展开流程伪码：（自己总结的，不一定对）
//loop:
//将实参代入文本中
//if 在某个实参之前有符号“#”（字符串化）或“##”（连接）then
// 对当前的文本做一次字符串化或者连接
//
// if 结果是另外一个宏名 then
// 替换一次
// end
//
// 结束当前的处理
//else
// foreach 实参 do
// if 是宏 then
// goto loop
// end
// end
//
// if 文本中不包含任何宏 then
// if 结果是另外一个宏名 then
// 替换一次
// end
//
// 结束全部处理
// else
// goto loop
// end
//end
示例：
#include <iostream>
using namespace std;
#define to_str(x) #x // 称【#x】为文本，称【x】为形参
#define macro_expansion(m) to_str(m)
#define token_cat(x, y) x##y
#define token_cat_ex(x, y) token_cat(x, y)
#define max(a, b) ((a) > (b) ? (a) : (b))
#define ab token_cat(1, 2)
int main(int argc, char* argv[])
{
cout << to_str(token_cat(1, 2)) << endl; // token_cat(1, 2)
// 代入实参=> #token_cat(1, 2)
// 实参之前有符号##，对当前文本做一次连接，然后结束当前的处理=> "token_cat(1, 2)"
cout << macro_expansion(to_str(token_cat(1, 2))) << endl; // "token_cat(1, 2)"
// 代入实参=> to_str(to_str(token_cat(1, 2)))
// 实参是宏，对实参做处理（这是当前处理），代入其实参=> to_str(#token_cat(1, 2))
// 当前处理中，实参之前有符号#，对当前文本做一次字符串化，然后结束当前的处理=> to_str("token_cat(1, 2)")
// 实参处理已完成，最外层还是一个宏，代入实参（注意当前处理变了）=> #"token_cat(1, 2)"
// 实参之前有符号#，对当前文本做一次字符串化，然后结束当前的处理=> "\"token_cat(1, 2)\""
cout << macro_expansion(token_cat(token_cat(1, 2), 3)) << endl; // token_cat(1, 2)3
// 代入实参=> to_str(token_cat(token_cat(1, 2), 3))
// 实参是宏，对实参做处理（这是当前处理），代入其实参=> to_str(token_cat(1, 2)##3))
// 当前处理中，实参之前有符号##，对当前文本做一次连接，然后结束当前的处理=> to_str(token_cat(1, 2)3))
// 实参处理已完成，最外层还是一个宏，代入实参（注意当前处理变了）=> #token_cat(1, 2)3)
// 实参之前有符号##，对当前文本做一次连接，然后结束当前的处理=> "token_cat(1, 2)3)"
cout << macro_expansion(token_cat_ex(token_cat_ex(1, 2), 3)) << endl; // 123
// 代入实参=> to_str(token_cat_ex(token_cat_ex(1, 2), 3))
// 实参是宏，对实参做处理（这是当前处理），代入其实参=> to_str(token_cat(token_cat_ex(1, 2), 3))
// 第二次代入实参后，第一个实参仍然是宏，继续代入=> to_str(token_cat(token_cat(1, 2), 3))
// 第一个实参仍然是宏，继续代入=> to_str(token_cat(1##2, 3))
// 连接第一个实参，至此第一个实参处理完成=> to_str(token_cat(12, 3))
// 后面的实参不是宏，为上层的宏代入实参=> to_str(12#3)
// 连接一次=> to_str(123)
// 全部实参处理完成，最外层还是一个宏，代入实参=> #123
// 实参之前有符号#，对当前文本做一次字符串化，然后结束当前的处理=> "123"
int n = max(1, 2);
// 代入实参=> ((1) > (2) ? (1) : (2))
// 文本中不包含任何宏，结束全部处理
cout << macro_expansion(max(1, 2)) << endl; // ((1) > (2) ? (1) : (2))
// 代入实参=> to_str(max(1, 2))
// 实参是宏，对实参做处理（这是当前处理），代入其实参=> to_str(((1) > (2) ? (1) : (2)))
// 实参处理完了，文本中还包含一个宏，代入实参=> #((1) > (2) ? (1) : (2))
// 实参之前有符号#，对当前文本做一次字符串化，然后结束当前的处理=> "((1) > (2) ? (1) : (2))"
cout << macro_expansion(token_cat(a, b)) << endl; // token_cat(1, 2)
// 代入实参=> to_str(token_cat(a, b))
// 实参是宏，对实参做处理（这是当前处理），代入其实参=> to_str(a##b)
