LLVM编译器相关C++技术

最新推荐文章于 2025-10-03 15:16:06 发布

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本文介绍了一个使用C++模板和注册机制实现的组件注册示例。通过具体的代码实例展示了如何为特定的目标（如X86_32）注册一个自定义的汇编词法分析器。

RegisterMCAsmLexer<X86AsmLexer> X(TheX86_32Target);

这个函数里面有个Allocator的赋值，相关的C++技术模拟代码如下，用VC2010编译成功并运行：

// CppTest.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
class Target;
class MCRegisterInfo {
};
class MCAsmLexer {
};


class MCAsmInfo {
};
class MCTargetAsmLexer {
	//	MCTargetAsmLexer(const MCTargetAsmLexer &);   // DO NOT IMPLEMENT
	//	void operator=(const MCTargetAsmLexer &);  // DO NOT IMPLEMENT
protected: // Can only create subclasses.
	MCTargetAsmLexer(const Target &T)
		: TheTarget(T), Lexer(NULL) {
	}
	/// TheTarget - The Target that this machine was created for.
	const Target &TheTarget;
	MCAsmLexer *Lexer;
};
class Target
{
public:
	char a;
	
	typedef MCTargetAsmLexer *(*MCAsmLexerCtorTy)(const Target &T,
		const MCRegisterInfo &MRI,
		const MCAsmInfo &MAI);
	MCAsmLexerCtorTy MCAsmLexerCtorFn;
};
struct TargetRegistry {
	static void RegisterMCAsmLexer(Target &T, Target::MCAsmLexerCtorTy Fn) {
		if (!T.MCAsmLexerCtorFn)
			T.MCAsmLexerCtorFn = Fn;
	}
};
template<class MCAsmLexerImpl>
struct RegisterMCAsmLexer {
	RegisterMCAsmLexer(Target &T) {
		TargetRegistry::RegisterMCAsmLexer(T, &Allocator);
	}

private:
	static MCTargetAsmLexer *Allocator(const Target &T,
		const MCRegisterInfo &MRI,
		const MCAsmInfo &MAI) {
			return new MCAsmLexerImpl(T, MRI, MAI);
	}
};

class X86AsmLexer : public MCTargetAsmLexer {
	const MCAsmInfo &AsmInfo;
	bool tentativeIsValid;
public:
	X86AsmLexer(const Target &T, const MCRegisterInfo &MRI, const MCAsmInfo &MAI)
		: MCTargetAsmLexer(T), AsmInfo(MAI), tentativeIsValid(false) {
	}
};
Target TheX86_32Target;
int _tmain(int argc, _TCHAR* argv[])
{
	RegisterMCAsmLexer<X86AsmLexer> X(TheX86_32Target);
	return 0;
}