From 78e9e32e1357d50313287dd2a3c437132c83aeb6 Mon Sep 17 00:00:00 2001 From: Nadrieril Date: Sun, 15 Dec 2019 20:10:54 +0000 Subject: Move contents of dhall_syntax to dhall --- dhall_syntax/src/core/visitor.rs | 360 --------------------------------------- 1 file changed, 360 deletions(-) delete mode 100644 dhall_syntax/src/core/visitor.rs (limited to 'dhall_syntax/src/core/visitor.rs') diff --git a/dhall_syntax/src/core/visitor.rs b/dhall_syntax/src/core/visitor.rs deleted file mode 100644 index 143e556..0000000 --- a/dhall_syntax/src/core/visitor.rs +++ /dev/null @@ -1,360 +0,0 @@ -use crate::*; -use std::iter::FromIterator; - -/// A visitor trait that can be used to traverse `ExprF`s. We need this pattern so that Rust lets -/// us have as much mutability as we can. -/// For example, `traverse_ref_with_special_handling_of_binders` cannot be made using only -/// `traverse_ref`, because `traverse_ref` takes a `FnMut` so we would need to pass multiple -/// mutable reverences to this argument to `traverse_ref`. But Rust's ownership system is all about -/// preventing exactly this ! So we have to be more clever. The visitor pattern allows us to have -/// only one mutable thing the whole time: the visitor itself. The visitor can then carry around -/// multiple closures or just one, and Rust is ok with either. See for example TraverseRefVisitor. -pub trait ExprFVisitor<'a, SE1, SE2, E1, E2>: Sized { - type Error; - - fn visit_subexpr(&mut self, subexpr: &'a SE1) -> Result; - fn visit_embed(self, embed: &'a E1) -> Result; - - fn visit_subexpr_under_binder( - mut self, - _label: &'a Label, - subexpr: &'a SE1, - ) -> Result { - self.visit_subexpr(subexpr) - } - - fn visit( - self, - input: &'a ExprF, - ) -> Result, Self::Error> { - visit_ref(self, input) - } -} - -/// Like `ExprFVisitor`, but by mutable reference -pub trait ExprFMutVisitor<'a, SE, E>: Sized { - type Error; - - fn visit_subexpr(&mut self, subexpr: &'a mut SE) - -> Result<(), Self::Error>; - fn visit_embed(self, _embed: &'a mut E) -> Result<(), Self::Error> { - Ok(()) - } - - fn visit_subexpr_under_binder( - mut self, - _label: &'a mut Label, - subexpr: &'a mut SE, - ) -> Result<(), Self::Error> { - self.visit_subexpr(subexpr) - } - - fn visit(self, input: &'a mut ExprF) -> Result<(), Self::Error> { - visit_mut(self, input) - } -} - -fn visit_ref<'a, V, SE1, SE2, E1, E2>( - mut v: V, - input: &'a ExprF, -) -> Result, V::Error> -where - V: ExprFVisitor<'a, SE1, SE2, E1, E2>, -{ - fn vec<'a, T, U, Err, F: FnMut(&'a T) -> Result>( - x: &'a [T], - f: F, - ) -> Result, Err> { - x.iter().map(f).collect() - } - fn opt<'a, T, U, Err, F: FnOnce(&'a T) -> Result>( - x: &'a Option, - f: F, - ) -> Result, Err> { - Ok(match x { - Some(x) => Some(f(x)?), - None => None, - }) - } - fn dupmap<'a, V, SE1, SE2, E1, E2, T>( - x: impl IntoIterator, - mut v: V, - ) -> Result - where - SE1: 'a, - T: FromIterator<(Label, SE2)>, - V: ExprFVisitor<'a, SE1, SE2, E1, E2>, - { - x.into_iter() - .map(|(k, x)| Ok((k.clone(), v.visit_subexpr(x)?))) - .collect() - } - fn