forked from Orchid/orchid
39 lines
1.3 KiB
Rust
39 lines
1.3 KiB
Rust
use std::rc::Rc;
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use crate::utils::replace_first;
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use crate::ast::{Expr, Clause};
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/// Traverse the tree, calling pred on every sibling list until it returns
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/// some vec then replace the sibling list with that vec and return true
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/// return false if pred never returned some
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pub fn exprv<
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F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>
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>(input: Rc<Vec<Expr>>, pred: &mut F) -> Option<Rc<Vec<Expr>>> {
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if let o@Some(_) = pred(input.clone()) {return o}
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replace_first(input.as_ref(), |ex| expr(ex, pred))
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.map(|i| Rc::new(i.collect()))
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}
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pub fn expr<
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F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>
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>(input: &Expr, pred: &mut F) -> Option<Expr> {
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if let Some(value) = clause(&input.value, pred) {
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Some(Expr{ value, location: input.location.clone() })
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} else {None}
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}
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pub fn clause<
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F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>
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>(c: &Clause, pred: &mut F) -> Option<Clause> {
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match c {
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Clause::P(_) | Clause::Placeh {..} | Clause::Name {..} => None,
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Clause::Lambda(arg, body) => {
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if let Some(arg) = expr(arg.as_ref(), pred) {
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Some(Clause::Lambda(Rc::new(arg), body.clone()))
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} else if let Some(body) = exprv(body.clone(), pred) {
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Some(Clause::Lambda(arg.clone(), body))
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} else {None}
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}
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Clause::S(c, body) => Some(Clause::S(*c, exprv(body.clone(), pred)?)),
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}
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} |