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// * Tag resolution.
15// * UTF-16.
16// * BOMs anywhere other than the first Unicode scalar value in the file.
17//
18// The most important class here is Stream. This represents a YAML stream with
19// 0, 1, or many documents.
20//
21// SourceMgr sm;
22// StringRef input = getInput();
23// yaml::Stream stream(input, sm);
24//
25// for (yaml::document_iterator di = stream.begin(), de = stream.end();
26// di != de; ++di) {
27// yaml::Node *n = di->getRoot();
28// if (n) {
29// // Do something with n...
30// } else
31// break;
32// }
33//
34//===----------------------------------------------------------------------===//
35
36#ifndef LLVM_SUPPORT_YAMLPARSER_H
37#define LLVM_SUPPORT_YAMLPARSER_H
38
39#include "llvm/ADT/StringRef.h"
40#include "llvm/Support/Allocator.h"
41#include "llvm/Support/SMLoc.h"
42#include "llvm/Support/SourceMgr.h"
43#include <cassert>
44#include <cstddef>
45#include <iterator>
46#include <map>
47#include <memory>
48#include <optional>
49#include <string>
50#include <system_error>
51
52namespace llvm {
53
54class MemoryBufferRef;
55class raw_ostream;
56class Twine;
57
58namespace yaml {
59
60class Document;
61class document_iterator;
62class Node;
63class Scanner;
64struct Token;
65
66/// Dump all the tokens in this stream to OS.
67/// \returns true if there was an error, false otherwise.
68bool 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.
73bool 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.
79std::string escape(StringRef Input, bool EscapePrintable = true);
80
81/// Parse \p S as a bool according to https://yaml.org/type/bool.html.
82std::optional<bool> parseBool(StringRef S);
83
84/// This class represents a YAML stream potentially containing multiple
85/// documents.
86class Stream {
87public:
88 /// This keeps a reference to the string referenced by \p Input.
89 Stream(StringRef Input, SourceMgr &, bool ShowColors = true,
90 std::error_code *EC = nullptr);
91
92 Stream(MemoryBufferRef InputBuffer, SourceMgr &, bool ShowColors = true,
93 std::error_code *EC = nullptr);
94 ~Stream();
95
96 document_iterator begin();
97 document_iterator end();
98 void skip();
99 bool failed();
100
101 bool validate() {
102 skip();
103 return !failed();
104 }
105
106 void printError(Node *N, const Twine &Msg,
107 SourceMgr::DiagKind Kind = SourceMgr::DK_Error);
108 void printError(const SMRange &Range, const Twine &Msg,
109 SourceMgr::DiagKind Kind = SourceMgr::DK_Error);
110
111private:
112 friend class Document;
113
114 std::unique_ptr<Scanner> scanner;
115 std::unique_ptr<Document> CurrentDoc;
116};
117
118/// Abstract base class for all Nodes.
119class Node {
120 virtual void anchor();
121
122public:
123 enum NodeKind {
124 NK_Null,
125 NK_Scalar,
126 NK_BlockScalar,
127 NK_KeyValue,
128 NK_Mapping,
129 NK_Sequence,
130 NK_Alias
131 };
132
133 Node(unsigned int Type, std::unique_ptr<Document> &, StringRef Anchor,
134 StringRef Tag);
135
136 // It's not safe to copy YAML nodes; the document is streamed and the position
137 // is part of the state.
138 Node(const Node &) = delete;
139 void operator=(const Node &) = delete;
140
141 void *operator new(size_t Size, BumpPtrAllocator &Alloc,
142 size_t Alignment = 16) noexcept {
143 return Alloc.Allocate(Size, Alignment);
144 }
145
146 void operator delete(void *Ptr, BumpPtrAllocator &Alloc,
147 size_t Size) noexcept {
148 Alloc.Deallocate(Ptr, Size, 0);
149 }
150
151 void operator delete(void *) noexcept = delete;
152
153 /// Get the value of the anchor attached to this node. If it does not
154 /// have one, getAnchor().size() will be 0.
155 StringRef getAnchor() const { return Anchor; }
156
157 /// Get the tag as it was written in the document. This does not
158 /// perform tag resolution.
159 StringRef getRawTag() const { return Tag; }
160
161 /// Get the verbatium tag for a given Node. This performs tag resoluton
162 /// and substitution.
163 std::string getVerbatimTag() const;
164
165 SMRange getSourceRange() const { return SourceRange; }
166 void setSourceRange(SMRange SR) { SourceRange = SR; }
167
168 // These functions forward to Document and Scanner.
