Notes

import java.io.*;
import java.util.*;

public class Main {

public static ArrayList<String> variables = new ArrayList<>();
public static int variableCounter = 1;
public static BufferedWriter bw;
public static void main(String[] args) throws IOException {

FileWriter outFile = new FileWriter(args[0].substring(args[0].indexOf("."))+"ll");
BufferedWriter bw = new BufferedWriter(outFile);

if (errorCheck(args)) {
printHead();
Scanner console = new Scanner(new File("input.txt"));
String line = "", lhs = "", rhs = "";
while (console.hasNextLine()) {
line = console.nextLine();
line = line.replaceAll("\s+", "");
if (line.contains("=")) {
lhs = line.substring(0, line.indexOf("="));
if (!variables.contains(lhs))
bw.write("%" + lhs + " = alloca i32");
variables.add(lhs);
rhs = line.substring(line.indexOf("=") + 1);
rhs = inf2postf(rhs);
expression(rhs, true, lhs); // expression, willBeAssigned, lhs
} else {
if (line.contains("*") || line.contains("/") || line.contains("+") || line.contains("-")) {
line = inf2postf(line);
line = expression(line, false, ""); // expression, willBeAssigned, lhs
bw.write("call i32 (i8*, ...)* @printf(i8* getelementptr ([4 x i8]* @print.str, i32 0, i32 0), i32 %" + (variableCounter - 1) + " )");
} else {
if (!isInteger(line)) bw.write("%" + variableCounter++ + " = load i32* %" + line);
bw.write("call i32 (i8*, ...)* @printf(i8* getelementptr ([4 x i8]* @print.str, i32 0, i32 0), i32 %" + (variableCounter - 1) + " )");
variableCounter++;
}
}
}
bw.write("ret i32 0n}");
}
}

private static boolean errorCheck(String[] args) throws FileNotFoundException{
Scanner console = new Scanner(new File("input.txt"));
ArrayList<String> definedVariables = new ArrayList<>();
String line = "";
int lineNum = 0;
while (console.hasNextLine()){
line = console.nextLine();
line = line.replaceAll("\s+", "");
lineNum++;

// parenthesis check
if (!parenthesisCheck(line)){
System.out.print("Error: Line: "+ lineNum + ": parenthesis error");
return false;
}

// lhs have operand
if (line.contains("=")) {
String lhs = line.substring(0, line.indexOf("="));
if (lhs.contains("+") || lhs.contains("-") || lhs.contains("*") || lhs.contains("/")) {
System.out.print("Error: Line: " + lineNum + ": lefthandside cannot have an operand");
return false;
}
}

// string starts and ends with operand
if ("/*-+".contains(line.charAt(0)+"") || "/*-+".contains(line.charAt(line.length()-1)+"")){
System.out.print("Error: Line: " + lineNum + ": an expression cannot start or end with an operand");
return false;
}
if (line.contains("=")){
if("/*-+".contains(line.charAt(line.indexOf("=")+1)+"") || "/*-+".contains(line.charAt(line.indexOf("=")-1)+"")){
System.out.print("Error: Line: " + lineNum + ": an expression cannot start or end with an operand");
return false;
}
}
// successive operand
String temp = "";
String newLine = line.substring(line.indexOf("=") + 1);
for (int i = 0; i < newLine.length(); i++) {
if ("+/-*".contains(newLine.charAt(i)+"")){
if (i + 1 < newLine.length()){
if ("+/-*".contains(newLine.charAt(i+1)+"")){
System.out.print("Error: Line: "+ lineNum + ": successive operand");
return false;
}
}
}
}

// undefined variable
if (line.contains("=")){
String lhs = line.substring(0, line.indexOf("="));
if (!definedVariables.contains(lhs)) definedVariables.add(lhs);
String rhs = line.substring(line.indexOf("=")+1);
rhs = inf2postf(rhs);
String str = "";
if (rhs.length() != 0 && !rhs.contains(",")){
if (!isInteger(rhs) && !definedVariables.contains(rhs)){
System.out.print("Error: Line: "+ lineNum + ": undefined variable");
return false;
} else continue;
}
for (int i = 0; i < rhs.length(); i++) {
if (!(rhs.charAt(i)+"").equals(",")){
str += rhs.charAt(i);
continue;
}
if (!"+-*/".contains(str) && !isInteger(str) && !definedVariables.contains(str)){
System.out.print("Error: Line: "+ lineNum + ": undefined variable");
return false;
}
str = "";
}
}

