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Diffstat (limited to 'src/chomp/ast/substitute.rs')
-rw-r--r-- | src/chomp/ast/substitute.rs | 412 |
1 files changed, 0 insertions, 412 deletions
diff --git a/src/chomp/ast/substitute.rs b/src/chomp/ast/substitute.rs deleted file mode 100644 index 80df588..0000000 --- a/src/chomp/ast/substitute.rs +++ /dev/null @@ -1,412 +0,0 @@ -use super::{ - error::TranslateError, Alt, Call, Cat, Epsilon, Fix, Lambda, Literal, NamedExpression, Variable, -}; -use crate::chomp::{ - visit::{Folder, Mapper, Visitable}, - Name, -}; -use proc_macro2::Span; - -struct Deepen { - pub depth: usize, - pub by: usize, -} - -impl Mapper for Deepen { - type Out = (); - - fn map_epsilon( - &mut self, - _name: &mut Option<Name>, - _span: Option<Span>, - _eps: &mut Epsilon, - ) -> Self::Out { - } - - fn map_literal( - &mut self, - _name: &mut Option<Name>, - _span: Option<Span>, - _lit: &mut Literal, - ) -> Self::Out { - } - - fn map_cat( - &mut self, - _name: &mut Option<Name>, - _span: Option<Span>, - cat: &mut Cat, - ) -> Self::Out { - cat.first.map(self); - for (_, other) in &mut cat.rest { - other.map(self); - } - } - - fn map_alt( - &mut self, - _name: &mut Option<Name>, - _span: Option<Span>, - alt: &mut Alt, - ) -> Self::Out { - alt.first.map(self); - for (_, other) in &mut alt.rest { - other.map(self); - } - } - - fn map_fix( - &mut self, - _name: &mut Option<Name>, - _span: Option<Span>, - fix: &mut Fix, - ) -> Self::Out { - fix.inner.map(self); - } - - fn map_variable( - &mut self, - _name: &mut Option<Name>, - _span: Option<Span>, - var: &mut Variable, - ) -> Self::Out { - if var.index >= self.depth { - var.index += self.by; - } - } - - fn map_call( - &mut self, - _name: &mut Option<Name>, - _span: Option<Span>, - call: &mut Call, - ) -> Self::Out { - call.on.map(self); - for arg in &mut call.args { - arg.map(self); - } - } - - fn map_lambda( - &mut self, - _name: &mut Option<Name>, - _span: Option<Span>, - lambda: &mut Lambda, - ) -> Self::Out { - self.depth += lambda.args.len(); - lambda.inner.map(self); - self.depth -= lambda.args.len(); - } -} - -pub struct Substitute { - pub index: usize, - pub expr: NamedExpression, -} - -impl Folder for Substitute { - type Out = NamedExpression; - - fn fold_epsilon(&mut self, name: Option<Name>, span: Option<Span>, eps: Epsilon) -> Self::Out { - NamedExpression { - name, - expr: eps.into(), - span, - } - } - - fn fold_literal(&mut self, name: Option<Name>, span: Option<Span>, lit: Literal) -> Self::Out { - NamedExpression { - name, - expr: lit.into(), - span, - } - } - - fn fold_cat(&mut self, name: Option<Name>, span: Option<Span>, mut cat: Cat) -> Self::Out { - cat.first = Box::new(cat.first.fold(self)); - cat.rest = cat - .rest - .into_iter() - .map(|(span, e)| (span, e.fold(self))) - .collect(); - NamedExpression { - name, - expr: cat.into(), - span, - } - } - - fn fold_alt(&mut self, name: Option<Name>, span: Option<Span>, mut alt: Alt) -> Self::Out { - alt.first = Box::new(alt.first.fold(self)); - alt.rest = alt - .rest - .into_iter() - .map(|(span, e)| (span, e.fold(self))) - .collect(); - NamedExpression { - name, - expr: alt.into(), - span, - } - } - - fn fold_fix(&mut self, name: Option<Name>, span: Option<Span>, mut fix: Fix) -> Self::Out { - fix.inner = Box::new(fix.inner.fold(self)); - NamedExpression { - name, - expr: fix.into(), - span, - } - } - - fn fold_variable( - &mut self, - name: Option<Name>, - span: Option<Span>, - var: Variable, - ) -> Self::Out { - if var.index == self.index { - self.expr.clone() - } else { - NamedExpression { - name, - expr: Variable { - index: if var.index > self.index { - var.index - 1 - } else { - var.index - }, - } - .into(), - span, - } - } - } - - fn fold_call(&mut self, name: Option<Name>, span: Option<Span>, mut call: Call) -> Self::Out { - call.on = Box::new(call.on.fold(self)); - call.args = call.args.into_iter().map(|e| e.fold(self)).collect(); - NamedExpression { - name, - expr: call.into(), - span, - } - } - - fn