169 Token &peekNext();
170 Token getNext();
171 Node *parseBlockNode();
172 BumpPtrAllocator &getAllocator();
173 void setError(const Twine &Message, Token &Location) const;
174 bool failed() const;
175
176 virtual void skip() {}
177
178 unsigned int getType() const { return TypeID; }
179
180protected:
181 std::unique_ptr<Document> &Doc;
182 SMRange SourceRange;
183
184 ~Node() = default;
185
186private:
187 unsigned int TypeID;
188 StringRef Anchor;
189 /// The tag as typed in the document.
190 StringRef Tag;
191};
192
193/// A null value.
194///
195/// Example:
196/// !!null null
197class NullNode final : public Node {
198 void anchor() override;
199
200public:
201 NullNode(std::unique_ptr<Document> &D)
202 : Node(NK_Null, D, StringRef(), StringRef()) {}
203
204 static bool classof(const Node *N) { return N->getType() == NK_Null; }
205};
206
207/// A scalar node is an opaque datum that can be presented as a
208/// series of zero or more Unicode scalar values.
209///
210/// Example:
211/// Adena
212class ScalarNode final : public Node {
213 void anchor() override;
214
215public:
216 ScalarNode(std::unique_ptr<Document> &D, StringRef Anchor, StringRef Tag,
217 StringRef Val)
218 : Node(NK_Scalar, D, Anchor, Tag), Value(Val) {
219 SMLoc Start = SMLoc::getFromPointer(Ptr: Val.begin());
220 SMLoc End = SMLoc::getFromPointer(Ptr: Val.end());
221 SourceRange = SMRange(Start, End);
222 }
223
224 // Return Value without any escaping or folding or other fun YAML stuff. This
225 // is the exact bytes that are contained in the file (after conversion to
226 // utf8).
227 StringRef getRawValue() const { return Value; }
228
229 /// Gets the value of this node as a StringRef.
230 ///
231 /// \param Storage is used to store the content of the returned StringRef if
232 /// it requires any modification from how it appeared in the source.
233 /// This happens with escaped characters and multi-line literals.
234 StringRef getValue(SmallVectorImpl<char> &Storage) const;
235
236 static bool classof(const Node *N) {
237 return N->getType() == NK_Scalar;
238 }
239
240private:
241 StringRef Value;
242
243 StringRef getDoubleQuotedValue(StringRef UnquotedValue,
244 SmallVectorImpl<char> &Storage) const;
245
246 static StringRef getSingleQuotedValue(StringRef RawValue,
247 SmallVectorImpl<char> &Storage);
248
249 static StringRef getPlainValue(StringRef RawValue,
250 SmallVectorImpl<char> &Storage);
251};
252
253/// A block scalar node is an opaque datum that can be presented as a
254/// series of zero or more Unicode scalar values.
255///
256/// Example:
257/// |
258/// Hello
259/// World
260class BlockScalarNode final : public Node {
261 void anchor() override;
262
263public:
264 BlockScalarNode(std::unique_ptr<Document> &D, StringRef Anchor, StringRef Tag,
265 StringRef Value, StringRef RawVal)
266 : Node(NK_BlockScalar, D, Anchor, Tag), Value(Value) {
267 SMLoc Start = SMLoc::getFromPointer(Ptr: RawVal.begin());
268 SMLoc End = SMLoc::getFromPointer(Ptr: RawVal.end());
269 SourceRange = SMRange(Start, End);
270 }
271
272 /// Gets the value of this node as a StringRef.
273 StringRef getValue() const { return Value; }
274
275 static bool classof(const Node *N) {
276 return N->getType() == NK_BlockScalar;
277 }
278
279private:
280 StringRef Value;
281};
282
283/// A key and value pair. While not technically a Node under the YAML
284/// representation graph, it is easier to treat them this way.
285///
286/// TODO: Consider making this not a child of Node.
287///
288/// Example:
289/// Section: .text
290class KeyValueNode final : public Node {
291 void anchor() override;
292
293public:
294 KeyValueNode(std::unique_ptr<Document> &D)
295 : Node(NK_KeyValue, D, StringRef(), StringRef()) {}
296
297 /// Parse and return the key.
298 ///
299 /// This may be called multiple times.
300 ///
301 /// \returns The key, or nullptr if failed() == true.
302 Node *getKey();
303
304 /// Parse and return the value.
305 ///
306 /// This may be called multiple times.
307 ///
308 /// \returns The value, or nullptr if failed() == true.
309 Node *getValue();
310
311 void skip() override {
312 if (Node *Key = getKey()) {
313 Key->skip();
314 if (Node *Val = getValue())
315 Val->skip();
316 }
317 }
318
319 static bool classof(const Node *N) {
320 return N->getType() == NK_KeyValue;
321 }
322
323private:
324 Node *Key = nullptr;
325 Node *Value = nullptr;
326};
327
328/// This is an iterator abstraction over YAML collections shared by both
329/// sequences and maps.
