Diffstat (limited to 'src/protocol/visitor/sequence.rs')
| -rw-r--r-- | src/protocol/visitor/sequence.rs | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/src/protocol/visitor/sequence.rs b/src/protocol/visitor/sequence.rs index afa6f9c..ef0c5e9 100644 --- a/src/protocol/visitor/sequence.rs +++ b/src/protocol/visitor/sequence.rs @@ -4,14 +4,18 @@ use crate::{ higher_ranked_type, hkt::Marker, protocol::{ - walker::hint::{HintKnown, HintMeta}, - Visitor, + walker::hint::{HintMeta, Meta}, + DynVisitor, }, Flow, }; use super::VisitResult; +/// Protocol for visiting a sequence. +/// +/// This protocol uses a scope to give temporary control to the visitor. +/// The visitor will drive the walker for each item. pub trait Sequence<'ctx, E: Effect> { fn visit<'a>( &'a mut self, @@ -40,13 +44,18 @@ higher_ranked_type! { pub trait SequenceScope<'ctx, E: Effect> { fn size_hint(&mut self) -> Future<'_, (usize, Option<usize>), E>; - fn next<'a>(&'a mut self, visitor: Visitor<'a, 'ctx>) -> Future<'a, Flow, E>; + fn next<'a>(&'a mut self, visitor: DynVisitor<'a, 'ctx>) -> Future<'a, Flow, E>; } pub type DynSequenceScope<'a, 'ctx, E> = &'a mut (dyn SequenceScope<'ctx, E> + Send + Sync + 'a); +#[derive(Default)] +pub struct SequenceKnown { + pub len: (usize, Option<usize>), +} + higher_ranked_type! { - impl HintKnown { + impl Meta { impl['a, 'ctx] type T['a, 'ctx] for SequenceKnown = SequenceKnown; @@ -55,26 +64,33 @@ higher_ranked_type! { } } -#[derive(Default)] -pub struct SequenceKnown { +pub struct SequenceHint { pub len: (usize, Option<usize>), } -pub struct SequenceHint { - pub len: (usize, Option<usize>), +higher_ranked_type! { + impl Meta { + impl['a, 'ctx] type T['a, 'ctx] for SequenceHint = + SequenceHint; + + impl['a, 'ctx] type HigherRanked['a, 'ctx] for SequenceHint = + SequenceHint; + } } impl<E: Effect> HintMeta for SequenceProto<E> { type Known = SequenceKnown; type Hint = SequenceHint; + + type Effect = E; } pub fn visit_sequence<'a, 'ctx, E: Effect>( - visitor: Visitor<'a, 'ctx>, + visitor: DynVisitor<'a, 'ctx>, scope: DynSequenceScope<'a, 'ctx, E>, ) -> Future<'a, VisitResult<DynSequenceScope<'a, 'ctx, E>>, E> { - if let Some(object) = visitor.upcast_mut::<SequenceProto<E>>() { + if let Some(object) = visitor.0.upcast_mut::<SequenceProto<E>>() { // Allow the visitor to give a hint if it wants. object.visit(scope) } else { |