1 //===- YAML.h ---------------------------------------------------*- 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 #ifndef LLVM_OBJECTYAML_YAML_H 10 #define LLVM_OBJECTYAML_YAML_H 11 12 #include "llvm/ADT/ArrayRef.h" 13 #include "llvm/ADT/StringRef.h" 14 #include "llvm/Support/Compiler.h" 15 #include "llvm/Support/YAMLTraits.h" 16 #include <cstdint> 17 18 namespace llvm { 19 20 class raw_ostream; 21 22 namespace yaml { 23 24 /// 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 67 /// Either raw binary data, or a string of hex bytes (must always 68 /// be an even number of characters). 69 ArrayRef<uint8_t> Data; 70 71 /// Discriminator between the two states of the `Data` member. 72 bool DataIsHexString = true; 73 74 public: 75 BinaryRef() = default; BinaryRef(ArrayRef<uint8_t> Data)76 BinaryRef(ArrayRef<uint8_t> Data) : Data(Data), DataIsHexString(false) {} BinaryRef(StringRef Data)77 BinaryRef(StringRef Data) : Data(arrayRefFromStringRef(Data)) {} 78 79 /// The number of bytes that are represented by this BinaryRef. 80 /// This is the number of bytes that writeAsBinary() will write. binary_size()81 ArrayRef<uint8_t>::size_type binary_size() const { 82 if (DataIsHexString) 83 return Data.size() / 2; 84 return Data.size(); 85 } 86 87 /// Write the contents (regardless of whether it is binary or a 88 /// hex string) as binary to the given raw_ostream. 89 /// N can be used to specify the maximum number of bytes. 90 LLVM_ABI void writeAsBinary(raw_ostream &OS, uint64_t N = UINT64_MAX) const; 91 92 /// Write the contents (regardless of whether it is binary or a 93 /// hex string) as hex to the given raw_ostream. 94 /// 95 /// For example, a possible output could be `DEADBEEFCAFEBABE`. 96 LLVM_ABI void writeAsHex(raw_ostream &OS) const; 97 }; 98 99 inline bool operator==(const BinaryRef &LHS, const BinaryRef &RHS) { 100 // Special case for default constructed BinaryRef. 101 if (LHS.Data.empty() && RHS.Data.empty()) 102 return true; 103 104 return LHS.DataIsHexString == RHS.DataIsHexString && LHS.Data == RHS.Data; 105 } 106 107 template <> struct ScalarTraits<BinaryRef> { 108 LLVM_ABI static void output(const BinaryRef &, void *, raw_ostream &); 109 LLVM_ABI static StringRef input(StringRef, void *, BinaryRef &); 110 static QuotingType mustQuote(StringRef S) { return needsQuotes(S); } 111 }; 112 113 } // end namespace yaml 114 115 } // end namespace llvm 116 117 #endif // LLVM_OBJECTYAML_YAML_H 118