private static void replace(Tree code, String data, Tree replacement) {
System.out.println("Trying to replace" + data + " with " + replacement + " in " + code);
if (code.getData().equals(data)) {
System.out.println("Replacing " + data + " with " + replacement);
code.removeChildren(false);
for (Tree t : replacement.getChildren()) {
code.addChild(new Tree(t), false);
}
code.setData(replacement.getData());
} else if (code.getData().equals(FUN)) {
// Shadowing
Vector<Tree> fn = code.getChildren();
Vector<Tree> args = fn.get(0).getChildren();
for (Tree t : args) {
if (t.getData().equals(data)) {
return;
}
}
// If we made it here, the replacement term is not in the args
replace(fn.get(1), data, replacement);
} else {
for (Tree t : code.getChildren()) {
replace(t, data, replacement);
}
}
}
Tree parse(String code) throws CompilationException {
if (code == null || code.isEmpty()) return null;
// Base Case
if (code.charAt(0) != '(') return new Tree(code);
// Recursive Case
ArrayList<String> chunks = findChunks(code);
List<Tree> kids = new LinkedList<Tree>();
for (String chunk : chunks) {
kids.add(parse(chunk));
}
if (!kids.isEmpty() && isReserved(kids.get(0).getData())) {
// Now we need to make special Trees based on what kind of special thing
// this is
Tree first = kids.get(0);
if (first.getChildren() != null && first.getChildren().size() > 0) return new Tree(kids);
kids.remove(0);
String word = first.getData();
if (word.equals(FUN)) {
// (FUN (arg1 arg2 [...]) body) ; note that args are optional
if (kids.size() <= 1) throw new CompilationException(code);
if (kids.get(1).getChildren() == null) throw new CompilationException(code);
return new Tree(FUN, kids);
} else if (word.equals(IF)) {
// (if cond then else)
if (kids.size() != 3) throw new CompilationException(code);
return new Tree(IF, kids);
} else {
return new Tree(word, kids);
}
} else {
return new Tree(kids);
}
}
private boolean step(Tree code) {
if (code.getData().equals(FUN)) return false;
if (code.getData().equals("")
&& code.getChildren().size() >= 1
&& code.getChild(0).getData().equals(FUN)) {
// This is an APPLY -- make sure it works.
Tree fn = code.getChild(0);
Vector<Tree> fnargs = fn.getChildren();
Tree body = fnargs.get(1);
fnargs = fnargs.get(0).getChildren();
Vector<Tree> inargs = code.getChildren();
inargs.remove(0);
for (Tree t : inargs) {
if (step(t)) return true;
}
if (fnargs.size() != inargs.size()) {
return false;
}
for (int i = 0; i < fnargs.size(); i++) {
replace(body, fnargs.get(i).getData(), inargs.get(i));
}
code.removeChildren(false);
for (Tree t : body.getChildren()) {
code.addChild(t, false);
}
code.setData(body.getData());
return true;
} else if (code.getData().equals(IF)) {
// IF
Vector<Tree> ifargs = code.getChildren();
if (step(ifargs.get(0))) return true;
if (ifargs.get(0).getData().equals("0")) { // "0" is our only false value
System.out.println("FALSE IF");
code.removeChildren(false);
for (Tree kkid : ifargs.get(2).getChildren()) {
code.addChild(kkid, false);
}
code.setData(ifargs.get(2).getData());
} else {
System.out.println("TRUE IF: " + ifargs.get(0));
code.removeChildren(false);
for (Tree kkid : ifargs.get(1).getChildren()) {
code.addChild(kkid, false);
}
code.setData(ifargs.get(1).getData());
}
return true;
}
for (Tree kid : code.getChildren()) {
if (step(kid)) {
System.out.println("stepped " + kid);
return true;
}
}
if (code.getData().equals("<")) {
Vector<Tree> ltargs = code.getChildren();
Double left = Double.parseDouble(ltargs.get(0).getData());
Double right = Double.parseDouble(ltargs.get(1).getData());
code.removeChildren(false);
if (left < right) {
code.setData("1");
} else {
code.setData("0");
}
return true;
} else if (code.getData().equals(">")) {
Vector<Tree> ltargs = code.getChildren();
Double left = Double.parseDouble(ltargs.get(0).getData());
Double right = Double.parseDouble(ltargs.get(1).getData());
code.removeChildren(false);
if (left > right) {
code.setData("1");
} else {
code.setData("0");
}
return true;
} else if (code.getData().equals("=")) {
Vector<Tree> ltargs = code.getChildren();
Double left = Double.parseDouble(ltargs.get(0).getData());
Double right = Double.parseDouble(ltargs.get(1).getData());
code.removeChildren(false);
if (left.equals(right)) {
code.setData("1");
} else {
code.setData("0");
}
return true;
} else if (code.getData().equals("+")) {
Vector<Tree> ltargs = code.getChildren();
Double left = Double.parseDouble(ltargs.get(0).getData());
Double right = Double.parseDouble(ltargs.get(1).getData());
code.removeChildren(false);
code.setData("" + (left + right));
return true;
} else if (code.getData().equals("-")) {
Vector<Tree> ltargs = code.getChildren();
Double left = Double.parseDouble(ltargs.get(0).getData());
Double right = Double.parseDouble(ltargs.get(1).getData());
code.removeChildren(false);
code.setData("" + (left - right));
return true;
} else if (code.getData().equals("*")) {
Vector<Tree> ltargs = code.getChildren();
Double left = Double.parseDouble(ltargs.get(0).getData());
Double right = Double.parseDouble(ltargs.get(1).getData());
code.removeChildren(false);
code.setData("" + (left * right));
return true;
} else if (code.getData().equals("/")) {
Vector<Tree> ltargs = code.getChildren();
Double left = Double.parseDouble(ltargs.get(0).getData());
Double right = Double.parseDouble(ltargs.get(1).getData());
code.removeChildren(false);
code.setData("" + (left / right));
return true;
} else if (code.getData().equals("^")) {
Vector<Tree> ltargs = code.getChildren();
Double left = Double.parseDouble(ltargs.get(0).getData());
Double right = Double.parseDouble(ltargs.get(1).getData());
code.removeChildren(false);
code.setData("" + Math.pow(left, right));
return true;
}
System.out.println("Couldn't step: " + code.getData());
return false;
}