From 83d6b5243ee42018b8577972436f2e54602a4bf7 Mon Sep 17 00:00:00 2001
From: rvcas <x@rvcas.dev>
Date: Thu, 2 Jun 2022 21:39:09 -0400
Subject: [PATCH] feat: get program ready for debruijn

---
 crates/uplc/src/ast.rs    | 29 +++++++++++++++++++----------
 crates/uplc/src/flat.rs   | 31 +++++++++++++++++++++----------
 crates/uplc/src/parser.rs | 22 +++++++++++-----------
 3 files changed, 51 insertions(+), 31 deletions(-)

diff --git a/crates/uplc/src/ast.rs b/crates/uplc/src/ast.rs
index 6e90a927..db9b0c89 100644
--- a/crates/uplc/src/ast.rs
+++ b/crates/uplc/src/ast.rs
@@ -1,31 +1,31 @@
 use crate::builtins::DefaultFunction;
 
 #[derive(Debug, Clone, PartialEq)]
-pub struct Program {
+pub struct Program<T> {
     pub version: (usize, usize, usize),
-    pub term: Term,
+    pub term: Term<T>,
 }
 
 #[derive(Debug, Clone, PartialEq)]
-pub enum Term {
+pub enum Term<T> {
     // tag: 0
-    Var(Name),
+    Var(T),
     // tag: 1
-    Delay(Box<Term>),
+    Delay(Box<Term<T>>),
     // tag: 2
     Lambda {
-        parameter_name: Name,
-        body: Box<Term>,
+        parameter_name: T,
+        body: Box<Term<T>>,
     },
     // tag: 3
     Apply {
-        function: Box<Term>,
-        argument: Box<Term>,
+        function: Box<Term<T>>,
+        argument: Box<Term<T>>,
     },
     // tag: 4
     Constant(Constant),
     // tag: 5
-    Force(Box<Term>),
+    Force(Box<Term<T>>),
     // tag: 6
     Error,
     // tag: 7
@@ -53,3 +53,12 @@ pub struct Name {
     pub text: String,
     pub unique: isize,
 }
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct NamedDeBruijn {
+    pub text: String,
+    pub index: isize,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct DeBruijn(isize);
diff --git a/crates/uplc/src/flat.rs b/crates/uplc/src/flat.rs
index c76e818c..c3ce2780 100644
--- a/crates/uplc/src/flat.rs
+++ b/crates/uplc/src/flat.rs
@@ -15,9 +15,12 @@ const BUILTIN_TAG_WIDTH: u32 = 7;
 const CONST_TAG_WIDTH: u32 = 4;
 const TERM_TAG_WIDTH: u32 = 4;
 
-impl<'b> Flat<'b> for Program {}
+impl<'b, T> Flat<'b> for Program<T> where T: Encode + Decode<'b> {}
 
-impl Program {
+impl<'b, T> Program<T>
+where
+    T: Encode + Decode<'b>,
+{
     // convenient so that people don't need to depend on the flat crate
     // directly to call programs flat function
     pub fn to_flat(&self) -> anyhow::Result<Vec<u8>> {
@@ -33,7 +36,7 @@ impl Program {
     }
 }
 
-impl Encode for Program {
+impl<T: Encode> Encode for Program<T> {
     fn encode(&self, e: &mut Encoder) -> Result<(), String> {
         let (major, minor, patch) = self.version;
 
@@ -47,7 +50,10 @@ impl Encode for Program {
     }
 }
 
-impl<'b> Decode<'b> for Program {
+impl<'b, T> Decode<'b> for Program<T>
+where
+    T: Decode<'b>,
+{
     fn decode(d: &mut Decoder) -> Result<Self, String> {
         let version = (usize::decode(d)?, usize::decode(d)?, usize::decode(d)?);
         let term = Term::decode(d)?;
@@ -55,7 +61,7 @@ impl<'b> Decode<'b> for Program {
     }
 }
 
-impl Encode for Term {
+impl<T: Encode> Encode for Term<T> {
     fn encode(&self, e: &mut Encoder) -> Result<(), String> {
         match self {
             Term::Var(name) => {
@@ -104,13 +110,16 @@ impl Encode for Term {
     }
 }
 
