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-rw-r--r--dhall/src/syntax/text/printer.rs141
1 files changed, 80 insertions, 61 deletions
diff --git a/dhall/src/syntax/text/printer.rs b/dhall/src/syntax/text/printer.rs
index 378f408..d655489 100644
--- a/dhall/src/syntax/text/printer.rs
+++ b/dhall/src/syntax/text/printer.rs
@@ -5,14 +5,15 @@ use std::fmt::{self, Display};
// There is a one-to-one correspondence between the formatter and the grammar. Each phase is
// named after a corresponding grammar group, and the structure of the formatter reflects
// the relationship between the corresponding grammar rules. This leads to the nice property
-// of automatically getting all the parentheses and precedences right.
+// of automatically getting all the parentheses and precedences right (in a manner dual do Pratt
+// parsing).
#[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
enum PrintPhase {
// `expression`
Base,
// `operator-expression`
Operator,
- // All the operator `*-expression`s
+ // All the `<operator>-expression`s
BinOp(ast::BinOp),
// `application-expression`
App,
@@ -37,6 +38,7 @@ impl UnspannedExpr {
// Annotate subexpressions with the appropriate phase, defaulting to Base
fn annotate_with_phases(&self) -> ExprKind<PhasedExpr<'_>> {
use crate::syntax::ExprKind::*;
+ use crate::syntax::OpKind::*;
use PrintPhase::*;
let with_base = self.map_ref(|e| PhasedExpr(e, Base));
match with_base {
@@ -47,31 +49,33 @@ impl UnspannedExpr {
Pi(a, b, c)
}
}
- Merge(a, b, c) => Merge(
+ Op(Merge(a, b, c)) => Op(Merge(
a.phase(PrintPhase::Import),
b.phase(PrintPhase::Import),
c.map(|x| x.phase(PrintPhase::App)),
- ),
- ToMap(a, b) => ToMap(
+ )),
+ Op(ToMap(a, b)) => Op(ToMap(
a.phase(PrintPhase::Import),
b.map(|x| x.phase(PrintPhase::App)),
- ),
+ )),
Annot(a, b) => Annot(a.phase(Operator), b),
- ExprKind::BinOp(op, a, b) => ExprKind::BinOp(
+ Op(OpKind::BinOp(op, a, b)) => Op(OpKind::BinOp(
op,
a.phase(PrintPhase::BinOp(op)),
b.phase(PrintPhase::BinOp(op)),
- ),
+ )),
SomeLit(e) => SomeLit(e.phase(PrintPhase::Import)),
- ExprKind::App(f, a) => ExprKind::App(
+ Op(OpKind::App(f, a)) => Op(OpKind::App(
f.phase(PrintPhase::App),
a.phase(PrintPhase::Import),
- ),
- Field(a, b) => Field(a.phase(Primitive), b),
- Projection(e, ls) => Projection(e.phase(Primitive), ls),
- ProjectionByExpr(a, b) => ProjectionByExpr(a.phase(Primitive), b),
- Completion(a, b) => {
- Completion(a.phase(Primitive), b.phase(Primitive))
+ )),
+ Op(Field(a, b)) => Op(Field(a.phase(Primitive), b)),
+ Op(Projection(e, ls)) => Op(Projection(e.phase(Primitive), ls)),
+ Op(ProjectionByExpr(a, b)) => {
+ Op(ProjectionByExpr(a.phase(Primitive), b))
+ }
+ Op(Completion(a, b)) => {
+ Op(Completion(a.phase(Primitive), b.phase(Primitive)))
}
ExprKind::Import(a) => {
ExprKind::Import(a.map_ref(|x| x.phase(PrintPhase::Import)))
@@ -86,21 +90,23 @@ impl UnspannedExpr {
phase: PrintPhase,
) -> Result<(), fmt::Error> {
use crate::syntax::ExprKind::*;
+ use crate::syntax::OpKind::*;
let needs_paren = match self {
Lam(_, _, _)
- | BoolIf(_, _, _)
| Pi(_, _, _)
| Let(_, _, _, _)
- | EmptyListLit(_)
| SomeLit(_)
- | Merge(_, _, _)
- | ToMap(_, _)
+ | EmptyListLit(_)
+ | Op(BoolIf(_, _, _))
+ | Op(Merge(_, _, _))
+ | Op(ToMap(_, _))
| Annot(_, _) => phase > PrintPhase::Base,
- // Precedence is magically handled by the ordering of BinOps.
- ExprKind::BinOp(op, _, _) => phase > PrintPhase::BinOp(*op),
- ExprKind::App(_, _) => phase > PrintPhase::App,
- Completion(_, _) => phase > PrintPhase::Import,
+ // Precedence is magically handled by the ordering of BinOps. This is reverse Pratt
+ // parsing.
