YAMLTraits.h

Go to the documentation of this file.

//===- llvm/Support/YAMLTraits.h --------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_YAMLTRAITS_H
#define LLVM_SUPPORT_YAMLTRAITS_H

#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/AlignOf.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/SMLoc.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/YAMLParser.h"
#include "llvm/Support/raw_ostream.h"
#include <array>
#include <cassert>
#include <map>
#include <memory>
#include <new>
#include <optional>
#include <string>
#include <system_error>
#include <type_traits>
#include <vector>

namespace llvm {

class VersionTuple;

namespace yaml {

enum classNodeKind : uint8_t {
Scalar,
Map,
Sequence,
};

struct EmptyContext {};

/// This class should be specialized by any type that needs to be converted
/// to/from a YAML mapping. For example:
///
/// struct MappingTraits<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);
// Optionally may provide:
// static std::string validate(IO &io, T &fields);
// static void enumInput(IO &io, T &value);
//
// The optional flow flag will cause generated YAML to use a flow mapping
// (e.g. { a: 0, b: 1 }):
// static const bool flow = true;
};

/// This class is similar to MappingTraits<T> but allows you to pass in
/// additional context for each map operation. For example:
///
/// struct MappingContextTraits<MyStruct, MyContext> {
/// static void mapping(IO &io, MyStruct &s, MyContext &c) {
/// io.mapRequired("name", s.name);
/// io.mapRequired("size", s.size);
/// io.mapOptional("age", s.age);
/// ++c.TimesMapped;
/// }
/// };
template <class T, class Context> struct MappingContextTraits {
// Must provide:
// static void mapping(IO &io, T &fields, Context &Ctx);
// Optionally may provide:
// static std::string validate(IO &io, T &fields, Context &Ctx);
//
// The optional flow flag will cause generated YAML to use a flow mapping
// (e.g. { a: 0, b: 1 }):
// static const bool flow = true;
};

/// 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, typename Enable = void> 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, typename Enable = void> struct ScalarBitSetTraits {
// Must provide:
// static void bitset(IO &io, T &value);
};

/// Describe which type of quotes should be used when quoting is necessary.
/// Some non-printable characters need to be double-quoted, while some others
/// are fine with simple-quoting, and some don't need any quoting.
enum class QuotingType { None, Single, Double };

/// 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();
/// }
/// static QuotingType mustQuote(StringRef) { return QuotingType::Single; }
/// };
template <typename T, typename Enable = void> 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);
//
// Function to determine if the value should be quoted.
// static QuotingType mustQuote(StringRef);
};

/// This class should be specialized by type that requires custom conversion
/// to/from a YAML literal block scalar. For example:
///
/// template <>
/// struct BlockScalarTraits<MyType> {
/// static void output(const MyType &Value, void*, llvm::raw_ostream &Out)
/// {
/// // stream out custom formatting
/// Out << Value;
/// }
/// 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 BlockScalarTraits {
// Must provide:
//
// Function to write the value as a string:
// static void output(const T &Value, void *ctx, 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);
//
// Optional:
// static StringRef inputTag(T &Val, std::string Tag)
// static void outputTag(const T &Val, raw_ostream &Out)
};

/// This class should be specialized by type that requires custom conversion
/// to/from a YAML scalar with optional tags. For example:
///
/// template <>
/// struct TaggedScalarTraits<MyType> {
/// static void output(const MyType &Value, void*, llvm::raw_ostream
/// &ScalarOut, llvm::raw_ostream &TagOut)
/// {
/// // stream out custom formatting including optional Tag
/// Out << Value;
/// }
/// static StringRef input(StringRef Scalar, StringRef Tag, void*, MyType
/// &Value) {
/// // parse scalar and set `value`
/// // return empty string on success, or error string
/// return StringRef();
/// }
/// static QuotingType mustQuote(const MyType &Value, StringRef) {
/// return QuotingType::Single;
/// }
/// };
template <typename T> struct TaggedScalarTraits {
// Must provide:
//
// Function to write the value and tag as strings:
// static void output(const T &Value, void *ctx, llvm::raw_ostream &ScalarOut,
// llvm::raw_ostream &TagOut);
//
// 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, StringRef Tag, void *ctxt, T
// &Value);
//
// Function to determine if the value should be quoted.
// static QuotingType mustQuote(const T &Value, StringRef Scalar);
};

/// This class should be specialized by any type that needs to be converted
/// to/from a YAML sequence. For example:
///
/// template<>
/// struct SequenceTraits<MyContainer> {
/// static size_t size(IO &io, MyContainer &seq) {
/// return seq.size();
/// }
/// static MyType& element(IO &, MyContainer &seq, size_t index) {
/// if ( index >= seq.size() )
/// seq.resize(index+1);
/// return seq[index];
/// }
/// };
template<typename T, typename EnableIf = void>
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 for which vectors of that
/// type need to be converted to/from a YAML sequence.
template<typename T, typename EnableIf = void>
struct SequenceElementTraits {
// Must provide:
// static const bool flow;
};

/// 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);
};

/// This class should be specialized by any type that needs to be converted
/// to/from a YAML mapping in the case where the names of the keys are not known
/// in advance, e.g. a string map.
template <typename T>
struct CustomMappingTraits {
// static void inputOne(IO &io, StringRef key, T &elem);
// static void output(IO &io, T &elem);
};

/// This class should be specialized by any type that can be represented as
/// a scalar, map, or sequence, decided dynamically. For example:
///
/// typedef std::unique_ptr<MyBase> MyPoly;
///
/// template<>
/// struct PolymorphicTraits<MyPoly> {
/// static NodeKind getKind(const MyPoly &poly) {
/// return poly->getKind();
/// }
/// static MyScalar& getAsScalar(MyPoly &poly) {
/// if (!poly || !isa<MyScalar>(poly))
/// poly.reset(new MyScalar());
/// return *cast<MyScalar>(poly.get());
/// }
/// // ...
/// };
template <typename T> struct PolymorphicTraits {
// Must provide:
// static NodeKind getKind(const T &poly);
// static scalar_type &getAsScalar(T &poly);
// static map_type &getAsMap(T &poly);
// static sequence_type &getAsSequence(T &poly);
};

// 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
{
using Signature_enumeration = void (*)(class IO&, T&);

template <typename U>
staticchartest(SameType<Signature_enumeration, &U::enumeration>*);

template <typename U>
staticdoubletest(...);

staticboolconstvalue =
 (sizeof(test<ScalarEnumerationTraits<T>>(nullptr)) == 1);
};

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

template <typename U>
staticchartest(SameType<Signature_bitset, &U::bitset>*);

template <typename U>
staticdoubletest(...);

staticboolconstvalue = (sizeof(test<ScalarBitSetTraits<T>>(nullptr)) == 1);
};

// Test if ScalarTraits<T> is defined on type T.
template <class T>
struct has_ScalarTraits
{
using Signature_input = StringRef (*)(StringRef, void*, T&);
using Signature_output = void (*)(constT&, void*, raw_ostream&);
using Signature_mustQuote = QuotingType (*)(StringRef);

template <typename U>
staticchartest(SameType<Signature_input, &U::input> *,
 SameType<Signature_output, &U::output> *,
 SameType<Signature_mustQuote, &U::mustQuote> *);

template <typename U>
staticdoubletest(...);

staticboolconstvalue =
 (sizeof(test<ScalarTraits<T>>(nullptr, nullptr, nullptr)) == 1);
};

// Test if BlockScalarTraits<T> is defined on type T.
template <class T>
struct has_BlockScalarTraits
{
using Signature_input = StringRef (*)(StringRef, void *, T &);
using Signature_output = void (*)(constT &, void *, raw_ostream &);

template <typename U>
staticchartest(SameType<Signature_input, &U::input> *,
 SameType<Signature_output, &U::output> *);

template <typename U>
staticdoubletest(...);

staticboolconstvalue =
 (sizeof(test<BlockScalarTraits<T>>(nullptr, nullptr)) == 1);
};

// Test if TaggedScalarTraits<T> is defined on type T.
template <class T> struct has_TaggedScalarTraits {
using Signature_input = StringRef (*)(StringRef, StringRef, void *, T &);
using Signature_output = void (*)(constT &, void *, raw_ostream &,
 raw_ostream &);
using Signature_mustQuote = QuotingType (*)(constT &, StringRef);

template <typename U>
staticchartest(SameType<Signature_input, &U::input> *,
 SameType<Signature_output, &U::output> *,
 SameType<Signature_mustQuote, &U::mustQuote> *);

template <typename U> staticdoubletest(...);

staticboolconstvalue =
 (sizeof(test<TaggedScalarTraits<T>>(nullptr, nullptr, nullptr)) == 1);
};

