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Break up print::Pat printing into several helper functions
This commit is contained in:
Zalathar
parent
6a2cd0d50c
commit
ccfd94e334
@ -64,130 +64,159 @@ pub(crate) enum PatKind<'tcx> {
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impl<'tcx> fmt::Display for Pat<'tcx> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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// Printing lists is a chore.
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let mut first = true;
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let mut start_or_continue = |s| {
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if first {
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first = false;
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""
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} else {
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s
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}
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};
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let mut start_or_comma = || start_or_continue(", ");
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match self.kind {
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PatKind::Wild => write!(f, "_"),
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PatKind::Never => write!(f, "!"),
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PatKind::Variant { ref subpatterns, .. } | PatKind::Leaf { ref subpatterns } => {
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let variant_and_name = match self.kind {
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PatKind::Variant { adt_def, variant_index, .. } => ty::tls::with(|tcx| {
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let variant = adt_def.variant(variant_index);
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let adt_did = adt_def.did();
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let name = if tcx.get_diagnostic_item(sym::Option) == Some(adt_did)
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|| tcx.get_diagnostic_item(sym::Result) == Some(adt_did)
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{
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variant.name.to_string()
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} else {
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format!("{}::{}", tcx.def_path_str(adt_def.did()), variant.name)
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};
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Some((variant, name))
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}),
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_ => self.ty.ty_adt_def().and_then(|adt_def| {
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if !adt_def.is_enum() {
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ty::tls::with(|tcx| {
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Some((adt_def.non_enum_variant(), tcx.def_path_str(adt_def.did())))
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})
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} else {
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None
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}
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}),
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};
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if let Some((variant, name)) = &variant_and_name {
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write!(f, "{name}")?;
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// Only for Adt we can have `S {...}`,
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// which we handle separately here.
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if variant.ctor.is_none() {
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write!(f, " {{ ")?;
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let mut printed = 0;
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for p in subpatterns {
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if let PatKind::Wild = p.pattern.kind {
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continue;
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}
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let name = variant.fields[p.field].name;
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write!(f, "{}{}: {}", start_or_comma(), name, p.pattern)?;
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printed += 1;
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}
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let is_union = self.ty.ty_adt_def().is_some_and(|adt| adt.is_union());
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if printed < variant.fields.len() && (!is_union || printed == 0) {
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write!(f, "{}..", start_or_comma())?;
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}
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return write!(f, " }}");
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}
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}
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let num_fields =
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variant_and_name.as_ref().map_or(subpatterns.len(), |(v, _)| v.fields.len());
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if num_fields != 0 || variant_and_name.is_none() {
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write!(f, "(")?;
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for i in 0..num_fields {
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write!(f, "{}", start_or_comma())?;
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// Common case: the field is where we expect it.
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if let Some(p) = subpatterns.get(i) {
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if p.field.index() == i {
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write!(f, "{}", p.pattern)?;
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continue;
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}
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}
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// Otherwise, we have to go looking for it.
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if let Some(p) = subpatterns.iter().find(|p| p.field.index() == i) {
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write!(f, "{}", p.pattern)?;
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} else {
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write!(f, "_")?;
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}
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}
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write!(f, ")")?;
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}
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Ok(())
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}
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PatKind::Deref { ref subpattern } => {
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match self.ty.kind() {
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ty::Adt(def, _) if def.is_box() => write!(f, "box ")?,
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ty::Ref(_, _, mutbl) => {
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write!(f, "&{}", mutbl.prefix_str())?;
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}
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_ => bug!("{} is a bad Deref pattern type", self.ty),
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}
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write!(f, "{subpattern}")
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write_struct_like(f, self.ty, &self.kind, subpatterns)
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}
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PatKind::Deref { ref subpattern } => write_ref_like(f, self.ty, subpattern),
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PatKind::Constant { value } => write!(f, "{value}"),
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PatKind::Range(ref range) => write!(f, "{range}"),
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PatKind::Slice { ref prefix, ref slice, ref suffix } => {
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write!(f, "[")?;
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for p in prefix.iter() {
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write!(f, "{}{}", start_or_comma(), p)?;
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}
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if let Some(ref slice) = *slice {
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write!(f, "{}", start_or_comma())?;
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match slice.kind {
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PatKind::Wild => {}
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_ => write!(f, "{slice}")?,
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}
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write!(f, "..")?;
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}
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for p in suffix.iter() {
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write!(f, "{}{}", start_or_comma(), p)?;
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}
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write!(f, "]")
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write_slice_like(f, prefix, slice, suffix)
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}
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}
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}
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}
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/// Returns a closure that will return `""` when called the first time,
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/// and then return `", "` when called any subsequent times.