+ Op(BinOp(op, _, _)) => phase > PrintPhase::BinOp(*op),
+ Op(App(_, _)) => phase > PrintPhase::App,
+ Op(Completion(_, _)) => phase > PrintPhase::Import,
_ => false,
};
@@ -143,12 +149,10 @@ impl<SE: Display + Clone> Display for ExprKind<SE> {
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
use crate::syntax::ExprKind::*;
match self {
+ Var(a) => a.fmt(f)?,
Lam(a, b, c) => {
write!(f, "λ({} : {}) → {}", a, b, c)?;
}
- BoolIf(a, b, c) => {
- write!(f, "if {} then {} else {}", a, b, c)?;
- }
Pi(a, b, c) if &String::from(a) == "_" => {
write!(f, "{} → {}", b, c)?;
}
@@ -162,14 +166,62 @@ impl<SE: Display + Clone> Display for ExprKind<SE> {
}
write!(f, " = {} in {}", c, d)?;
}
+ Const(k) => k.fmt(f)?,
+ Builtin(v) => v.fmt(f)?,
+ Num(a) => a.fmt(f)?,
+ TextLit(a) => a.fmt(f)?,
+ SomeLit(e) => {
+ write!(f, "Some {}", e)?;
+ }
EmptyListLit(t) => {
write!(f, "[] : {}", t)?;
}
NEListLit(es) => {
fmt_list("[", ", ", "]", es, f, Display::fmt)?;
}
- SomeLit(e) => {
- write!(f, "Some {}", e)?;
+ RecordLit(a) if a.is_empty() => f.write_str("{=}")?,
+ RecordLit(a) => fmt_list("{ ", ", ", " }", a, f, |(k, v), f| {
+ write!(f, "{} = {}", k, v)
+ })?,
+ RecordType(a) if a.is_empty() => f.write_str("{}")?,
+ RecordType(a) => fmt_list("{ ", ", ", " }", a, f, |(k, t), f| {
+ write!(f, "{} : {}", k, t)
+ })?,
+ UnionType(a) => fmt_list("< ", " | ", " >", a, f, |(k, v), f| {
+ write!(f, "{}", k)?;
+ if let Some(v) = v {
+ write!(f, ": {}", v)?;
+ }
+ Ok(())
+ })?,
+ Op(op) => {
+ op.fmt(f)?;
+ }
+ Annot(a, b) => {
+ write!(f, "{} : {}", a, b)?;
+ }
+ Assert(a) => {
+ write!(f, "assert : {}", a)?;
+ }
+ Import(a) => a.fmt(f)?,
+ }
+ Ok(())
+ }
+}
+
+/// Generic instance that delegates to subexpressions
+impl<SE: Display + Clone> Display for OpKind<SE> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+ use crate::syntax::OpKind::*;
+ match self {
+ App(a, b) => {
+ write!(f, "{} {}", a, b)?;
+ }
+ BinOp(op, a, b) => {
+ write!(f, "{} {} {}", a, op, b)?;
+ }
+ BoolIf(a, b, c) => {
+ write!(f, "if {} then {} else {}", a, b, c)?;
}
Merge(a, b, c) => {
write!(f, "merge {} {}", a, b)?;
@@ -183,41 +235,9 @@ impl<SE: Display + Clone> Display for ExprKind<SE> {
write!(f, " : {}", b)?;
}
}
- Annot(a, b) => {
- write!(f, "{} : {}", a, b)?;
- }
- Assert(a) => {
- write!(f, "assert : {}", a)?;
- }
- ExprKind::BinOp(op, a, b) => {
- write!(f, "{} {} {}", a, op, b)?;
- }
- ExprKind::App(a, b) => {
- write!(f, "{} {}", a, b)?;
- }
Field(a, b) => {
write!(f, "{}.{}", a, b)?;
}
- Var(a) => a.fmt(f)?,
- Const(k) => k.fmt(f)?,
- Builtin(v) => v.fmt(f)?,
- Num(a) => a.fmt(f)?,
- TextLit(a) => a.fmt(f)?,
- RecordType(a) if a.is_empty() => f.write_str("{}")?,
- RecordType(a) => fmt_list("{ ", ", ", " }", a, f, |(k, t), f| {
- write!(f, "{} : {}", k, t)
- })?,
- RecordLit(a) if a.is_empty() => f.write_str("{=}")?,
- RecordLit(a) => fmt_list("{ ", ", ", " }", a, f, |(k, v), f| {
- write!(f, "{} = {}", k, v)
- })?,
- UnionType(a) => fmt_list("< ", " | ", " >", a, f, |(k, v), f| {
- write!(f, "{}", k)?;
- if let Some(v) = v {
- write!(f, ": {}", v)?;
- }
- Ok(())
- })?,
Projection(e, ls) => {
write!(f, "{}.", e)?;
fmt_list("{ ", ", ", " }", ls, f, Display::fmt)?;
@@ -228,7 +248,6 @@ impl<SE: Display + Clone> Display for ExprKind<SE> {
Completion(a, b) => {
write!(f, "{}::{}", a, b)?;
}
- Import(a) => a.fmt(f)?,
}
Ok(())
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-29 11:02:56 +0000