Struct Origin 

pub struct Origin { /* private fields */ }

What the host can tell the front end about an invocation, over and above the tokens themselves.

Two of the three capture strategies need something a TokenStream does not carry:

• The search that finds the invocation in the crate’s own sources needs the crate’s directory — CARGO_MANIFEST_DIR, which Cargo sets for rustc and for rust-analyzer alike — and the name the invocation may be written with, which narrows the candidates.
• String-literal mode needs the Subspan hook to put a caret inside the literal.

The default is an origin that says nothing: no directory, so no search, and no hook. That is what capture, analyze and expand use — a test building a TokenStream from a string must not depend on the developer’s working directory, or on what happens to be written in the crate around it. The procedural macros pass Origin::new, which is the real thing.

Implementations

impl Origin

pub fn unknown() -> Self

An origin that tells capture nothing; see the type documentation.

pub fn new(entry_names: &'static [&'static str]) -> Self

The origin of a real expansion of an entry point that may be written with any of entry_names (&["c89", "c90"] for the two names one entry point has), in the crate Cargo names.

The names carry no ! and no path: an invocation is looked for by its last path segment, so cinrs::c99! is found by "c99".

pub fn with_subspan(self, subspan: Option<Subspan>) -> Self

This origin with a hook that can point inside a string literal; see Subspan.

pub fn in_dir(self, dir: impl Into<PathBuf>) -> Self

This origin with the directory to search set explicitly.

Origin::new reads CARGO_MANIFEST_DIR, which is process-global; a test says which directory it means instead.

pub fn entry_names(&self) -> &'static [&'static str]

The names an invocation of this entry point may be written with.

pub fn crate_dir(&self) -> Option<&Path>

The directory the search walks, when there is one.

Trait Implementations

impl Clone for Origin

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Origin

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

Formats the value using the given formatter.

impl Default for Origin

fn default() -> Self

Returns the “default value” for a type.