}
return true;
}

private static boolean parenthesisCheck(String line) {
int c = 0;
for (int i = 0; i < line.length(); i++) {
if ((""+line.charAt(i)).equals("(")) c++;
else if ((""+line.charAt(i)).equals(")")) c--;
if (c < 0) return false;
}
return c == 0;
}

private static String expression(String line, Boolean isAssign, String lhs) {
Stack<String> stack = new Stack<>();
while (line.length() != 0){
String temp = "";
if (line.contains(",")){
temp = line.substring(0, line.indexOf(","));
line = line.substring(line.indexOf(",") + 1);
if (!"+-*/".contains(temp)) {
stack.push(temp);
} else {
stack.push(calculate(stack.pop(), stack.pop(), temp));
}
} else if (!stack.empty()){
stack.push(calculate(stack.pop(), stack.pop(), line));
line = "";
} else {
stack.push(line);
line = "";
}
}
if (isAssign){
try {
if (isInteger(stack.peek())) bw.write("store i32 " + stack.peek() + ", i32* " + "%" + lhs);
else bw.write("store i32 %" + (variableCounter - 1) + ", i32* " + "%" + lhs);
}catch (IOException e) {
e.printStackTrace();
}
}
return stack.pop();
}
private static String calculate(String f, String s, String opr){
f = loadIfNot(f);
s = loadIfNot(s);
if (f.substring(0,1).equals("%")) f = "%" + (Integer.parseInt(f.substring(1))-1) + "";
if (s.substring(0,1).equals("%")) s = "%" + (Integer.parseInt(s.substring(1))-1) + "";
try {
if (opr.equals("*")) {
bw.write("%" + variableCounter++ + " = mul i32 " + s + "," + f);
} else if (opr.equals("/")) {
bw.write("%" + variableCounter++ + " = sdiv i32 " + s + "," + f);
} else if (opr.equals("+")) {
bw.write("%" + variableCounter++ + " = add i32 " + s + "," + f);
} else {
bw.write("%" + variableCounter++ + " = sub i32 " + s + "," + f);
}
}catch (IOException e) {
e.printStackTrace();
}
return "%"+ variableCounter;
}
private static String loadIfNot(String str) {
if (isInteger(str) || str.substring(0,1).equals("%")) return str;
else try {
bw.write("%" + variableCounter++ + " = load i32* %" + str);
} catch (IOException e) {
e.printStackTrace();
}
return "%"+variableCounter;
}

private static String inf2postf(String infix) {
String postfix = "";
Stack<String> operator = new Stack<>();
String popped;
for (int i = 0; i < infix.length(); i++) {
String get = infix.charAt(i) + "";
while (!"+-*/()".contains(get) && i < infix.length()-1 && !"+-*/()".contains(infix.charAt(i+1)+"")){
get += infix.charAt(i+1)+"";
i++;
}
if (!isOperator(get))
postfix += get + ",";
else if (get.equals(")"))
while (!(popped = operator.pop()).equals("("))
postfix += popped + ",";
else {
while (!operator.isEmpty() && !get.equals("(") && precedence(operator.peek()) >= precedence(get))
postfix += operator.pop() + ",";
operator.push(get);
}
}
while (!operator.isEmpty())
postfix += operator.pop() + ",";
return postfix.substring(0,postfix.length()-1);
}
private static boolean isOperator(String i) {
return precedence(i) > 0;
}
private static int precedence(String i) {
if (i.equals("(") || i.equals(")")) return 1;
else if (i.equals("-") || i.equals("+")) return 2;
else if (i.equals("*") || i.equals("/")) return 3;
else return 0;
}

private static boolean isInteger(String str) {
if (str == null) return false;
int length = str.length();
if (length == 0) return false;
int i = 0;
if (str.charAt(0) == '-') {
if (length == 1) return false;
i = 1;
}
for (; i < length; i++) {
char c = str.charAt(i);
if (c < '0' || c > '9') return false;
}
return true;
}
private static void printHead() {
try {
bw.write("; ModuleID = 'stm2ir'n" +
"declare i32 @printf(i8*, ...)n" +
"@print.str = constant [4 x i8] c"%d\0A\00"nn" +
"define i32 @main() {");
} catch (IOException e) {
e.printStackTrace();
}
}

}