// Test if MappingContextTraits<T> is defined on type T.
template <class T, class Context> struct has_MappingTraits {
using Signature_mapping = void (*)(class IO &, T &, Context &);

template <typename U>
staticchartest(SameType<Signature_mapping, &U::mapping>*);

template <typename U>
staticdoubletest(...);

staticboolconstvalue =
 (sizeof(test<MappingContextTraits<T, Context>>(nullptr)) == 1);
};

// Test if MappingTraits<T> is defined on type T.
template <class T> struct has_MappingTraits<T, EmptyContext> {
using Signature_mapping = void (*)(class IO &, T &);

template <typename U>
staticchartest(SameType<Signature_mapping, &U::mapping> *);

template <typename U> staticdoubletest(...);

staticboolconstvalue = (sizeof(test<MappingTraits<T>>(nullptr)) == 1);
};

// Test if MappingContextTraits<T>::validate() is defined on type T.
template <class T, class Context> struct has_MappingValidateTraits {
using Signature_validate = std::string (*)(class IO &, T &, Context &);

template <typename U>
staticchartest(SameType<Signature_validate, &U::validate>*);

template <typename U>
staticdoubletest(...);

staticboolconstvalue =
 (sizeof(test<MappingContextTraits<T, Context>>(nullptr)) == 1);
};

// Test if MappingTraits<T>::validate() is defined on type T.
template <class T> struct has_MappingValidateTraits<T, EmptyContext> {
using Signature_validate = std::string (*)(class IO &, T &);

template <typename U>
staticchartest(SameType<Signature_validate, &U::validate> *);

template <typename U> staticdoubletest(...);

staticboolconstvalue = (sizeof(test<MappingTraits<T>>(nullptr)) == 1);
};

// Test if MappingContextTraits<T>::enumInput() is defined on type T.
template <class T, class Context> struct has_MappingEnumInputTraits {
using Signature_validate = void (*)(class IO &, T &);

template <typename U>
staticchartest(SameType<Signature_validate, &U::enumInput> *);

template <typename U> staticdoubletest(...);

staticboolconstvalue =
 (sizeof(test<MappingContextTraits<T, Context>>(nullptr)) == 1);
};

// Test if MappingTraits<T>::enumInput() is defined on type T.
template <class T> struct has_MappingEnumInputTraits<T, EmptyContext> {
using Signature_validate = void (*)(class IO &, T &);

template <typename U>
staticchartest(SameType<Signature_validate, &U::enumInput> *);

template <typename U> staticdoubletest(...);

staticboolconstvalue = (sizeof(test<MappingTraits<T>>(nullptr)) == 1);
};

// Test if SequenceTraits<T> is defined on type T.
template <class T>
struct has_SequenceMethodTraits
{
using Signature_size = size_t (*)(class IO&, T&);

template <typename U>
staticchartest(SameType<Signature_size, &U::size>*);

template <typename U>
staticdoubletest(...);

staticboolconstvalue = (sizeof(test<SequenceTraits<T>>(nullptr)) == 1);
};

// Test if CustomMappingTraits<T> is defined on type T.
template <class T>
struct has_CustomMappingTraits
{
using Signature_input = void (*)(IO &io, StringRef key, T &v);

template <typename U>
staticchartest(SameType<Signature_input, &U::inputOne>*);

template <typename U>
staticdoubletest(...);

staticboolconstvalue =
 (sizeof(test<CustomMappingTraits<T>>(nullptr)) == 1);
};

// has_FlowTraits<int> will cause an error with some compilers because
// it subclasses int. Using this wrapper only instantiates the
// real has_FlowTraits only if the template type is a class.
template <typename T, bool Enabled = std::is_class_v<T>> class has_FlowTraits {
public:
staticconstboolvalue = false;
};

// Some older gcc compilers don't support straight forward tests
// for members, so test for ambiguity cause by the base and derived
// classes both defining the member.
template <class T>
struct has_FlowTraits<T, true>
{
struct Fallback { bool flow; };
struct Derived : T, Fallback { };

template<typename C>
staticchar (&f(SameType<bool Fallback::*, &C::flow>*))[1];

template<typename C>
staticchar (&f(...))[2];

staticboolconstvalue = sizeof(f<Derived>(nullptr)) == 2;
};

// Test if SequenceTraits<T> is defined on type T
template<typename T>
struct has_SequenceTraits : public std::integral_constant<bool,
 has_SequenceMethodTraits<T>::value > { };

// Test if DocumentListTraits<T> is defined on type T
template <class T>
struct has_DocumentListTraits
{
using Signature_size = size_t (*)(class IO &, T &);

template <typename U>
staticchartest(SameType<Signature_size, &U::size>*);

template <typename U>
staticdoubletest(...);

staticboolconstvalue = (sizeof(test<DocumentListTraits<T>>(nullptr))==1);
};

template <class T> struct has_PolymorphicTraits {
using Signature_getKind = NodeKind (*)(constT &);

template <typename U>
staticchartest(SameType<Signature_getKind, &U::getKind> *);

template <typename U> staticdoubletest(...);

staticboolconstvalue = (sizeof(test<PolymorphicTraits<T>>(nullptr)) == 1);
};

inlinebool isNumeric(StringRef S) {
constauto skipDigits = [](StringRef Input) {
return Input.ltrim("0123456789");
 };

// Make S.front() and S.drop_front().front() (if S.front() is [+-]) calls
// safe.
if (S.empty() || S == "+" || S == "-")
returnfalse;

if (S == ".nan" || S == ".NaN" || S == ".NAN")
returntrue;

// Infinity and decimal numbers can be prefixed with sign.
 StringRef Tail = (S.front() == '-' || S.front() == '+') ? S.drop_front() : S;

// Check for infinity first, because checking for hex and oct numbers is more
// expensive.
if (Tail == ".inf" || Tail == ".Inf" || Tail == ".INF")
returntrue;

// Section 10.3.2 Tag Resolution
// YAML 1.2 Specification prohibits Base 8 and Base 16 numbers prefixed with
// [-+], so S should be used instead of Tail.
if (S.starts_with("0o"))
return S.size() > 2 &&
 S.drop_front(2).find_first_not_of("01234567") == StringRef::npos;

if (S.starts_with("0x"))
return S.size() > 2 && S.drop_front(2).find_first_not_of(
"0123456789abcdefABCDEF") == StringRef::npos;

// Parse float: [-+]? (\. [0-9]+ | [0-9]+ (\. [0-9]* )?) ([eE] [-+]? [0-9]+)?
 S = Tail;

// Handle cases when the number starts with '.' and hence needs at least one
// digit after dot (as opposed by number which has digits before the dot), but
// doesn't have one.
if (S.starts_with(".") &&
 (S == "." ||
 (S.size() > 1 && std::strchr("0123456789", S[1]) == nullptr)))
returnfalse;

if (S.starts_with("E") || S.starts_with("e"))
returnfalse;

enum ParseState {
Default,
 FoundDot,
 FoundExponent,
 };
 ParseState State = Default;

 S = skipDigits(S);

// Accept decimal integer.
if (S.empty())
returntrue;

if (S.front() == '.') {
 State = FoundDot;
 S = S.drop_front();
 } elseif (S.front() == 'e' || S.front() == 'E') {
 State = FoundExponent;
 S = S.drop_front();
 } else {
returnfalse;
 }

if (State == FoundDot) {
 S = skipDigits(S);
if (S.empty())
returntrue;

if (S.front() == 'e' || S.front() == 'E') {
 State = FoundExponent;
 S = S.drop_front();
 } else {
returnfalse;
 }
 }

assert(State == FoundExponent && "Should have found exponent at this point.");
if (S.empty())
returnfalse;

if (S.front() == '+' || S.front() == '-') {
 S = S.drop_front();
if (S.empty())
returnfalse;
 }

return skipDigits(S).empty();
}

inlinebool isNull(StringRef S) {
return S == "null" || S == "Null" || S == "NULL" || S == "~";
}

inlinebool isBool(StringRef S) {
// FIXME: using parseBool is causing multiple tests to fail.
return S == "true" || S == "True" || S == "TRUE" || S == "false" ||
 S == "False" || S == "FALSE";
}