optdupmap<'a, V, SE1, SE2, E1, E2, T>( - x: impl IntoIterator)>, - mut v: V, - ) -> Result - where - SE1: 'a, - T: FromIterator<(Label, Option)>, - V: ExprFVisitor<'a, SE1, SE2, E1, E2>, - { - x.into_iter() - .map(|(k, x)| { - Ok(( - k.clone(), - match x { - Some(x) => Some(v.visit_subexpr(x)?), - None => None, - }, - )) - }) - .collect() - } - - use crate::ExprF::*; - Ok(match input { - Var(v) => Var(v.clone()), - Lam(l, t, e) => { - let t = v.visit_subexpr(t)?; - let e = v.visit_subexpr_under_binder(l, e)?; - Lam(l.clone(), t, e) - } - Pi(l, t, e) => { - let t = v.visit_subexpr(t)?; - let e = v.visit_subexpr_under_binder(l, e)?; - Pi(l.clone(), t, e) - } - Let(l, t, a, e) => { - let t = opt(t, &mut |e| v.visit_subexpr(e))?; - let a = v.visit_subexpr(a)?; - let e = v.visit_subexpr_under_binder(l, e)?; - Let(l.clone(), t, a, e) - } - App(f, a) => App(v.visit_subexpr(f)?, v.visit_subexpr(a)?), - Annot(x, t) => Annot(v.visit_subexpr(x)?, v.visit_subexpr(t)?), - Const(k) => Const(*k), - Builtin(v) => Builtin(*v), - BoolLit(b) => BoolLit(*b), - NaturalLit(n) => NaturalLit(*n), - IntegerLit(n) => IntegerLit(*n), - DoubleLit(n) => DoubleLit(*n), - TextLit(t) => TextLit(t.traverse_ref(|e| v.visit_subexpr(e))?), - BinOp(o, x, y) => BinOp(*o, v.visit_subexpr(x)?, v.visit_subexpr(y)?), - BoolIf(b, t, f) => BoolIf( - v.visit_subexpr(b)?, - v.visit_subexpr(t)?, - v.visit_subexpr(f)?, - ), - EmptyListLit(t) => EmptyListLit(v.visit_subexpr(t)?), - NEListLit(es) => NEListLit(vec(es, |e| v.visit_subexpr(e))?), - SomeLit(e) => SomeLit(v.visit_subexpr(e)?), - RecordType(kts) => RecordType(dupmap(kts, v)?), - RecordLit(kvs) => RecordLit(dupmap(kvs, v)?), - UnionType(kts) => UnionType(optdupmap(kts, v)?), - Merge(x, y, t) => Merge( - v.visit_subexpr(x)?, - v.visit_subexpr(y)?, - opt(t, |e| v.visit_subexpr(e))?, - ), - ToMap(x, t) => { - ToMap(v.visit_subexpr(x)?, opt(t, |e| v.visit_subexpr(e))?) - } - Field(e, l) => Field(v.visit_subexpr(e)?, l.clone()), - Projection(e, ls) => Projection(v.visit_subexpr(e)?, ls.clone()), - ProjectionByExpr(e, x) => { - ProjectionByExpr(v.visit_subexpr(e)?, v.visit_subexpr(x)?) - } - Assert(e) => Assert(v.visit_subexpr(e)?), - Import(i) => Import(i.traverse_ref(|e| v.visit_subexpr(e))?), - Embed(a) => Embed(v.visit_embed(a)?), - }) -} - -fn visit_mut<'a, V, SE, E>( - mut v: V, - input: &'a mut ExprF, -) -> Result<(), V::Error> -where - V: ExprFMutVisitor<'a, SE, E>, -{ - fn vec<'a, V, SE, E>(v: &mut V, x: &'a mut Vec) -> Result<(), V::Error> - where - V: ExprFMutVisitor<'a, SE, E>, - { - for x in x { - v.visit_subexpr(x)?; - } - Ok(()) - } - fn opt<'a, V, SE, E>( - v: &mut V, - x: &'a mut Option, - ) -> Result<(), V::Error> - where - V: ExprFMutVisitor<'a, SE, E>, - { - if let Some(x) = x { - v.visit_subexpr(x)?; - } - Ok(()) - } - fn dupmap<'a, V, SE, E>( - mut v: V, - x: impl IntoIterator, - ) -> Result<(), V::Error> - where - SE: 'a, - V: ExprFMutVisitor<'a, SE, E>, - { - for (_, x) in x { - v.visit_subexpr(x)?; - } - Ok(()) - } - fn optdupmap<'a, V, SE, E>( - mut v: V, - x: impl