编程实战：类C语法的编译型脚本解释器（五）

系列入口：

编程实战：类C语法的编译型脚本解释器（系列）-CSDN博客

        本文介绍变量表的实现。

一、变量表的组织结构

        堆栈结构，进入一层新建一个层级，退出一层则丢弃整个层。

        查找时自顶向下逐级查找，直到最后的环境变量（执行脚本前预设的变量）。

二、代码

		//变量表
		struct T_VARIABLE_BLOCK : public vector >
		{
			bool AddVariable(string const& var_name, Variable const& var)
			{
				for (const_iterator it = begin(); it != end(); ++it)
				{
					if (it->first == var_name)
					{
						return false;
					}
				}

				push_back(pair(var_name, var));
				return true;
			}
			Variable* FindVariable(string const& var_name)const
			{
				return FindVariable(var_name.c_str());
			}
			Variable* FindVariable(char const* var_name)const
			{
				for (const_reverse_iterator it = rbegin(); it != rend(); ++it)
				{
					if (it->first != var_name)
					{
						continue;
					}
					return (Variable*)&it->second;
				}
				return NULL;
			}
		};
		class T_VARIABLE_S
		{
		private:
			typedef vector T_DATA;

			T_VARIABLE_BLOCK* m_pEnvs;//指向环境变量
			T_VARIABLE_BLOCK* m_pGlobals;//指向全局变量
			long m_Globals_count;//全局变量个数
			T_VARIABLE_BLOCK* m_pParams;//指向参数
			T_DATA m_local_variables;//局部变量
		public:
			T_VARIABLE_S() :m_pEnvs(NULL), m_pGlobals(NULL), m_Globals_count(-1), m_pParams(NULL) {}
			long getGlobalCount()const { return m_pGlobals->size(); }
			void T_VARIABLE_S_init(T_VARIABLE_BLOCK* pEnv, T_VARIABLE_BLOCK* pG, long Globals_count, T_VARIABLE_BLOCK* pP)
			{
				m_pEnvs = pEnv;
				m_pGlobals = pG;
				m_Globals_count = Globals_count;
				m_pParams = pP;
				m_local_variables.clear();
			}
			void T_VARIABLE_S_init(T_VARIABLE_BLOCK const* pEnv, T_VARIABLE_BLOCK const* pG, long Globals_count, T_VARIABLE_BLOCK const* pP)
			{
				m_pEnvs = (T_VARIABLE_BLOCK*)pEnv;
				m_pGlobals = (T_VARIABLE_BLOCK*)pG;
				m_Globals_count = Globals_count;
				m_pParams = (T_VARIABLE_BLOCK*)pP;
				m_local_variables.clear();
			}
			void FromParentVars(T_VARIABLE_S& vars, long Globals_count, T_VARIABLE_BLOCK const* pP)
			{
				T_VARIABLE_S_init(vars.m_pEnvs, vars.m_pGlobals, Globals_count, pP);
			}
			void FromParentVars(T_VARIABLE_S const& vars, long Globals_count, T_VARIABLE_BLOCK const* pP)
			{
				T_VARIABLE_S_init(vars.m_pEnvs, vars.m_pGlobals, Globals_count, pP);
			}
			void PushLevel()
			{
				m_local_variables.resize(m_local_variables.size() + 1);
				//cout << "PushLevel " << m_datas.size() << endl;
			}
			void PopLevel()
			{
				if (m_local_variables.size() > 0)m_local_variables.resize(m_local_variables.size() - 1);
				//cout << "PopLevel " << m_datas.size() << endl;
			}
			bool AddVariable(string const& var_name, Variable const& var)
			{
				if (NULL != FindVariable(var_name))return false;
				if (0 == m_local_variables.size())
				{//全局变量
					m_pGlobals->push_back(pair(var_name, var));
				}
				else
				{//局部变量
					m_local_variables.rbegin()->push_back(pair(var_name, var));
				}
				return true;
			}
			Variable* FindVariable(string const& var_name)const
			{
				return FindVariable(var_name.c_str());
			}
			Variable* FindVariable(char const* var_name)const
			{
				long count;

				//从顶层向底层查找
				for (T_DATA::const_reverse_iterator it = m_local_variables.rbegin(); it != m_local_variables.rend(); ++it)
				{
					for (T_VARIABLE_BLOCK::const_iterator it_block = it->begin(); it_block != it->end(); ++it_block)
					{
						if (it_block->first != var_name)
						{
							continue;
						}
						return (Variable*)&it_block->second;
					}
				}

				//再找参数
				count = m_pParams->size();
				for (--count; count >= 0; --count)
				{
					if ((*m_pParams)[count].first != var_name)
					{
						continue;
					}
					return (Variable*) & (*m_pParams)[count].second;
				}

				//再找全局变量
				count = (m_Globals_count < 0 ? m_pGlobals->size() : m_Globals_count);
				if (m_Globals_count >= 0 && m_Globals_count > (long)m_pGlobals->size())
				{
					cout << "错误的有效全局变量个数 " << m_Globals_count << " 最大 " << m_pGlobals->size() << endl;
					return NULL;
				}
				for (--count; count >= 0; --count)
				{
					if ((*m_pGlobals)[count].first != var_name)
					{
						continue;
					}
					return (Variable*) & (*m_pGlobals)[count].second;
				}

				//最后找环境变量
				for (T_VARIABLE_BLOCK::const_reverse_iterator it = m_pEnvs->rbegin(); it != m_pEnvs->rend(); ++it)
				{
					if (it->first != var_name)
					{
						continue;
					}
					return (Variable*)&it->second;
				}

				return NULL;
			}
			string ToString(long level = 0)const
			{
				stringstream ret;
				ret << this << endl;
				long n = 0;
				ret << "环境变量：" << endl;
				for (T_VARIABLE_BLOCK::const_iterator it = m_pEnvs->begin(); it != m_pEnvs->end(); ++it)
				{
					ret << n << " : " << it->first << " : " << it->second.ToString() << endl;
					++n;
				}
				ret << "全局变量：有效数" << this->m_Globals_count << endl;
				for (T_VARIABLE_BLOCK::const_iterator it = m_pGlobals->begin(); it != m_pGlobals->end(); ++it)
				{
					ret << n << " : " << it->first << " : " << it->second.ToString() << endl;
					++n;
				}
				ret << "参数：" << endl;
				for (T_VARIABLE_BLOCK::const_iterator it = m_pParams->begin(); it != m_pParams->end(); ++it)
				{
					ret << n << " : " << it->first << " : " << it->second.ToString() << endl;
					++n;
				}
				ret << "局部变量：" << endl;
				for (T_DATA::const_iterator it = m_local_variables.begin(); it != m_local_variables.end(); ++it)
				{
					for (T_VARIABLE_BLOCK::const_iterator it_block = it->begin(); it_block != it->end(); ++it_block)
					{
						//if(it_block->second->isconst)continue;
						ret << n << " : " << it_block->first << " : " << it_block->second.ToString() << endl;
					}
					++n;
				}
				return ret.str();
			}
		};