6 files changed, 379 insertions, 0 deletions

diff --git a/simple-linked-list/.exercism/metadata.json b/simple-linked-list/.exercism/metadata.json
new file mode 100644
index 0000000..4c7e1a6
--- /dev/null
+++ b/simple-linked-list/.exercism/metadata.json
@@ -0,0 +1 @@
+{"track":"rust","exercise":"simple-linked-list","id":"a0e2dbad46184d6a8ee961fff5e6c497","url":"https://exercism.io/my/solutions/a0e2dbad46184d6a8ee961fff5e6c497","handle":"dyamon","is_requester":true,"auto_approve":false}
\ No newline at end of file
diff --git a/simple-linked-list/.gitignore b/simple-linked-list/.gitignore
new file mode 100644
index 0000000..db7f315
--- /dev/null
+++ b/simple-linked-list/.gitignore
@@ -0,0 +1,8 @@
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+**/*.rs.bk
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here http://doc.crates.io/guide.html#cargotoml-vs-cargolock
+Cargo.lock
diff --git a/simple-linked-list/Cargo.toml b/simple-linked-list/Cargo.toml
new file mode 100644
index 0000000..25a62e7
--- /dev/null
+++ b/simple-linked-list/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+edition = "2018"
+name = "simple_linked_list"
+version = "0.1.0"
+
+[dependencies]
diff --git a/simple-linked-list/README.md b/simple-linked-list/README.md
new file mode 100644
index 0000000..47178e8
--- /dev/null
+++ b/simple-linked-list/README.md
@@ -0,0 +1,137 @@
+# Simple Linked List
+
+Write a simple linked list implementation that uses Elements and a List.
+
+The linked list is a fundamental data structure in computer science,
+often used in the implementation of other data structures. They're
+pervasive in functional programming languages, such as Clojure, Erlang,
+or Haskell, but far less common in imperative languages such as Ruby or
+Python.
+
+The simplest kind of linked list is a singly linked list. Each element in the
+list contains data and a "next" field pointing to the next element in the list
+of elements.
+
+This variant of linked lists is often used to represent sequences or
+push-down stacks (also called a LIFO stack; Last In, First Out).
+
+As a first take, lets create a singly linked list to contain the range (1..10),
+and provide functions to reverse a linked list and convert to and from arrays.
+
+When implementing this in a language with built-in linked lists,
+implement your own abstract data type.
+
+## Implementation Hints
+
+Do not implement the struct `SimpleLinkedList` as a wrapper around a `Vec`. Instead, allocate nodes on the heap.  
+This might be implemented as:
+```
+pub struct SimpleLinkedList<T> {
+    head: Option<Box<Node<T>>>,
+}
+```
+The `head` field points to the first element (Node) of this linked list.  
+This implementation also requires a struct `Node` with the following fields:
+```
+struct Node<T> {
+    data: T,
+    next: Option<Box<Node<T>>>,
+}
+```
+`data` contains the stored data, and `next` points to the following node (if available) or None.  
+
+### Why `Option<Box<Node<T>>>` and not just `Option<Node<T>>`?
+Try it on your own. You will get the following error.
+
+```
+| struct Node<T>
+| ^^^^^^^^^^^^^^ recursive type has infinite size
+...
+|     next: Option<Node<T>>,
+|     --------------------- recursive without indirection
+ ```
+
+ The problem is that at compile time the size of next must be known.
+ Since `next` is recursive ("a node has a node has a node..."), the compiler does not know how much memory is to be allocated.
+ In contrast, [Box](https://doc.rust-lang.org/std/boxed/) is a heap pointer with a defined size.
+
+
+## Rust Installation
+
+Refer to the [exercism help page][help-page] for Rust installation and learning
+resources.
+
+## Writing the Code
+
+Execute the tests with:
+
+```bash
+$ cargo test
+```
+
+All but the first test have been ignored. After you get the first test to
+pass, open the tests source file which is located in the `tests` directory
+and remove the `#[ignore]` flag from the next test and get the tests to pass
+again. Each separate test is a function with `#[test]` flag above it.
+Continue, until you pass every test.
+
+If you wish to run all ignored tests without editing the tests source file, use:
+
+```bash
+$ cargo test -- --ignored
+```
+
+To run a specific test, for example `some_test`, you can use:
+
+```bash
+$ cargo test some_test
+```
+
+If the specific test is ignored use:
+
+```bash
+$ cargo test some_test -- --ignored
+```
+
+To learn more about Rust tests refer to the [online test documentation][rust-tests]
+
+Make sure to read the [Modules][modules] chapter if you
+haven't already, it will help you with organizing your files.
+
+## Further improvements
+
+After you have solved the exercise, please consider using the additional utilities, described in the [installation guide](https://exercism.io/tracks/rust/installation), to further refine your final solution.
