1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
//! Defines traits used to embed the chalk-engine in another crate.
//!
//! chalk and rustc both define types which implement the traits in this
//! module. This allows each user of chalk-engine to define their own
//! `DomainGoal` type, add arena lifetime parameters, and more. See
//! [`Context`] trait for a list of types.
use crate::CompleteAnswer;
use chalk_ir::interner::Interner;
use chalk_ir::Substitution;
use std::fmt::Debug;
pub enum AnswerResult<I: Interner> {
/// The next available answer.
Answer(CompleteAnswer<I>),
/// No answer could be returned because there are no more solutions.
NoMoreSolutions,
/// No answer could be returned because the goal has floundered.
Floundered,
// No answer could be returned *yet*, because we exceeded our
// quantum (`should_continue` returned false).
QuantumExceeded,
}
impl<I: Interner> AnswerResult<I> {
pub fn is_answer(&self) -> bool {
matches!(self, Self::Answer(_))
}
pub fn answer(self) -> CompleteAnswer<I> {
match self {
Self::Answer(answer) => answer,
_ => panic!("Not an answer."),
}
}
pub fn is_no_more_solutions(&self) -> bool {
matches!(self, Self::NoMoreSolutions)
}
pub fn is_quantum_exceeded(&self) -> bool {
matches!(self, Self::QuantumExceeded)
}
}
impl<I: Interner> Debug for AnswerResult<I> {
fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
AnswerResult::Answer(answer) => write!(fmt, "{:?}", answer),
AnswerResult::Floundered => write!(fmt, "Floundered"),
AnswerResult::NoMoreSolutions => write!(fmt, "None"),
AnswerResult::QuantumExceeded => write!(fmt, "QuantumExceeded"),
}
}
}
pub trait AnswerStream<I: Interner> {
/// Gets the next answer for a given goal, but doesn't increment the answer index.
/// Calling this or `next_answer` again will give the same answer.
fn peek_answer(&mut self, should_continue: impl Fn() -> bool) -> AnswerResult<I>;
/// Gets the next answer for a given goal, incrementing the answer index.
/// Calling this or `peek_answer` again will give the next answer.
fn next_answer(&mut self, should_continue: impl Fn() -> bool) -> AnswerResult<I>;
/// Invokes `test` with each possible future answer, returning true immediately
/// if we find any answer for which `test` returns true.
fn any_future_answer(&self, test: impl Fn(&Substitution<I>) -> bool) -> bool;
}
|
