include/llvm/Support/Printable.h

   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
  18 namespace llvm {
  19
  20 class 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.
  37 class Printable {
  38 public:
  39   std::function<void(raw_ostream &OS)> Print;
  40   Printable(std::function<void(raw_ostream &OS)> Print)
  41       : Print(std::move(Print)) {}
  42 };
  43
  44 inline raw_ostream &operator<<(raw_ostream &OS, const Printable &P) {
  45   P.Print(OS);
  46   return OS;
  47 }
  48
  49 }
  50
  51 #endif