Execute SNUSP/Java
This implementation has all of the basic characters plus '%', '@', and '#' (characters from modular and bloated SNUSP found on esolangs). The memory space grows to the right as needed, and the memory pointer cannot go negative. The program will exit if the memory pointer moves to a negative value or if the code pointer leaves the code space. The input ignores return characters because of the way BufferedReader is set up. The random command places a random ASCII value (code 0 through the value in the cell inclusive) in the current memory space.
The implementation comes in two classes: the main program and a code pointer class. The separation is for the easier addition of '&' (split) which could come in the future (the code pointer class would only need to extend Thread and code would need to be added to deal with the command). The main class decides on the input method (file or std in), reads the code, and starts the code pointer. It also figures out where the starting point in the code is ('$' or 0,0).
The main class:<java>import java.awt.Point; import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList;
public class SNUSP{ static Point start; public static void main(String[] args){ try{ start= new Point(0,0); BufferedReader in; ArrayList<String> code = new ArrayList<String>(); if(args.length > 0){ in= new BufferedReader(new FileReader(args[0])); }else{ in= new BufferedReader(new InputStreamReader(System.in)); } code= parse(in); CodePtr cp = new CodePtr(code, start); cp.run(); }catch(FileNotFoundException e){ e.printStackTrace(); }catch(IOException e){ e.printStackTrace(); } }
private static ArrayList<String> parse(BufferedReader in) throws IOException{ String line; ArrayList<String> code= new ArrayList<String>(); while((line= in.readLine())!=null){ code.add(line); if(line.contains("$")){ start = new Point(line.indexOf('$'), code.size() - 1); } } return code; } }</java> The code pointer class:<java>import java.awt.Point; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.LinkedList;
public class CodePtr{ final String instChars= "><.,/\\+-#@$%!?";//valid chars ArrayList<String> code;//code array Direction dir;//current direction ArrayList<Character> mem;//memory space int memPtr;//memory pointer Point place;//code pointer LinkedList<Point> pStack;//code pointer stack LinkedList<Direction> dStack;//direction stack //input stream BufferedReader input= new BufferedReader(new InputStreamReader(System.in));
public CodePtr(final ArrayList<String> code, final Point place){ this.code= code; dir= Direction.RIGHT; this.place= place; mem = new ArrayList<Character>(); mem.add('\0');//initial memory memPtr= 0; dStack= new LinkedList<Direction>(); pStack= new LinkedList<Point>(); }
public CodePtr(final Point place, final Direction dir){ //This constructor is left over from attempts at '&' this.dir= dir; this.place= place; }
public void run(){ while(execute(code.get(place.y).charAt(place.x))){ place= moveCP(); } }
private boolean execute(final char inst){ //ignore char and keep going if(!instChars.contains("" + inst)) return true; switch(inst){ case '.'://print System.out.print(mem.get(memPtr)); break; case ','://input try{ int in; while((in= input.read()) == 10 || in == 13);//skip return chars mem.set(memPtr, (char)in); }catch(final IOException e){ e.printStackTrace(); } break; case '!'://skip place= moveCP(); break; case '?'://conditional skip if(mem.get(memPtr) == 0) place= moveCP(); break; case '>'://move pointer right memPtr++; while(mem.size() <= memPtr){ mem.add('\0');//add more memory cells if necessary } break; case '<'://move memory pointer left memPtr--; if(memPtr < 0){//no negative values System.err.println("memory pointer out of range (negative)"); return false;//stop executing } break; case '/'://mirror switch(dir){ case Direction.RIGHT: dir= Direction.UP; break; case Direction.DOWN: dir= Direction.LEFT; break; case Direction.LEFT: dir= Direction.DOWN; break; case Direction.UP: dir= Direction.RIGHT; break; default: } break; case '\\'://mirror switch(dir){ case Direction.RIGHT: dir= Direction.DOWN; break; case Direction.DOWN: dir= Direction.RIGHT; break; case Direction.LEFT: dir= Direction.UP; break; case Direction.UP: dir= Direction.LEFT; break; default: } break; case '+'://inc mem.set(memPtr, (char)(mem.get(memPtr) + 1)); break; case '-'://dec mem.set(memPtr, (char)(mem.get(memPtr) - 1)); break; case '#'://pop if(dStack.size() > 0){ final Direction oldDir= dStack.pop(); final Point oldPlace= pStack.pop(); place= oldPlace; dir= oldDir; return true; } return false; case '@'://push //protect the reference with a new object pStack.push(new Point(place)); dStack.push(dir); place= moveCP();//skip break; case '%': mem.set(memPtr, (char)(Math.random() * (mem.get(memPtr) + 1))); break; default: } return true; }
private Point moveCP(){ final Point retVal= new Point(place); switch(dir){ case Direction.RIGHT: retVal.x++; break; case Direction.DOWN: retVal.y++; break; case Direction.LEFT: retVal.x--; break; case Direction.UP: retVal.y--; break; default: } if(retVal.x<0 || retVal.y<0 || retVal.y >= code.size() || retVal.x >= code.get(0).length()){ System.err.println("Code pointer has left the code space"); System.exit(-1); } return retVal; } enum Direction{ UP,DOWN,LEFT,RIGHT; } } </java>