syntree/node/
skip_tokens.rs

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1use core::iter::FusedIterator;
2
3use crate::flavor::Flavor;
4use crate::node::Node;
5
6/// Wrapped around an iterator that excludes nodes without children.
7///
8/// See [`Siblings::skip_tokens`] or [`Walk::skip_tokens`].
9///
10/// [`Siblings::skip_tokens`]: crate::node::Siblings::skip_tokens
11/// [`Walk::skip_tokens`]: crate::node::Walk::skip_tokens
12///
13/// # Examples
14///
15/// Filtering childless nodes from a [`Siblings`] iterator:
16///
17/// ```
18/// let tree = syntree::tree! {
19///     ("token1", 1),
20///     "child1" => {
21///         "token2"
22///     },
23///     ("token3", 1),
24///     "child2" => {
25///         "toke4"
26///     },
27///     ("token5", 1),
28///     "child3" => {
29///         "token6"
30///     },
31///     ("token7", 1)
32/// };
33///
34/// let mut it = tree.children().skip_tokens();
35///
36/// assert_eq!(
37///     it.map(|n| n.value()).collect::<Vec<_>>(),
38///     ["child1", "child2", "child3"]
39/// );
40/// # Ok::<_, Box<dyn core::error::Error>>(())
41/// ```
42///
43/// Filtering tokens from a [`Walk`] iterator:
44///
45/// ```
46/// let tree = syntree::tree! {
47///     "child1" => {
48///         "child2" => {
49///             "token1"
50///         },
51///         ("token2", 1),
52///         "child3" => {
53///             "token3"
54///         },
55///     },
56///     "child4" => {
57///         ("token4", 1)
58///     }
59/// };
60///
61/// let mut it = tree.walk().skip_tokens();
62///
63/// assert_eq!(
64///     it.map(|n| n.value()).collect::<Vec<_>>(),
65///     ["child1", "child2", "child3", "child4"]
66/// );
67/// # Ok::<_, Box<dyn core::error::Error>>(())
68/// ```
69///
70/// [`Siblings`]: crate::node::Siblings
71/// [`Walk`]: crate::node::Walk
72pub struct SkipTokens<U> {
73    iter: U,
74}
75
76impl<U> SkipTokens<U> {
77    #[inline]
78    pub(crate) const fn new(iter: U) -> Self {
79        Self { iter }
80    }
81}
82
83impl<'a, U, T: 'a, F: 'a> Iterator for SkipTokens<U>
84where
85    T: Copy,
86    F: Flavor,
87    U: Iterator<Item = Node<'a, T, F>>,
88{
89    type Item = U::Item;
90
91    #[inline]
92    fn next(&mut self) -> Option<Self::Item> {
93        self.iter.find(|n| n.has_children())
94    }
95
96    #[inline]
97    fn size_hint(&self) -> (usize, Option<usize>) {
98        let (_, upper) = self.iter.size_hint();
99        (0, upper)
100    }
101
102    #[inline]
103    fn find<P>(&mut self, mut predicate: P) -> Option<Self::Item>
104    where
105        Self: Sized,
106        P: FnMut(&Self::Item) -> bool,
107    {
108        self.iter.find(move |n| n.has_children() && predicate(n))
109    }
110}
111
112impl<'a, U, T: 'a, F: 'a> DoubleEndedIterator for SkipTokens<U>
113where
114    T: Copy,
115    F: Flavor,
116    U: DoubleEndedIterator<Item = Node<'a, T, F>>,
117{
118    #[inline]
119    fn next_back(&mut self) -> Option<Self::Item> {
120        self.iter.rfind(|n| n.has_children())
121    }
122
123    #[inline]
124    fn rfind<P>(&mut self, mut predicate: P) -> Option<Self::Item>
125    where
126        Self: Sized,
127        P: FnMut(&Self::Item) -> bool,
128    {
129        self.iter.rfind(move |n| n.has_children() && predicate(n))
130    }
131}
132
133impl<'a, U, T: 'a, F: 'a> FusedIterator for SkipTokens<U>
134where
135    T: Copy,
136    F: Flavor,
137    U: FusedIterator<Item = Node<'a, T, F>>,
138{
139}
140
141impl<U> Clone for SkipTokens<U>
142where
143    U: Clone,
144{
145    #[inline]
146    fn clone(&self) -> Self {
147        Self {
148            iter: self.iter.clone(),
149        }
150    }
151}
152
153impl<U> Default for SkipTokens<U>
154where
155    U: Default,
156{
157    #[inline]
158    fn default() -> Self {
159        Self {
160            iter: Default::default(),
161        }
162    }
163}
syntree/node/skip_tokens.rs

syntree/node/
skip_tokens.rs
