Printable.h revision 355940 
177298Sobrien//===--- Printable.h - Print function helpers -------------------*- 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//  This file defines the Printable struct.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_SUPPORT_PRINTABLE_H
14#define LLVM_SUPPORT_PRINTABLE_H
15
16#include <functional>
17
18namespace llvm {
19
20class raw_ostream;
21
22/// Simple wrapper around std::function<void(raw_ostream&)>.
23/// This class is useful to construct print helpers for raw_ostream.
24///
25/// Example:
26///     Printable PrintRegister(unsigned Register) {
27///       return Printable([Register](raw_ostream &OS) {
28///         OS << getRegisterName(Register);
29///       }
30///     }
31///     ... OS << PrintRegister(Register); ...
32///
33/// Implementation note: Ideally this would just be a typedef, but doing so
34/// leads to operator << being ambiguous as function has matching constructors
35/// in some STL versions. I have seen the problem on gcc 4.6 libstdc++ and
36/// microsoft STL.
37class Printable {
38public:
39  std::function<void(raw_ostream &OS)> Print;
40  Printable(std::function<void(raw_ostream &OS)> Print)
41      : Print(std::move(Print)) {}
42};
43
44inline raw_ostream &operator<<(raw_ostream &OS, const Printable &P) {
45  P.Print(OS);
46  return OS;
47}
48
49}
50
51#endif
52