mumei.cpp

#include <string>
#include <iostream>
#include <algorithm>
#include <vector>
#include <cstdio>
using namespace std;
vector<string> nameTable;
int getVarID(string name) {
	auto it=nameTable.end();
	for(auto it=nameTable.begin(); it!=nameTable.end(); it++) {
		if(nameTable[it-nameTable.begin()]==name)
			return it-nameTable.begin()+1;
	}
	nameTable.push_back(name);
	return nameTable.size();
}
int labelGen() {
	static int labelNum=0;
	return labelNum++;
}
//This is a conversion of Crenshaw's "Let's Build a Compiler" series.
char look;
void GetChar() {
	look=getchar();
	if(cin.eof())
		look='\0';
}

void error(string s) {
	cerr << "\n\aError: " << s << ".\n";
}
void abort(string s) {
	error(s);
	exit(-1);
}
void expected(string s) {
	abort(s + " Expected");
}
bool isAlpha(char c) {
	return (c<='Z')?((c<='Z')&&(c>='A')):((c<='z')&&(c>='a'));
}
bool isDigit(char c) {
	return (c<='9')&&(c>='0');
}
bool isAddop(char c) {
	return (c=='+')||(c=='-');
}
bool isMulop(char c) {
	return (c=='*')||(c=='/');
}
bool isAlNum(char c) {
	return isAlpha(c) || isDigit(c);
}
bool isWhite(char c) {
	return (c==' ')||(c=='\t')||(c=='\n');
}
void skipWhite() {
	while(isWhite(look))
		GetChar();
}

void match(char x) {
	if(look==x) {
		GetChar();
		skipWhite();
	} else
		expected(""s+x);
}
void match(string x) {
	for(int i=0;i<x.length();i++) {
		match(x[i]);
	}
}

string getName() {
	string token="";
	if(!isAlpha(look))
		expected("Name");
	while(isAlNum(look)) {
		token+=look;
		GetChar();
	}
	skipWhite();
	return token;
}
string getNum() {
	string value;
	if(!isDigit(look))
		expected("Integer");
	while(isDigit(look)) {
		value+=look;
		GetChar();
	}
	skipWhite();
	return value;
}
void emit(string s) {
	cout << "\t" << s;
}
void emitLn(string s) {
	emit(s);
	cout << "\n";
}

void expression();
void ident() {
	string name=getName();
	if(look=='(') {
		match('(');
		match(')');
		emitLn("cpget");
		emitLn("jmp @"s+name);
		emitLn("load "s + to_string(getVarID(name)));
	} else if(look=='=') {
		match('=');
		expression();
		emitLn("store "+to_string(getVarID(name)));
	} else {
		emitLn("load "s + to_string(getVarID(name)));
	}
}
void factor() {
	if(look=='(') {
		match('(');
		expression();
		match(')');
	} else if(isAlpha(look)) {
		ident();
	} else {
		emitLn("push "s + getNum());
	}
}

void multiply() {
	match('*');
	factor();
	emitLn("mul");
}
void divide() {
	match('/');
	emitLn("store 0");
	factor();
	emitLn("load 0");
	emitLn("div");
}
void term() {
	factor();
	while(isMulop(look)) {
		switch(look) {
			case '*':
				multiply();
				break;
			case '/':
				divide();
				break;
			default:
				expected("Mulop");
		}
	}
}

void add() {
	match('+');
	term();
	emitLn("add");
}
void subtract() {
	match('-');
	term();
	emitLn("sub");
	emitLn("not");
	emitLn("[i0:arg] add 1");
}
void expression() {
	if(isAddop(look)) {
		emitLn("push 0");
	} else
		term();
	while(isAddop(look)) {
		switch(look) {
			case '+':
				add();
				break;
			case '-':
				subtract();
				break;
			default:
				expected("Addop");
		}
	}
}
void assignment() {
	if(isAlpha(look)) {
		ident();
	} else {
		expression();
		emitLn("drop");
	}
}

