reorganized build-ins and implement a circular queue as an example

examples/data_structures/queue.noja

@@ -0,0 +1,142 @@
+# This script implements a circular queue and
+# it's relative tests!
+
+fun newCircularQueue(T: Type = int, max: int = 3) {
+    
+    if T == None:
+        error("Invalid type");
+
+    if max <= 0:
+        error("Maximum queue size must be positive");
+
+    list = [];
+    i = 0;
+    while i < max: {
+        list[i] = none;
+        i = i+1;
+    }
+
+    return {
+        max: max,
+        head: 0,
+        tail: 0,
+        list: list,
+        type: T
+    };
+}
+
+fun getSize(queue: Map) {
+    
+    size = none;
+    if queue.tail == queue.head: {
+        if queue.list[queue.tail] == none: {
+            size = 0;
+        } else {
+            size = queue.max;
+        }
+    } else if queue.tail < queue.head: {
+        size = queue.head 
+             - queue.tail;
+    } else {
+        size = queue.head 
+             + queue.max 
+             - queue.tail;
+    }
+    return size;
+}
+
+fun append(queue: Map, value) {
+    
+    if type(value) != queue.type:
+        error("Invalid type");
+
+    size = getSize(queue);
+
+    queue.list[queue.head] = value;
+
+    if size == queue.max: {
+        queue.tail = queue.tail+1;
+        if queue.tail == queue.max:
+            queue.tail = 0;
+    }
+
+    queue.head = queue.head+1;
+    if queue.head == queue.max:
+        queue.head = 0;
+}
+
+fun pop(queue: Map) {
+    
+    if getSize(queue) == 0:
+        return none;
+
+    value = queue.list[queue.tail];
+    queue.list[queue.tail] = none;
+
+    queue.tail = queue.tail+1;
+    if queue.tail == queue.max:
+        queue.tail = 0;
+
+    return value;
+}
+
+{
+    utils = import("../utils.noja");
+
+    queue = newCircularQueue(int, 3);
+    assert(getSize(queue) == 0);
+    assert(queue.head == 0);
+    assert(queue.tail == 0);
+
+    append(queue, 1);
+    assert(queue.head == 1);
+    assert(queue.tail == 0);
+    assert(getSize(queue) == 1);
+    assert(utils.compareAny(queue.list, [1, none, none]));
+
+    append(queue, 2);
+    assert(queue.head == 2);
+    assert(queue.tail == 0);
+    assert(getSize(queue) == 2);
+    assert(utils.compareAny(queue.list, [1, 2, none]));
+
+    append(queue, 3);
+    assert(queue.head == 0);
+    assert(queue.tail == 0);
+    assert(getSize(queue) == 3);
+    assert(utils.compareAny(queue.list, [1, 2, 3]));
+
+    append(queue, 4);
+    assert(queue.head == 1);
+    assert(queue.tail == 1);
+    assert(getSize(queue) == 3);
+    assert(utils.compareAny(queue.list, [4, 2, 3]));
+
+    v = pop(queue);
+    assert(v == 2);
+    assert(queue.head == 1);
+    assert(queue.tail == 2);
+    assert(getSize(queue) == 2);
+    assert(utils.compareAny(queue.list, [4, none, 3]));
+
+    v = pop(queue);
+    assert(v == 3);
+    assert(queue.head == 1);
+    assert(queue.tail == 0);
+    assert(getSize(queue) == 1);
+    assert(utils.compareAny(queue.list, [4, none, none]));
+
+    v = pop(queue);
+    assert(v == 4);
+    assert(queue.head == 1);
+    assert(queue.tail == 1);
+    assert(getSize(queue) == 0);
+    assert(utils.compareAny(queue.list, [none, none, none]));
+
+    v = pop(queue);
+    assert(v == none);
+    assert(queue.head == 1);
+    assert(queue.tail == 1);
+    assert(getSize(queue) == 0);
+    assert(utils.compareAny(queue.list, [none, none, none]));
+}