+
+To format your solution, inside the solution directory use
+
+```bash
+cargo fmt
+```
+
+To see, if your solution contains some common ineffective use cases, inside the solution directory use
+
+```bash
+cargo clippy --all-targets
+```
+
+## Submitting the solution
+
+Generally you should submit all files in which you implemented your solution (`src/lib.rs` in most cases). If you are using any external crates, please consider submitting the `Cargo.toml` file. This will make the review process faster and clearer.
+
+## Feedback, Issues, Pull Requests
+
+The [exercism/rust](https://github.com/exercism/rust) repository on GitHub is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!
+
+If you want to know more about Exercism, take a look at the [contribution guide](https://github.com/exercism/docs/blob/master/contributing-to-language-tracks/README.md).
+
+[help-page]: https://exercism.io/tracks/rust/learning
+[modules]: https://doc.rust-lang.org/book/ch07-02-defining-modules-to-control-scope-and-privacy.html
+[cargo]: https://doc.rust-lang.org/book/ch14-00-more-about-cargo.html
+[rust-tests]: https://doc.rust-lang.org/book/ch11-02-running-tests.html
+
+## Source
+
+Inspired by 'Data Structures and Algorithms with Object-Oriented Design Patterns in Ruby', singly linked-lists. [https://web.archive.org/web/20160731005714/http://brpreiss.com/books/opus8/html/page96.html](https://web.archive.org/web/20160731005714/http://brpreiss.com/books/opus8/html/page96.html)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
diff --git a/simple-linked-list/src/lib.rs b/simple-linked-list/src/lib.rs
new file mode 100644
index 0000000..75e82f5
--- /dev/null
+++ b/simple-linked-list/src/lib.rs
@@ -0,0 +1,109 @@
+use std::iter::FromIterator;
+
+#[derive(Debug)]
+struct Node<T> {
+    data: T,
+    next: Option<Box<Node<T>>>,
+}
+
+impl<T> Node<T> {
+    pub fn new(data: T, next: Option<Box<Node<T>>>) -> Self {
+        Node { data, next }
+    }
+
+    pub fn len(&self) -> usize {
+        1 + self.next.as_ref().map(|n| n.len()).unwrap_or(0)
+    }
+}
+
+#[derive(Debug)]
+pub struct SimpleLinkedList<T> {
+    head: Option<Box<Node<T>>>,
+}
+
+impl<T> SimpleLinkedList<T> {
+    pub fn new() -> Self {
+        SimpleLinkedList { head: None }
+    }
+
+    // You may be wondering why it's necessary to have is_empty()
+    // when it can easily be determined from len().
+    // It's good custom to have both because len() can be expensive for some types,
+    // whereas is_empty() is almost always cheap.
+    // (Also ask yourself whether len() is expensive for SimpleLinkedList)
+    pub fn is_empty(&self) -> bool {
+        self.head.is_none()
+    }
+
+    pub fn len(&self) -> usize {
+        self.head.as_ref().map(|n| n.len()).unwrap_or(0)
+    }
+
+    pub fn push(&mut self, _element: T) {
+        // let node = Box::new(Node::new(_element, self.head.take()));
+        // self.head.replace(node);
+        self.head = Some(Box::new(Node::new(_element, self.head.take())));
+    }
+
+    pub fn pop(&mut self) -> Option<T> {
+        self.head.take().map(|n| {
+            // n.next.map(|n1| self.head.replace(n1));
+            self.head = n.next;
+            n.data
+        })
+    }
+
+    pub fn peek(&self) -> Option<&T> {
+        self.head.as_ref().map(|n| &n.data)
+    }
+
+    pub fn rev(self) -> SimpleLinkedList<T> {
+        self.rev_aux(SimpleLinkedList::new())
+    }
+
+    pub fn rev_aux(mut self, mut acc: SimpleLinkedList<T>) -> SimpleLinkedList<T> {
+        if let Some(e) = self.pop() {
+            acc.push(e);
+            self.rev_aux(acc)
+        } else {
+            acc
+        }
+    }
+
+    fn into_aux(mut self, mut acc: Vec<T>) -> Vec<T> {
+        if let Some(e) = self.pop() {
+            acc.push(e);
+            self.into_aux(acc)
+        } else {
+            acc
+        }
+    }
+}
+
+impl<T> FromIterator<T> for SimpleLinkedList<T> {
+    fn from_iter<I: IntoIterator<Item = T>>(_iter: I) -> Self {
+        _iter
+            .into_iter()
+            .fold(SimpleLinkedList::new(), |mut acc, n| {
+                acc.push(n);
+                acc
+            })
+    }
+}
+
+// In general, it would be preferable to implement IntoIterator for SimpleLinkedList<T>
+// instead of implementing an explicit conversion to a vector. This is because, together,
+// FromIterator and IntoIterator enable conversion between arbitrary collections.
+// Given that implementation, converting to a vector is trivial:
+//
+// let vec: Vec<_> = simple_linked_list.into_iter().collect();
+//
+// The reason this exercise's API includes an explicit conversion to Vec<T> instead
+// of IntoIterator is that implementing that interface is fairly complicated, and
+// demands more of the student than we expect at this point in the track.
