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-rw-r--r--third_party/rust/syn/src/gen_helper.rs154
1 files changed, 154 insertions, 0 deletions
diff --git a/third_party/rust/syn/src/gen_helper.rs b/third_party/rust/syn/src/gen_helper.rs
new file mode 100644
index 0000000000..b2796126a3
--- /dev/null
+++ b/third_party/rust/syn/src/gen_helper.rs
@@ -0,0 +1,154 @@
+#[cfg(feature = "fold")]
+pub mod fold {
+ use crate::fold::Fold;
+ use crate::punctuated::{Pair, Punctuated};
+ use proc_macro2::Span;
+
+ pub trait FoldHelper {
+ type Item;
+ fn lift<F>(self, f: F) -> Self
+ where
+ F: FnMut(Self::Item) -> Self::Item;
+ }
+
+ impl<T> FoldHelper for Vec<T> {
+ type Item = T;
+ fn lift<F>(self, f: F) -> Self
+ where
+ F: FnMut(Self::Item) -> Self::Item,
+ {
+ self.into_iter().map(f).collect()
+ }
+ }
+
+ impl<T, U> FoldHelper for Punctuated<T, U> {
+ type Item = T;
+ fn lift<F>(self, mut f: F) -> Self
+ where
+ F: FnMut(Self::Item) -> Self::Item,
+ {
+ self.into_pairs()
+ .map(Pair::into_tuple)
+ .map(|(t, u)| Pair::new(f(t), u))
+ .collect()
+ }
+ }
+
+ pub fn tokens_helper<F: Fold + ?Sized, S: Spans>(folder: &mut F, spans: &S) -> S {
+ spans.fold(folder)
+ }
+
+ pub trait Spans {
+ fn fold<F: Fold + ?Sized>(&self, folder: &mut F) -> Self;
+ }
+
+ impl Spans for Span {
+ fn fold<F: Fold + ?Sized>(&self, folder: &mut F) -> Self {
+ folder.fold_span(*self)
+ }
+ }
+
+ impl Spans for [Span; 1] {
+ fn fold<F: Fold + ?Sized>(&self, folder: &mut F) -> Self {
+ [folder.fold_span(self[0])]
+ }
+ }
+
+ impl Spans for [Span; 2] {
+ fn fold<F: Fold + ?Sized>(&self, folder: &mut F) -> Self {
+ [folder.fold_span(self[0]), folder.fold_span(self[1])]
+ }
+ }
+
+ impl Spans for [Span; 3] {
+ fn fold<F: Fold + ?Sized>(&self, folder: &mut F) -> Self {
+ [
+ folder.fold_span(self[0]),
+ folder.fold_span(self[1]),
+ folder.fold_span(self[2]),
+ ]
+ }
+ }
+}
+
+#[cfg(feature = "visit")]
+pub mod visit {
+ use crate::visit::Visit;
+ use proc_macro2::Span;
+
+ pub fn tokens_helper<'ast, V: Visit<'ast> + ?Sized, S: Spans>(visitor: &mut V, spans: &S) {
+ spans.visit(visitor);
+ }
+
+ pub trait Spans {
+ fn visit<'ast, V: Visit<'ast> + ?Sized>(&self, visitor: &mut V);
+ }
+
+ impl Spans for Span {
+ fn visit<'ast, V: Visit<'ast> + ?Sized>(&self, visitor: &mut V) {
+ visitor.visit_span(self);
+ }
+ }
+
+ impl Spans for [Span; 1] {
+ fn visit<'ast, V: Visit<'ast> + ?Sized>(&self, visitor: &mut V) {
+ visitor.visit_span(&self[0]);
+ }
+ }
+
+ impl Spans for [Span; 2] {
+ fn visit<'ast, V: Visit<'ast> + ?Sized>(&self, visitor: &mut V) {
+ visitor.visit_span(&self[0]);
+ visitor.visit_span(&self[1]);
+ }
+ }
+
+ impl Spans for [Span; 3] {
+ fn visit<'ast, V: Visit<'ast> + ?Sized>(&self, visitor: &mut V) {
+ visitor.visit_span(&self[0]);
+ visitor.visit_span(&self[1]);
+ visitor.visit_span(&self[2]);
+ }
+ }
+}
+
+#[cfg(feature = "visit-mut")]
+pub mod visit_mut {
+ use crate::visit_mut::VisitMut;
+ use proc_macro2::Span;
+
+ pub fn tokens_helper<V: VisitMut + ?Sized, S: Spans>(visitor: &mut V, spans: &mut S) {
+ spans.visit_mut(visitor);
+ }
+
+ pub trait Spans {
+ fn visit_mut<V: VisitMut + ?Sized>(&mut self, visitor: &mut V);
+ }
+
+ impl Spans for Span {
+ fn visit_mut<V: VisitMut + ?Sized>(&mut self, visitor: &mut V) {
+ visitor.visit_span_mut(self);
+ }
+ }
+
+ impl Spans for [Span; 1] {
+ fn visit_mut<V: VisitMut + ?Sized>(&mut self, visitor: &mut V) {
+ visitor.visit_span_mut(&mut self[0]);
+ }
+ }
+
+ impl Spans for [Span; 2] {
+ fn visit_mut<V: VisitMut + ?Sized>(&mut self, visitor: &mut V) {
+ visitor.visit_span_mut(&mut self[0]);
+ visitor.visit_span_mut(&mut self[1]);
+ }
+ }
+
+ impl Spans for [Span; 3] {
+ fn visit_mut<V: VisitMut + ?Sized>(&mut self, visitor: &mut V) {
+ visitor.visit_span_mut(&mut self[0]);
+ visitor.visit_span_mut(&mut self[1]);
+ visitor.visit_span_mut(&mut self[2]);
+ }
+ }
+}