Break up print::Pat printing into several helper functions

This commit is contained in:
Zalathar 2024-08-02 19:55:16 +10:00
parent 6a2cd0d50c
commit ccfd94e334

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@ -64,130 +64,159 @@ pub(crate) enum PatKind<'tcx> {
impl<'tcx> fmt::Display for Pat<'tcx> { impl<'tcx> fmt::Display for Pat<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// Printing lists is a chore.
let mut first = true;
let mut start_or_continue = |s| {
if first {
first = false;
""
} else {
s
}
};
let mut start_or_comma = || start_or_continue(", ");
match self.kind { match self.kind {
PatKind::Wild => write!(f, "_"), PatKind::Wild => write!(f, "_"),
PatKind::Never => write!(f, "!"), PatKind::Never => write!(f, "!"),
PatKind::Variant { ref subpatterns, .. } | PatKind::Leaf { ref subpatterns } => { PatKind::Variant { ref subpatterns, .. } | PatKind::Leaf { ref subpatterns } => {
let variant_and_name = match self.kind { write_struct_like(f, self.ty, &self.kind, subpatterns)
PatKind::Variant { adt_def, variant_index, .. } => ty::tls::with(|tcx| {
let variant = adt_def.variant(variant_index);
let adt_did = adt_def.did();
let name = if tcx.get_diagnostic_item(sym::Option) == Some(adt_did)
|| tcx.get_diagnostic_item(sym::Result) == Some(adt_did)
{
variant.name.to_string()
} else {
format!("{}::{}", tcx.def_path_str(adt_def.did()), variant.name)
};
Some((variant, name))
}),
_ => self.ty.ty_adt_def().and_then(|adt_def| {
if !adt_def.is_enum() {
ty::tls::with(|tcx| {
Some((adt_def.non_enum_variant(), tcx.def_path_str(adt_def.did())))
})
} else {
None
}
}),
};
if let Some((variant, name)) = &variant_and_name {
write!(f, "{name}")?;
// Only for Adt we can have `S {...}`,
// which we handle separately here.
if variant.ctor.is_none() {
write!(f, " {{ ")?;
let mut printed = 0;
for p in subpatterns {
if let PatKind::Wild = p.pattern.kind {
continue;
}
let name = variant.fields[p.field].name;
write!(f, "{}{}: {}", start_or_comma(), name, p.pattern)?;
printed += 1;
}
let is_union = self.ty.ty_adt_def().is_some_and(|adt| adt.is_union());
if printed < variant.fields.len() && (!is_union || printed == 0) {
write!(f, "{}..", start_or_comma())?;
}
return write!(f, " }}");
}
}
let num_fields =
variant_and_name.as_ref().map_or(subpatterns.len(), |(v, _)| v.fields.len());
if num_fields != 0 || variant_and_name.is_none() {
write!(f, "(")?;
for i in 0..num_fields {
write!(f, "{}", start_or_comma())?;
// Common case: the field is where we expect it.
if let Some(p) = subpatterns.get(i) {
if p.field.index() == i {
write!(f, "{}", p.pattern)?;
continue;
}
}
// Otherwise, we have to go looking for it.
if let Some(p) = subpatterns.iter().find(|p| p.field.index() == i) {
write!(f, "{}", p.pattern)?;
} else {
write!(f, "_")?;
}
}
write!(f, ")")?;
}
Ok(())
}
PatKind::Deref { ref subpattern } => {
match self.ty.kind() {
ty::Adt(def, _) if def.is_box() => write!(f, "box ")?,
ty::Ref(_, _, mutbl) => {
write!(f, "&{}", mutbl.prefix_str())?;
}
_ => bug!("{} is a bad Deref pattern type", self.ty),
}
write!(f, "{subpattern}")
} }
PatKind::Deref { ref subpattern } => write_ref_like(f, self.ty, subpattern),
PatKind::Constant { value } => write!(f, "{value}"), PatKind::Constant { value } => write!(f, "{value}"),
PatKind::Range(ref range) => write!(f, "{range}"), PatKind::Range(ref range) => write!(f, "{range}"),
PatKind::Slice { ref prefix, ref slice, ref suffix } => { PatKind::Slice { ref prefix, ref slice, ref suffix } => {
write!(f, "[")?; write_slice_like(f, prefix, slice, suffix)
for p in prefix.iter() {
write!(f, "{}{}", start_or_comma(), p)?;
}
if let Some(ref slice) = *slice {
write!(f, "{}", start_or_comma())?;
match slice.kind {
PatKind::Wild => {}
_ => write!(f, "{slice}")?,
}
write!(f, "..")?;
}
for p in suffix.iter() {
write!(f, "{}{}", start_or_comma(), p)?;
}
write!(f, "]")
} }
} }
} }
} }
/// Returns a closure that will return `""` when called the first time,
/// and then return `", "` when called any subsequent times.
