Struct ForSource 

#[non_exhaustive]
pub struct ForSource {
    pub kind: ForSourceKind,
    pub span: Span,
}

What a for iterates: inline comprehension text, or the name of a bound producer wire.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

kind: ForSourceKind

What the source denotes. This is the source: its text is rendered from here (ForSource::to_text), never stored beside it, so a source cannot read as one thing and traverse another.

span: Span

Where the source appears, for diagnostics. Position is provenance and belongs on the node; a copy of the text the author wrote is not provenance, it is a second answer to a question that has one.

Implementations

impl ForSource

pub fn comprehension(tree: Comprehension, span: Span) -> Option<ForSource>

A traversal source over a comprehension, its text the tree’s canonical text (Comprehension::to_text). None when the tree is outside the text grammar, so a source never carries a text that reads back as a different comprehension.

pub fn producer(name: impl Into<String>, span: Span) -> ForSource

A traversal source naming a producer bound in the same scope.

pub fn derived( base: impl Into<String>, filter: Option<String>, order: Option<String>, span: Span, ) -> ForSource

A traversal source deriving from a bound producer: the base with an optional filter and order, written as the text writes them.

pub fn to_text(&self) -> String

The source as the text after for writes it, rendered from what it denotes.

A comprehension renders through Comprehension::to_text, a producer is its name, and a derivation is its base with the where and order it carries. Re-reading the result yields the same source, so nothing downstream can traverse one thing and report another.

Total for every source that exists: Self::comprehension refuses a tree the text cannot write, so the fallback below is unreachable through the constructors. It renders a form no parser accepts rather than a plausible one, so a source that somehow evaded them fails loudly at the next read instead of quietly meaning something else.

pub fn element_names(&self) -> Vec<String>

The element names the source dispenses, when known statically. A producer reference or derivation resolves its names at compile time.

Trait Implementations

impl Clone for ForSource

fn clone(&self) -> ForSource

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ForSource

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

Formats the value using the given formatter.