lua_types/
string.rs

1//! `LuaString` — Lua's byte-string (NOT UTF-8). PORT_STRATEGY §3.3.
2//!
3//! Phase A-C: a simple `Rc<[u8]>`-backed struct with a short/long flag.
4//! Phase D may revisit for interning + content-hash equality.
5
6#[derive(Debug, Clone)]
7pub struct LuaString {
8    bytes: std::rc::Rc<[u8]>,
9    is_short: bool,
10    hash: u32,
11}
12
13impl LuaString {
14    pub fn from_bytes(b: Vec<u8>) -> Self {
15        let is_short = b.len() <= 40;
16        let hash = Self::hash_bytes(&b, 0);
17        LuaString {
18            bytes: b.into(),
19            is_short,
20            hash,
21        }
22    }
23
24    pub fn placeholder() -> Self {
25        Self::from_bytes(Vec::new())
26    }
27
28    pub fn as_bytes(&self) -> &[u8] {
29        &self.bytes
30    }
31    pub fn len(&self) -> usize {
32        self.bytes.len()
33    }
34    pub fn is_empty(&self) -> bool {
35        self.bytes.is_empty()
36    }
37    pub fn is_short(&self) -> bool {
38        self.is_short
39    }
40    pub fn is_long(&self) -> bool {
41        !self.is_short
42    }
43    pub fn hash(&self) -> u32 {
44        self.hash
45    }
46    pub fn buffer_bytes(&self) -> usize {
47        self.bytes.len() + 2 * std::mem::size_of::<usize>()
48    }
49
50    pub fn is_reserved_word(&self) -> bool {
51        // TODO(port): proper reserved-word check via lexer's token enum.
52        false
53    }
54
55    pub fn hash_bytes(bytes: &[u8], seed: u32) -> u32 {
56        // Stub WyHash. Real impl ports bun_wyhash. Stable for now so
57        // intern-table equality works.
58        let mut h: u32 = seed.wrapping_add(0x9e3779b9);
59        for &b in bytes {
60            h = h.wrapping_mul(31).wrapping_add(b as u32);
61        }
62        h
63    }
64
65    pub fn hash_long(&mut self) -> u32 {
66        self.hash
67    }
68}
69
70impl PartialEq for LuaString {
71    fn eq(&self, other: &Self) -> bool {
72        self.bytes == other.bytes
73    }
74}
75impl Eq for LuaString {}
76
77// ──────────────────────────────────────────────────────────────────────────────
78// PORT STATUS
79//   source:        src/lstring.h, src/lstring.c (TString)
80//   target_crate:  lua-types
81//   confidence:    high
82//   todos:         0
83//   port_notes:    0
84//   unsafe_blocks: 0
85//   notes:         LuaString interned-string type. Mirrors C's TString with the short/long
86//                  variant distinction and the hash field; uses GcRef-style ptr
87//                  identity for interning.
88// ──────────────────────────────────────────────────────────────────────────────
lua_types/string.rs

lua_types/
string.rs