/// Useful for printing comma-separated lists.
fn start_or_comma() -> impl FnMut() -> &'static str {
let mut first = true;
move || {
if first {
first = false;
""
} else {
", "
}
}
}
fn write_struct_like<'tcx>(
f: &mut impl fmt::Write,
ty: Ty<'tcx>,
kind: &PatKind<'tcx>,
subpatterns: &[FieldPat<'tcx>],
) -> fmt::Result {
let variant_and_name = match *kind {
PatKind::Variant { adt_def, variant_index, .. } => ty::tls::with(|tcx| {
let variant = adt_def.variant(variant_index);
let adt_did = adt_def.did();
let name = if tcx.get_diagnostic_item(sym::Option) == Some(adt_did)
|| tcx.get_diagnostic_item(sym::Result) == Some(adt_did)
{
variant.name.to_string()
} else {
format!("{}::{}", tcx.def_path_str(adt_def.did()), variant.name)
};
Some((variant, name))
}),
_ => ty.ty_adt_def().and_then(|adt_def| {
if !adt_def.is_enum() {
ty::tls::with(|tcx| {
Some((adt_def.non_enum_variant(), tcx.def_path_str(adt_def.did())))
})
} else {
None
}
}),
};
let mut start_or_comma = start_or_comma();
if let Some((variant, name)) = &variant_and_name {
write!(f, "{name}")?;
// Only for Adt we can have `S {...}`,
// which we handle separately here.
if variant.ctor.is_none() {
write!(f, " {{ ")?;
let mut printed = 0;
for p in subpatterns {
if let PatKind::Wild = p.pattern.kind {
continue;
}
let name = variant.fields[p.field].name;
write!(f, "{}{}: {}", start_or_comma(), name, p.pattern)?;
printed += 1;
}
let is_union = ty.ty_adt_def().is_some_and(|adt| adt.is_union());
if printed < variant.fields.len() && (!is_union || printed == 0) {
write!(f, "{}..", start_or_comma())?;
}
return write!(f, " }}");
}
}
let num_fields = variant_and_name.as_ref().map_or(subpatterns.len(), |(v, _)| v.fields.len());
if num_fields != 0 || variant_and_name.is_none() {
write!(f, "(")?;
for i in 0..num_fields {
write!(f, "{}", start_or_comma())?;
// Common case: the field is where we expect it.
if let Some(p) = subpatterns.get(i) {
if p.field.index() == i {
write!(f, "{}", p.pattern)?;
continue;
}
}
// Otherwise, we have to go looking for it.
if let Some(p) = subpatterns.iter().find(|p| p.field.index() == i) {
write!(f, "{}", p.pattern)?;
} else {
write!(f, "_")?;
}
}
write!(f, ")")?;
}
Ok(())
}
fn write_ref_like<'tcx>(
f: &mut impl fmt::Write,
ty: Ty<'tcx>,
subpattern: &Pat<'tcx>,
) -> fmt::Result {
match ty.kind() {
ty::Adt(def, _) if def.is_box() => write!(f, "box ")?,
ty::Ref(_, _, mutbl) => {
write!(f, "&{}", mutbl.prefix_str())?;
}
_ => bug!("{ty} is a bad ref pattern type"),
}
write!(f, "{subpattern}")
}
fn write_slice_like<'tcx>(
f: &mut impl fmt::Write,
prefix: &[Box<Pat<'tcx>>],
slice: &Option<Box<Pat<'tcx>>>,
suffix: &[Box<Pat<'tcx>>],
) -> fmt::Result {
let mut start_or_comma = start_or_comma();
write!(f, "[")?;
for p in prefix.iter() {
write!(f, "{}{}", start_or_comma(), p)?;
}
if let Some(ref slice) = *slice {
write!(f, "{}", start_or_comma())?;
match slice.kind {
PatKind::Wild => {}
_ => write!(f, "{slice}")?,
}
write!(f, "..")?;
}
for p in suffix.iter() {
write!(f, "{}{}", start_or_comma(), p)?;
}
write!(f, "]")
}