Chapter One Straight-Line Program Interpreter from “Modern Compiler Implementation in Java Second Edition” (c) 2002 by Andrew W. Appel, Translation to C++ by James Pate Williams, Jr. on Thursday, April 3, 2025

// Chapter One program translated from Java to C++ by
// James Pate Williams, Jr. (c) Wednesday April 3, 2025
// Reference: "Modern Complier Implementation in Java
// Second Edition" (c) 2002 by Andrew W. Appel

#ifndef _SLPInterpreter_H
#include <iostream>
#include <stack>
#include <string>
#include <vector>

class TableEntry {
public:
	std::string symbol, value;
	TableEntry(std::string symbol, std::string value) {
		this->symbol = symbol;
		this->value = value;
	}
};

std::stack<std::string> sStack;
std::vector<TableEntry> symbolTable;

class Exp {
public:
	Exp() { };
	virtual ~Exp() { };
};

std::stack<Exp> eStack;

class ExpList {
public:
	ExpList() { };
	virtual ~ExpList() { };
};

class Stm {
public:
	Stm() { };
	virtual ~Stm() { };
};

class CompoundStm : public Stm {
public:
	Stm stm1, stm2;
	CompoundStm(Stm stm1, Stm stm2) {
		this->stm1 = stm1;
		this->stm2 = stm2;
	};
};

class AssignStm : public Stm {
public:
	std::string id;
	Exp exp;
	AssignStm(std::string id, Exp exp) {
		this->id = id;
		this->exp = exp;
		bool found = false;
		for (int i = 0; !found && i < (int)symbolTable.size(); i++) {
			if (symbolTable[i].symbol == id) {
				found = true;
			}
		}
		if (!found) {
			symbolTable.push_back(TableEntry(id, ""));
		}
	};
	void Print() {
		std::cout << this->id << ' ';
	};
};

class PrintStm : public Stm {
public:
	ExpList exps;
	PrintStm(ExpList exps) {
		this->exps = exps;
	};
};

class IdExp : public Exp {
public:
	std::string id;
	IdExp(std::string id) {
		this->id = id;
		Print();
		TableEntry te(id, "");
	};
	void Print() {
		std::cout << id << ' ';
	};
};

class NumExp : public Exp {
public:
	int num;
	NumExp(int num) {
		this->num = num;
		Print();
		char buffer[128] = { };
		_itoa_s(num, buffer, 127, 10);
		sStack.push(std::string(buffer));
	};
	void Print() {
		std::cout << num << ' ';
	};
};

enum class ArithmeticOp {
	Plus, Minus, Times, Div
};

class OpExp : public Exp {
public:
	Exp left, right;
	ArithmeticOp op;
	OpExp(Exp left, ArithmeticOp op, Exp right) {
		this->left = left;
		this->op = op;
		this->right = right;
		std::string ops = "";
		switch (op) {
		case ArithmeticOp::Plus:
			ops = "+";
			break;
		case ArithmeticOp::Minus:
			ops = "-";
			break;
		case ArithmeticOp::Times:
			ops = "*";
			break;
		case ArithmeticOp::Div:
			ops = "/";
			break;
		};
		std::cout << ops << std::endl;
		eStack.push(left);
		eStack.push(right);
		sStack.push(ops);
	};
};

class EseqExp : public Exp {
public:
	Stm stm; Exp exp;
	EseqExp(Stm stm, Exp exp) {
		this->stm = stm;
		this->exp = exp;
	};
};

class PairExpList : public ExpList {
public:
	Exp head;
	ExpList tail;
	PairExpList(Exp head, ExpList tail) {
		this->head = head;
		this->tail = tail;
	};
};

class LastExpList : public ExpList {
public:
	Exp head;
	LastExpList(Exp head) {
		this->head = head;
	};
};

#endif _SLPInterpreter_H

int main() {
	int a = 0, b = 0;
	Stm prog(CompoundStm(AssignStm("a",
		OpExp(NumExp(5), ArithmeticOp::Plus, NumExp(3))),
		CompoundStm(AssignStm("b",
			EseqExp(PrintStm(PairExpList(IdExp("a"),
				LastExpList(OpExp(IdExp("a"),
					ArithmeticOp::Minus, NumExp(1))))),
				OpExp(NumExp(10), ArithmeticOp::Times, IdExp("a")))),
			PrintStm(LastExpList(IdExp("b"))))));
	bool first = true;
	int result = 0;
	//sStack.push("0");
	while (!sStack.empty()) {
		std::string lts, ops, rts;
		if (first) {
			ops = sStack.top();
			sStack.pop();
			lts = sStack.top();
			sStack.pop();
			rts = sStack.top();
			sStack.pop();
			first = false;
		}
		else {
			lts = sStack.top();
			sStack.pop();
			ops = sStack.top();
			sStack.pop();
			rts = sStack.top();
			sStack.pop();
		}
		int lvi = std::stoi(lts);
		int rvi = std::stoi(rts);
		if (ops == "+") {
			result = lvi + rvi;
		}
		else if (ops == "-") {
			result = lvi - rvi;
		}
		else if (ops == "*") {
			result = lvi * rvi;
		}
		else if (ops == "/") {
			result = lvi / rvi;
		}
		char ascii[128] = { };
		_itoa_s(result, ascii, 10);
		if (sStack.size() != 0) {
			sStack.push(std::string(ascii));
		}
	}
	std::cout << "Result = " << result << std::endl;
	return 0;
}