IntoIterator)>, - ) -> Result<(), V::Error> - where - SE: 'a, - V: ExprFMutVisitor<'a, SE, E>, - { - for (_, x) in x { - opt(&mut v, x)?; - } - Ok(()) - } - - use crate::ExprF::*; - match input { - Var(_) | Const(_) | Builtin(_) | BoolLit(_) | NaturalLit(_) - | IntegerLit(_) | DoubleLit(_) => {} - Lam(l, t, e) => { - v.visit_subexpr(t)?; - v.visit_subexpr_under_binder(l, e)?; - } - Pi(l, t, e) => { - v.visit_subexpr(t)?; - v.visit_subexpr_under_binder(l, e)?; - } - Let(l, t, a, e) => { - opt(&mut v, t)?; - v.visit_subexpr(a)?; - v.visit_subexpr_under_binder(l, e)?; - } - App(f, a) => { - v.visit_subexpr(f)?; - v.visit_subexpr(a)?; - } - Annot(x, t) => { - v.visit_subexpr(x)?; - v.visit_subexpr(t)?; - } - TextLit(t) => t.traverse_mut(|e| v.visit_subexpr(e))?, - BinOp(_, x, y) => { - v.visit_subexpr(x)?; - v.visit_subexpr(y)?; - } - BoolIf(b, t, f) => { - v.visit_subexpr(b)?; - v.visit_subexpr(t)?; - v.visit_subexpr(f)?; - } - EmptyListLit(t) => v.visit_subexpr(t)?, - NEListLit(es) => vec(&mut v, es)?, - SomeLit(e) => v.visit_subexpr(e)?, - RecordType(kts) => dupmap(v, kts)?, - RecordLit(kvs) => dupmap(v, kvs)?, - UnionType(kts) => optdupmap(v, kts)?, - Merge(x, y, t) => { - v.visit_subexpr(x)?; - v.visit_subexpr(y)?; - opt(&mut v, t)?; - } - ToMap(x, t) => { - v.visit_subexpr(x)?; - opt(&mut v, t)?; - } - Field(e, _) => v.visit_subexpr(e)?, - Projection(e, _) => v.visit_subexpr(e)?, - ProjectionByExpr(e, x) => { - v.visit_subexpr(e)?; - v.visit_subexpr(x)?; - } - Assert(e) => v.visit_subexpr(e)?, - Import(i) => i.traverse_mut(|e| v.visit_subexpr(e))?, - Embed(a) => v.visit_embed(a)?, - } - Ok(()) -} - -pub struct TraverseRefWithBindersVisitor { - pub visit_subexpr: F1, - pub visit_under_binder: F2, -} - -impl<'a, SE, E, SE2, Err, F1, F2> ExprFVisitor<'a, SE, SE2, E, E> - for TraverseRefWithBindersVisitor -where - SE: 'a, - E: 'a + Clone, - F1: FnMut(&'a SE) -> Result, - F2: FnOnce(&'a Label, &'a SE) -> Result, -{ - type Error = Err; - - fn visit_subexpr(&mut self, subexpr: &'a SE) -> Result { - (self.visit_subexpr)(subexpr) - } - fn visit_subexpr_under_binder( - self, - label: &'a Label, - subexpr: &'a SE, - ) -> Result { - (self.visit_under_binder)(label, subexpr) - } - fn visit_embed(self, embed: &'a E) -> Result { - Ok(embed.clone()) - } -} - -pub struct TraverseRefVisitor { - pub visit_subexpr: F1, -} - -impl<'a, SE, E, SE2, Err, F1> ExprFVisitor<'a, SE, SE2, E, E> - for TraverseRefVisitor -where - SE: 'a, - E: 'a + Clone, - F1: FnMut(&'a SE) -> Result, -{ - type Error = Err; - - fn visit_subexpr(&mut self, subexpr: &'a SE) -> Result { - (self.visit_subexpr)(subexpr) - } - fn visit_embed(self, embed: &'a E) -> Result { - Ok(embed.clone()) - } -} - -pub struct TraverseMutVisitor { - pub visit_subexpr: F1, -} - -impl<'a, SE, E, Err, F1> ExprFMutVisitor<'a, SE, E> for TraverseMutVisitor -where - SE: 'a, - E: 'a, - F1: FnMut(&'a mut SE) -> Result<(), Err>, -{ - type Error = Err; - - fn visit_subexpr( - &mut self, - subexpr: &'a mut SE, - ) -> Result<(), Self::Error> { - (self.visit_subexpr)(subexpr) - } -} -- cgit v1.2.3