Determine which of a topic's name/aliases actually look callable

A name/alias "looks callable" if it appears followed by ( in the topic's \\usage{} text - e.g. mutate.Rd has usage mutate(.data, ...), so "mutate" qualifies. Infix operators (e.g. %||%, %>%) are never followed by ( in \\usage{} - they're invoked as x %op% y, not %op%(x, y) - so they get a second check: an operator-shaped name (^%.+%$) qualifies if it appears anywhere in a non-empty usage, which is safe precisely because that syntax is unambiguous (never a dataset or concept-page name). Datasets and concept pages (\\usage{} is just a bare name, or empty) never qualify either way. A single Rd topic can document several callables at once (e.g. lead-lag.Rd documents both lead() and lag(), with topic name "lead-lag" matching neither) - hence this returns a vector, not a single yes/no. Fixed-string matching (not regex) is used for the name( check deliberately: Rd names can contain regex metacharacters (%>%, [<-, ...).

Usage

.callable_candidates(name, aliases, usage)

Arguments

name

Topic name.

aliases

Character vector of the topic's aliases (possibly empty).

usage

The topic's \\usage{} text (possibly "").

Value

Character vector of callable names (possibly empty).

Details

Shared by .render_topic_heading() in render_md.R (decides whether to append () to the heading) and .compute_is_private() in parse_rd.R (a topic whose usage is a bare name - a dataset - is never flagged private just because datasets aren't in NAMESPACE's export() list the way functions are; an operator, unlike a dataset, still needs to be checkable against NAMESPACE, which is exactly what this second branch enables).