// 5.1. Character Set
// The allowed character range explicitly excludes the C0 control block #x0-#x1F
// (except for TAB #x9, LF #xA, and CR #xD which are allowed), DEL #x7F, the C1
// control block #x80-#x9F (except for NEL #x85 which is allowed), the surrogate
// block #xD800-#xDFFF, #xFFFE, and #xFFFF.
//
// Some strings are valid YAML values even unquoted, but without quotes are
// interpreted as non-string type, for instance null, boolean or numeric values.
// If ForcePreserveAsString is set, such strings are quoted.
inline QuotingType needsQuotes(StringRef S, bool ForcePreserveAsString = true) {
if (S.empty())
return QuotingType::Single;

 QuotingType MaxQuotingNeeded = QuotingType::None;
if (isSpace(static_cast<unsignedchar>(S.front())) ||
 isSpace(static_cast<unsignedchar>(S.back())))
 MaxQuotingNeeded = QuotingType::Single;
if (ForcePreserveAsString) {
if (isNull(S))
 MaxQuotingNeeded = QuotingType::Single;
if (isBool(S))
 MaxQuotingNeeded = QuotingType::Single;
if (isNumeric(S))
 MaxQuotingNeeded = QuotingType::Single;
 }

// 7.3.3 Plain Style
// Plain scalars must not begin with most indicators, as this would cause
// ambiguity with other YAML constructs.
if (std::strchr(R"(-?:\,[]{}#&*!|>'"%@`)", S[0]) != nullptr)
 MaxQuotingNeeded = QuotingType::Single;

for (unsignedcharC : S) {
// Alphanum is safe.
if (isAlnum(C))
continue;

switch (C) {
// Safe scalar characters.
case'_':
case'-':
case'^':
case'.':
case',':
case' ':
// TAB (0x9) is allowed in unquoted strings.
case 0x9:
continue;
// LF(0xA) and CR(0xD) may delimit values and so require at least single
// quotes. LLVM YAML parser cannot handle single quoted multiline so use
// double quoting to produce valid YAML.
case 0xA:
case 0xD:
return QuotingType::Double;
// DEL (0x7F) are excluded from the allowed character range.
case 0x7F:
return QuotingType::Double;
// Forward slash is allowed to be unquoted, but we quote it anyway. We have
// many tests that use FileCheck against YAML output, and this output often
// contains paths. If we quote backslashes but not forward slashes then
// paths will come out either quoted or unquoted depending on which platform
// the test is run on, making FileCheck comparisons difficult.
case'/':
default: {
// C0 control block (0x0 - 0x1F) is excluded from the allowed character
// range.
if (C <= 0x1F)
return QuotingType::Double;

// Always double quote UTF-8.
if ((C & 0x80) != 0)
return QuotingType::Double;

// The character is not safe, at least simple quoting needed.
 MaxQuotingNeeded = QuotingType::Single;
 }
 }
 }

return MaxQuotingNeeded;
}

template <typename T, typename Context>
struct missingTraits
 : public std::integral_constant<bool,
 !has_ScalarEnumerationTraits<T>::value &&
 !has_ScalarBitSetTraits<T>::value &&
 !has_ScalarTraits<T>::value &&
 !has_BlockScalarTraits<T>::value &&
 !has_TaggedScalarTraits<T>::value &&
 !has_MappingTraits<T, Context>::value &&
 !has_SequenceTraits<T>::value &&
 !has_CustomMappingTraits<T>::value &&
 !has_DocumentListTraits<T>::value &&
 !has_PolymorphicTraits<T>::value> {};

template <typename T, typename Context>
struct validatedMappingTraits
 : public std::integral_constant<
 bool, has_MappingTraits<T, Context>::value &&
 has_MappingValidateTraits<T, Context>::value> {};

template <typename T, typename Context>
struct unvalidatedMappingTraits
 : public std::integral_constant<
 bool, has_MappingTraits<T, Context>::value &&
 !has_MappingValidateTraits<T, Context>::value> {};

// Base class for Input and Output.
class IO {
public:
 IO(void *Ctxt = nullptr);
virtual ~IO();

virtualbool outputting() const = 0;

virtualunsigned beginSequence() = 0;
virtualbool preflightElement(unsigned, void *&) = 0;
virtualvoid postflightElement(void*) = 0;
virtualvoid endSequence() = 0;
virtualbool canElideEmptySequence() = 0;

virtualunsigned beginFlowSequence() = 0;
virtualbool preflightFlowElement(unsigned, void *&) = 0;
virtualvoid postflightFlowElement(void*) = 0;
virtualvoid endFlowSequence() = 0;

virtualbool mapTag(StringRef Tag, boolDefault=false) = 0;
virtualvoid beginMapping() = 0;
virtualvoid endMapping() = 0;
virtualbool preflightKey(constchar*, bool, bool, bool &, void *&) = 0;
virtualvoid postflightKey(void*) = 0;
virtual std::vector<StringRef> keys() = 0;

virtualvoid beginFlowMapping() = 0;
virtualvoid endFlowMapping() = 0;

virtualvoid beginEnumScalar() = 0;
virtualbool matchEnumScalar(constchar*, bool) = 0;
virtualbool matchEnumFallback() = 0;
virtualvoid endEnumScalar() = 0;

virtualbool beginBitSetScalar(bool &) = 0;
virtualbool bitSetMatch(constchar*, bool) = 0;
virtualvoid endBitSetScalar() = 0;

virtualvoid scalarString(StringRef &, QuotingType) = 0;
virtualvoid blockScalarString(StringRef &) = 0;
virtualvoid scalarTag(std::string &) = 0;

virtualNodeKind getNodeKind() = 0;

virtualvoid setError(const Twine &) = 0;
virtualvoid setAllowUnknownKeys(bool Allow);

template <typename T>
void enumCase(T &Val, constchar* Str, constT ConstVal) {
if ( matchEnumScalar(Str, outputting() && Val == ConstVal) ) {
 Val = ConstVal;
 }
 }

// allow anonymous enum values to be used with LLVM_YAML_STRONG_TYPEDEF
template <typename T>
void enumCase(T &Val, constchar* Str, constuint32_t ConstVal) {
if ( matchEnumScalar(Str, outputting() && Val == static_cast<T>(ConstVal)) ) {
 Val = ConstVal;
 }
 }

template <typename FBT, typename T>
void enumFallback(T &Val) {
if (matchEnumFallback()) {
 EmptyContext Context;
// FIXME: Force integral conversion to allow strong typedefs to convert.
 FBT Res = static_cast<typename FBT::BaseType>(Val);
 yamlize(*this, Res, true, Context);
 Val = static_cast<T>(static_cast<typename FBT::BaseType>(Res));
 }
 }

template <typename T>
void bitSetCase(T &Val, constchar* Str, constT ConstVal) {
if ( bitSetMatch(Str, outputting() && (Val & ConstVal) == ConstVal) ) {
 Val = static_cast<T>(Val | ConstVal);
 }
 }

// allow anonymous enum values to be used with LLVM_YAML_STRONG_TYPEDEF
template <typename T>
void bitSetCase(T &Val, constchar* Str, constuint32_t ConstVal) {
if ( bitSetMatch(Str, outputting() && (Val & ConstVal) == ConstVal) ) {
 Val = static_cast<T>(Val | ConstVal);
 }
 }

template <typename T>
void maskedBitSetCase(T &Val, constchar *Str, T ConstVal, T Mask) {
if (bitSetMatch(Str, outputting() && (Val & Mask) == ConstVal))
 Val = Val | ConstVal;
 }

template <typename T>
void maskedBitSetCase(T &Val, constchar *Str, uint32_t ConstVal,
uint32_t Mask) {
if (bitSetMatch(Str, outputting() && (Val & Mask) == ConstVal))
 Val = Val | ConstVal;
 }

void *getContext() const;
void setContext(void *);

template <typename T> void mapRequired(constchar *Key, T &Val) {
 EmptyContext Ctx;
 this->processKey(Key, Val, true, Ctx);
 }

template <typename T, typename Context>
void mapRequired(constchar *Key, T &Val, Context &Ctx) {
 this->processKey(Key, Val, true, Ctx);
 }

template <typename T> voidmapOptional(constchar *Key, T &Val) {
 EmptyContext Ctx;
 mapOptionalWithContext(Key, Val, Ctx);
 }

template <typename T, typename DefaultT>
voidmapOptional(constchar *Key, T &Val, const DefaultT &Default) {
 EmptyContext Ctx;
 mapOptionalWithContext(Key, Val, Default, Ctx);
 }

