1 //===--- 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 #include <utility>
18 
19 namespace llvm {
20 
21 class raw_ostream;
22 
23 /// Simple wrapper around std::function<void(raw_ostream&)>.
24 /// This class is useful to construct print helpers for raw_ostream.
25 ///
26 /// Example:
27 ///     Printable printRegister(unsigned Register) {
28 ///       return Printable([Register](raw_ostream &OS) {
29 ///         OS << getRegisterName(Register);
30 ///       });
31 ///     }
32 ///     ... OS << printRegister(Register); ...
33 ///
34 /// Implementation note: Ideally this would just be a typedef, but doing so
35 /// leads to operator << being ambiguous as function has matching constructors
36 /// in some STL versions. I have seen the problem on gcc 4.6 libstdc++ and
37 /// microsoft STL.
38 class Printable {
39 public:
40   std::function<void(raw_ostream &OS)> Print;
41   Printable(std::function<void(raw_ostream &OS)> Print)
42       : Print(std::move(Print)) {}
43 };
44 
45 inline raw_ostream &operator<<(raw_ostream &OS, const Printable &P) {
46   P.Print(OS);
47   return OS;
48 }
49 
50 } // namespace llvm
51 
52 #endif
53