June 2018 Update

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-1.stata

@@ -0,0 +1,8 @@
+struct item {
+	transmorphic scalar value
+	pointer(struct item scalar) scalar next
+}
+
+struct list {
+	pointer(struct item scalar) scalar head, tail
+}

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-10.stata

@@ -0,0 +1,2 @@
+list_insert_after(a, list_get(a, 2), 40)
+list_show(a);

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-11.stata

@@ -0,0 +1 @@
+list_pop(a)

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-12.stata

@@ -0,0 +1,5 @@
+a = list()
+list_insert_end(a, "A")
+list_insert_end(a, "B")
+list_insert_after(a, list_get(a, 1), "C")
+list_show(a)

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-13.stata

@@ -0,0 +1,7 @@
+a = list()
+for (i = 1; i <= 4; i++) {
+	list_insert(a, i)
+}
+while (!list_empty(a)) {
+	printf("%f\n", list_pop(a))
+}

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-14.stata

@@ -0,0 +1,7 @@
+a = list()
+for (i = 1; i <= 4; i++) {
+	list_insert_end(a, i)
+}
+while (!list_empty(a)) {
+	printf("%f\n", list_pop(a))
+}

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-2.stata

@@ -0,0 +1,3 @@
+real scalar list_empty(struct list scalar a) {
+	return(a.head == NULL)
+}

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-3.stata

@@ -0,0 +1,36 @@
+void function list_insert(struct list scalar a, transmorphic scalar x) {
+	struct item scalar i
+	i.value = x
+	if (a.head == NULL) {
+		i.next = NULL
+		a.head = a.tail = &i
+	} else {
+		i.next = a.head
+		a.head = &i
+	}
+}
+
+void function list_insert_end(struct list scalar a, transmorphic scalar x) {
+	struct item scalar i
+	i.value = x
+	i.next = NULL
+	if (a.head==NULL) {
+		a.head = a.tail = &i
+	} else {
+		(*a.tail).next = &i
+		a.tail = &i
+	}
+}
+
+void function list_insert_after(struct list scalar a,
+	pointer(struct item scalar) scalar p,
+	transmorphic scalar x) {
+	
+	struct item scalar i
+	i.value = x
+	i.next = (*p).next
+	(*p).next = &i
+	if (a.tail == p) {
+		a.tail = &i
+	}
+}

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-4.stata

@@ -0,0 +1,22 @@
+real scalar list_length(struct list scalar a) {
+	real scalar n
+	pointer(struct item scalar) scalar p
+	
+	n = 0
+	for (p = a.head; p != NULL; p = (*p).next) {
+		n++
+	}
+	return(n)
+}
+
+void list_show(struct list scalar a) {
+	pointer(struct item scalar) scalar p
+	
+	for (p = a.head; p != NULL; p = (*p).next) {
+		if (eltype((*p).value) == "string") {
+			printf("%s\n", (*p).value);
+		} else {
+			printf("%f\n", (*p).value);
+		}
+	}
+}

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-5.stata

@@ -0,0 +1,12 @@
+pointer(struct item scalar) scalar list_get(struct list scalar a,
+	real scalar n) {
+	
+	pointer(struct item scalar) scalar p
+	real scalar i
+	
+	p = a.head
+	for (i = 1; p != NULL & i < n; i++) {
+		p = (*p).next
+	}
+	return(p)
+}

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-6.stata

@@ -0,0 +1,13 @@
+transmorphic scalar list_pop(struct list scalar a) {
+	transmorphic scalar x
+	if (a.head == NULL) {
+		_error("empty list")
+	}
+	x = (*a.head).value
+	if (a.head == a.tail) {
+		a.head = a.tail = NULL
+	} else {
+		a.head = (*a.head).next
+	}
+	return(x)
+}

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-7.stata

@@ -0,0 +1,37 @@
+transmorphic scalar list_remove(struct list scalar a,
+	real scalar n) {
+	
+	pointer(struct item scalar) scalar p, q
+	real scalar i
+	transmorphic scalar x
+	
+	p = a.head
+	if (n == 1) {
+		if (p == NULL) {
+			_error("empty list")
+		}
+		x = (*p).value
+		if (p == a.tail) {
+			a.head = a.tail = NULL
+		} else {
+			a.head = (*p).next
+		}
+	} else {
+		for (i = 2; p != NULL & i < n; i++) {
+			p = (*p).next
+		}
+		if (p == NULL) {
+			_error("too few elements in list")
+		}
+		q = (*p).next
+		if (q == NULL) {
+			_error("too few elements in list")
+		}
+		x = (*q).value
+		if (q == a.tail) {
+			a.tail = p
+		}
+		(*p).next = (*q).next
+	}
+	return(x)
+}

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-8.stata

@@ -0,0 +1,6 @@
+a = list()
+list_insert(a, 10)
+list_insert(a, 20)
+list_insert(a, 30)
+list_length(a)
+list_show(a);

Task/Singly-linked-list-Element-definition/Stata/singly-linked-list-element-definition-9.stata

@@ -0,0 +1,6 @@
+a = list()
+list_insert_end(a, 10)
+list_insert_end(a, 20)
+list_insert_end(a, 30)
+list_length(a)
+list_show(a);