lib/symbolset.x

Immutable ordered sets of compact Symbols.

Primary API

SymbolSet

SymbolSet.contains

int SymbolSet.contains(SymbolSet x, Symbol symbol)

Reports whether symbol belongs to set.

Source: lib/symbolset.x:100

SymbolSet.getindex

Symbol SymbolSet.getindex(SymbolSet x, int index)

Returns the Symbol at index, or zero when the index is out of range. Negative indices count from the end. Zero is also a valid empty Symbol, so use SymbolSet.len when an out-of-range result must be distinguished.

Source: lib/symbolset.x:107

SymbolSet.index

int SymbolSet.index(SymbolSet x, Symbol symbol)

Returns symbol’s source-order index, or -1 when it is absent. A null or empty set returns -1. The ordered table verifies the hash candidate, so a nonmember collision is not reported as membership.

Source: lib/symbolset.x:83

SymbolSet.iter

Iter SymbolSet.iter(SymbolSet x, Iter dest)

Initializes dest to iterate over the Symbols in source order. The caller owns dest, which must remain valid through every pull. The iterator borrows the generated set storage and allocates nothing. A null dest returns NULL; a null set produces an empty iterator.

Source: lib/symbolset.x:128

SymbolSet.len

size_t SymbolSet.len(SymbolSet x)

Returns the number of Symbols in set, or zero for a null set.

Source: lib/symbolset.x:77

Design notes

A SymbolSet is a compiler-generated byte string. Its perfect hash maps each member to its source-order index; the ordered Symbol table also rejects nonmembers that happen to reach the same index. The set borrows its generated static storage; no operation retains or frees it.

Tests and examples

make verify (compiler SymbolSet fixtures).