1 //===- YAML.h - YAMLIO utilities for object files ---------------*- 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 // This file declares utility classes for handling the YAML representation of 11 // object files. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_OBJECT_YAML_H 16 #define LLVM_OBJECT_YAML_H 17 18 #include "llvm/Support/YAMLTraits.h" 19 20 namespace llvm { 21 namespace object { 22 namespace yaml { 23 24 /// \brief Specialized YAMLIO scalar type for representing a binary blob. 25 /// 26 /// A typical use case would be to represent the content of a section in a 27 /// binary file. 28 /// This class has custom YAMLIO traits for convenient reading and writing. 29 /// It renders as a string of hex digits in a YAML file. 30 /// For example, it might render as `DEADBEEFCAFEBABE` (YAML does not 31 /// require the quotation marks, so for simplicity when outputting they are 32 /// omitted). 33 /// When reading, any string whose content is an even number of hex digits 34 /// will be accepted. 35 /// For example, all of the following are acceptable: 36 /// `DEADBEEF`, `"DeADbEeF"`, `"\x44EADBEEF"` (Note: '\x44' == 'D') 37 /// 38 /// A significant advantage of using this class is that it never allocates 39 /// temporary strings or buffers for any of its functionality. 40 /// 41 /// Example: 42 /// 43 /// The YAML mapping: 44 /// \code 45 /// Foo: DEADBEEFCAFEBABE 46 /// \endcode 47 /// 48 /// Could be modeled in YAMLIO by the struct: 49 /// \code 50 /// struct FooHolder { 51 /// BinaryRef Foo; 52 /// }; 53 /// namespace llvm { 54 /// namespace yaml { 55 /// template <> 56 /// struct MappingTraits<FooHolder> { 57 /// static void mapping(IO &IO, FooHolder &FH) { 58 /// IO.mapRequired("Foo", FH.Foo); 59 /// } 60 /// }; 61 /// } // end namespace yaml 62 /// } // end namespace llvm 63 /// \endcode 64 class BinaryRef { 65 friend bool operator==(const BinaryRef &LHS, const BinaryRef &RHS); 66 /// \brief Either raw binary data, or a string of hex bytes (must always 67 /// be an even number of characters). 68 ArrayRef<uint8_t> Data; 69 /// \brief Discriminator between the two states of the `Data` member. 70 bool DataIsHexString; 71 72 public: 73 BinaryRef(ArrayRef<uint8_t> Data) : Data(Data), DataIsHexString(false) {} 74 BinaryRef(StringRef Data) 75 : Data(reinterpret_cast<const uint8_t *>(Data.data()), Data.size()), 76 DataIsHexString(true) {} 77 BinaryRef() : DataIsHexString(true) {} 78 /// \brief The number of bytes that are represented by this BinaryRef. 79 /// This is the number of bytes that writeAsBinary() will write. 80 ArrayRef<uint8_t>::size_type binary_size() const { 81 if (DataIsHexString) 82 return Data.size() / 2; 83 return Data.size(); 84 } 85 /// \brief Write the contents (regardless of whether it is binary or a 86 /// hex string) as binary to the given raw_ostream. 87 void writeAsBinary(raw_ostream &OS) const; 88 /// \brief Write the contents (regardless of whether it is binary or a 89 /// hex string) as hex to the given raw_ostream. 90 /// 91 /// For example, a possible output could be `DEADBEEFCAFEBABE`. 92 void writeAsHex(raw_ostream &OS) const; 93 }; 94 95 inline bool operator==(const BinaryRef &LHS, const BinaryRef &RHS) { 96 // Special case for default constructed BinaryRef. 97 if (LHS.Data.empty() && RHS.Data.empty()) 98 return true; 99 100 return LHS.DataIsHexString == RHS.DataIsHexString && LHS.Data == RHS.Data; 101 } 102 103 } 104 } 105 106 namespace yaml { 107 template <> struct ScalarTraits<object::yaml::BinaryRef> { 108 static void output(const object::yaml::BinaryRef &, void *, 109 llvm::raw_ostream &); 110 static StringRef input(StringRef, void *, object::yaml::BinaryRef &); 111 }; 112 } 113 114 } 115 116 #endif 117
