98 lines
2.4 KiB
C++
98 lines
2.4 KiB
C++
#include"PostfixEval.h"
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#include<algorithm>
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#include<cctype>
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double PostfixEval::run(const std::vector<Token>& postfix, const unordered_map<string, double>& vars) {
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stack<double> stk;
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for (const auto& token : postfix) {
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if (token.is_num())
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//数字转换为double入栈
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stk.push(stod(token.value));
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else if (token.is_var()) {
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//查找变量映射表
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auto it = vars.find(token.value);
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// 支持内置常量 PAI 和 e
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if (it == vars.end()) {
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if (token.value == "PAI")
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stk.push(2.0 * std::asin(1.0)); // π = 2 * arcsin(1)
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else if (token.value == "e")
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stk.push(std::exp(1.0)); // e = exp(1)
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else
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throw runtime_error("变量未定义：" + token.value);
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}
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else stk.push(it->second);
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}
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else if (token.is_ope()) {
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//取出两个操作数，执行二元运算
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if (stk.size() < 2) throw runtime_error("操作数不足");
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double b = stk.top();
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stk.pop();
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double a = stk.top();
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stk.pop();
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double res = apply_BO(token.value, a, b);
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stk.push(res);
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}
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else if (token.is_fun()) {
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//取出一个操作数，执行一元基本初等函数的计算
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if (stk.empty()) throw runtime_error("操作数不足");
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double x = stk.top();
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stk.pop();
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double res = apply_UF(token.value, x);
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stk.push(res);
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}
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else
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throw runtime_error("未知Token类型");
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}
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if (stk.size() != 1)
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throw runtime_error("表达式错误，计算结果栈不唯一");
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return stk.top();
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}
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//进行二元运算符的运算
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double PostfixEval::apply_BO(const string& op, double a, double b) {
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if (op == "+") return a + b;
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if (op == "-") return a - b;
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if (op == "*") return a * b;
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if (op == "/") {
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if (b == 0) throw runtime_error("除数不能为0");
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return a / b;
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}
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if (op == "^") return pow(a, b);
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if (op == "%") {
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if (b == 0) throw runtime_error("模除数不能为零");
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return std::fmod(a, b);
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}
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throw runtime_error("未知运算符：" + op);
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}
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//进行一元基本初等函数的运算
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double PostfixEval::apply_UF(const string& func, double x) {
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string f = func;
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transform(f.begin(), f.end(), f.begin(), ::tolower);
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if (f == "sin") return sin(x);
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if (f == "cos") return cos(x);
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if (f == "tan") return tan(x);
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if (f == "sqrt") {
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if (x < 0)
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throw runtime_error("sqrt参数不能为负");
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return sqrt(x);
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}
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if (f == "log") {
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if (x <= 0)
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throw runtime_error("log参数必须大于0");
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return log(x);
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}
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if (f == "exp") return exp(x);
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if (f == "abs") return fabs(x);
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if (f == "asin") return asin(x);
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if (f == "acos") return acos(x);
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if (f == "atan") return atan(x);
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throw runtime_error("未知函数：" + func);
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}
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