template <typename T, typename Context>
 std::enable_if_t<has_SequenceTraits<T>::value, void>
 mapOptionalWithContext(constchar *Key, T &Val, Context &Ctx) {
// omit key/value instead of outputting empty sequence
if (this->canElideEmptySequence() && !(Val.begin() != Val.end()))
return;
 this->processKey(Key, Val, false, Ctx);
 }

template <typename T, typename Context>
void mapOptionalWithContext(constchar *Key, std::optional<T> &Val,
 Context &Ctx) {
 this->processKeyWithDefault(Key, Val, std::optional<T>(),
/*Required=*/false, Ctx);
 }

template <typename T, typename Context>
 std::enable_if_t<!has_SequenceTraits<T>::value, void>
 mapOptionalWithContext(constchar *Key, T &Val, Context &Ctx) {
 this->processKey(Key, Val, false, Ctx);
 }

template <typename T, typename Context, typename DefaultT>
void mapOptionalWithContext(constchar *Key, T &Val, const DefaultT &Default,
 Context &Ctx) {
static_assert(std::is_convertible<DefaultT, T>::value,
"Default type must be implicitly convertible to value type!");
 this->processKeyWithDefault(Key, Val, static_cast<const T &>(Default),
false, Ctx);
 }

private:
template <typename T, typename Context>
void processKeyWithDefault(constchar *Key, std::optional<T> &Val,
const std::optional<T> &DefaultValue,
bool Required, Context &Ctx);

template <typename T, typename Context>
void processKeyWithDefault(constchar *Key, T &Val, constT &DefaultValue,
bool Required, Context &Ctx) {
void *SaveInfo;
bool UseDefault;
constbool sameAsDefault = outputting() && Val == DefaultValue;
if ( this->preflightKey(Key, Required, sameAsDefault, UseDefault,
 SaveInfo) ) {
 yamlize(*this, Val, Required, Ctx);
 this->postflightKey(SaveInfo);
 }
else {
if ( UseDefault )
 Val = DefaultValue;
 }
 }

template <typename T, typename Context>
void processKey(constchar *Key, T &Val, bool Required, Context &Ctx) {
void *SaveInfo;
bool UseDefault;
if ( this->preflightKey(Key, Required, false, UseDefault, SaveInfo) ) {
 yamlize(*this, Val, Required, Ctx);
 this->postflightKey(SaveInfo);
 }
 }

private:
void *Ctxt;
};

namespace detail {

template <typename T, typename Context>
void doMapping(IO &io, T &Val, Context &Ctx) {
 MappingContextTraits<T, Context>::mapping(io, Val, Ctx);
}

template <typename T> void doMapping(IO &io, T &Val, EmptyContext &Ctx) {
 MappingTraits<T>::mapping(io, Val);
}

} // end namespace detail

template <typename T>
std::enable_if_t<has_ScalarEnumerationTraits<T>::value, void>
yamlize(IO &io, T &Val, bool, EmptyContext &Ctx) {
 io.beginEnumScalar();
 ScalarEnumerationTraits<T>::enumeration(io, Val);
 io.endEnumScalar();
}

template <typename T>
std::enable_if_t<has_ScalarBitSetTraits<T>::value, void>
yamlize(IO &io, T &Val, bool, EmptyContext &Ctx) {
bool DoClear;
if ( io.beginBitSetScalar(DoClear) ) {
if ( DoClear )
 Val = T();
 ScalarBitSetTraits<T>::bitset(io, Val);
 io.endBitSetScalar();
 }
}

template <typename T>
std::enable_if_t<has_ScalarTraits<T>::value, void> yamlize(IO &io, T &Val, bool,
 EmptyContext &Ctx) {
if ( io.outputting() ) {
 SmallString<128> Storage;
 raw_svector_ostream Buffer(Storage);
 ScalarTraits<T>::output(Val, io.getContext(), Buffer);
 StringRef Str = Buffer.str();
 io.scalarString(Str, ScalarTraits<T>::mustQuote(Str));
 }
else {
 StringRef Str;
 io.scalarString(Str, ScalarTraits<T>::mustQuote(Str));
 StringRef Result = ScalarTraits<T>::input(Str, io.getContext(), Val);
if ( !Result.empty() ) {
 io.setError(Twine(Result));
 }
 }
}

template <typename T>
std::enable_if_t<has_BlockScalarTraits<T>::value, void>
yamlize(IO &YamlIO, T &Val, bool, EmptyContext &Ctx) {
if (YamlIO.outputting()) {
 std::string Storage;
 raw_string_ostream Buffer(Storage);
 BlockScalarTraits<T>::output(Val, YamlIO.getContext(), Buffer);
 StringRef Str(Storage);
YamlIO.blockScalarString(Str);
 } else {
 StringRef Str;
YamlIO.blockScalarString(Str);
 StringRef Result =
 BlockScalarTraits<T>::input(Str, YamlIO.getContext(), Val);
if (!Result.empty())
YamlIO.setError(Twine(Result));
 }
}

template <typename T>
std::enable_if_t<has_TaggedScalarTraits<T>::value, void>
yamlize(IO &io, T &Val, bool, EmptyContext &Ctx) {
if (io.outputting()) {
 std::string ScalarStorage, TagStorage;
 raw_string_ostream ScalarBuffer(ScalarStorage), TagBuffer(TagStorage);
 TaggedScalarTraits<T>::output(Val, io.getContext(), ScalarBuffer,
 TagBuffer);
 io.scalarTag(TagStorage);
 StringRef ScalarStr(ScalarStorage);
 io.scalarString(ScalarStr,
 TaggedScalarTraits<T>::mustQuote(Val, ScalarStr));
 } else {
 std::string Tag;
 io.scalarTag(Tag);
 StringRef Str;
 io.scalarString(Str, QuotingType::None);
 StringRef Result =
 TaggedScalarTraits<T>::input(Str, Tag, io.getContext(), Val);
if (!Result.empty()) {
 io.setError(Twine(Result));
 }
 }
}

namespace detail {

template <typename T, typename Context>
std::string doValidate(IO &io, T &Val, Context &Ctx) {
return MappingContextTraits<T, Context>::validate(io, Val, Ctx);
}

template <typename T> std::string doValidate(IO &io, T &Val, EmptyContext &) {
return MappingTraits<T>::validate(io, Val);
}

} // namespace detail

template <typename T, typename Context>
std::enable_if_t<validatedMappingTraits<T, Context>::value, void>
yamlize(IO &io, T &Val, bool, Context &Ctx) {
if (has_FlowTraits<MappingTraits<T>>::value)
 io.beginFlowMapping();
else
 io.beginMapping();
if (io.outputting()) {
 std::string Err = detail::doValidate(io, Val, Ctx);
if (!Err.empty()) {
errs() << Err << "\n";
assert(Err.empty() && "invalid struct trying to be written as yaml");
 }
 }
 detail::doMapping(io, Val, Ctx);
if (!io.outputting()) {
 std::string Err = detail::doValidate(io, Val, Ctx);
if (!Err.empty())
 io.setError(Err);
 }
if (has_FlowTraits<MappingTraits<T>>::value)
 io.endFlowMapping();
else
 io.endMapping();
}

template <typename T, typename Context>
std::enable_if_t<!has_MappingEnumInputTraits<T, Context>::value, bool>
yamlizeMappingEnumInput(IO &io, T &Val) {
returnfalse;
}

template <typename T, typename Context>
std::enable_if_t<has_MappingEnumInputTraits<T, Context>::value, bool>
yamlizeMappingEnumInput(IO &io, T &Val) {
if (io.outputting())
returnfalse;

 io.beginEnumScalar();
 MappingTraits<T>::enumInput(io, Val);
bool Matched = !io.matchEnumFallback();
 io.endEnumScalar();
return Matched;
}

template <typename T, typename Context>
std::enable_if_t<unvalidatedMappingTraits<T, Context>::value, void>
yamlize(IO &io, T &Val, bool, Context &Ctx) {
if (yamlizeMappingEnumInput<T, Context>(io, Val))
return;
if (has_FlowTraits<MappingTraits<T>>::value) {
 io.beginFlowMapping();
 detail::doMapping(io, Val, Ctx);
 io.endFlowMapping();
 } else {
 io.beginMapping();
 detail::doMapping(io, Val, Ctx);
 io.endMapping();
 }
}

template <typename T>
std::enable_if_t<has_CustomMappingTraits<T>::value, void>
yamlize(IO &io, T &Val, bool, EmptyContext &Ctx) {
if ( io.outputting() ) {
 io.beginMapping();
 CustomMappingTraits<T>::output(io, Val);
 io.endMapping();
 } else {
 io.beginMapping();
for (StringRef key : io.keys())
 CustomMappingTraits<T>::inputOne(io, key, Val);
 io.endMapping();
 }
}