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/// Useful for printing comma-separated lists.
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fn start_or_comma() -> impl FnMut() -> &'static str {
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let mut first = true;
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move || {
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if first {
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first = false;
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""
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} else {
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", "
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}
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}
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}
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fn write_struct_like<'tcx>(
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f: &mut impl fmt::Write,
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ty: Ty<'tcx>,
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kind: &PatKind<'tcx>,
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subpatterns: &[FieldPat<'tcx>],
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) -> fmt::Result {
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let variant_and_name = match *kind {
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PatKind::Variant { adt_def, variant_index, .. } => ty::tls::with(|tcx| {
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let variant = adt_def.variant(variant_index);
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let adt_did = adt_def.did();
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let name = if tcx.get_diagnostic_item(sym::Option) == Some(adt_did)
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|| tcx.get_diagnostic_item(sym::Result) == Some(adt_did)
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{
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variant.name.to_string()
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} else {
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format!("{}::{}", tcx.def_path_str(adt_def.did()), variant.name)
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};
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Some((variant, name))
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}),
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_ => ty.ty_adt_def().and_then(|adt_def| {
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if !adt_def.is_enum() {
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ty::tls::with(|tcx| {
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Some((adt_def.non_enum_variant(), tcx.def_path_str(adt_def.did())))
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})
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} else {
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None
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}
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}),
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};
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let mut start_or_comma = start_or_comma();
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if let Some((variant, name)) = &variant_and_name {
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write!(f, "{name}")?;
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// Only for Adt we can have `S {...}`,
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// which we handle separately here.
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if variant.ctor.is_none() {
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write!(f, " {{ ")?;
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let mut printed = 0;
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for p in subpatterns {
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if let PatKind::Wild = p.pattern.kind {
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continue;
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}
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let name = variant.fields[p.field].name;
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write!(f, "{}{}: {}", start_or_comma(), name, p.pattern)?;
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printed += 1;
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}
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let is_union = ty.ty_adt_def().is_some_and(|adt| adt.is_union());
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if printed < variant.fields.len() && (!is_union || printed == 0) {
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write!(f, "{}..", start_or_comma())?;
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}
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return write!(f, " }}");
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}
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}
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let num_fields = variant_and_name.as_ref().map_or(subpatterns.len(), |(v, _)| v.fields.len());
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if num_fields != 0 || variant_and_name.is_none() {
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write!(f, "(")?;
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for i in 0..num_fields {
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write!(f, "{}", start_or_comma())?;
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// Common case: the field is where we expect it.
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if let Some(p) = subpatterns.get(i) {
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if p.field.index() == i {
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write!(f, "{}", p.pattern)?;
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continue;
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}
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}
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// Otherwise, we have to go looking for it.
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if let Some(p) = subpatterns.iter().find(|p| p.field.index() == i) {
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write!(f, "{}", p.pattern)?;
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} else {
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write!(f, "_")?;
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}
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}
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write!(f, ")")?;
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}
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Ok(())
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}
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fn write_ref_like<'tcx>(
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f: &mut impl fmt::Write,
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ty: Ty<'tcx>,
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subpattern: &Pat<'tcx>,
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) -> fmt::Result {
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match ty.kind() {
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ty::Adt(def, _) if def.is_box() => write!(f, "box ")?,
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ty::Ref(_, _, mutbl) => {
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write!(f, "&{}", mutbl.prefix_str())?;
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}
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_ => bug!("{ty} is a bad ref pattern type"),
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}
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write!(f, "{subpattern}")
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}
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fn write_slice_like<'tcx>(
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f: &mut impl fmt::Write,
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prefix: &[Box<Pat<'tcx>>],
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slice: &Option<Box<Pat<'tcx>>>,
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suffix: &[Box<Pat<'tcx>>],
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) -> fmt::Result {
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let mut start_or_comma = start_or_comma();
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write!(f, "[")?;
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for p in prefix.iter() {
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write!(f, "{}{}", start_or_comma(), p)?;
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}
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if let Some(ref slice) = *slice {
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write!(f, "{}", start_or_comma())?;
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match slice.kind {
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PatKind::Wild => {}
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_ => write!(f, "{slice}")?,
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}
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write!(f, "..")?;
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}
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for p in suffix.iter() {
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write!(f, "{}{}", start_or_comma(), p)?;
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}
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write!(f, "]")
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}
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