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share one binary search across large string maps #39517

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share one binary search across large string maps
alii Aug 18, 2026
148645c
[autofix.ci] apply automated fixes
autofix-ci[bot] Aug 18, 2026
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315 changes: 315 additions & 0 deletions src/bun_core/comptime_string_map.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,52 @@ impl HasLength for &crate::String {
}
}

/// Key tables of a large map (see `SORTED_LOOKUP_MIN_KEYS` in the macro
/// crate): the same length-then-bytes dispatch as the small-map compare
/// tree, but as data plus one shared binary search instead of an unrolled
/// compare per key.
#[doc(hidden)]
pub struct SortedKeys {
/// All keys concatenated in declaration order.
pub blob: &'static [u8],
/// `n + 1` prefix byte offsets into `blob`, declaration order.
pub offsets: &'static [u16],
/// Declaration indexes ordered by (length, bytes).
pub sorted: &'static [u16],
/// `MAX_LEN - MIN_LEN + 2` cumulative starts into `sorted`, one per length.
pub buckets: &'static [u16],
pub min_len: usize,
}

impl SortedKeys {
/// The key declared at index `decl`.
#[inline]
pub fn key(&self, decl: usize) -> &'static [u8] {
&self.blob[self.offsets[decl] as usize..self.offsets[decl + 1] as usize]
}

/// Declaration indexes of all keys of length `len`, sorted by bytes.
#[inline]
pub fn bucket(&self, len: usize) -> &'static [u16] {
let Some(i) = len.checked_sub(self.min_len) else {
return &[];
};
if i + 1 >= self.buckets.len() {
return &[];
}
&self.sorted[self.buckets[i] as usize..self.buckets[i + 1] as usize]
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}

/// Declaration index of `key`, or `u32::MAX` for a miss.
#[inline(never)]
pub fn index_of(&self, key: &[u8]) -> u32 {
let bucket = self.bucket(key.len());
bucket
.binary_search_by(|&i| self.key(i as usize).cmp(key))
.map_or(u32::MAX, |pos| bucket[pos] as u32)
}
}

