Module byte_set 

const builders for [bool; 256] byte-set lookup tables.

A lookup table turns a byte-class predicate into a single branchless load, which beats a match / compare-chain on hot per-byte paths (URI validation, HTML tokenizing, …) and is deterministic across compilers. Build the table once at const time, then index it by byte as usize.

Reach for a table only for irregular byte sets on a hot path: a simple range such as b < 0x80 is one compare and should stay a comparison.

Functions

set_ascii_alpha

Mark the ASCII alpha bytes (A-Z, a-z) as true.

set_ascii_alphanum

Mark the ASCII alphanumeric bytes (0-9, A-Z, a-z) as true.

set_each

Mark every byte present in bytes as true.

set_range

Mark every byte in the half-open range [lo, hi_exclusive) as true.