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| //===- FormatVariadicDetails.h - Helpers for FormatVariadic.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_FORMATVARIADIC_DETAILS_H
#define LLVM_SUPPORT_FORMATVARIADIC_DETAILS_H
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/raw_ostream.h"
#include <type_traits>
namespace llvm {
template <typename T, typename Enable = void> struct format_provider {};
class Error;
namespace detail {
class format_adapter {
virtual void anchor();
protected:
virtual ~format_adapter() {}
public:
virtual void format(raw_ostream &S, StringRef Options) = 0;
};
template <typename T> class provider_format_adapter : public format_adapter {
T Item;
public:
explicit provider_format_adapter(T &&Item) : Item(std::forward<T>(Item)) {}
void format(llvm::raw_ostream &S, StringRef Options) override {
format_provider<typename std::decay<T>::type>::format(Item, S, Options);
}
};
template <typename T>
class stream_operator_format_adapter : public format_adapter {
T Item;
public:
explicit stream_operator_format_adapter(T &&Item)
: Item(std::forward<T>(Item)) {}
void format(llvm::raw_ostream &S, StringRef Options) override { S << Item; }
};
template <typename T> class missing_format_adapter;
// Test if format_provider<T> is defined on T and contains a member function
// with the signature:
// static void format(const T&, raw_stream &, StringRef);
//
template <class T> class has_FormatProvider {
public:
using Decayed = typename std::decay<T>::type;
typedef void (*Signature_format)(const Decayed &, llvm::raw_ostream &,
StringRef);
template <typename U>
static char test(SameType<Signature_format, &U::format> *);
template <typename U> static double test(...);
static bool const value =
(sizeof(test<llvm::format_provider<Decayed>>(nullptr)) == 1);
};
// Test if raw_ostream& << T -> raw_ostream& is findable via ADL.
template <class T> class has_StreamOperator {
public:
using ConstRefT = const typename std::decay<T>::type &;
template <typename U>
static char test(typename std::enable_if<
std::is_same<decltype(std::declval<llvm::raw_ostream &>()
<< std::declval<U>()),
llvm::raw_ostream &>::value,
int *>::type);
template <typename U> static double test(...);
static bool const value = (sizeof(test<ConstRefT>(nullptr)) == 1);
};
// Simple template that decides whether a type T should use the member-function
// based format() invocation.
template <typename T>
struct uses_format_member
: public std::integral_constant<
bool,
std::is_base_of<format_adapter,
typename std::remove_reference<T>::type>::value> {};
// Simple template that decides whether a type T should use the format_provider
// based format() invocation. The member function takes priority, so this test
// will only be true if there is not ALSO a format member.
template <typename T>
struct uses_format_provider
: public std::integral_constant<
bool, !uses_format_member<T>::value && has_FormatProvider<T>::value> {
};
// Simple template that decides whether a type T should use the operator<<
// based format() invocation. This takes last priority.
template <typename T>
struct uses_stream_operator
: public std::integral_constant<bool, !uses_format_member<T>::value &&
!uses_format_provider<T>::value &&
has_StreamOperator<T>::value> {};
// Simple template that decides whether a type T has neither a member-function
// nor format_provider based implementation that it can use. Mostly used so
// that the compiler spits out a nice diagnostic when a type with no format
// implementation can be located.
template <typename T>
struct uses_missing_provider
: public std::integral_constant<bool, !uses_format_member<T>::value &&
!uses_format_provider<T>::value &&
!uses_stream_operator<T>::value> {
};
template <typename T>
typename std::enable_if<uses_format_member<T>::value, T>::type
build_format_adapter(T &&Item) {
return std::forward<T>(Item);
}
template <typename T>
typename std::enable_if<uses_format_provider<T>::value,
provider_format_adapter<T>>::type
build_format_adapter(T &&Item) {
return provider_format_adapter<T>(std::forward<T>(Item));
}
template <typename T>
typename std::enable_if<uses_stream_operator<T>::value,
stream_operator_format_adapter<T>>::type
build_format_adapter(T &&Item) {
// If the caller passed an Error by value, then stream_operator_format_adapter
// would be responsible for consuming it.
// Make the caller opt into this by calling fmt_consume().
static_assert(
!std::is_same<llvm::Error, typename std::remove_cv<T>::type>::value,
"llvm::Error-by-value must be wrapped in fmt_consume() for formatv");
return stream_operator_format_adapter<T>(std::forward<T>(Item));
}
template <typename T>
typename std::enable_if<uses_missing_provider<T>::value,
missing_format_adapter<T>>::type
build_format_adapter(T &&Item) {
return missing_format_adapter<T>();
}
}
}
#endif
|