lox-lang 0.0.3

A Lox language runtime for Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

//! general purpose linked list
//!
//! mostly cribbed from the immortal [Rust in Entirely Too Many Linked
//! Lists](https://rust-unofficial.github.io/too-many-lists) but improved with reference passing
//! and utility methods to get, insert, and delete conditionally

#[derive(Debug)]
pub(crate) struct List<T> {
    head: Option<Box<Node<T>>>,
}

#[derive(Debug)]
struct Node<T> {
    item: T,
    next: Option<Box<Node<T>>>,
}

impl<T> List<T> {
    pub(crate) fn new() -> Self {
        Self { head: None }
    }

    #[allow(dead_code)]
    pub(crate) fn peek(&self) -> Option<&T> {
        self.head.as_ref().map(|node| &node.item)
    }

    #[allow(dead_code)]
    pub(crate) fn peek_mut(&mut self) -> Option<&mut T> {
        self.head.as_mut().map(|node| &mut node.item)
    }

    pub(crate) fn push(&mut self, item: T) -> &mut T {
        Node::splice_in(&mut self.head, item)
    }

    #[allow(dead_code)]
    pub(crate) fn pop(&mut self) -> Option<T> {
        self.head.take().map(|node| node.item)
    }

    pub(crate) fn insert_before<F>(&mut self, value: T, predicate: F) -> &mut T
    where
        F: Fn(&T) -> bool,
    {
        let mut current = &mut self.head;

        while current
            .as_ref()
            .filter(|node| predicate(&node.item))
            .is_some()
        {
            current = &mut current.as_mut().unwrap().next;
        }

        Node::splice_in(current, value)
    }

    pub(crate) fn find<F>(&self, predicate: F) -> Option<&T>
    where
        F: Fn(&T) -> bool,
    {
        let mut current = &self.head;

        while let Some(ref head) = &current {
            if predicate(&head.item) {
                break;
            }

            current = &head.next;
        }

        current.as_ref().map(|node| &node.item)
    }

    pub(crate) fn retain<F>(&mut self, predicate: F) -> Vec<T>
    where
        F: Fn(&T) -> bool,
    {
        let mut out = Vec::new();

        let mut current = &mut self.head;

        while current.is_some() {
            if current
                .as_ref()
                .filter(|node| predicate(&node.item))
                .is_some()
            {
                current = &mut current.as_mut().unwrap().next;
            } else if let Some(to_remove) = current.take() {
                *current = to_remove.next;
                out.push(to_remove.item);
            }
        }

        out
    }

    pub(crate) fn iter(&self) -> Iter<'_, T> {
        Iter {
            next: self.head.as_ref().map(|node| &**node),
        }
    }
}

pub(crate) struct Iter<'a, T> {
    next: Option<&'a Node<T>>,
}

impl<'a, T> Iterator for Iter<'a, T> {
    type Item = &'a T;
    fn next(&mut self) -> Option<Self::Item> {
        self.next.map(|node| {
            self.next = node.next.as_ref().map(|node| &**node);
            &node.item
        })
    }
}

impl<T> Node<T> {
    fn splice_in(maybe_node: &mut Option<Box<Self>>, item: T) -> &mut T {
        let new_node = Box::new(Node {
            item,
            next: maybe_node.take().and_then(|mut node| node.next.take()),
        });

        &mut maybe_node.get_or_insert(new_node).item
    }
}