qs_rust 1.0.0

A query string encoding and decoding library for Rust. Ported from qs for JavaScript.
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
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172

//! Shared key-path builder for the encoder.

use std::cell::OnceCell;
use std::rc::Rc;

/// A persistent raw key path used by the encoder.
///
/// The structure shares parent segments and caches its materialized forms so
/// deep traversals avoid repeatedly rebuilding the same key prefixes.
#[derive(Clone, Debug)]
pub(crate) struct KeyPathNode(Rc<KeyPathInner>);

#[derive(Debug)]
struct KeyPathInner {
    parent: Option<KeyPathNode>,
    segment: String,
    depth: usize,
    length: usize,
    materialized: OnceCell<String>,
    dot_encoded: OnceCell<KeyPathNode>,
}

impl KeyPathNode {
    pub(crate) fn from_raw(raw: impl Into<String>) -> Self {
        let raw = raw.into();
        let node = Self(Rc::new(KeyPathInner {
            parent: None,
            segment: raw.clone(),
            depth: 1,
            length: raw.len(),
            materialized: OnceCell::new(),
            dot_encoded: OnceCell::new(),
        }));
        let _ = node.0.materialized.set(raw);
        node
    }

    pub(crate) fn append(&self, segment: &str) -> Self {
        if segment.is_empty() {
            return self.clone();
        }

        self.append_owned(segment.to_owned())
    }

    pub(crate) fn append_dot_component(&self, component: &str) -> Self {
        if component.is_empty() {
            return self.clone();
        }

        let mut segment = String::with_capacity(component.len() + 1);
        segment.push('.');
        segment.push_str(component);
        self.append_owned(segment)
    }

    pub(crate) fn append_bracketed_component(&self, component: &str) -> Self {
        let mut segment = String::with_capacity(component.len() + 2);
        segment.push('[');
        segment.push_str(component);
        segment.push(']');
        self.append_owned(segment)
    }

    pub(crate) fn append_empty_list_suffix(&self) -> Self {
        self.append_owned("[]".to_owned())
    }

    pub(crate) fn as_dot_encoded(&self, replacement: &str) -> Self {
        if let Some(cached) = self.0.dot_encoded.get() {
            return cached.clone();
        }

        let mut unresolved = Vec::new();
        let mut current = Some(self.clone());
        let mut base = None;

        while let Some(node) = current {
            if let Some(cached) = node.0.dot_encoded.get() {
                base = Some(cached.clone());
                break;
            }
            unresolved.push(node.clone());
            current = node.0.parent.clone();
        }

        let mut encoded_parent = base;
        for node in unresolved.into_iter().rev() {
            let encoded_segment = if node.0.segment.contains('.') {
                node.0.segment.replace('.', replacement)
            } else {
                node.0.segment.clone()
            };

            let encoded = match (encoded_parent.clone(), node.0.parent.as_ref()) {
                (None, None) => {
                    if encoded_segment == node.0.segment {
                        node.clone()
                    } else {
                        Self::from_raw(encoded_segment)
                    }
                }
                (Some(parent), Some(original_parent))
                    if Rc::ptr_eq(&parent.0, &original_parent.0)
                        && encoded_segment == node.0.segment =>
                {
                    node.clone()
                }
                (Some(parent), _) => parent.append(&encoded_segment),
                (None, Some(_)) => Self::from_raw(encoded_segment),
            };

            let _ = node.0.dot_encoded.set(encoded.clone());
            encoded_parent = Some(encoded);
        }

        self.0
            .dot_encoded
            .get()
            .cloned()
            .unwrap_or_else(|| self.clone())
    }

    pub(crate) fn materialize(&self) -> &str {
        if let Some(cached) = self.0.materialized.get() {
            return cached;
        }

        let mut suffix = Vec::new();
        let mut current = Some(self.clone());
        let mut base = String::new();

        while let Some(node) = current {
            if let Some(cached) = node.0.materialized.get() {
                base = cached.clone();
                break;
            }
            suffix.push(node.clone());
            current = node.0.parent.clone();
        }

        let extra = suffix
            .iter()
            .map(|node| node.0.segment.len())
            .sum::<usize>();
        let mut materialized = String::with_capacity(base.len() + extra);
        materialized.push_str(&base);
        for node in suffix.into_iter().rev() {
            materialized.push_str(&node.0.segment);
        }

        let _ = self.0.materialized.set(materialized);
        self.0
            .materialized
            .get()
            .expect("materialized key path should be cached")
    }

    fn append_owned(&self, segment: String) -> Self {
        Self(Rc::new(KeyPathInner {
            parent: Some(self.clone()),
            length: self.0.length + segment.len(),
            depth: self.0.depth + 1,
            segment,
            materialized: OnceCell::new(),
            dot_encoded: OnceCell::new(),
        }))
    }
}

#[cfg(test)]
mod tests;