clang/lib/Driver/ToolChains/LazyDetector.h

   1 //===--- LazyDetector.h - Lazy ToolChain Detection --------------*- 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 #ifndef LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_LAZYDETECTOR_H
  10 #define LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_LAZYDETECTOR_H
  11
  12 #include "clang/Driver/Tool.h"
  13 #include "clang/Driver/ToolChain.h"
  14 #include <optional>
  15
  16 namespace clang {
  17
  18 /// Simple wrapper for toolchain detector with costly initialization. This
  19 /// delays the creation of the actual detector until its first usage.
  20
  21 template <class T> class LazyDetector {
  22   const driver::Driver &D;
  23   llvm::Triple Triple;
  24   const llvm::opt::ArgList &Args;
  25
  26   std::optional<T> Detector;
  27
  28 public:
  29   LazyDetector(const driver::Driver &D, const llvm::Triple &Triple,
  30                const llvm::opt::ArgList &Args)
  31       : D(D), Triple(Triple), Args(Args) {}
  32   T *operator->() {
  33     if (!Detector)
  34       Detector.emplace(D, Triple, Args);
  35     return &*Detector;
  36   }
  37   const T *operator->() const {
  38     return const_cast<T const *>(
  39         const_cast<LazyDetector &>(*this).operator->());
  40   }
  41 };
  42
  43 } // end namespace clang
  44
  45 #endif // LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_LAZYDETECTOR_H