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namespace Utils {
[CCode (cname = "VStack", cprefix = "v_stack_")]
public class Stack <T> {
private static int step_size = 11;
private T[] stack;
private int pntr;
public size_t elements {get {return pntr + 1;}}
private size_t size;
[CCode (has_target = true)]
public delegate bool ForEachFunc<V> (V item);
public Stack (size_t size = 23) {
this.stack = new T[size];
this.pntr = -1;
this.size = size;
}
public void push (T val) {
this.pntr++;
this.stack[this.pntr] = val;
if (this.pntr + 1 >= this.size) {
this.stack.resize (this.stack.length + Stack.step_size);
}
}
public T pop () {
if (this.pntr < 0) {
info ("Tryinng to pop value from empty Stack:\n" +
"\treturning NULL.");
return null;
}
T ret_val = this.stack[this.pntr];
this.stack[this.pntr] = null;
this.pntr--;
return ret_val;
}
public bool is_empty () {
return (this.pntr == -1);
}
public T peek () {
return peek_n (0);
}
public T peek_n (size_t n) requires (n >= 0) {
if (this.pntr < 0) {
info ("Trying to peek a value from empty Stack:\n" +
"\tReturning NULL.");
return null;
}
if ((this.pntr - n) <= 0) {
return stack[0];
}
return this.stack[this.pntr - n];
}
/**
* Applies func to each item in the stack, popping the stack content.
* (Consumes the list)
*
* Adding items into the list is a violation.
*/
public void foreach_pop (ForEachFunc<T> func) {
while (this.elements < 0) {
var i = elements;
func (pop ());
// Make sure the user does not put anpthing back into the stacstackk.
assert (elements < i);
}
}
/**
* Applies func to each item in the stack, peeking the staks content.
*
* Changing the number of items in the list is a violation.
*/
public void foreach_peek (ForEachFunc<T> func) {
for (var i = this.pntr; i >= 0; i--) {
var k = this.elements;
func (this.stack[i]);
assert (k == this.elements);
}
}
}
}
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