330///
331/// BaseT must have a ValueT* member named CurrentEntry and a member function
332/// increment() which must set CurrentEntry to 0 to create an end iterator.
333template <class BaseT, class ValueT> class basic_collection_iterator {
334public:
335 using iterator_category = std::input_iterator_tag;
336 using value_type = ValueT;
337 using difference_type = std::ptrdiff_t;
338 using pointer = value_type *;
339 using reference = value_type &;
340
341 basic_collection_iterator() = default;
342 basic_collection_iterator(BaseT *B) : Base(B) {}
343
344 ValueT *operator->() const {
345 assert(Base && Base->CurrentEntry && "Attempted to access end iterator!");
346 return Base->CurrentEntry;
347 }
348
349 ValueT &operator*() const {
350 assert(Base && Base->CurrentEntry &&
351 "Attempted to dereference end iterator!");
352 return *Base->CurrentEntry;
353 }
354
355 operator ValueT *() const {
356 assert(Base && Base->CurrentEntry && "Attempted to access end iterator!");
357 return Base->CurrentEntry;
358 }
359
360 /// Note on EqualityComparable:
361 ///
362 /// The iterator is not re-entrant,
363 /// it is meant to be used for parsing YAML on-demand
364 /// Once iteration started - it can point only to one entry at a time
365 /// hence Base.CurrentEntry and Other.Base.CurrentEntry are equal
366 /// iff Base and Other.Base are equal.
367 bool operator==(const basic_collection_iterator &Other) const {
368 if (Base && (Base == Other.Base)) {
369 assert((Base->CurrentEntry == Other.Base->CurrentEntry)
370 && "Equal Bases expected to point to equal Entries");
371 }
372
373 return Base == Other.Base;
374 }
375
376 bool operator!=(const basic_collection_iterator &Other) const {
377 return !(Base == Other.Base);
378 }
379
380 basic_collection_iterator &operator++() {
381 assert(Base && "Attempted to advance iterator past end!");
382 Base->increment();
383 // Create an end iterator.
384 if (!Base->CurrentEntry)
385 Base = nullptr;
386 return *this;
387 }
388
389private:
390 BaseT *Base = nullptr;
391};
392
393// The following two templates are used for both MappingNode and Sequence Node.
394template <class CollectionType>
395typename CollectionType::iterator begin(CollectionType &C) {
396 assert(C.IsAtBeginning && "You may only iterate over a collection once!");
397 C.IsAtBeginning = false;
398 typename CollectionType::iterator ret(&C);
399 ++ret;
400 return ret;
401}
402
403template <class CollectionType> void skip(CollectionType &C) {
404 // TODO: support skipping from the middle of a parsed collection ;/
405 assert((C.IsAtBeginning || C.IsAtEnd) && "Cannot skip mid parse!");
406 if (C.IsAtBeginning)
407 for (typename CollectionType::iterator i = begin(C), e = C.end(); i != e;
408 ++i)
409 i->skip();
410}
411
412/// Represents a YAML map created from either a block map for a flow map.
413///
414/// This parses the YAML stream as increment() is called.
415///
416/// Example:
417/// Name: _main
418/// Scope: Global
419class MappingNode final : public Node {
420 void anchor() override;
421
422public:
423 enum MappingType {
424 MT_Block,
425 MT_Flow,
426 MT_Inline ///< An inline mapping node is used for "[key: value]".
427 };
428
429 MappingNode(std::unique_ptr<Document> &D, StringRef Anchor, StringRef Tag,
430 MappingType MT)
431 : Node(NK_Mapping, D, Anchor, Tag), Type(MT) {}
432
433 friend class basic_collection_iterator<MappingNode, KeyValueNode>;
434
435 using iterator = basic_collection_iterator<MappingNode, KeyValueNode>;
436
437 template <class T> friend typename T::iterator yaml::begin(T &);
438 template <class T> friend void yaml::skip(T &);
439
440 iterator begin() { return yaml::begin(C&: *this); }
441
442 iterator end() { return iterator(); }
443
444 void skip() override { yaml::skip(C&: *this); }
445
446 static bool classof(const Node *N) {
447 return N->getType() == NK_Mapping;
448 }
449
450private:
451 MappingType Type;
452 bool IsAtBeginning = true;
453 bool IsAtEnd = false;
454 KeyValueNode *CurrentEntry = nullptr;
455
456 void increment();
457};
458
459/// Represents a YAML sequence created from either a block sequence for a
460/// flow sequence.
461///
462/// This parses the YAML stream as increment() is called.
