Loop instead of recursion
This commit is contained in:
Dániel Buga
parent
a9cd294cf2
commit
f88d6e8437
@ -10,82 +10,90 @@ use rustc_span::symbol::Ident;
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use rustc_span::{source_map::Spanned, Span};
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impl<'a, 'hir> LoweringContext<'a, 'hir> {
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crate fn lower_pat(&mut self, p: &Pat) -> &'hir hir::Pat<'hir> {
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crate fn lower_pat(&mut self, mut pattern: &Pat) -> &'hir hir::Pat<'hir> {
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ensure_sufficient_stack(|| {
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let node = match p.kind {
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PatKind::Wild => hir::PatKind::Wild,
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PatKind::Ident(ref binding_mode, ident, ref sub) => {
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let lower_sub = |this: &mut Self| sub.as_ref().map(|s| this.lower_pat(&*s));
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let node = self.lower_pat_ident(p, binding_mode, ident, lower_sub);
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node
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}
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PatKind::Lit(ref e) => hir::PatKind::Lit(self.lower_expr(e)),
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PatKind::TupleStruct(ref path, ref pats) => {
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let qpath = self.lower_qpath(
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p.id,
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&None,
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path,
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ParamMode::Optional,
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ImplTraitContext::disallowed(),
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);
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let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple struct");
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hir::PatKind::TupleStruct(qpath, pats, ddpos)
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}
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PatKind::Or(ref pats) => hir::PatKind::Or(
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self.arena.alloc_from_iter(pats.iter().map(|x| self.lower_pat(x))),
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),
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PatKind::Path(ref qself, ref path) => {
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let qpath = self.lower_qpath(
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p.id,
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qself,
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path,
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ParamMode::Optional,
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ImplTraitContext::disallowed(),
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);
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hir::PatKind::Path(qpath)
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}
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PatKind::Struct(ref path, ref fields, etc) => {
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let qpath = self.lower_qpath(
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p.id,
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&None,
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path,
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ParamMode::Optional,
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ImplTraitContext::disallowed(),
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);
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// loop here to avoid recursion
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let node = loop {
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match pattern.kind {
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PatKind::Wild => break hir::PatKind::Wild,
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PatKind::Ident(ref binding_mode, ident, ref sub) => {
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let lower_sub = |this: &mut Self| sub.as_ref().map(|s| this.lower_pat(&*s));
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break self.lower_pat_ident(pattern, binding_mode, ident, lower_sub);
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}
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PatKind::Lit(ref e) => break hir::PatKind::Lit(self.lower_expr(e)),
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PatKind::TupleStruct(ref path, ref pats) => {
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let qpath = self.lower_qpath(
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pattern.id,
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&None,
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path,
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ParamMode::Optional,
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ImplTraitContext::disallowed(),
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);
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let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple struct");
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break hir::PatKind::TupleStruct(qpath, pats, ddpos);
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}
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PatKind::Or(ref pats) => {
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break hir::PatKind::Or(
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self.arena.alloc_from_iter(pats.iter().map(|x| self.lower_pat(x))),
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);
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}
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PatKind::Path(ref qself, ref path) => {
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let qpath = self.lower_qpath(
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pattern.id,
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qself,
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path,
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ParamMode::Optional,
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ImplTraitContext::disallowed(),
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);
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break hir::PatKind::Path(qpath);
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}
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PatKind::Struct(ref path, ref fields, etc) => {
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let qpath = self.lower_qpath(
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pattern.id,
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&None,
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path,
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ParamMode::Optional,
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ImplTraitContext::disallowed(),
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);
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let fs = self.arena.alloc_from_iter(fields.iter().map(|f| hir::FieldPat {
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hir_id: self.next_id(),
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ident: f.ident,
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pat: self.lower_pat(&f.pat),
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is_shorthand: f.is_shorthand,
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span: f.span,
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}));
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hir::PatKind::Struct(qpath, fs, etc)
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let fs = self.arena.alloc_from_iter(fields.iter().map(|f| hir::FieldPat {
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hir_id: self.next_id(),
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ident: f.ident,
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pat: self.lower_pat(&f.pat),
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is_shorthand: f.is_shorthand,
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span: f.span,
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}));
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break hir::PatKind::Struct(qpath, fs, etc);
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}
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PatKind::Tuple(ref pats) => {
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let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple");
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break hir::PatKind::Tuple(pats, ddpos);
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}
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PatKind::Box(ref inner) => {
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break hir::PatKind::Box(self.lower_pat(inner));
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}
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PatKind::Ref(ref inner, mutbl) => {
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break hir::PatKind::Ref(self.lower_pat(inner), mutbl);
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}
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PatKind::Range(ref e1, ref e2, Spanned { node: ref end, .. }) => {
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break hir::PatKind::Range(
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e1.as_deref().map(|e| self.lower_expr(e)),
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e2.as_deref().map(|e| self.lower_expr(e)),
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self.lower_range_end(end, e2.is_some()),
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);
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}
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PatKind::Slice(ref pats) => break self.lower_pat_slice(pats),
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PatKind::Rest => {
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// If we reach here the `..` pattern is not semantically allowed.
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break self.ban_illegal_rest_pat(pattern.span);
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}
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// return inner to be processed in next loop
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PatKind::Paren(ref inner) => pattern = inner,
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PatKind::MacCall(_) => panic!("{:?} shouldn't exist here", pattern.span),
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}
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PatKind::Tuple(ref pats) => {
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let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple");
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hir::PatKind::Tuple(pats, ddpos)
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}
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PatKind::Box(ref inner) => hir::PatKind::Box(self.lower_pat(inner)),
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PatKind::Ref(ref inner, mutbl) => hir::PatKind::Ref(self.lower_pat(inner), mutbl),
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PatKind::Range(ref e1, ref e2, Spanned { node: ref end, .. }) => {
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hir::PatKind::Range(
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e1.as_deref().map(|e| self.lower_expr(e)),
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e2.as_deref().map(|e| self.lower_expr(e)),
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self.lower_range_end(end, e2.is_some()),
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)
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}
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PatKind::Slice(ref pats) => self.lower_pat_slice(pats),
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PatKind::Rest => {
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// If we reach here the `..` pattern is not semantically allowed.
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self.ban_illegal_rest_pat(p.span)
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}
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// FIXME: consider not using recursion to lower this.
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PatKind::Paren(ref inner) => return self.lower_pat(inner),
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PatKind::MacCall(_) => panic!("{:?} shouldn't exist here", p.span),
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};
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self.pat_with_node_id_of(p, node)
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self.pat_with_node_id_of(pattern, node)
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})
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}
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