Struct Signatures 

pub struct Signatures<'a> { /* private fields */ }

A two-tier signature lookup: a per-document SignatureDb of scanned \newcommand/\newenvironment/xparse definitions consulted first, falling back to the process-wide builtin DB. Cheap to copy (it borrows the scanned DB), so it threads through the formatter’s lowering like a context handle.

Scanned-first matches TeX scoping intuition: a locally (re)defined command shadows a built-in of the same name. (We do not yet model where a definition becomes visible — a whole-file union — which is sound for the formatter’s arity needs; lexical/conditional visibility is out of scope, per AGENTS.md #1.)

Implementations

impl<'a> Signatures<'a>

pub fn new(user: &'a SignatureDb) -> Self

Resolve against user first, then the built-in DB.

pub fn command(&self, name: &str) -> Option<&'a CommandSig>

The signature of command name: scanned definition first, then the curated built-in, then the bulk CWL tier. CWL is consulted last and contributes only argument arity (its behavior flags are all default), so a CWL-only command is laid out like any unknown command, just with its argument count known.

pub fn environment(&self, name: &str) -> Option<&'a EnvironmentSig>

The signature of environment name: scanned, then built-in, then CWL. See command for why the CWL tier is safe to consult here.

Environment aliases are deliberately not consulted: an alias names a command, and a name alone cannot tell a \bea-opened delimiter from a literal \begin{bea} that happens to spell the same word. Resolve those through environment_at, which has the node.

pub fn environment_at(&self, node: &SyntaxNode) -> Option<&'a EnvironmentSig>

The signature governing node — an ENVIRONMENT or its BEGIN — which is environment except that an environment-alias delimiter resolves through the alias map instead.

This is the node-keyed lookup every layout decision wants, because an alias BEGIN (a bare control word, Begin::is_alias) and a literal \begin{X} are indistinguishable once reduced to a name. Only the former inherits the target’s behavior; a literal \begin{bea} in a file that also defines \bea as an alias is an unrelated environment of that name and stays unknown.

The alias arm resolves against curated data only, for the same reason the parser’s ParseCtx::is_math_environment does: an alias declares a spelling, never a semantic, so every behavior flag still comes from curated data. That means builtin plus the scope’s declared entries — a declaration is curated (like copies a built-in entry and resolves against nothing else), which is what lets \startmyenv … \endmyenv reach the behavior of a myenv that has no built-in counterpart. A scanned \newenvironment of the same name still lends an alias nothing.

Trait Implementations

impl<'a> Clone for Signatures<'a>

fn clone(&self) -> Signatures<'a>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'a> Copy for Signatures<'a>

impl<'a> Debug for Signatures<'a>

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

Formats the value using the given formatter.