(NK_Mapping, D, Anchor, Tag), Type(MT) {}
417
418 friend class basic_collection_iterator<MappingNode, KeyValueNode>;
419
420 using iterator = basic_collection_iterator<MappingNode, KeyValueNode>;
421
422 template <class T> friend typename T::iterator yaml::begin(T &);
423 template <class T> friend void yaml::skip(T &);
424
begin()425 iterator begin() { return yaml::begin(*this); }
426
end()427 iterator end() { return iterator(); }
428
skip()429 void skip() override { yaml::skip(*this); }
430
classof(const Node * N)431 static bool classof(const Node *N) {
432 return N->getType() == NK_Mapping;
433 }
434
435 private:
436 MappingType Type;
437 bool IsAtBeginning = true;
438 bool IsAtEnd = false;
439 KeyValueNode *CurrentEntry = nullptr;
440
441 void increment();
442 };
443
444 /// Represents a YAML sequence created from either a block sequence for a
445 /// flow sequence.
446 ///
447 /// This parses the YAML stream as increment() is called.
448 ///
449 /// Example:
450 /// - Hello
451 /// - World
452 class SequenceNode final : public Node {
453 void anchor() override;
454
455 public:
456 enum SequenceType {
457 ST_Block,
458 ST_Flow,
459 // Use for:
460 //
461 // key:
462 // - val1
463 // - val2
464 //
465 // As a BlockMappingEntry and BlockEnd are not created in this case.
466 ST_Indentless
467 };
468
SequenceNode(std::unique_ptr<Document> & D,StringRef Anchor,StringRef Tag,SequenceType ST)469 SequenceNode(std::unique_ptr<Document> &D, StringRef Anchor, StringRef Tag,
470 SequenceType ST)
471 : Node(NK_Sequence, D, Anchor, Tag), SeqType(ST) {}
472
473 friend class basic_collection_iterator<SequenceNode, Node>;
474
475 using iterator = basic_collection_iterator<SequenceNode, Node>;
476
477 template <class T> friend typename T::iterator yaml::begin(T &);
478 template <class T> friend void yaml::skip(T &);
479
480 void increment();
481
begin()482 iterator begin() { return yaml::begin(*this); }
483
end()484 iterator end() { return iterator(); }
485
skip()486 void skip() override { yaml::skip(*this); }
487
classof(const Node * N)488 static bool classof(const Node *N) {
489 return N->getType() == NK_Sequence;
490 }
491
492 private:
493 SequenceType SeqType;
494 bool IsAtBeginning = true;
495 bool IsAtEnd = false;
496 bool WasPreviousTokenFlowEntry = true; // Start with an imaginary ','.
497 Node *CurrentEntry = nullptr;
498 };
499
500 /// Represents an alias to a Node with an anchor.
501 ///
502 /// Example:
503 /// *AnchorName
504 class AliasNode final : public Node {
505 void anchor() override;
506
507 public:
AliasNode(std::unique_ptr<Document> & D,StringRef Val)508 AliasNode(std::unique_ptr<Document> &D, StringRef Val)
509 : Node(NK_Alias, D, StringRef(), StringRef()), Name(Val) {}
510
getName()511 StringRef getName() const { return Name; }
512 Node *getTarget();
513
classof(const Node * N)514 static bool classof(const Node *N) { return N->getType() == NK_Alias; }
515
516 private:
517 StringRef Name;
518 };
519
520 /// A YAML Stream is a sequence of Documents. A document contains a root
521 /// node.
522 class Document {
523 public:
524 Document(Stream &ParentStream);
525
526 /// Root for parsing a node. Returns a single node.
527 Node *parseBlockNode();
528
529 /// Finish parsing the current document and return true if there are
530 /// more. Return false otherwise.
531 bool skip();
532
533 /// Parse and return the root level node.
getRoot()534 Node *getRoot() {
535 if (Root)
536 return Root;
537 return Root = parseBlockNode();
538 }
539
getTagMap()540 const std::map<StringRef, StringRef> &getTagMap() const { return TagMap; }
541
542 private:
543 friend class Node;
544 friend class document_iterator;
545
546 /// Stream to read tokens from.
547 Stream &stream;
548
549 /// Used to allocate nodes to. All are destroyed without calling their
550 /// destructor when the document is destroyed.
551 BumpPtrAllocator NodeAllocator;
552
553 /// The root node. Used to support skipping a partially parsed
554 /// document.
555 Node *Root;
556
557 /// Maps tag prefixes to their expansion.
558 std::map<StringRef, StringRef> TagMap;
559
560 Token &peekNext();
561 Token getNext();
562 void setError(const Twine &Message, Token &Location) const;
563 bool failed() const;
564
565 /// Parse %BLAH directives and return true if any were encountered.
566 bool parseDirectives();
567
568 /// Parse %YAML
569 void parseYAMLDirective();
570
571 /// Parse %TAG
572 void parseTAGDirective();
573
574 /// Consume the next token and error if it is not \a TK.
575 bool expectToken(int TK);
576 };
577
578 /// Iterator abstraction for Documents over a Stream.
579 class document_iterator {
580 public:
581 document_iterator() = default;
document_iterator(std::unique_ptr<Document> & D)582 document_iterator(std::unique_ptr<Document> &D) : Doc(&D) {}
583
584 bool operator==(const document_iterator &Other) const {
585 if (isAtEnd() || Other.isAtEnd())
586 return isAtEnd() && Other.isAtEnd();
587
588 return Doc == Other.Doc;
589 }
590 bool operator!=(const document_iterator &Other) const {
591 return !(*this == Other);
592 }
593
594 document_iterator operator++() {
595 assert(Doc && "incrementing iterator past the end.");
596 if (!(*Doc)->skip()) {
597 Doc->reset(nullptr);
598 } else {
599 Stream &S = (*Doc)->stream;
600 Doc->reset(new Document(S));
601 }
602 return *this;
603 }
604
605 Document &operator*() { return *Doc->get(); }
606
607 std::unique_ptr<Document> &operator->() { return *Doc; }
608
609 private:
isAtEnd()610 bool isAtEnd() const { return !Doc || !*Doc; }
611
612 std::unique_ptr<Document> *Doc = nullptr;
613 };
614
615 } // end namespace yaml
616
617 } // end namespace llvm
618
619 #endif // LLVM_SUPPORT_YAMLPARSER_H
620