template <typename T>
std::enable_if_t<has_PolymorphicTraits<T>::value, void>
yamlize(IO &io, T &Val, bool, EmptyContext &Ctx) {
switch (io.outputting() ? PolymorphicTraits<T>::getKind(Val)
 : io.getNodeKind()) {
case NodeKind::Scalar:
return yamlize(io, PolymorphicTraits<T>::getAsScalar(Val), true, Ctx);
case NodeKind::Map:
return yamlize(io, PolymorphicTraits<T>::getAsMap(Val), true, Ctx);
case NodeKind::Sequence:
return yamlize(io, PolymorphicTraits<T>::getAsSequence(Val), true, Ctx);
 }
}

template <typename T>
std::enable_if_t<missingTraits<T, EmptyContext>::value, void>
yamlize(IO &io, T &Val, bool, EmptyContext &Ctx) {
char missing_yaml_trait_for_type[sizeof(MissingTrait<T>)];
}

template <typename T, typename Context>
std::enable_if_t<has_SequenceTraits<T>::value, void>
yamlize(IO &io, T &Seq, bool, Context &Ctx) {
if ( has_FlowTraits< SequenceTraits<T>>::value ) {
unsigned incnt = io.beginFlowSequence();
unsignedcount = io.outputting() ? SequenceTraits<T>::size(io, Seq) : incnt;
for(unsigned i=0; i < count; ++i) {
void *SaveInfo;
if ( io.preflightFlowElement(i, SaveInfo) ) {
 yamlize(io, SequenceTraits<T>::element(io, Seq, i), true, Ctx);
 io.postflightFlowElement(SaveInfo);
 }
 }
 io.endFlowSequence();
 }
else {
unsigned incnt = io.beginSequence();
unsignedcount = io.outputting() ? SequenceTraits<T>::size(io, Seq) : incnt;
for(unsigned i=0; i < count; ++i) {
void *SaveInfo;
if ( io.preflightElement(i, SaveInfo) ) {
 yamlize(io, SequenceTraits<T>::element(io, Seq, i), true, Ctx);
 io.postflightElement(SaveInfo);
 }
 }
 io.endSequence();
 }
}

template<>
struct ScalarTraits<bool> {
staticvoid output(constbool &, void* , raw_ostream &);
static StringRef input(StringRef, void *, bool &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<StringRef> {
staticvoid output(const StringRef &, void *, raw_ostream &);
static StringRef input(StringRef, void *, StringRef &);
static QuotingType mustQuote(StringRef S) { return needsQuotes(S); }
};

template<>
struct ScalarTraits<std::string> {
staticvoid output(const std::string &, void *, raw_ostream &);
static StringRef input(StringRef, void *, std::string &);
static QuotingType mustQuote(StringRef S) { return needsQuotes(S); }
};

template<>
struct ScalarTraits<uint8_t> {
staticvoid output(constuint8_t &, void *, raw_ostream &);
static StringRef input(StringRef, void *, uint8_t &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<uint16_t> {
staticvoid output(constuint16_t &, void *, raw_ostream &);
static StringRef input(StringRef, void *, uint16_t &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<uint32_t> {
staticvoid output(constuint32_t &, void *, raw_ostream &);
static StringRef input(StringRef, void *, uint32_t &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<uint64_t> {
staticvoid output(constuint64_t &, void *, raw_ostream &);
static StringRef input(StringRef, void *, uint64_t &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<int8_t> {
staticvoid output(const int8_t &, void *, raw_ostream &);
static StringRef input(StringRef, void *, int8_t &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<int16_t> {
staticvoid output(const int16_t &, void *, raw_ostream &);
static StringRef input(StringRef, void *, int16_t &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<int32_t> {
staticvoid output(const int32_t &, void *, raw_ostream &);
static StringRef input(StringRef, void *, int32_t &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<int64_t> {
staticvoid output(const int64_t &, void *, raw_ostream &);
static StringRef input(StringRef, void *, int64_t &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<float> {
staticvoid output(constfloat &, void *, raw_ostream &);
static StringRef input(StringRef, void *, float &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<double> {
staticvoid output(constdouble &, void *, raw_ostream &);
static StringRef input(StringRef, void *, double &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

// For endian types, we use existing scalar Traits class for the underlying
// type. This way endian aware types are supported whenever the traits are
// defined for the underlying type.
template <typename value_type, llvm::endianness endian, size_t alignment>
struct ScalarTraits<support::detail::packed_endian_specific_integral<
 value_type, endian, alignment>,
 std::enable_if_t<has_ScalarTraits<value_type>::value>> {
using endian_type =
 support::detail::packed_endian_specific_integral<value_type, endian,
 alignment>;

staticvoid output(const endian_type &E, void *Ctx, raw_ostream &Stream) {
 ScalarTraits<value_type>::output(static_cast<value_type>(E), Ctx, Stream);
 }

static StringRef input(StringRef Str, void *Ctx, endian_type &E) {
 value_type V;
autoR = ScalarTraits<value_type>::input(Str, Ctx, V);
E = static_cast<endian_type>(V);
returnR;
 }

static QuotingType mustQuote(StringRef Str) {
return ScalarTraits<value_type>::mustQuote(Str);
 }
};

template <typename value_type, llvm::endianness endian, size_t alignment>
struct ScalarEnumerationTraits<
 support::detail::packed_endian_specific_integral<value_type, endian,
 alignment>,
 std::enable_if_t<has_ScalarEnumerationTraits<value_type>::value>> {
using endian_type =
 support::detail::packed_endian_specific_integral<value_type, endian,
 alignment>;

staticvoid enumeration(IO &io, endian_type &E) {
 value_type V = E;
 ScalarEnumerationTraits<value_type>::enumeration(io, V);
E = V;
 }
};

template <typename value_type, llvm::endianness endian, size_t alignment>
struct ScalarBitSetTraits<
 support::detail::packed_endian_specific_integral<value_type, endian,
 alignment>,
 std::enable_if_t<has_ScalarBitSetTraits<value_type>::value>> {
using endian_type =
 support::detail::packed_endian_specific_integral<value_type, endian,
 alignment>;
staticvoid bitset(IO &io, endian_type &E) {
 value_type V = E;
 ScalarBitSetTraits<value_type>::bitset(io, V);
E = V;
 }
};

// Utility for use within MappingTraits<>::mapping() method
// to [de]normalize an object for use with YAML conversion.
template <typename TNorm, typename TFinal>
struct MappingNormalization {
 MappingNormalization(IO &i_o, TFinal &Obj)
 : io(i_o), BufPtr(nullptr), Result(Obj) {
if ( io.outputting() ) {
 BufPtr = new (&Buffer) TNorm(io, Obj);
 }
else {
 BufPtr = new (&Buffer) TNorm(io);
 }
 }

 ~MappingNormalization() {
if ( ! io.outputting() ) {
Result = BufPtr->denormalize(io);
 }
 BufPtr->~TNorm();
 }

 TNorm* operator->() { return BufPtr; }

private:
using Storage = AlignedCharArrayUnion<TNorm>;

 Storage Buffer;
 IO &io;
 TNorm *BufPtr;
 TFinal &Result;
};

// Utility for use within MappingTraits<>::mapping() method
// to [de]normalize an object for use with YAML conversion.
template <typename TNorm, typename TFinal>
struct MappingNormalizationHeap {
 MappingNormalizationHeap(IO &i_o, TFinal &Obj, BumpPtrAllocator *allocator)
 : io(i_o), Result(Obj) {
if ( io.outputting() ) {
 BufPtr = new (&Buffer) TNorm(io, Obj);
 }
elseif (allocator) {
 BufPtr = allocator->Allocate<TNorm>();
new (BufPtr) TNorm(io);
 } else {
 BufPtr = new TNorm(io);
 }
 }

 ~MappingNormalizationHeap() {
if ( io.outputting() ) {
 BufPtr->~TNorm();
 }
else {
Result = BufPtr->denormalize(io);
 }
 }

 TNorm* operator->() { return BufPtr; }

private:
using Storage = AlignedCharArrayUnion<TNorm>;

 Storage Buffer;
 IO &io;
 TNorm *BufPtr = nullptr;
 TFinal &Result;
};

