From 2e04bcdfc1c906ff7d2b0b264c13f1abead7f52d Mon Sep 17 00:00:00 2001
From: Dane Johnson <daneallenjohnson@protonmail.com>
Date: Mon, 31 Jan 2022 17:16:32 -0600
Subject: [PATCH] One line functions

---
 rust/src/parser.rs | 71 ++++++++++++++++++++++++++++++++--------------
 1 file changed, 49 insertions(+), 22 deletions(-)

diff --git a/rust/src/parser.rs b/rust/src/parser.rs
index f0eb719..8589845 100644
--- a/rust/src/parser.rs
+++ b/rust/src/parser.rs
@@ -1,34 +1,29 @@
 #[derive(Debug,PartialEq)]
 pub enum Stmt<'a> {
     Assignment(&'a str, Expr<'a>),
-    Funcall(Funcall<'a>),
+    Funcall(Expr<'a>),
 }
 
 #[derive(Debug,PartialEq)]
 pub enum Expr<'a> {
     Id(&'a str),
     Num(f64),
-    Funcall(Funcall<'a>),
+    Funcall(&'a str, Vec<Expr<'a>>),
+    Funcdef(Option<&'a str>, Vec<Stmt<'a>>),
     Plus(Box<Expr<'a>>, Box<Expr<'a>>),
     Minus(Box<Expr<'a>>, Box<Expr<'a>>),
     Mult(Box<Expr<'a>>, Box<Expr<'a>>),
     Div(Box<Expr<'a>>, Box<Expr<'a>>),
 }
 
-#[derive(Debug,PartialEq)]
-pub struct Funcall<'a> {
-    id: &'a str,
-    args: Vec<Expr<'a>>,
-}
-
 peg::parser! {
     grammar deelang_parser() for str {
 	pub rule program() -> Vec<Stmt<'input>>
-	    = __* s:stmt()* { s }
+	    = __*  s:stmt()* { s }
 	pub rule stmt() -> Stmt<'input>
 	    = i:id() "<-" _ e:expr() stop() { Stmt::Assignment(i, e) } /
 	    f:funcall() stop() { Stmt::Funcall(f) }
-	rule expr() -> Expr<'input> = precedence!{
+	rule expr() -> Expr<'input> = precedence! {
 	    e1:(@) "+" _ e2:@ { Expr::Plus(Box::new(e1), Box::new(e2)) }
 	    e1:(@) "-" _ e2:@ { Expr::Minus(Box::new(e1), Box::new(e2)) }
 	    --
@@ -36,7 +31,8 @@ peg::parser! {
 	    e1:(@) "/" _ e2:@ { Expr::Div(Box::new(e1), Box::new(e2)) }
 	    --
             "(" _ e:expr() ")" _ { e } 
-	    f:funcall() _ { Expr::Funcall(f) }
+	    f:funcall() _ { f }
+	    i:id()? "->" _ s:stmt() { Expr::Funcdef(i, vec![s]) }
 	    i:id() _ { Expr::Id(i) }
 	    n:num() _ { Expr::Num(n) }
 	}
@@ -45,8 +41,8 @@ peg::parser! {
 	    = i:$(letter() (letter() / digit() / ['?'|'.'|'-'])*) _ { i }
 	rule num() -> f64
 	    = n:$(digit()+ "."? digit()* / "." digit()+) _ { n.parse().unwrap() }
-	rule funcall() -> Funcall<'input>
-	    = i:id() "(" _ e:(expr() ** ("," _)) ")" _ { Funcall{id: i, args: e} }
+	rule funcall() -> Expr<'input>
+	    = i:id() "(" _ e:(expr() ** ("," _)) ")" _ { Expr::Funcall(i, e) }
 	
 	rule letter()
 	    = ['A'..='Z'] / ['a'..='z']
@@ -84,11 +80,10 @@ apple <- 1 ## This is too
     #[test]
     fn test_funcall() {
 	let expected = vec![
-	    Stmt::Funcall(Funcall{id: "pear", args: vec![]}),
- 	    Stmt::Funcall(Funcall {
- 		id: "pear",
- 		args: vec![Expr::Id("x"), Expr::Id("y")],
- 	    })
+	    Stmt::Funcall(Expr::Funcall("pear", vec![])),
+ 	    Stmt::Funcall(Expr::Funcall("pear",
+ 					vec![Expr::Id("x"), Expr::Id("y")],
+ 	    ))
 	];
 	let prgm = r"pear()
 pear(x, y)";
@@ -103,12 +98,11 @@ apple <- pear(x, y)";
 	    Stmt::Assignment("apple",
 				  Expr::Num(1.0)),
 	    Stmt::Assignment("apple",
-				  Expr::Funcall(Funcall {
-				      id: "pear",
-				      args: vec![
+				  Expr::Funcall("pear",
+				      vec![
 					  Expr::Id("x"),
 					  Expr::Id("y"),
-				      ]})),
+				      ])),
 	];
 	assert_eq!(deelang_parser::program(prgm).unwrap(), expected);
     }
@@ -140,4 +134,37 @@ four <- (3 - 1) * 2";
 	];
 	assert_eq!(deelang_parser::program(prgm).unwrap(), expected);
     }
+
+    #[test]
+    fn test_compound_expression() {
+	let prgm = "apple <- pear(x, y) + z";
+	let expected = vec![
+	    Stmt::Assignment("apple",
+			     Expr::Plus(
+				 Box::new(Expr::Funcall(
+				     "pear",
+				     vec![Expr::Id("x"), Expr::Id("y")],
+				 )),
+				 Box::new(Expr::Id("z"))
+			     )
+	    ),
+	];
+	assert_eq!(deelang_parser::program(prgm).unwrap(), expected);
+    }
+
+    #[test]
+    fn test_funcdef() {
+	let prgm = r"foo <- -> bar()";
+	let expected = vec![
+	    Stmt::Assignment("foo",
+			     Expr::Funcdef(
+				 None,
+				 vec![
+				     Stmt::Funcall(Expr::Funcall("bar", vec![])),
+				 ])
+			     )
+	];
+
+	assert_eq!(deelang_parser::program(prgm).unwrap(), expected);
+    }
 }