private void addOperator(Operator operator) {
Section section = stack.peek();
Tree tree = section.unwind(operator);
Tree tree1 = Tree.of(operator, tree.getRight(), Atom.NIL);
Tree.forceSetRight(tree, tree1);
section.push(tree1);
}
private class Section {
private char kind;
private Deque<Tree> list = new ArrayDeque<>(Arrays.asList(Tree.of(null, null, Atom.NIL)));
private boolean isDanglingRight = true;
public Section(char kind) {
this.kind = kind;
}
private Tree unwind(Operator operator) {
int prec0 = operator != null ? operator.getPrecedence() : -1;
Operator op;
Tree tree;
while ((op = (tree = list.getLast()).getOperator()) != null) {
int prec1 = op.getPrecedence();
if (prec0 < prec1 || operator.getAssoc() == Assoc.LEFT && prec0 == prec1) pop();
else break;
}
return tree;
}
private void push(Tree tree) {
list.addLast(tree);
isDanglingRight = true;
}
private Tree pop() {
return list.removeLast();
}
}
private Node parse() {
Lexer lex = new Lexer(operators, in);
stack.push(new Section(' '));
Token token;
while ((token = lex.lex()) != null) {
Operator operator = token.operator;
String data = token.getData();
char ch = data.charAt(0);
if (operator != null) {
addOperator(operator);
if (operator == TermOp.BRACES) stack.push(new Section('{'));
} else if (ch == '(' || ch == '[' || ch == '{') stack.push(new Section(ch));
else if (ch == ')' || ch == ']' || ch == '}') {
Section section = stack.pop();
if (section.kind == '(' && ch == ')' //
|| section.kind == '[' && ch == ']' //
|| section.kind == '{' && ch == '}') {
Node node = section.unwind(null).getRight();
if (ch == ']') node = Tree.of(TermOp.TUPLE_, Atom.of("["), node);
add(node);
} else throw new RuntimeException("Cannot parse " + in);
} else if (ch == '`')
if (stack.peek().kind == ch) {
Node node = stack.pop().unwind(null).getRight();
node = Tree.of(TermOp.TUPLE_, Atom.of("`"), node);
add(node);
} else stack.push(new Section(ch));
else if (Util.isNotBlank(data)) add(terminalParser.parseTerminal(data));
}
if (stack.size() == 1) return stack.pop().unwind(null).getRight();
else throw new RuntimeException("Cannot parse " + in);
}
private void add(Node node) {
Section section = stack.peek();
if (!section.isDanglingRight) addOperator(TermOp.TUPLE_);
Tree.forceSetRight(section.list.getLast(), node);
section.isDanglingRight = false;
}