///
/// The Input class is used to parse a yaml document into in-memory structs
/// and vectors.
///
/// It works by using YAMLParser to do a syntax parse of the entire yaml
/// document, then the Input class builds a graph of HNodes which wraps
/// each yaml Node. The extra layer is buffering. The low level yaml
/// parser only lets you look at each node once. The buffering layer lets
/// you search and interate multiple times. This is necessary because
/// the mapRequired() method calls may not be in the same order
/// as the keys in the document.
///
class Input : public IO {
public:
// Construct a yaml Input object from a StringRef and optional
// user-data. The DiagHandler can be specified to provide
// alternative error reporting.
 Input(StringRef InputContent,
void *Ctxt = nullptr,
 SourceMgr::DiagHandlerTy DiagHandler = nullptr,
void *DiagHandlerCtxt = nullptr);
 Input(MemoryBufferRef Input,
void *Ctxt = nullptr,
 SourceMgr::DiagHandlerTy DiagHandler = nullptr,
void *DiagHandlerCtxt = nullptr);
 ~Input() override;

// Check if there was an syntax or semantic error during parsing.
 std::error_code error();

private:
bool outputting() const override;
bool mapTag(StringRef, bool) override;
void beginMapping() override;
void endMapping() override;
bool preflightKey(constchar *, bool, bool, bool &, void *&) override;
void postflightKey(void *) override;
 std::vector<StringRef> keys() override;
void beginFlowMapping() override;
void endFlowMapping() override;
unsigned beginSequence() override;
void endSequence() override;
bool preflightElement(unsigned index, void *&) override;
void postflightElement(void *) override;
unsigned beginFlowSequence() override;
bool preflightFlowElement(unsigned , void *&) override;
void postflightFlowElement(void *) override;
void endFlowSequence() override;
void beginEnumScalar() override;
bool matchEnumScalar(constchar*, bool) override;
bool matchEnumFallback() override;
void endEnumScalar() override;
bool beginBitSetScalar(bool &) override;
bool bitSetMatch(constchar *, bool ) override;
void endBitSetScalar() override;
void scalarString(StringRef &, QuotingType) override;
void blockScalarString(StringRef &) override;
void scalarTag(std::string &) override;
NodeKind getNodeKind() override;
void setError(const Twine &message) override;
bool canElideEmptySequence() override;

class HNode {
public:
 HNode(Node *n) : _node(n) {}

staticbool classof(const HNode *) { returntrue; }

Node *_node;
 };

class EmptyHNode : public HNode {
public:
 EmptyHNode(Node *n) : HNode(n) { }

staticbool classof(const HNode *n) { return NullNode::classof(n->_node); }

staticbool classof(const EmptyHNode *) { returntrue; }
 };

class ScalarHNode : public HNode {
public:
 ScalarHNode(Node *n, StringRef s) : HNode(n), _value(s) { }

 StringRef value() const { return _value; }

staticbool classof(const HNode *n) {
return ScalarNode::classof(n->_node) ||
 BlockScalarNode::classof(n->_node);
 }

staticbool classof(const ScalarHNode *) { returntrue; }

protected:
 StringRef _value;
 };

class MapHNode : public HNode {
public:
 MapHNode(Node *n) : HNode(n) { }

staticbool classof(const HNode *n) {
return MappingNode::classof(n->_node);
 }

staticbool classof(const MapHNode *) { returntrue; }

using NameToNodeAndLoc = StringMap<std::pair<HNode *, SMRange>>;

 NameToNodeAndLoc Mapping;
 SmallVector<std::string, 6> ValidKeys;
 };

class SequenceHNode : public HNode {
public:
 SequenceHNode(Node *n) : HNode(n) { }

staticbool classof(const HNode *n) {
return SequenceNode::classof(n->_node);
 }

staticbool classof(const SequenceHNode *) { returntrue; }

 std::vector<HNode *> Entries;
 };

 Input::HNode *createHNodes(Node *node);
void setError(HNode *hnode, const Twine &message);
void setError(Node *node, const Twine &message);
void setError(const SMRange &Range, const Twine &message);

void reportWarning(HNode *hnode, const Twine &message);
void reportWarning(Node *hnode, const Twine &message);
void reportWarning(const SMRange &Range, const Twine &message);

 /// Release memory used by HNodes.
void releaseHNodeBuffers();

public:
// These are only used by operator>>. They could be private
// if those templated things could be made friends.
bool setCurrentDocument();
bool nextDocument();

 /// Returns the current node that's being parsed by the YAML Parser.
constNode *getCurrentNode() const;

void setAllowUnknownKeys(bool Allow) override;

private:
 SourceMgr SrcMgr; // must be before Strm
 std::unique_ptr<llvm::yaml::Stream> Strm;
 HNode *TopNode = nullptr;
 std::error_code EC;
BumpPtrAllocator StringAllocator;
 SpecificBumpPtrAllocator<EmptyHNode> EmptyHNodeAllocator;
 SpecificBumpPtrAllocator<ScalarHNode> ScalarHNodeAllocator;
 SpecificBumpPtrAllocator<MapHNode> MapHNodeAllocator;
 SpecificBumpPtrAllocator<SequenceHNode> SequenceHNodeAllocator;
 document_iterator DocIterator;
llvm::BitVector BitValuesUsed;
 HNode *CurrentNode = nullptr;
bool ScalarMatchFound = false;
bool AllowUnknownKeys = false;
};

///
/// The Output class is used to generate a yaml document from in-memory structs
/// and vectors.
///
class Output : public IO {
public:
 Output(raw_ostream &, void *Ctxt = nullptr, int WrapColumn = 70);
 ~Output() override;

 /// Set whether or not to output optional values which are equal
 /// to the default value. By default, when outputting if you attempt
 /// to write a value that is equal to the default, the value gets ignored.
 /// Sometimes, it is useful to be able to see these in the resulting YAML
 /// anyway.
void setWriteDefaultValues(bool Write) { WriteDefaultValues = Write; }

bool outputting() const override;
bool mapTag(StringRef, bool) override;
void beginMapping() override;
void endMapping() override;
bool preflightKey(constchar *key, bool, bool, bool &, void *&) override;
void postflightKey(void *) override;
 std::vector<StringRef> keys() override;
void beginFlowMapping() override;
void endFlowMapping() override;
unsigned beginSequence() override;
void endSequence() override;
bool preflightElement(unsigned, void *&) override;
void postflightElement(void *) override;
unsigned beginFlowSequence() override;
bool preflightFlowElement(unsigned, void *&) override;
void postflightFlowElement(void *) override;
void endFlowSequence() override;
void beginEnumScalar() override;
bool matchEnumScalar(constchar*, bool) override;
bool matchEnumFallback() override;
void endEnumScalar() override;
bool beginBitSetScalar(bool &) override;
bool bitSetMatch(constchar *, bool ) override;
void endBitSetScalar() override;
void scalarString(StringRef &, QuotingType) override;
void blockScalarString(StringRef &) override;
void scalarTag(std::string &) override;
NodeKind getNodeKind() override;
void setError(const Twine &message) override;
bool canElideEmptySequence() override;

// These are only used by operator<<. They could be private
// if that templated operator could be made a friend.
void beginDocuments();
bool preflightDocument(unsigned);
void postflightDocument();
void endDocuments();

private:
void output(StringRef s);
void output(StringRef, QuotingType);
void outputUpToEndOfLine(StringRef s);
void newLineCheck(bool EmptySequence = false);
void outputNewLine();
void paddedKey(StringRef key);
void flowKey(StringRef Key);

enum InState {
 inSeqFirstElement,
 inSeqOtherElement,
 inFlowSeqFirstElement,
 inFlowSeqOtherElement,
 inMapFirstKey,
 inMapOtherKey,
 inFlowMapFirstKey,
 inFlowMapOtherKey
 };

staticbool inSeqAnyElement(InState State);
staticbool inFlowSeqAnyElement(InState State);
staticbool inMapAnyKey(InState State);
staticbool inFlowMapAnyKey(InState State);

 raw_ostream &Out;
int WrapColumn;
 SmallVector<InState, 8> StateStack;
int Column = 0;
int ColumnAtFlowStart = 0;
int ColumnAtMapFlowStart = 0;
bool NeedBitValueComma = false;
bool NeedFlowSequenceComma = false;
bool EnumerationMatchFound = false;
bool WriteDefaultValues = false;
 StringRef Padding;
 StringRef PaddingBeforeContainer;
};

template <typename T, typename Context>
void IO::processKeyWithDefault(constchar *Key, std::optional<T> &Val,
const std::optional<T> &DefaultValue,
bool Required, Context &Ctx) {
assert(!DefaultValue && "std::optional<T> shouldn't have a value!");
void *SaveInfo;
bool UseDefault = true;
constbool sameAsDefault = outputting() && !Val;
if (!outputting() && !Val)
 Val = T();
if (Val &&
 this->preflightKey(Key, Required, sameAsDefault, UseDefault, SaveInfo)) {

