1 //===- YAML.h ---------------------------------------------------*- C++ -*-===// 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 #ifndef LLVM_OBJECTYAML_YAML_H 11 #define LLVM_OBJECTYAML_YAML_H 12 13 #include "llvm/Support/YAMLTraits.h" 14 15 namespace llvm { 16 namespace yaml { 17 /// \brief Specialized YAMLIO scalar type for representing a binary blob. 18 /// 19 /// A typical use case would be to represent the content of a section in a 20 /// binary file. 21 /// This class has custom YAMLIO traits for convenient reading and writing. 22 /// It renders as a string of hex digits in a YAML file. 23 /// For example, it might render as `DEADBEEFCAFEBABE` (YAML does not 24 /// require the quotation marks, so for simplicity when outputting they are 25 /// omitted). 26 /// When reading, any string whose content is an even number of hex digits 27 /// will be accepted. 28 /// For example, all of the following are acceptable: 29 /// `DEADBEEF`, `"DeADbEeF"`, `"\x44EADBEEF"` (Note: '\x44' == 'D') 30 /// 31 /// A significant advantage of using this class is that it never allocates 32 /// temporary strings or buffers for any of its functionality. 33 /// 34 /// Example: 35 /// 36 /// The YAML mapping: 37 /// \code 38 /// Foo: DEADBEEFCAFEBABE 39 /// \endcode 40 /// 41 /// Could be modeled in YAMLIO by the struct: 42 /// \code 43 /// struct FooHolder { 44 /// BinaryRef Foo; 45 /// }; 46 /// namespace llvm { 47 /// namespace yaml { 48 /// template <> 49 /// struct MappingTraits<FooHolder> { 50 /// static void mapping(IO &IO, FooHolder &FH) { 51 /// IO.mapRequired("Foo", FH.Foo); 52 /// } 53 /// }; 54 /// } // end namespace yaml 55 /// } // end namespace llvm 56 /// \endcode 57 class BinaryRef { 58 friend bool operator==(const BinaryRef &LHS, const BinaryRef &RHS); 59 /// \brief Either raw binary data, or a string of hex bytes (must always 60 /// be an even number of characters). 61 ArrayRef<uint8_t> Data; 62 /// \brief Discriminator between the two states of the `Data` member. 63 bool DataIsHexString; 64 65 public: 66 BinaryRef(ArrayRef<uint8_t> Data) : Data(Data), DataIsHexString(false) {} 67 BinaryRef(StringRef Data) 68 : Data(reinterpret_cast<const uint8_t *>(Data.data()), Data.size()), 69 DataIsHexString(true) {} 70 BinaryRef() : DataIsHexString(true) {} 71 /// \brief The number of bytes that are represented by this BinaryRef. 72 /// This is the number of bytes that writeAsBinary() will write. 73 ArrayRef<uint8_t>::size_type binary_size() const { 74 if (DataIsHexString) 75 return Data.size() / 2; 76 return Data.size(); 77 } 78 /// \brief Write the contents (regardless of whether it is binary or a 79 /// hex string) as binary to the given raw_ostream. 80 void writeAsBinary(raw_ostream &OS) const; 81 /// \brief Write the contents (regardless of whether it is binary or a 82 /// hex string) as hex to the given raw_ostream. 83 /// 84 /// For example, a possible output could be `DEADBEEFCAFEBABE`. 85 void writeAsHex(raw_ostream &OS) const; 86 }; 87 88 inline bool operator==(const BinaryRef &LHS, const BinaryRef &RHS) { 89 // Special case for default constructed BinaryRef. 90 if (LHS.Data.empty() && RHS.Data.empty()) 91 return true; 92 93 return LHS.DataIsHexString == RHS.DataIsHexString && LHS.Data == RHS.Data; 94 } 95 96 template <> struct ScalarTraits<BinaryRef> { 97 static void output(const BinaryRef &, void *, llvm::raw_ostream &); 98 static StringRef input(StringRef, void *, BinaryRef &); 99 static bool mustQuote(StringRef S) { return needsQuotes(S); } 100 }; 101 } 102 } 103 #endif 104