void block(int label); 
int condition(int blk) {
	expression(); //First part of expression
	string comparision=getName(); //Middle part of expression
	expression(); //Last part of expression
	match(':');
	emitLn("sub [r:discard] [f:yes] ");
	int after=labelGen();
	int label=(block<0)?after:blk;
	if(comparision=="eq") {
		emitLn("[ex(z)=0] jmp @_L"s + to_string(after));
		block(label);
	} else if(comparision=="ne") {
		emitLn("[ex(z)=1] jmp @_L"s + to_string(after));
		block(label);
	} else if(comparision=="gt") {
		emitLn("[ex(n)=1] jmp @_L"s + to_string(after));
		emitLn("[ex(z)=1] jmp @_L"s + to_string(after));
		block(label);
	} else if(comparision=="lt") {
		emitLn("[ex(n)=0] jmp @_L"s + to_string(after));
		block(label);
	} else {
		expected("Comparision");
	}
	return after;
}
void doIf(int blk) {
	int after=condition(blk);
	if(look=='!') {
		match("!ELSE:");
		int afterElse=labelGen();
		emitLn("jmp @_L"+to_string(afterElse));
		cout << "_L" << after << ":\n";
		block(blk);
		cout << "_L" << afterElse << ":\n";
	} else {
		cout << "_L" << after << ":\n";
	}
}
void doWhile() {
	int before=labelGen();
	cout << "_L" << before << ":\n";
	int after=condition(-1);
	emitLn("jmp @_L"s+to_string(before));
	cout << "_L" << after << ":\n";
}
void doLoop() {
	int before=labelGen();
	int after=labelGen();
	cout << "_L" << before << ":\n";
	block(after);
	emitLn("jmp @_L"s+to_string(before));
	cout << "_L" << after << ":\n";
}
void doFor() {
	string varname = getName();
	int varID = getVarID(varname);
	int varCheck = labelGen();
	int after = labelGen();
	match('=');
	expression();
	emitLn("store "s+to_string(varID));
	cout << "_L" << varCheck << ":\n";
	emitLn("load "s+to_string(varID));
	match("TO");
	expression();
	match(':');
	emitLn("[i0:arg] add 1");
	emitLn("sub [r:discard] [f:yes]");
	emitLn("[ex(n)=0] jmp @_L"s + to_string(after));
	block(after);
	emitLn("load "s+to_string(varID));
	emitLn("[i0:arg] add 1");
	emitLn("store "s+to_string(varID));
	emitLn("jmp @_L"s+to_string(varCheck));
	cout << "_L" << after << ":\n";
}
void doBreak(int lbl) {
	if(lbl<0)
		abort("No loop to break from");
	emitLn("jmp @_L"s + to_string(lbl));
}
bool other(int block) {
	string token=getName();
	if(token=="END")
		return true;
	if(token=="IF")
		doIf(block);
	if(token=="WHILE")
		doWhile();
	if(token=="LOOP")
		doLoop();
	if(token=="FOR")
		doFor();
	if(token=="BREAK")
		doBreak(block);
	return false;
}
void block(int block) {
	while(true) {
		if(look=='%') {
			match('%');
			if(other(block))
				return;
		} else if (!look)
			return;
		else if (look=='!')
			return;
		else
			assignment();
	}
}
bool function() {
	match("%FUNCTION");
	cout << getName() << ":\n"; //Start function
	match(':');
	block(-1);
	emitLn("ret");
	
}
void init() {
	//Output standard library
	cout << "_start:\n";
	emitLn("cpget");
	emitLn("jmp @main");
	emitLn("[i0:zero] syscall [ci:0]");
	cout << "putc:\n";
	emitLn("load "s+to_string(getVarID("putChar")));
	emitLn("[i0:pop] syscall [ci:1]");
	emitLn("ret");
	cout << "puti:\n";
	emitLn("load "s+to_string(getVarID("putNumber")));
	emitLn("[i0:pop] syscall [ci:2]");
	emitLn("ret");
	GetChar();
	skipWhite();
}
int main() {
	
	init();
	bool fin=false;
	while(look=='%')
		function();
	cout << ";Name table:\n";
	for(int i=0;i<nameTable.size();i++) {
		cout << ";"<<i<<": "<<nameTable[i]<<"\n";
	}
	return 0;
}