// 当前处理中，实参之前有符号##，对当前文本做一次连接，然后结束当前的处理=> to_str(ab)
// ab是另外一个宏的名字，替换一次，注意只替换一次=> to_str(token_cat(1, 2))
// 实参处理已完成，最外层还是一个宏，代入实参（注意当前处理变了）=> #token_cat(1, 2)
// 实参之前有符号#，对当前文本做一次字符串化，然后结束当前的处理=> "token_cat(1, 2)"
return 0;
}
我自己的一些使用
#define TOKEN_CAT(x, y) x##y
//AUX_OSS_ACTORID(rstOssExploreSecret, ActorID, m_poPetOnDuty->GetExclusiveItemID());
// 参数：日志消息体，字段名，程序中的Actor ID对象
#define AUX_OSS_ACTORID(x, y, z)\
do {\
x.TOKEN_CAT(y, _Sid) = z.uSid;\
x.TOKEN_CAT(y, _ZoneID) = z.uZoneID;\
} while (0)
//AUX_OSS_THING_GUID(rstOssExploreSecret, PetGUID, m_poPetOnDuty->GetExclusiveItemID());
// 参数：日志消息体，字段名，程序中的GUID对象
#define AUX_OSS_THING_GUID(x, y, z) \
do {\
unsigned int* apu32GUIDField[4] = {\
&TOKEN_CAT(TOKEN_CAT(x, .), TOKEN_CAT(y, _Time)),\
&TOKEN_CAT(TOKEN_CAT(x, .), TOKEN_CAT(y, _Reserve)),\
&TOKEN_CAT(TOKEN_CAT(x, .), TOKEN_CAT(y, _Seq)),\
&TOKEN_CAT(TOKEN_CAT(x, .), TOKEN_CAT(y, _SrvID))\
};\
*apu32GUIDField[0] = (z).dwTime;\
*apu32GUIDField[1] = (z).dwReserve;\
*apu32GUIDField[2] = (z).dwSeq;\
*apu32GUIDField[3] = (z).dwSrvID;\
} while (0)
struct TRewardGroup
{
int m_i32RewardGroupID;
float m_f32Prop;
int m_i32BindMark;
int m_i32OutputMode;
};
#define REWARD_GROUP(_pstCfg, i) {TOKEN_CAT(TOKEN_CAT(_pstCfg, ->), TOKEN_CAT(iRewardGroupID, i)),\
TOKEN_CAT(TOKEN_CAT(_pstCfg, ->), TOKEN_CAT(iProp, i)) / reward_group_rate_base, \
TOKEN_CAT(TOKEN_CAT(_pstCfg, ->), TOKEN_CAT(iBindMark, i)), \
TOKEN_CAT(TOKEN_CAT(_pstCfg, ->), TOKEN_CAT(iOutputMode, i))}
TRewardGroup astDynamicRewardGroup[] = {
REWARD_GROUP(pstDynamicOutputGoods, 1), REWARD_GROUP(pstDynamicOutputGoods, 2),
REWARD_GROUP(pstDynamicOutputGoods, 3), REWARD_GROUP(pstDynamicOutputGoods, 4),
REWARD_GROUP(pstDynamicOutputGoods, 5), REWARD_GROUP(pstDynamicOutputGoods, 6),
REWARD_GROUP(pstDynamicOutputGoods, 7), REWARD_GROUP(pstDynamicOutputGoods, 8),
REWARD_GROUP(pstDynamicOutputGoods, 9), REWARD_GROUP(pstDynamicOutputGoods, 10)
};
struct TRewardGoods
{
int m_i32RewardItemID;
int m_i32RewardItemCount;
int m_i32RewardItemBind;
};
#define REWARD_GOODS(i) {pstRewardCfg->TOKEN_CAT(iRewardItemID, i), \
pstRewardCfg->TOKEN_CAT(iRewardItemCount, i), \
pstRewardCfg->TOKEN_CAT(iRewardItemBind, i)}
TRewardGoods astRewardGoods[] = {
REWARD_GOODS(1), REWARD_GOODS(2), REWARD_GOODS(3)
};
下面一篇文章http://www.boost.org/doc/libs/1_37_0/libs/wave/doc/macro_expansion_process.html
The Macro Expansion Process
The macro expansion process described here was initially developed by Paul Mensonides and is implemented in Wave.