// When reading an std::optional<X> key from a YAML description, we allow
// the special "<none>" value, which can be used to specify that no value
// was requested, i.e. the DefaultValue will be assigned. The DefaultValue
// is usually None.
bool IsNone = false;
if (!outputting())
if (constauto *Node =
 dyn_cast<ScalarNode>(((Input *)this)->getCurrentNode()))
// We use rtrim to ignore possible white spaces that might exist when a
// comment is present on the same line.
 IsNone = Node->getRawValue().rtrim(' ') == "<none>";

if (IsNone)
 Val = DefaultValue;
else
 yamlize(*this, *Val, Required, Ctx);
 this->postflightKey(SaveInfo);
 } else {
if (UseDefault)
 Val = DefaultValue;
 }
}

/// YAML I/O does conversion based on types. But often native data types
/// are just a typedef of built in intergral types (e.g. int). But the C++
/// type matching system sees through the typedef and all the typedefed types
/// look like a built in type. This will cause the generic YAML I/O conversion
/// to be used. To provide better control over the YAML conversion, you can
/// use this macro instead of typedef. It will create a class with one field
/// and automatic conversion operators to and from the base type.
/// Based on BOOST_STRONG_TYPEDEF
#define LLVM_YAML_STRONG_TYPEDEF(_base, _type) \
 struct _type { \
 _type() = default; \
 _type(const _base v) : value(v) {} \
 _type(const _type &v) = default; \
 _type &operator=(const _type &rhs) = default; \
 _type &operator=(const _base &rhs) { value = rhs; return *this; } \
 operator const _base & () const { return value; } \
 bool operator==(const _type &rhs) const { return value == rhs.value; } \
 bool operator==(const _base &rhs) const { return value == rhs; } \
 bool operator<(const _type &rhs) const { return value < rhs.value; } \
 _base value; \
 using BaseType = _base; \
 };

///
/// Use these types instead of uintXX_t in any mapping to have
/// its yaml output formatted as hexadecimal.
///
LLVM_YAML_STRONG_TYPEDEF(uint8_t, Hex8)
LLVM_YAML_STRONG_TYPEDEF(uint16_t, Hex16)
LLVM_YAML_STRONG_TYPEDEF(uint32_t, Hex32)
LLVM_YAML_STRONG_TYPEDEF(uint64_t, Hex64)

template<>
struct ScalarTraits<Hex8> {
staticvoid output(const Hex8 &, void *, raw_ostream &);
static StringRef input(StringRef, void *, Hex8 &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<Hex16> {
staticvoid output(const Hex16 &, void *, raw_ostream &);
static StringRef input(StringRef, void *, Hex16 &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<Hex32> {
staticvoid output(const Hex32 &, void *, raw_ostream &);
static StringRef input(StringRef, void *, Hex32 &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template<>
struct ScalarTraits<Hex64> {
staticvoid output(const Hex64 &, void *, raw_ostream &);
static StringRef input(StringRef, void *, Hex64 &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

template <> struct ScalarTraits<VersionTuple> {
staticvoid output(const VersionTuple &Value, void *, llvm::raw_ostream &Out);
static StringRef input(StringRef, void *, VersionTuple &);
static QuotingType mustQuote(StringRef) { return QuotingType::None; }
};

// Define non-member operator>> so that Input can stream in a document list.
template <typename T>
inline std::enable_if_t<has_DocumentListTraits<T>::value, Input &>
operator>>(Input &yin, T &docList) {
int i = 0;
 EmptyContext Ctx;
while ( yin.setCurrentDocument() ) {
 yamlize(yin, DocumentListTraits<T>::element(yin, docList, i), true, Ctx);
if ( yin.error() )
return yin;
 yin.nextDocument();
 ++i;
 }
return yin;
}

// Define non-member operator>> so that Input can stream in a map as a document.
template <typename T>
inline std::enable_if_t<has_MappingTraits<T, EmptyContext>::value, Input &>
operator>>(Input &yin, T &docMap) {
 EmptyContext Ctx;
 yin.setCurrentDocument();
 yamlize(yin, docMap, true, Ctx);
return yin;
}

// Define non-member operator>> so that Input can stream in a sequence as
// a document.
template <typename T>
inline std::enable_if_t<has_SequenceTraits<T>::value, Input &>
operator>>(Input &yin, T &docSeq) {
 EmptyContext Ctx;
if (yin.setCurrentDocument())
 yamlize(yin, docSeq, true, Ctx);
return yin;
}

// Define non-member operator>> so that Input can stream in a block scalar.
template <typename T>
inline std::enable_if_t<has_BlockScalarTraits<T>::value, Input &>
operator>>(Input &In, T &Val) {
 EmptyContext Ctx;
if (In.setCurrentDocument())
 yamlize(In, Val, true, Ctx);
returnIn;
}

// Define non-member operator>> so that Input can stream in a string map.
template <typename T>
inline std::enable_if_t<has_CustomMappingTraits<T>::value, Input &>
operator>>(Input &In, T &Val) {
 EmptyContext Ctx;
if (In.setCurrentDocument())
 yamlize(In, Val, true, Ctx);
returnIn;
}

// Define non-member operator>> so that Input can stream in a polymorphic type.
template <typename T>
inline std::enable_if_t<has_PolymorphicTraits<T>::value, Input &>
operator>>(Input &In, T &Val) {
 EmptyContext Ctx;
if (In.setCurrentDocument())
 yamlize(In, Val, true, Ctx);
returnIn;
}

// Provide better error message about types missing a trait specialization
template <typename T>
inline std::enable_if_t<missingTraits<T, EmptyContext>::value, Input &>
operator>>(Input &yin, T &docSeq) {
char missing_yaml_trait_for_type[sizeof(MissingTrait<T>)];
return yin;
}

// Define non-member operator<< so that Output can stream out document list.
template <typename T>
inline std::enable_if_t<has_DocumentListTraits<T>::value, Output &>
operator<<(Output &yout, T &docList) {
 EmptyContext Ctx;
 yout.beginDocuments();
constsize_tcount = DocumentListTraits<T>::size(yout, docList);
for(size_t i=0; i < count; ++i) {
if ( yout.preflightDocument(i) ) {
 yamlize(yout, DocumentListTraits<T>::element(yout, docList, i), true,
 Ctx);
 yout.postflightDocument();
 }
 }
 yout.endDocuments();
return yout;
}

// Define non-member operator<< so that Output can stream out a map.
template <typename T>
inline std::enable_if_t<has_MappingTraits<T, EmptyContext>::value, Output &>
operator<<(Output &yout, T &map) {
 EmptyContext Ctx;
 yout.beginDocuments();
if ( yout.preflightDocument(0) ) {
 yamlize(yout, map, true, Ctx);
 yout.postflightDocument();
 }
 yout.endDocuments();
return yout;
}

// Define non-member operator<< so that Output can stream out a sequence.
template <typename T>
inline std::enable_if_t<has_SequenceTraits<T>::value, Output &>
operator<<(Output &yout, T &seq) {
 EmptyContext Ctx;
 yout.beginDocuments();
if ( yout.preflightDocument(0) ) {
 yamlize(yout, seq, true, Ctx);
 yout.postflightDocument();
 }
 yout.endDocuments();
return yout;
}

// Define non-member operator<< so that Output can stream out a block scalar.
template <typename T>
inline std::enable_if_t<has_BlockScalarTraits<T>::value, Output &>
operator<<(Output &Out, T &Val) {
 EmptyContext Ctx;
 Out.beginDocuments();
if (Out.preflightDocument(0)) {
 yamlize(Out, Val, true, Ctx);
 Out.postflightDocument();
 }
 Out.endDocuments();
return Out;
}

// Define non-member operator<< so that Output can stream out a string map.
template <typename T>
inline std::enable_if_t<has_CustomMappingTraits<T>::value, Output &>
operator<<(Output &Out, T &Val) {
 EmptyContext Ctx;
 Out.beginDocuments();
if (Out.preflightDocument(0)) {
 yamlize(Out, Val, true, Ctx);
 Out.postflightDocument();
 }
 Out.endDocuments();
return Out;
}

