Struct StringSink 

pub struct StringSink { /* private fields */ }

Query-scoped sink for strings produced by expression evaluation — the result of CONCAT/SUBSTR/UCASE/…, an xsd:dateTime lexical from NOW, a UUID string, or a value-producing BIND. EvalResult only carries a u64 hash, so a produced string must be interned somewhere its hash can be resolved again; this is that table.

It uses interior mutability (RefCell) so it can be carried by the Copy TextResolver and written during evaluation without threading &mut through the recursive evaluator. This is the cold expression-eval tier (which already allocates Strings for text builtins), not the §6 zero-heap hot path, so a small interning table here does not violate the hot-path invariant.

Implementations

impl StringSink

pub fn new() -> Self

pub fn intern(&self, text: &str) -> u64

Intern a produced plain string, returning its stable content-derived token. Deterministic (same text → same token), so repeated/​reordered evaluation of a pure builtin is referentially transparent (plan §4.4, QISP-R06).

pub fn intern_tagged( &self, text: &str, lang: Option<&str>, datatype: Option<&str>, ) -> u64

Intern a produced string carrying an optional language tag / datatype IRI (STRLANG/STRDT). The token distinguishes "x", "x"@en, "x"^^:t via literal_term_hash, so LANG/DATATYPE can read the tag back.

pub fn resolve(&self, hash: u64) -> Option<String>

Resolve a previously-interned produced string.

pub fn lang(&self, hash: u64) -> Option<String>

The language tag of a produced string term, if any.

pub fn datatype(&self, hash: u64) -> Option<String>

The datatype IRI of a produced string term, if any.

Trait Implementations

impl Debug for StringSink

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for StringSink

fn default() -> StringSink

Returns the “default value” for a type.