Struct rustlr::generic_absyn::Bumper

pub struct Bumper<'t, ET: Default> { /* private fields */ }

Structure intended to support bumpalo AST generations, which allows recursive AST types to be defined using references instead of smart pointers (LBox). The benefit of bump-allocated ASTs is the ability to pattern match against nested, recursive structures, e.g., Negative(Negative(x)). The lifetime 't of a Bumper should be the same as the lifetime of the parser’s input. This structure is intended to become the ‘external state’ that’s carried by the runtime parser (parser.exstate), and therefore wraps another value (exstate) of the declared externtype.

Implementations

impl<'t, T: Default> Bumper<'t, T>

pub fn set(&mut self, b: &'t Bump)

sets the encapsulated Bump allocator

pub fn is_set(&self) -> bool

tests if the allocator has been set

pub fn get(&self) -> &'t Bump

returns pointer to the bump allocator. Warning: this function calls unwrap and should only be called after Bumper::set has been called

pub fn make<S>(&self, x: S) -> &'t S

bump-allocates x and returns a reference, which will live as long as the bump allocator. Warning: this function calls unwrap and will panic if the Bumper is not set.

pub fn make_safe<S>(&self, x: S) -> Option<&'t S>

version of make that returns Option, but will not panic

pub fn alloc<S>(&self, x: S) -> Option<&'t mut S>

version of make_safe that returns a mutable reference to the allocated value

pub fn state(&mut self) -> &mut T

returns a mut reference to the encapsulated “state” of type ET

Trait Implementations

impl<T: Default> Default for Bumper<'_, T>

fn default() -> Self

Returns the “default value” for a type.