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
46