#[macro_export]
macro_rules! comptime_string_map {
($($t:tt)*) => {
Expand Down Expand Up @@ -211,4 +257,273 @@ mod tests {
assert_eq!(COMMANDS.len(), 3);
assert_eq!(COMMANDS.iter().count(), 3);
}
#[test]
fn large_map_uses_sorted_tables() {
crate::comptime_string_map! {
static BIG: usize = {
"k0000x" => 0,
"key1" => 1,
"key2" => 2,
"k0003xyyy" => 3,
"key4" => 4,
"key5" => 5,
"k0006xyyyyyy" => 6,
"key7" => 7,
"key8" => 8,
"k0009xyy" => 9,
"key10" => 10,
"key11" => 11,
"k0012xyyyyy" => 12,
"key13" => 13,
"key14" => 14,
"k0015xy" => 15,
"key16" => 16,
"key17" => 17,
"k0018xyyyy" => 18,
"key19" => 19,
"key20" => 20,
"k0021x" => 21,
"key22" => 22,
"key23" => 23,
"k0024xyyy" => 24,
"key25" => 25,
"key26" => 26,
"k0027xyyyyyy" => 27,
"key28" => 28,
"key29" => 29,
"k0030xyy" => 30,
"key31" => 31,
"key32" => 32,
"k0033xyyyyy" => 33,
"key34" => 34,
"key35" => 35,
"k0036xy" => 36,
"key37" => 37,
"key38" => 38,
"k0039xyyyy" => 39,
"key40" => 40,
"key41" => 41,
"k0042x" => 42,
"key43" => 43,
"key44" => 44,
"k0045xyyy" => 45,
"key46" => 46,
"key47" => 47,
"k0048xyyyyyy" => 48,
"key49" => 49,
"key50" => 50,
"k0051xyy" => 51,
"key52" => 52,
"key53" => 53,
"k0054xyyyyy" => 54,
"key55" => 55,
"key56" => 56,
"k0057xy" => 57,
"key58" => 58,
"key59" => 59,
"k0060xyyyy" => 60,
"key61" => 61,
"key62" => 62,
"k0063x" => 63,
"key64" => 64,
"key65" => 65,
"k0066xyyy" => 66,
"key67" => 67,
"key68" => 68,
"k0069xyyyyyy" => 69,
"key70" => 70,
"key71" => 71,
"k0072xyy" => 72,
"key73" => 73,
"key74" => 74,
"k0075xyyyyy" => 75,
"key76" => 76,
"key77" => 77,
"k0078xy" => 78,
"key79" => 79,
"key80" => 80,
"k0081xyyyy" => 81,
"key82" => 82,
"key83" => 83,
"k0084x" => 84,
"key85" => 85,
"key86" => 86,
"k0087xyyy" => 87,
"key88" => 88,
"key89" => 89,
"k0090xyyyyyy" => 90,
"key91" => 91,
"key92" => 92,
"k0093xyy" => 93,
"key94" => 94,
"key95" => 95,
"k0096xyyyyy" => 96,
"key97" => 97,
"key98" => 98,
"k0099xy" => 99,
"key100" => 100,
"key101" => 101,
"k0102xyyyy" => 102,
"key103" => 103,
"key104" => 104,
"k0105x" => 105,
"key106" => 106,
"key107" => 107,
"k0108xyyy" => 108,
"key109" => 109,
"key110" => 110,
"k0111xyyyyyy" => 111,
"key112" => 112,
"key113" => 113,
"k0114xyy" => 114,
"key115" => 115,
"key116" => 116,
"k0117xyyyyy" => 117,
"key118" => 118,
"key119" => 119,
"k0120xy" => 120,
"key121" => 121,
"key122" => 122,
"k0123xyyyy" => 123,
"key124" => 124,
"key125" => 125,
"k0126x" => 126,
"key127" => 127,
"key128" => 128,
"k0129xyyy" => 129,
"key130" => 130,
"key131" => 131,
"k0132xyyyyyy" => 132,
"key133" => 133,
"key134" => 134,
"k0135xyy" => 135,
"key136" => 136,
"key137" => 137,
"k0138xyyyyy" => 138,
"key139" => 139,
"key140" => 140,
"k0141xy" => 141,
"key142" => 142,
"key143" => 143,
"k0144xyyyy" => 144,
"key145" => 145,
"key146" => 146,
"k0147x" => 147,
"key148" => 148,
"key149" => 149,
"k0150xyyy" => 150,
"key151" => 151,
"key152" => 152,
"k0153xyyyyyy" => 153,
"key154" => 154,
"key155" => 155,
"k0156xyy" => 156,
"key157" => 157,
"key158" => 158,
"k0159xyyyyy" => 159,
"key160" => 160,
"key161" => 161,
"k0162xy" => 162,
"key163" => 163,
"key164" => 164,
"k0165xyyyy" => 165,
"key166" => 166,
"key167" => 167,
"k0168x" => 168,
"key169" => 169,
"key170" => 170,
"k0171xyyy" => 171,
"key172" => 172,
"key173" => 173,
"k0174xyyyyyy" => 174,
"key175" => 175,
"key176" => 176,
"k0177xyy" => 177,
"key178" => 178,
"key179" => 179,
"k0180xyyyyy" => 180,
"key181" => 181,
"key182" => 182,
"k0183xy" => 183,
"key184" => 184,
"key185" => 185,
"k0186xyyyy" => 186,
"key187" => 187,
"key188" => 188,
"k0189x" => 189,
"key190" => 190,
"key191" => 191,
"k0192xyyy" => 192,
"key193" => 193,
"key194" => 194,
"k0195xyyyyyy" => 195,
"key196" => 196,
"key197" => 197,
"k0198xyy" => 198,
"key199" => 199,
"key200" => 200,
"k0201xyyyyy" => 201,
"key202" => 202,
"key203" => 203,
"k0204xy" => 204,
"key205" => 205,
"key206" => 206,
"k0207xyyyy" => 207,
"key208" => 208,
"key209" => 209,
"k0210x" => 210,
"key211" => 211,
"key212" => 212,
"k0213xyyy" => 213,
"key214" => 214,
"key215" => 215,
"k0216xyyyyyy" => 216,
"key217" => 217,
"key218" => 218,
"k0219xyy" => 219,
"key220" => 220,
"key221" => 221,
"k0222xyyyyy" => 222,
"key223" => 223,
"key224" => 224,
"k0225xy" => 225,
"key226" => 226,
"key227" => 227,
"k0228xyyyy" => 228,
"key229" => 229,
"key230" => 230,
"k0231x" => 231,
"key232" => 232,
"key233" => 233,
"k0234xyyy" => 234,
"key235" => 235,
"key236" => 236,
"k0237xyyyyyy" => 237,
"key238" => 238,
"key239" => 239
};
}
assert_eq!(BIG.len(), 240);
for (i, (key, value)) in BIG.entries().enumerate() {
assert_eq!(*value, i);
assert_eq!(BIG.get(key), Some(&i));
let upper = key.to_ascii_uppercase();
assert_eq!(BIG.get_ascii_case_insensitive(&upper), Some(&i));
assert_eq!(BIG.get(&upper), None, "{}", key.escape_ascii());
}
assert_eq!(BIG.keys().next(), Some(b"k0000x".as_slice()));
assert_eq!(BIG.get(b""), None);
assert_eq!(BIG.get(b"key"), None);
assert_eq!(BIG.get(b"key1000"), None);
assert_eq!(BIG.get(b"k0000xyyyyyyyyyyyyyyyyy"), None);
assert_eq!(BIG.get_ascii_case_insensitive(b"KEY"), None);
assert_eq!(
BIG.get_with_eql(b"key7".as_slice(), |a: &[u8], b| a == b),
Some(&7)
);
assert_eq!(
BIG.get_with_eql(b"key0".as_slice(), |a: &[u8], b| a == b),
None
);
}
}
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