rename all things

1 files changed, 110 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/algo/visit.rs b/crates/ra_syntax/src/algo/visit.rs
new file mode 100644
index 000000000..9f1c127c7
--- /dev/null
+++ b/crates/ra_syntax/src/algo/visit.rs
@@ -0,0 +1,110 @@
+use std::marker::PhantomData;
+use {SyntaxNodeRef, AstNode};
+
+
+pub fn visitor<'a, T>() -> impl Visitor<'a, Output=T> {
+    EmptyVisitor { ph: PhantomData }
+}
+
+pub fn visitor_ctx<'a, T, C>(ctx: C) -> impl VisitorCtx<'a, Output=T, Ctx=C> {
+    EmptyVisitorCtx { ph: PhantomData, ctx }
+}
+
+pub trait Visitor<'a>: Sized {
+    type Output;
+    fn accept(self, node: SyntaxNodeRef<'a>) -> Option<Self::Output>;
+    fn visit<N, F>(self, f: F) -> Vis<Self, N, F>
+        where N: AstNode<'a>,
+              F: FnOnce(N) -> Self::Output,
+    {
+        Vis { inner: self, f, ph: PhantomData }
+    }
+}
+
+pub trait VisitorCtx<'a>: Sized {
+    type Output;
+    type Ctx;
+    fn accept(self, node: SyntaxNodeRef<'a>) -> Result<Self::Output, Self::Ctx>;
+    fn visit<N, F>(self, f: F) -> VisCtx<Self, N, F>
+        where N: AstNode<'a>,
+              F: FnOnce(N, Self::Ctx) -> Self::Output,
+    {
+        VisCtx { inner: self, f, ph: PhantomData }
+    }
+}
+
+#[derive(Debug)]
+struct EmptyVisitor<T> {
+    ph: PhantomData<fn() -> T>
+}
+
+impl<'a, T> Visitor<'a> for EmptyVisitor<T> {
+    type Output = T;
+
+    fn accept(self, _node: SyntaxNodeRef<'a>) -> Option<T> {
+        None
+    }
+}
+
+#[derive(Debug)]
+struct EmptyVisitorCtx<T, C> {
+    ctx: C,
+    ph: PhantomData<fn() -> T>,
+}
+
+impl<'a, T, C> VisitorCtx<'a> for EmptyVisitorCtx<T, C> {
+    type Output = T;
+    type Ctx = C;
+
+    fn accept(self, _node: SyntaxNodeRef<'a>) -> Result<T, C> {
+        Err(self.ctx)
+    }
+}
+
+#[derive(Debug)]
+pub struct Vis<V, N, F> {
+    inner: V,
+    f: F,
+    ph: PhantomData<fn(N)>,
+}
+
+impl<'a, V, N, F> Visitor<'a> for Vis<V, N, F>
+    where
+        V: Visitor<'a>,
+        N: AstNode<'a>,
+        F: FnOnce(N) -> <V as Visitor<'a>>::Output,
+{
+    type Output = <V as Visitor<'a>>::Output;
+
+    fn accept(self, node: SyntaxNodeRef<'a>) -> Option<Self::Output> {
+        let Vis { inner, f, .. } = self;
+        inner.accept(node).or_else(|| N::cast(node).map(f))
+    }
+}
+
+#[derive(Debug)]
+pub struct VisCtx<V, N, F> {
+    inner: V,
+    f: F,
+    ph: PhantomData<fn(N)>,
+}
+
+impl<'a, V, N, F> VisitorCtx<'a> for VisCtx<V, N, F>
+    where
+        V: VisitorCtx<'a>,
+        N: AstNode<'a>,
+        F: FnOnce(N, <V as VisitorCtx<'a>>::Ctx) -> <V as VisitorCtx<'a>>::Output,
+{
+    type Output = <V as VisitorCtx<'a>>::Output;
+    type Ctx = <V as VisitorCtx<'a>>::Ctx;
+
+    fn accept(self, node: SyntaxNodeRef<'a>) -> Result<Self::Output, Self::Ctx> {
+        let VisCtx { inner, f, .. } = self;
+        inner.accept(node).or_else(|ctx|
+            match N::cast(node) {
+                None => Err(ctx),
+                Some(node) => Ok(f(node, ctx))
+            }
+        )
+    }
+}