path: root/include/llvm/Support/YAMLTraits.h

//===- llvm/Supporrt/YAMLTraits.h -------------------------------*- C++ -*-===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_YAMLTRAITS_H
#define LLVM_SUPPORT_YAMLTRAITS_H


#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/YAMLParser.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/system_error.h"
#include "llvm/Support/type_traits.h"


namespace llvm {
namespace yaml {


/// This class should be specialized by any type that needs to be converted
/// to/from a YAML mapping.  For example:
///
///     struct ScalarBitSetTraits<MyStruct> {
///       static void mapping(IO &io, MyStruct &s) {
///         io.mapRequired("name", s.name);
///         io.mapRequired("size", s.size);
///         io.mapOptional("age",  s.age);
///       }
///     };
template<class T>
struct MappingTraits {
  // Must provide:
  // static void mapping(IO &io, T &fields);
};


/// This class should be specialized by any integral type that converts
/// to/from a YAML scalar where there is a one-to-one mapping between
/// in-memory values and a string in YAML.  For example:
///
///     struct ScalarEnumerationTraits<Colors> {
///         static void enumeration(IO &io, Colors &value) {
///           io.enumCase(value, "red",   cRed);
///           io.enumCase(value, "blue",  cBlue);
///           io.enumCase(value, "green", cGreen);
///         }
///       };
template<typename T>
struct ScalarEnumerationTraits {
  // Must provide:
  // static void enumeration(IO &io, T &value);
};


/// This class should be specialized by any integer type that is a union
/// of bit values and the YAML representation is a flow sequence of
/// strings.  For example:
///
///      struct ScalarBitSetTraits<MyFlags> {
///        static void bitset(IO &io, MyFlags &value) {
///          io.bitSetCase(value, "big",   flagBig);
///          io.bitSetCase(value, "flat",  flagFlat);
///          io.bitSetCase(value, "round", flagRound);
///        }
///      };
template<typename T>
struct ScalarBitSetTraits {
  // Must provide:
  // static void bitset(IO &io, T &value);
};


/// This class should be specialized by type that requires custom conversion
/// to/from a yaml scalar.  For example:
///
///    template<>
///    struct ScalarTraits<MyType> {
///      static void output(const MyType &val, void*, llvm::raw_ostream &out) {
///        // stream out custom formatting
///        out << llvm::format("%x", val);
///      }
///      static StringRef input(StringRef scalar, void*, MyType &value) {
///        // parse scalar and set `value`
///        // return empty string on success, or error string
///        return StringRef();
///      }
///    };
template<typename T>
struct ScalarTraits {
  // Must provide:
  //
  // Function to write the value as a string:
  //static void output(const T &value, void *ctxt, llvm::raw_ostream &out);
  //
  // Function to convert a string to a value.  Returns the empty
  // StringRef on success or an error string if string is malformed:
  //static StringRef input(StringRef scalar, void *ctxt, T &value);
};


/// This class should be specialized by any type that needs to be converted
/// to/from a YAML sequence.  For example:
///
///    template<>
///    struct SequenceTraits< std::vector<MyType> > {
///      static size_t size(IO &io, std::vector<MyType> &seq) {
///        return seq.size();
///      }
///      static MyType& element(IO &, std::vector<MyType> &seq, size_t index) {
///        if ( index >= seq.size() )
///          seq.resize(index+1);
///        return seq[index];
///      }
///    };
template<typename T>
struct SequenceTraits {
  // Must provide:
  // static size_t size(IO &io, T &seq);
  // static T::value_type& element(IO &io, T &seq, size_t index);
  //
  // The following is option and will cause generated YAML to use
  // a flow sequence (e.g. [a,b,c]).
  // static const bool flow = true;
};


/// This class should be specialized by any type that needs to be converted
/// to/from a list of YAML documents.
template<typename T>
struct DocumentListTraits {
  // Must provide:
  // static size_t size(IO &io, T &seq);
  // static T::value_type& element(IO &io, T &seq, size_t index);
};


// Only used by compiler if both template types are the same
template <typename T, T>
struct SameType;

// Only used for better diagnostics of missing traits
template <typename T>
struct MissingTrait;



// Test if ScalarEnumerationTraits<T> is defined on type T.
template <class T>
struct has_ScalarEnumerationTraits
{
  typedef void (*Signature_enumeration)(class IO&, T&);

  template <typename U>
  static char test(SameType<Signature_enumeration, &U::enumeration>*);

  template <typename U>
  static double test(...);

public:
  static bool const value = (sizeof(test<ScalarEnumerationTraits<T> >(0)) == 1);
};


// Test if ScalarBitSetTraits<T> is defined on type T.
template <class T>
struct has_ScalarBitSetTraits
{
  typedef void (*Signature_bitset)(class IO&, T&);

  template <typename U>
  static char test(SameType<Signature_bitset, &U::bitset>*);

  template <typename U>
  static double test(...);

public:
  static bool const value = (sizeof(test<ScalarBitSetTraits<T> >(0)) == 1);
};


// Test if ScalarTraits<T> is defined on type T.
template <class T>
struct has_ScalarTraits
{
  typedef StringRef (*Signature_input)(StringRef, void*, T&);
  typedef void (*Signature_output)(const T&, void*, llvm::raw_ostream&);

  template <typename U>