463///
464/// Example:
465/// - Hello
466/// - World
467class SequenceNode final : public Node {
468 void anchor() override;
469
470public:
471 enum SequenceType {
472 ST_Block,
473 ST_Flow,
474 // Use for:
475 //
476 // key:
477 // - val1
478 // - val2
479 //
480 // As a BlockMappingEntry and BlockEnd are not created in this case.
481 ST_Indentless
482 };
483
484 SequenceNode(std::unique_ptr<Document> &D, StringRef Anchor, StringRef Tag,
485 SequenceType ST)
486 : Node(NK_Sequence, D, Anchor, Tag), SeqType(ST) {}
487
488 friend class basic_collection_iterator<SequenceNode, Node>;
489
490 using iterator = basic_collection_iterator<SequenceNode, Node>;
491
492 template <class T> friend typename T::iterator yaml::begin(T &);
493 template <class T> friend void yaml::skip(T &);
494
495 void increment();
496
497 iterator begin() { return yaml::begin(C&: *this); }
498
499 iterator end() { return iterator(); }
500
501 void skip() override { yaml::skip(C&: *this); }
502
503 static bool classof(const Node *N) {
504 return N->getType() == NK_Sequence;
505 }
506
507private:
508 SequenceType SeqType;
509 bool IsAtBeginning = true;
510 bool IsAtEnd = false;
511 bool WasPreviousTokenFlowEntry = true; // Start with an imaginary ','.
512 Node *CurrentEntry = nullptr;
513};
514
515/// Represents an alias to a Node with an anchor.
516///
517/// Example:
518/// *AnchorName
519class AliasNode final : public Node {
520 void anchor() override;
521
522public:
523 AliasNode(std::unique_ptr<Document> &D, StringRef Val)
524 : Node(NK_Alias, D, StringRef(), StringRef()), Name(Val) {}
525
526 StringRef getName() const { return Name; }
527
528 static bool classof(const Node *N) { return N->getType() == NK_Alias; }
529
530private:
531 StringRef Name;
532};
533
534/// A YAML Stream is a sequence of Documents. A document contains a root
535/// node.
536class Document {
537public:
538 Document(Stream &ParentStream);
539
540 /// Root for parsing a node. Returns a single node.
541 Node *parseBlockNode();
542
543 /// Finish parsing the current document and return true if there are
544 /// more. Return false otherwise.
545 bool skip();
546
547 /// Parse and return the root level node.
548 Node *getRoot() {
549 if (Root)
550 return Root;
551 return Root = parseBlockNode();
552 }
553
554 const std::map<StringRef, StringRef> &getTagMap() const { return TagMap; }
555
556private:
557 friend class Node;
558 friend class document_iterator;
559
560 /// Stream to read tokens from.
561 Stream &stream;
562
563 /// Used to allocate nodes to. All are destroyed without calling their
564 /// destructor when the document is destroyed.
565 BumpPtrAllocator NodeAllocator;
566
567 /// The root node. Used to support skipping a partially parsed
568 /// document.
569 Node *Root;
570
571 /// Maps tag prefixes to their expansion.
572 std::map<StringRef, StringRef> TagMap;
573
574 Token &peekNext();
575 Token getNext();
576 void setError(const Twine &Message, Token &Location) const;
577 bool failed() const;
578
579 /// Parse %BLAH directives and return true if any were encountered.
580 bool parseDirectives();
581
582 /// Parse %YAML
583 void parseYAMLDirective();
584
585 /// Parse %TAG
586 void parseTAGDirective();
587
588 /// Consume the next token and error if it is not \a TK.
589 bool expectToken(int TK);
590};
591
592/// Iterator abstraction for Documents over a Stream.
593class document_iterator {
594public:
595 document_iterator() = default;
596 document_iterator(std::unique_ptr<Document> &D) : Doc(&D) {}
597
598 bool operator==(const document_iterator &Other) const {
599 if (isAtEnd() || Other.isAtEnd())
600 return isAtEnd() && Other.isAtEnd();
601
602 return Doc == Other.Doc;
603 }
604 bool operator!=(const document_iterator &Other) const {
605 return !(*this == Other);
606 }
607
608 document_iterator operator++() {
609 assert(Doc && "incrementing iterator past the end.");
610 if (!(*Doc)->skip()) {
611 Doc->reset(p: nullptr);
612 } else {
613 Stream &S = (*Doc)->stream;
614 Doc->reset(p: new Document(S));
615 }
616 return *this;
617 }
618
619 Document &operator*() { return **Doc; }
620
621 std::unique_ptr<Document> &operator->() { return *Doc; }
622
623private:
624 bool isAtEnd() const { return !Doc || !*Doc; }
625
626 std::unique_ptr<Document> *Doc = nullptr;
627};
628
629} // end namespace yaml
630
631} // end namespace llvm
632
633#endif // LLVM_SUPPORT_YAMLPARSER_H
634