forked from Orchid/orchid
Lawrence Bethlenfalvy
86e520e8b8
- manual parser - stl refinements - all language constructs are now Send
55 lines
1.8 KiB
Rust
55 lines
1.8 KiB
Rust
use crate::foreign::{xfn_1ary, xfn_2ary, XfnResult, Atom};
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use crate::interner::Interner;
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use crate::representations::interpreted::Clause;
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use crate::error::AssertionError;
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use crate::{ConstTree, Location, OrcString};
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use super::Numeric;
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/// Takes a boolean and two branches, runs the first if the bool is true, the
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/// second if it's false.
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// Even though it's a ternary function, IfThenElse is implemented as an unary
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// foreign function, as the rest of the logic can be defined in Orchid.
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pub fn if_then_else(b: bool) -> XfnResult<Clause> {
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Ok(match b {
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true => Clause::pick(Clause::constfn(Clause::LambdaArg)),
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false => Clause::constfn(Clause::pick(Clause::LambdaArg)),
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})
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}
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/// Compares the inner values if
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///
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/// - both are string,
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/// - both are bool,
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/// - both are either uint or num
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pub fn equals(a: Atom, b: Atom) -> XfnResult<bool> {
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let (a, b) = match (a.try_downcast::<OrcString>(), b.try_downcast::<OrcString>()) {
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(Ok(a), Ok(b)) => return Ok(a == b),
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(Err(a), Err(b)) => (a, b),
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_ => return Ok(false),
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};
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match (a.request::<Numeric>(), b.request::<Numeric>()) {
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(Some(a), Some(b)) => return Ok(a.as_float() == b.as_float()),
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(None, None) => (),
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_ => return Ok(false),
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};
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match (a.try_downcast::<bool>(), b.try_downcast::<bool>()) {
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(Ok(a), Ok(b)) => return Ok(a == b),
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(Err(_), Err(_)) => (),
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_ => return Ok(false),
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};
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AssertionError::fail(Location::Unknown, "the expected type")
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}
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pub fn bool(i: &Interner) -> ConstTree {
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ConstTree::tree([(
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i.i("bool"),
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ConstTree::tree([
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(i.i("ifthenelse"), ConstTree::xfn(xfn_1ary(if_then_else))),
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(i.i("equals"), ConstTree::xfn(xfn_2ary(equals))),
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(i.i("true"), ConstTree::atom(true)),
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(i.i("false"), ConstTree::atom(false)),
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]),
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)])
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}
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