《python源码剖析》之实现small python
基本上是照着《python源码剖析》里面的代码写的，当然它有一点细节的地方没有指出来，我也就补全了一下，
先来看下运行的效果图：
下面直接上代码：
#include<iostream>#include<string.h>#include<iterator>#include<stdlib.h>#include<stdio.h>#include<memory>#include<map>#include<ctype.h>using namespace std;#define PyObject_HEAD\int refCount; \struct tagPyTypeObject *type#define PyObject_HEAD_INIT(typePtr) \0,typePtrtypedef struct tagPyObject{PyObject_HEAD;}PyObject;typedef void (*PrintFun)(PyObject*object);typedef PyObject* (*AddFun)(PyObject* left,PyObject*right);typedef long (*HashFun)(PyObject* object);typedef struct tagPyTypeObject{PyObject_HEAD;char* name;PrintFun print;AddFun add;HashFun hash;}PyTypeObject;PyTypeObject PyType_Type ={PyObject_HEAD_INIT(&PyType_Type),"type",0,0,0};typedef struct tagIntObject{PyObject_HEAD;int value;}PyIntObject;static void int_print(PyObject*object);static PyObject* int_add(PyObject*left,PyObject* right);static long int_hash(PyObject* object);PyTypeObject PyInt_Type ={PyObject_HEAD_INIT(&PyType_Type),"int",int_print,int_add,int_hash};PyObject* PyInt_Create(int value){PyIntObject *object = new PyIntObject;object->refCount = 1;object->type = &PyInt_Type;object->value = value;return (PyObject*)object;}static void int_print(PyObject*object){PyIntObject* intObject = (PyIntObject*)object;printf("%d\n",intObject->value);}static PyObject* int_add(PyObject*left,PyObject* right){PyIntObject* leftInt = (PyIntObject*)left;PyIntObject* rightInt = (PyIntObject*)right;PyIntObject* result = (PyIntObject*)PyInt_Create(0);if(result == NULL){printf("we have no enough memory");exit(1);}else{result->value = leftInt->value+rightInt->value;}return (PyObject*)result;}static long int_hash(PyObject* object){return (long)((PyIntObject*)object)->value;}typedef struct tagPyStrObject{PyObject_HEAD;int length;long hashValue;char value[50];}PyStringObject;static void string_print(PyObject*object);static long string_hash(PyObject*object);static PyObject* string_add(PyObject*left, PyObject*right);PyTypeObject PyString_Type ={PyObject_HEAD_INIT(&PyType_Type),"str",string_print,string_add,string_hash};PyObject* PyStr_Create(const char*value){PyStringObject* object = new PyStringObject;object->refCount = 1;object->type = &PyString_Type;object->length = (value ==NULL? 0: strlen(value));object->hashValue = -1;memset(object->value,0,50);if(value!=NULL){strcpy(object->value,value);}return (PyObject*)object;}static void string_print(PyObject*object){PyStringObject*strObject = (PyStringObject*)object;printf("%s\n",strObject->value);}static long string_hash(PyObject*object){PyStringObject* strObject = (PyStringObject*)object;register int len;register unsigned char* p;register long x;if(strObject->hashValue!=-1)return strObject->hashValue;len = strObject->length;p = (unsigned char*)strObject->value;x = *p<<7;while(--len>0)x = (1000003*x)^*p++;x^=strObject->length;if(x==-1)x=-2;strObject->hashValue = x;return x;}static PyObject* string_add(PyObject*left, PyObject*right){PyStringObject*leftStr = (PyStringObject*)left;PyStringObject*rightStr = (PyStringObject*)right;PyStringObject*result = (PyStringObject*)PyStr_Create(NULL);if(result == NULL){printf("we have no enough memory");exit(1);}else{strcpy(result->value,leftStr->value);strcat(result->value,rightStr->value);//something in book wrong}return (PyObject*)result;}typedef struct tagPyDictObject{PyObject_HEAD;map<long,PyObject*>dict;}PyDictObject;PyDictObject *m_LocalEnvironment= new PyDictObject;static void dict_print(PyObject*object);PyTypeObject PyDict_Type ={PyObject_HEAD_INIT(&PyType_Type),"dict",dict_print,0,0};PyObject*PyDict_Create(){PyDictObject*object = new PyDictObject;object->refCount = 1;object->type = &PyDict_Type;return (PyObject*)object;}PyObject* PyDict_GetItem(PyObject*target,PyObject*key){long keyHashValue = (key->type)->hash(key);map<long,PyObject*>&dict = ((PyDictObject*)target)->dict;map<long,PyObject*>::iterator it= dict.find(keyHashValue);map<long,PyObject*>::iterator end= dict.end();if(it==end)return NULL;return it->second;}int PyDict_SetItem(PyObject*target,PyObject*key,PyObject*value){long keyHashValue = (key->type)->hash(key);PyDictObject* dictObject = (PyDictObject*)target;(dictObject->dict)[keyHashValue]=value;return 0;}static void dict_print(PyObject*object){PyDictObject*dictObject = (PyDictObject*)object;printf("(");map<long,PyObject*>::iterator it =(dictObject->dict).begin();map<long,PyObject*>::iterator end =(dictObject->dict).end();for(;it!=end;++it){printf("%ld: ",it->first);PyObject*value=it->second;(value->type)->print(value);printf(", ");}printf(")\n");}PyObject* GetObjectBySymbol(string &symbol){PyObject* key = PyStr_Create(symbol.c_str());PyObject *value = PyDict_GetItem((PyObject*)m_LocalEnvironment,key);if(value == NULL){cout<<"[Error]: "<<symbol<<" is not defined!"<<endl;return NULL;}return value;}bool IsSourceAllDigit(string source){bool result =true;for(int i=0;i<source.size();i++){result = isdigit(source[i]);if(result == false)break;}return result;}void ExcuteAdd(string&target,string&source){string::size_type pos;PyObject* strValue = NULL;PyObject* resultValue = NULL;if(IsSourceAllDigit(source)){PyObject* intValue = PyInt_Create(atoi(source.c_str()));PyObject* key = PyStr_Create(target.c_str());PyDict_SetItem((PyObject*)m_LocalEnvironment,key,intValue);}else if(source.find("\"") !=string::npos){strValue = PyStr_Create(source.substr(1,source.size()-2).c_str());PyObject* key = PyStr_Create(target.c_str());PyDict_SetItem((PyObject*)m_LocalEnvironment,key,strValue);}else if((pos = source.find("+"))!=string::npos){string left = source.substr(0,pos);string right = source.substr(pos+1);PyObject*leftObject = GetObjectBySymbol(left);PyObject*rightObject = GetObjectBySymbol(right);if(leftObject!=NULL&&rightObject!=NULL&&leftObject->type==rightObject->type){resultValue = (leftObject->type)->add(leftObject,rightObject);PyObject*key = PyStr_Create(target.c_str());PyDict_SetItem((PyObject*)m_LocalEnvironment,key,resultValue);}//(m_LocalEnvironment->type)->print((PyObject*)m_LocalEnvironment);}}void ExcutePrint(string symbol){PyObject* object = GetObjectBySymbol(symbol);if(object!=NULL){PyTypeObject* type = object->type;type->print(object);}}void ExcuteCommand(string&command){string::size_type pos = 0;if((pos = command.find("print "))!=string::npos){ExcutePrint(command.substr(6));}else if((pos=command.find(" = "))!=string::npos){string target = command.substr(0,pos);string source = command.substr(pos+3);ExcuteAdd(target,source);}}const char* info = "*********Python Research*********\n";const char* prompt = ">>>";string m_Command;void Excute(){cout<<info;cout<<prompt;while(getline(cin,m_Command)){if(m_Command.size()==0){cout<<prompt;continue;}else if(m_Command == "exit"){return;}else{ExcuteCommand(m_Command);}cout<<prompt;}}int main(){Excute();return 0;}