idhash.cpp

来自「一个用C++实现的C的Compiler。 代码风格良好。 原作者自己写了」· C++ 代码 · 共 77 行

#ifndef __IDHASH_CPP__
#define __IDHASH_CPP__

#include <string>
#include <memory>
#include "common.cpp"

using namespace std;

const		int			IDHash_LimitHash		=		99997;

struct IDHash_IDStruct {
	string str;
	int next;
};

IDHash_IDStruct IDHash_Data[Limit_ID];
int IDHash[IDHash_LimitHash];
int IDCount = 0;

struct IDHash_Init {
	IDHash_Init() { memset(IDHash, 0xff, sizeof(IDHash)); }
} IDHash_Init;

int IDHash_ID2int(char* str, int create_new);
int IDHash_ID2int(const string& str, int create_new);
string IDHash_int2ID(int id);

int IDHash_ID2int(char* str, int create_new = 1)
{
	int hashnum = 0;
	for (int i = 0; str[i]; i++)
	{
		hashnum = (hashnum * 100 + (str[i] - ' ')) % IDHash_LimitHash;
	}
	for (int i = IDHash[hashnum]; i != -1; i = IDHash_Data[i].next)
	{
		if (IDHash_Data[i].str == str)
		{
			return i;
		}
	}
	if (!create_new) return -1;
	IDHash_Data[IDCount].str = str;
	IDHash_Data[IDCount].next = IDHash[hashnum];
	IDHash[hashnum] = IDCount;
	return IDCount ++;
}

int IDHash_ID2int(const string& str, int create_new = 1)
{
	int hashnum = 0;
	for (unsigned int i = 0; i < str.length(); i++)
	{
		hashnum = (hashnum * 100 + (str[i] - ' ')) % IDHash_LimitHash;
	}
	for (int i = IDHash[hashnum]; i != -1; i = IDHash_Data[i].next)
	{
		if (IDHash_Data[i].str == str)
		{
			return i;
		}
	}
	if (!create_new) return -1;
	IDHash_Data[IDCount].str = str;
	IDHash_Data[IDCount].next = IDHash[hashnum];
	IDHash[hashnum] = IDCount;
	return IDCount ++;
}

string IDHash_int2ID(int id)
{
	return IDHash_Data[id].str;
}

#endif				// __IDHASH_CPP__