fold_lambda( - &mut self, - name: Option<Name>, - span: Option<Span>, - mut lambda: Lambda, - ) -> Self::Out { - self.index += lambda.args.len(); - lambda.inner = Box::new(lambda.inner.fold(self)); - self.index -= lambda.args.len(); - NamedExpression { - name, - expr: lambda.into(), - span, - } - } -} - -pub struct Translate { - changed: bool, -} - -impl Translate { - pub fn new() -> Self { - Self { changed: false } - } -} - -impl Default for Translate { - fn default() -> Self { - Self::new() - } -} - -impl Folder for Translate { - type Out = Result<NamedExpression, TranslateError>; - - fn fold_epsilon(&mut self, name: Option<Name>, span: Option<Span>, eps: Epsilon) -> Self::Out { - Ok(NamedExpression { - name, - expr: eps.into(), - span, - }) - } - - fn fold_literal(&mut self, name: Option<Name>, span: Option<Span>, lit: Literal) -> Self::Out { - Ok(NamedExpression { - name, - expr: lit.into(), - span, - }) - } - - fn fold_cat(&mut self, name: Option<Name>, span: Option<Span>, cat: Cat) -> Self::Out { - Ok(NamedExpression { - name, - expr: cat.into(), - span, - }) - } - - fn fold_alt(&mut self, name: Option<Name>, span: Option<Span>, alt: Alt) -> Self::Out { - Ok(NamedExpression { - name, - expr: alt.into(), - span, - }) - } - - fn fold_fix(&mut self, name: Option<Name>, span: Option<Span>, fix: Fix) -> Self::Out { - Ok(NamedExpression { - name, - expr: fix.into(), - span, - }) - } - - fn fold_variable( - &mut self, - name: Option<Name>, - span: Option<Span>, - var: Variable, - ) -> Self::Out { - Ok(NamedExpression { - name, - expr: var.into(), - span, - }) - } - - fn fold_call(&mut self, name: Option<Name>, span: Option<Span>, call: Call) -> Self::Out { - let mut on = *call.on; - self.changed = true; - while self.changed { - self.changed = false; - on = on.fold(self)?; - } - - let lambda = on - .expr - .try_into_lambda() - .map_err(|on| TranslateError::CallNotAFunction { on, span })?; - - if lambda.args.len() != call.args.len() { - return Err(TranslateError::WrongArgCount { - lambda, - args: call.args, - span, - }); - } - - let mut out = *lambda.inner; - - for ((i, mut arg), name) in call.args.into_iter().enumerate().zip(lambda.args).rev() { - arg.name = arg.name.or(Some(name)); - arg.map(&mut Deepen { depth: 0, by: i }); - out = out.fold(&mut Substitute { - index: 0, - expr: arg, - }); - } - - self.changed = true; - while self.changed { - self.changed = false; - out = out.fold(self)?; - } - - self.changed = true; - out.name = name.or(out.name); - out.span = span.or(out.span); - Ok(out) - } - - fn fold_lambda(&mut self, name: Option<Name>, span: Option<Span>, lambda: Lambda) -> Self::Out { - Ok(NamedExpression { - name, - expr: lambda.into(), - span, - }) - } -} - -#[cfg(test)] -mod tests { - use super::*; - - /// Returns (/x/ x) 'index - fn make_expr(index: usize) -> NamedExpression { - let var = NamedExpression { - name: None, - expr: Variable { index: 0 }.into(), - span: None, - }; - - let lambda = NamedExpression { - name: None, - expr: Lambda { - args: vec!["x".to_owned().into()], - inner: Box::new(var), - } - .into(), - span: None, - }; - - let var = NamedExpression { - name: None, - expr: Variable { index }.into(), - span: None, - }; - - NamedExpression { - name: None, - expr: Call { - on: Box::new(lambda), - args: vec![var], - } - .into(), - span: None, - } - } - - #[test] - fn deepen_lambda() { - let mut expr = make_expr(0); - expr.map(&mut Deepen { depth: 0, by: 1 }); - assert_eq!(expr, make_expr(1)) - } - - #[test] - fn substitute_renames_bigger() { - let expr = make_expr(1); - let expr = expr.fold(&mut Substitute { - index: 0, - expr: NamedExpression { - name: None, - expr: Epsilon.into(), - span: None, - }, - }); - assert_eq!(expr, make_expr(0)) - } - - #[test] - fn translate_lambda() { - let expr = make_expr(1); - let expr = expr.fold(&mut Translate::new()).unwrap(); - assert_eq!( - expr, - NamedExpression { - name: Some("x".to_owned().into()), - expr: Variable { index: 1 }.into(), - span: None - } - ) - } -} |