+
+impl<T> Into<Vec<T>> for SimpleLinkedList<T> {
+    fn into(self) -> Vec<T> {
+        self.rev().into_aux(Vec::new())
+    }
+}
diff --git a/simple-linked-list/tests/simple-linked-list.rs b/simple-linked-list/tests/simple-linked-list.rs
new file mode 100644
index 0000000..c89f8b5
--- /dev/null
+++ b/simple-linked-list/tests/simple-linked-list.rs
@@ -0,0 +1,118 @@
+use simple_linked_list::SimpleLinkedList;
+
+#[test]
+fn test_new_list_is_empty() {
+    let list: SimpleLinkedList<u32> = SimpleLinkedList::new();
+    assert_eq!(list.len(), 0, "list's length must be 0");
+}
+
+#[test]
+fn test_push_increments_length() {
+    let mut list: SimpleLinkedList<u32> = SimpleLinkedList::new();
+    list.push(1);
+    assert_eq!(list.len(), 1, "list's length must be 1");
+    list.push(2);
+    assert_eq!(list.len(), 2, "list's length must be 2");
+}
+
+#[test]
+fn test_pop_decrements_length() {
+    let mut list: SimpleLinkedList<u32> = SimpleLinkedList::new();
+    list.push(1);
+    list.push(2);
+    list.pop();
+    assert_eq!(list.len(), 1, "list's length must be 1");
+    list.pop();
+    assert_eq!(list.len(), 0, "list's length must be 0");
+}
+
+#[test]
+fn test_is_empty() {
+    let mut list: SimpleLinkedList<u32> = SimpleLinkedList::new();
+    assert!(list.is_empty(), "List wasn't empty on creation");
+    for inserts in 0..100 {
+        for i in 0..inserts {
+            list.push(i);
+            assert!(
+                !list.is_empty(),
+                "List was empty after having inserted {}/{} elements",
+                i,
+                inserts
+            );
+        }
+        for i in 0..inserts {
+            assert!(
+                !list.is_empty(),
+                "List was empty before removing {}/{} elements",
+                i,
+                inserts
+            );
+            list.pop();
+        }
+        assert!(
+            list.is_empty(),
+            "List wasn't empty after having removed {} elements",
+            inserts
+        );
+    }
+}
+
+#[test]
+fn test_pop_returns_head_element_and_removes_it() {
+    let mut list: SimpleLinkedList<u32> = SimpleLinkedList::new();
+    list.push(1);
+    list.push(2);
+    assert_eq!(list.pop(), Some(2), "Element must be 2");
+    assert_eq!(list.pop(), Some(1), "Element must be 1");
+    assert_eq!(list.pop(), None, "No element should be contained in list");
+}
+
+#[test]
+fn test_peek_returns_reference_to_head_element_but_does_not_remove_it() {
+    let mut list: SimpleLinkedList<u32> = SimpleLinkedList::new();
+    assert_eq!(list.peek(), None, "No element should be contained in list");
+    list.push(2);
+    assert_eq!(list.peek(), Some(&2), "Element must be 2");
+    assert_eq!(list.peek(), Some(&2), "Element must be still 2");
+    list.push(3);
+    assert_eq!(list.peek(), Some(&3), "Head element is now 3");
+    assert_eq!(list.pop(), Some(3), "Element must be 3");
+    assert_eq!(list.peek(), Some(&2), "Head element is now 2");
+    assert_eq!(list.pop(), Some(2), "Element must be 2");
+    assert_eq!(list.peek(), None, "No element should be contained in list");
+}
+
+#[test]
+fn test_from_slice() {
+    let mut array = vec!["1", "2", "3", "4"];
+    let mut list: SimpleLinkedList<_> = array.drain(..).collect();
+    assert_eq!(list.pop(), Some("4"));
+    assert_eq!(list.pop(), Some("3"));
+    assert_eq!(list.pop(), Some("2"));
+    assert_eq!(list.pop(), Some("1"));
+}
+
+#[test]
+fn test_reverse() {
+    let mut list: SimpleLinkedList<u32> = SimpleLinkedList::new();
+    list.push(1);
+    list.push(2);
+    list.push(3);
+    let mut rev_list = list.rev();
+    assert_eq!(rev_list.pop(), Some(1));
+    assert_eq!(rev_list.pop(), Some(2));
+    assert_eq!(rev_list.pop(), Some(3));
+    assert_eq!(rev_list.pop(), None);
+}
+
+#[test]
+fn test_into_vector() {
+    let mut v = Vec::new();
+    let mut s = SimpleLinkedList::new();
+    for i in 1..4 {
+        v.push(i);
+        s.push(i);
+    }
+    let s_as_vec: Vec<i32> = s.into();
+    assert_eq!(v, s_as_vec);
+}