It is much more understandable as the description of the desired macro expansion algorithm provided in the C++ Standard [1].
Macro replacement proceeds left-to-right.
If, during scanning (or rescanning) an identifier is found, it is looked up in the symbol table. If the identifier is not found in the symbol table, it is not a macro and scanning continues.
If the identifier is found, the value of a flag associated with the identifier is used to determine if the identifier is available for expansion. If it is not, the specific token (i.e. the specific instance of the identifier) is marked as disabled and is not
expanded. If the identifier is available for expansion, the value of a different flag associated with the identifier in the symbol table is used to determine if the identifier is an object-like or function-like macro. If it is an object-like macro, it is expanded.
If it is a function-like macro, it is only expanded if the next token is an left parenthesis.
An identifier is available for expansion if it is not marked as disabled and if the the value of the flag associated with the identifier is not set, which is used to determine if the identifier is available for expansion.
(If a macro is an object-like macro, skip past the next two paragraphs.)
If a macro to be expanded is a function-like macro, it must have the exact number of actual arguments as the number of formal parameters required by the definition of the macro. Each argument is recursively scanned and expanded. Each parameter name found in
the replacement list is replaced by the expanded actual argument after leading and trailing whitespace and all placeholder tokens are removed unless the parameter name immediately follows the stringizing operator ('#')
or is adjacent to the token-pasting operator ('##').
If the parameter name immediately follows the stringizing operator ('#'), a stringized version of the unexpanded actual argument is inserted. If the
parameter name is adjacent to the token-pasting operator ('##'), the unexpanded actual argument is inserted after all placeholder tokens are removed.
All concatenation takes place in the replacement list. (If a single concatenation yields multiple tokens, the behavior is undefined. Moreover, Wave in
normal C++98 and C99 modes issues an error, if more then one token is produced as the result of the concatenation. In C++0x mode Wave treats token-pasting
of unrelated tokens as well defined and inserts the reparsed string representation of the concatenated tokens into the replacement list.).
The flag in the symbol table entry associated with the name of the macro being expanded is set to indicate the that the macro is not available for expansion.
The replacement list is rescanned for further macro expansion. All leading and trailing whitespace tokens in the replacement list are removed (the placeholder tokens are left intact).
After rescanning completes, the flag in the symbol table entry associated with the name of macro being expanded is cleared to indicate that the macro is again available for expansion, and the sequence of tokens that constitutes the rescanned replacement list
is returned to the point of invocation of the macro.
If this sequence of tokens is empty, it is replaced by a placeholder token. If a placeholder is found during scanning (or rescanning) it is ignored. (Also, if the only thing separating a parameter from the stringizing operator or token-pasting operator is placeholder,
it is also ignored in that context.)
This sequence of tokens is inserted at the original point that the macro was invoked, and scanning continues starting with the last token of the newly inserted sequence of tokens. I.e. scanning looks back a single token (possibly a placeholder token) and continues.