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