// Define non-member operator<< so that Output can stream out a polymorphic
// type.
template <typename T>
inline std::enable_if_t<has_PolymorphicTraits<T>::value, Output &>
operator<<(Output &Out, T &Val) {
 EmptyContext Ctx;
 Out.beginDocuments();
if (Out.preflightDocument(0)) {
// FIXME: The parser does not support explicit documents terminated with a
// plain scalar; the end-marker is included as part of the scalar token.
assert(PolymorphicTraits<T>::getKind(Val) != NodeKind::Scalar && "plain scalar documents are not supported");
 yamlize(Out, Val, true, Ctx);
 Out.postflightDocument();
 }
 Out.endDocuments();
return Out;
}

// Provide better error message about types missing a trait specialization
template <typename T>
inline std::enable_if_t<missingTraits<T, EmptyContext>::value, Output &>
operator<<(Output &yout, T &seq) {
char missing_yaml_trait_for_type[sizeof(MissingTrait<T>)];
return yout;
}

template <bool B> struct IsFlowSequenceBase {};
template <> struct IsFlowSequenceBase<true> { staticconstbool flow = true; };

template <typename T, typename U = void>
struct IsResizable : std::false_type {};

template <typename T>
struct IsResizable<T, std::void_t<decltype(std::declval<T>().resize(0))>>
 : public std::true_type {};

template <typename T, bool B> struct IsResizableBase {
using type = typename T::value_type;

static type &element(IO &io, T &seq, size_t index) {
if (index >= seq.size())
seq.resize(index + 1);
returnseq[index];
 }
};

template <typename T> struct IsResizableBase<T, false> {
using type = typename T::value_type;

static type &element(IO &io, T &seq, size_t index) {
if (index >= seq.size()) {
 io.setError(Twine("value sequence extends beyond static size (") +
 Twine(seq.size()) + ")");
returnseq[0];
 }
returnseq[index];
 }
};

template <typename T, bool Flow>
struct SequenceTraitsImpl
 : IsFlowSequenceBase<Flow>, IsResizableBase<T, IsResizable<T>::value> {
staticsize_tsize(IO &io, T &seq) { returnseq.size(); }
};

// Simple helper to check an expression can be used as a bool-valued template
// argument.
template <bool> struct CheckIsBool { staticconstboolvalue = true; };

// If T has SequenceElementTraits, then vector<T> and SmallVector<T, N> have
// SequenceTraits that do the obvious thing.
template <typename T>
struct SequenceTraits<
std::vector<T>,
 std::enable_if_t<CheckIsBool<SequenceElementTraits<T>::flow>::value>>
 : SequenceTraitsImpl<std::vector<T>, SequenceElementTraits<T>::flow> {};
template <typename T, size_t N>
struct SequenceTraits<
std::array<T, N>,
 std::enable_if_t<CheckIsBool<SequenceElementTraits<T>::flow>::value>>
 : SequenceTraitsImpl<std::array<T, N>, SequenceElementTraits<T>::flow> {};
template <typename T, unsigned N>
struct SequenceTraits<
SmallVector<T, N>,
std::enable_if_t<CheckIsBool<SequenceElementTraits<T>::flow>::value>>
 : SequenceTraitsImpl<SmallVector<T, N>, SequenceElementTraits<T>::flow> {};
template <typename T>
struct SequenceTraits<
 SmallVectorImpl<T>,
std::enable_if_t<CheckIsBool<SequenceElementTraits<T>::flow>::value>>
 : SequenceTraitsImpl<SmallVectorImpl<T>, SequenceElementTraits<T>::flow> {};
template <typename T>
struct SequenceTraits<
MutableArrayRef<T>,
std::enable_if_t<CheckIsBool<SequenceElementTraits<T>::flow>::value>>
 : SequenceTraitsImpl<MutableArrayRef<T>, SequenceElementTraits<T>::flow> {};

// Sequences of fundamental types use flow formatting.
template <typename T>
struct SequenceElementTraits<T, std::enable_if_t<std::is_fundamental_v<T>>> {
staticconstbool flow = true;
};

// Sequences of strings use block formatting.
template<> struct SequenceElementTraits<std::string> {
staticconstbool flow = false;
};
template<> struct SequenceElementTraits<StringRef> {
staticconstbool flow = false;
};
template<> struct SequenceElementTraits<std::pair<std::string, std::string>> {
staticconstbool flow = false;
};

/// Implementation of CustomMappingTraits for std::map<std::string, T>.
template <typename T> struct StdMapStringCustomMappingTraitsImpl {
using map_type = std::map<std::string, T>;

staticvoid inputOne(IO &io, StringRef key, map_type &v) {
 io.mapRequired(key.str().c_str(), v[std::string(key)]);
 }

staticvoid output(IO &io, map_type &v) {
for (auto &p : v)
 io.mapRequired(p.first.c_str(), p.second);
 }
};

} // end namespace yaml
} // end namespace llvm

#define LLVM_YAML_IS_SEQUENCE_VECTOR_IMPL(TYPE, FLOW) \
 namespace llvm { \
 namespace yaml { \
 static_assert( \
 !std::is_fundamental_v<TYPE> && !std::is_same_v<TYPE, std::string> && \
 !std::is_same_v<TYPE, llvm::StringRef>, \
 "only use LLVM_YAML_IS_SEQUENCE_VECTOR for types you control"); \
 template <> struct SequenceElementTraits<TYPE> { \
 static const bool flow = FLOW; \
 }; \
 } \
 }

/// Utility for declaring that a std::vector of a particular type
/// should be considered a YAML sequence.
#define LLVM_YAML_IS_SEQUENCE_VECTOR(type) \
 LLVM_YAML_IS_SEQUENCE_VECTOR_IMPL(type, false)

/// Utility for declaring that a std::vector of a particular type
/// should be considered a YAML flow sequence.
#define LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(type) \
 LLVM_YAML_IS_SEQUENCE_VECTOR_IMPL(type, true)

#define LLVM_YAML_DECLARE_MAPPING_TRAITS(Type) \
 namespace llvm { \
 namespace yaml { \
 template <> struct LLVM_ABI MappingTraits<Type> { \
 static void mapping(IO &IO, Type &Obj); \
 }; \
 } \
 }

#define LLVM_YAML_DECLARE_MAPPING_TRAITS_PRIVATE(Type) \
 namespace llvm { \
 namespace yaml { \
 template <> struct MappingTraits<Type> { \
 static void mapping(IO &IO, Type &Obj); \
 }; \
 } \
 }

#define LLVM_YAML_DECLARE_ENUM_TRAITS(Type) \
 namespace llvm { \
 namespace yaml { \
 template <> struct LLVM_ABI ScalarEnumerationTraits<Type> { \
 static void enumeration(IO &io, Type &Value); \
 }; \
 } \
 }

#define LLVM_YAML_DECLARE_BITSET_TRAITS(Type) \
 namespace llvm { \
 namespace yaml { \
 template <> struct LLVM_ABI ScalarBitSetTraits<Type> { \
 static void bitset(IO &IO, Type &Options); \
 }; \
 } \
 }

#define LLVM_YAML_DECLARE_SCALAR_TRAITS(Type, MustQuote) \
 namespace llvm { \
 namespace yaml { \
 template <> struct LLVM_ABI ScalarTraits<Type> { \
 static void output(const Type &Value, void *ctx, raw_ostream &Out); \
 static StringRef input(StringRef Scalar, void *ctxt, Type &Value); \
 static QuotingType mustQuote(StringRef) { return MustQuote; } \
 }; \
 } \
 }

/// Utility for declaring that a std::vector of a particular type
/// should be considered a YAML document list.
#define LLVM_YAML_IS_DOCUMENT_LIST_VECTOR(_type) \
 namespace llvm { \
 namespace yaml { \
 template <unsigned N> \
 struct DocumentListTraits<SmallVector<_type, N>> \
 : public SequenceTraitsImpl<SmallVector<_type, N>, false> {}; \
 template <> \
 struct DocumentListTraits<std::vector<_type>> \
 : public SequenceTraitsImpl<std::vector<_type>, false> {}; \
 } \
 }

/// Utility for declaring that std::map<std::string, _type> should be considered
/// a YAML map.
#define LLVM_YAML_IS_STRING_MAP(_type) \
 namespace llvm { \
 namespace yaml { \
 template <> \
 struct CustomMappingTraits<std::map<std::string, _type>> \
 : public StdMapStringCustomMappingTraitsImpl<_type> {}; \
 } \
 }

LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(llvm::yaml::Hex64)
LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(llvm::yaml::Hex32)
LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(llvm::yaml::Hex16)
LLVM_YAML_IS_FLOW_SEQUENCE_VECTOR(llvm::yaml::Hex8)

#endif // LLVM_SUPPORT_YAMLTRAITS_H