Allow exprs+bindings to optionally be ascripted

1 files changed, 104 insertions, 0 deletions

diff --git a/src/parser/type_.rs b/src/parser/type_.rs
new file mode 100644
index 0000000000..076df7d6bd
--- /dev/null
+++ b/src/parser/type_.rs
@@ -0,0 +1,104 @@
+use nom::character::complete::{multispace0, multispace1};
+use nom::{alt, delimited, do_parse, map, named, opt, separated_list0, tag, terminated, tuple};
+
+use crate::ast::{FunctionType, Type};
+
+named!(function_type(&str) -> Type, do_parse!(
+    tag!("fn")
+        >> multispace1
+        >> args: map!(opt!(terminated!(separated_list0!(
+            tuple!(
+                multispace0,
+                tag!(","),
+                multispace0
+            ),
+            type_
+        ), multispace1)), |args| args.unwrap_or_default())
+        >> tag!("->")
+        >> multispace1
+        >> ret: type_
+        >> (Type::Function(FunctionType {
+            args,
+            ret: Box::new(ret)
+        }))
+));
+
+named!(pub type_(&str) -> Type, alt!(
+    tag!("int") => { |_| Type::Int } |
+    tag!("float") => { |_| Type::Float } |
+    tag!("bool") => { |_| Type::Bool } |
+    function_type |
+    delimited!(
+        tuple!(tag!("("), multispace0),
+        type_,
+        tuple!(tag!(")"), multispace0)
+    )
+));
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn simple_types() {
+        assert_eq!(test_parse!(type_, "int"), Type::Int);
+        assert_eq!(test_parse!(type_, "float"), Type::Float);
+        assert_eq!(test_parse!(type_, "bool"), Type::Bool);
+    }
+
+    #[test]
+    fn no_arg_fn_type() {
+        assert_eq!(
+            test_parse!(type_, "fn -> int"),
+            Type::Function(FunctionType {
+                args: vec![],
+                ret: Box::new(Type::Int)
+            })
+        );
+    }
+
+    #[test]
+    fn fn_type_with_args() {
+        assert_eq!(
+            test_parse!(type_, "fn int, bool -> int"),
+            Type::Function(FunctionType {
+                args: vec![Type::Int, Type::Bool],
+                ret: Box::new(Type::Int)
+            })
+        );
+    }
+
+    #[test]
+    fn fn_taking_fn() {
+        assert_eq!(
+            test_parse!(type_, "fn fn int, bool -> bool, float -> float"),
+            Type::Function(FunctionType {
+                args: vec![
+                    Type::Function(FunctionType {
+                        args: vec![Type::Int, Type::Bool],
+                        ret: Box::new(Type::Bool)
+                    }),
+                    Type::Float
+                ],
+                ret: Box::new(Type::Float)
+            })
+        )
+    }
+
+    #[test]
+    fn parenthesized() {
+        assert_eq!(
+            test_parse!(type_, "fn (fn int, bool -> bool), float -> float"),
+            Type::Function(FunctionType {
+                args: vec![
+                    Type::Function(FunctionType {
+                        args: vec![Type::Int, Type::Bool],
+                        ret: Box::new(Type::Bool)
+                    }),
+                    Type::Float
+                ],
+                ret: Box::new(Type::Float)
+            })
+        )
+    }
+}