1 files changed, 136 insertions, 0 deletions
diff --git a/src/chomp/visit.rs b/src/chomp/visit.rs
new file mode 100644
index 0000000..4113b64
--- /dev/null
+++ b/src/chomp/visit.rs
@@ -0,0 +1,136 @@
+use super::ast::{Alt, Call, Cat, Epsilon, Expression, Fix, Literal, Parameter, Variable};
+
+pub trait Visitor {
+    type Out;
+    fn visit_epsilon(&mut self, eps: &Epsilon) -> Self::Out;
+
+    fn visit_literal(&mut self, lit: &Literal) -> Self::Out;
+
+    fn visit_cat(&mut self, cat: &Cat) -> Self::Out;
+
+    fn visit_alt(&mut self, alt: &Alt) -> Self::Out;
+
+    fn visit_fix(&mut self, fix: &Fix) -> Self::Out;
+
+    fn visit_variable(&mut self, var: &Variable) -> Self::Out;
+
+    fn visit_parameter(&mut self, param: &Parameter) -> Self::Out;
+
+    fn visit_call(&mut self, call: &Call) -> Self::Out;
+}
+
+pub trait Mapper {
+    type Out;
+
+    fn map_epsilon(&mut self, eps: &mut Epsilon) -> Self::Out;
+
+    fn map_literal(&mut self, lit: &mut Literal) -> Self::Out;
+
+    fn map_cat(&mut self, cat: &mut Cat) -> Self::Out;
+
+    fn map_alt(&mut self, alt: &mut Alt) -> Self::Out;
+
+    fn map_fix(&mut self, fix: &mut Fix) -> Self::Out;
+
+    fn map_variable(&mut self, var: &mut Variable) -> Self::Out;
+
+    fn map_parameter(&mut self, param: &mut Parameter) -> Self::Out;
+
+    fn map_call(&mut self, call: &mut Call) -> Self::Out;
+}
+
+pub trait Folder {
+    type Out;
+
+    fn fold_epsilon(&mut self, eps: Epsilon) -> Self::Out;
+
+    fn fold_literal(&mut self, lit: Literal) -> Self::Out;
+
+    fn fold_cat(&mut self, cat: Cat) -> Self::Out;
+
+    fn fold_alt(&mut self, alt: Alt) -> Self::Out;
+
+    fn fold_fix(&mut self, fix: Fix) -> Self::Out;
+
+    fn fold_variable(&mut self, var: Variable) -> Self::Out;
+
+    fn fold_parameter(&mut self, param: Parameter) -> Self::Out;
+
+    fn fold_call(&mut self, call: Call) -> Self::Out;
+}
+
+pub trait Visitable {
+    fn visit<V: Visitor>(&self, visitor: &mut V) -> <V as Visitor>::Out;
+
+    fn map<M: Mapper>(&mut self, mapper: &mut M) -> <M as Mapper>::Out;
+
+    fn fold<F: Folder>(self, folder: &mut F) -> <F as Folder>::Out;
+}
+
+macro_rules! visitable_leaf {
+    ($ty:ty, $visit:ident, $map:ident, $fold:ident) => {
+        impl Visitable for $ty {
+            fn visit<V: Visitor>(&self, visitor: &mut V) -> <V as Visitor>::Out {
+                visitor.$visit(self)
+            }
+
+            fn map<M: Mapper>(&mut self, mapper: &mut M) -> <M as Mapper>::Out {
+                mapper.$map(self)
+            }
+
+            fn fold<F: Folder>(self, folder: &mut F) -> <F as Folder>::Out {
+                folder.$fold(self)
+            }
+        }
+    };
+}
+
+visitable_leaf!(Epsilon, visit_epsilon, map_epsilon, fold_epsilon);
+visitable_leaf!(Literal, visit_literal, map_literal, fold_literal);
+visitable_leaf!(Cat, visit_cat, map_cat, fold_cat);
+visitable_leaf!(Alt, visit_alt, map_alt, fold_alt);
+visitable_leaf!(Fix, visit_fix, map_fix, fold_fix);
+visitable_leaf!(Variable, visit_variable, map_variable, fold_variable);
+visitable_leaf!(Parameter, visit_parameter, map_parameter, fold_parameter);
+visitable_leaf!(Call, visit_call, map_call, fold_call);
+
+impl Visitable for Expression {
+    fn visit<V: Visitor>(&self, visitor: &mut V) -> <V as Visitor>::Out {
+        match self {
+            Self::Epsilon(e) => visitor.visit_epsilon(e),
+            Self::Literal(l) => visitor.visit_literal(l),
+            Self::Cat(c) => visitor.visit_cat(c),
+            Self::Alt(a) => visitor.visit_alt(a),
+            Self::Fix(f) => visitor.visit_fix(f),
+            Self::Variable(v) => visitor.visit_variable(v),
+            Self::Parameter(p) => visitor.visit_parameter(p),
+            Self::Call(c) => visitor.visit_call(c),
+        }
+    }
+
+    fn map<M: Mapper>(&mut self, mapper: &mut M) -> <M as Mapper>::Out {
+        match self {
+            Self::Epsilon(e) => mapper.map_epsilon(e),
+            Self::Literal(l) => mapper.map_literal(l),
+            Self::Cat(c) => mapper.map_cat(c),
+            Self::Alt(a) => mapper.map_alt(a),
+            Self::Fix(f) => mapper.map_fix(f),
+            Self::Variable(v) => mapper.map_variable(v),
+            Self::Parameter(p) => mapper.map_parameter(p),
+            Self::Call(c) => mapper.map_call(c),
+        }
+    }
+
+    fn fold<F: Folder>(self, folder: &mut F) -> <F as Folder>::Out {
+        match self {
+            Self::Epsilon(e) => folder.fold_epsilon(e),
+            Self::Literal(l) => folder.fold_literal(l),
+            Self::Cat(c) => folder.fold_cat(c),
+            Self::Alt(a) => folder.fold_alt(a),
+            Self::Fix(f) => folder.fold_fix(f),
+            Self::Variable(v) => folder.fold_variable(v),
+            Self::Parameter(p) => folder.fold_parameter(p),
+            Self::Call(c) => folder.fold_call(c),
+        }
+    }
+}