fd_core/
id.rs

1use lasso::{Spur, ThreadedRodeo};
2use serde::{Deserialize, Deserializer, Serialize, Serializer};
3use std::fmt;
4use std::sync::LazyLock;
5
6/// Global string interner for node IDs — fast comparisons, low memory.
7static INTERNER: LazyLock<ThreadedRodeo> = LazyLock::new(ThreadedRodeo::default);
8
9/// A lightweight, interned identifier for nodes in the scene graph.
10/// Internally a `Spur` index — 4 bytes, Copy, Eq, Hash in O(1).
11#[derive(Clone, Copy, PartialEq, Eq, Hash)]
12pub struct NodeId(Spur);
13
14impl NodeId {
15    /// Intern a new string as a NodeId, or return existing if already interned.
16    pub fn intern(s: &str) -> Self {
17        NodeId(INTERNER.get_or_intern(s))
18    }
19
20    /// Resolve back to a string slice.
21    pub fn as_str(&self) -> &str {
22        INTERNER.resolve(&self.0)
23    }
24
25    /// Generate a unique anonymous ID (for nodes without explicit @id).
26    /// Uses the node kind as prefix: `_rect_0`, `_text_1`, `_group_2`, etc.
27    pub fn anonymous(kind: &str) -> Self {
28        Self::with_prefix(&format!("_{kind}"))
29    }
30
31    /// Generate a unique ID with a type prefix (e.g. `rect_1`, `ellipse_2`).
32    pub fn with_prefix(prefix: &str) -> Self {
33        use std::sync::atomic::{AtomicU64, Ordering};
34        static COUNTER: AtomicU64 = AtomicU64::new(0);
35        let n = COUNTER.fetch_add(1, Ordering::Relaxed);
36        Self::intern(&format!("{prefix}_{n}"))
37    }
38}
39
40impl fmt::Debug for NodeId {
41    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
42        write!(f, "@{}", self.as_str())
43    }
44}
45
46impl fmt::Display for NodeId {
47    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
48        write!(f, "@{}", self.as_str())
49    }
50}
51
52impl Serialize for NodeId {
53    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
54        serializer.serialize_str(self.as_str())
55    }
56}
57
58impl<'de> Deserialize<'de> for NodeId {
59    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
60        let s = String::deserialize(deserializer)?;
61        Ok(NodeId::intern(&s))
62    }
63}
64
65#[cfg(test)]
66mod tests {
67    use super::*;
68
69    #[test]
70    fn interning_roundtrip() {
71        let a = NodeId::intern("login_form");
72        let b = NodeId::intern("login_form");
73        assert_eq!(a, b);
74        assert_eq!(a.as_str(), "login_form");
75    }
76
77    #[test]
78    fn anonymous_ids_are_unique() {
79        let a = NodeId::anonymous("rect");
80        let b = NodeId::anonymous("rect");
81        assert_ne!(a, b);
82    }
83}
fd_core/id.rs

fd_core/
id.rs
