Struct DynExt 

pub struct DynExt(/* private fields */);

A type-erased extension node — the opt-in X for runtime-composed extension sets.

DynExt reconstructs the full Extension + Render surface from the object-safe DynAstExt shims, so it drops into any node (Statement<DynExt>, Expr<DynExt>, …) and every render/visit site exactly where NoExt or a concrete X would go — while the static paths keep their zero-cost layout. The newtype (rather than a bare Box<dyn DynAstExt>) is what lets the node types’ derived PartialEq/Hash/Clone compose; see the module docs.

Build one with new from any concrete extension node, and recover the concrete type with downcast_ref:

use squonk_ast::render::{DynExt, Render, RenderCtx};
use squonk_ast::{Span, Spanned};
use std::fmt;

#[derive(Clone, Debug, PartialEq, Eq, Hash)]
struct MyNode(u32);
impl Spanned for MyNode {
    fn span(&self) -> Span { Span::SYNTHETIC }
}
impl Render for MyNode {
    fn render(&self, _ctx: &RenderCtx<'_>, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "my({})", self.0)
    }
}

let ext = DynExt::new(MyNode(7));
assert_eq!(ext.downcast_ref::<MyNode>(), Some(&MyNode(7)));
assert_eq!(ext.clone(), ext);

Implementations

impl DynExt

pub fn new<T: Extension + Render + 'static>(ext: T) -> Self

Erase a concrete extension node into the dynamic hatch.

pub fn downcast_ref<T: 'static>(&self) -> Option<&T>

Recover the concrete extension type, or None if this node is some other type.

Trait Implementations

impl Clone for DynExt

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 DynExt

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

Formats the value using the given formatter.

impl Eq for DynExt

impl Hash for DynExt

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for DynExt

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Render for DynExt

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

Return the render for this value.

fn operand_binding_power(&self) -> Option<BindingPower>

The binding power this node contributes when it appears as an operand, or None (the default) for a self-delimiting node — an atom, call, or constructor — that never needs parentheses.

impl Spanned for DynExt

fn span(&self) -> Span

Return the span for this value.