-impl<'b> Decode<'b> for Term {
+impl<'b, T> Decode<'b> for Term<T>
+where
+    T: Decode<'b>,
+{
     fn decode(d: &mut Decoder) -> Result<Self, String> {
         match decode_term_tag(d)? {
-            0 => Ok(Term::Var(Name::decode(d)?)),
+            0 => Ok(Term::Var(T::decode(d)?)),
             1 => Ok(Term::Delay(Box::new(Term::decode(d)?))),
             2 => Ok(Term::Lambda {
-                parameter_name: Name::decode(d)?,
+                parameter_name: T::decode(d)?,
                 body: Box::new(Term::decode(d)?),
             }),
             3 => Ok(Term::Apply {
@@ -255,11 +264,13 @@ pub fn decode_constant_tag(d: &mut Decoder) -> Result<u8, String> {
 mod test {
     use flat::Flat;
 
+    use crate::ast::Name;
+
     use super::{Constant, Program, Term};
 
     #[test]
     fn flat_encode_integer() {
-        let program = Program {
+        let program = Program::<Name> {
             version: (11, 22, 33),
             term: Term::Constant(Constant::Integer(11)),
         };
@@ -283,7 +294,7 @@ mod test {
             term: Term::Constant(Constant::Integer(11)),
         };
 
-        let actual_program: Program = Program::unflat(&flat_encoded).unwrap();
+        let actual_program: Program<Name> = Program::unflat(&flat_encoded).unwrap();
 
         assert_eq!(actual_program, expected_program)
     }
diff --git a/crates/uplc/src/parser.rs b/crates/uplc/src/parser.rs
index 8c3b07b7..28468b57 100644
--- a/crates/uplc/src/parser.rs
+++ b/crates/uplc/src/parser.rs
@@ -43,7 +43,7 @@ impl ParserState {
     }
 }
 
-pub fn program(src: &str) -> anyhow::Result<Program> {
+pub fn program(src: &str) -> anyhow::Result<Program<Name>> {
     let mut parser = program_();
 
     let result = parser.parse(state::Stream {
@@ -57,7 +57,7 @@ pub fn program(src: &str) -> anyhow::Result<Program> {
     }
 }
 
-fn program_<Input>() -> impl Parser<StateStream<Input>, Output = Program>
+fn program_<Input>() -> impl Parser<StateStream<Input>, Output = Program<Name>>
 where
     Input: Stream<Token = char>,
     Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
@@ -93,7 +93,7 @@ where
         )
 }
 
-fn term<Input>() -> impl Parser<StateStream<Input>, Output = Term>
+fn term<Input>() -> impl Parser<StateStream<Input>, Output = Term<Name>>
 where
     Input: Stream<Token = char>,
     Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
@@ -109,7 +109,7 @@ where
     ))))
 }
 
-fn delay<Input>() -> impl Parser<StateStream<Input>, Output = Term>
+fn delay<Input>() -> impl Parser<StateStream<Input>, Output = Term<Name>>
 where
     Input: Stream<Token = char>,
     Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
@@ -124,7 +124,7 @@ where
     )
 }
 
-fn force<Input>() -> impl Parser<StateStream<Input>, Output = Term>
+fn force<Input>() -> impl Parser<StateStream<Input>, Output = Term<Name>>
 where
     Input: Stream<Token = char>,
     Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
@@ -139,7 +139,7 @@ where
     )
 }
 
-fn lambda<Input>() -> impl Parser<StateStream<Input>, Output = Term>
+fn lambda<Input>() -> impl Parser<StateStream<Input>, Output = Term<Name>>
 where
     Input: Stream<Token = char>,
     Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
@@ -151,7 +151,7 @@ where
             .with(skip_many1(space()))
             .with((many1(alpha_num()), skip_many1(space()), term()))
             .map_input(
-                |(parameter_name, _, term): (String, _, Term), input| Term::Lambda {
+                |(parameter_name, _, term): (String, _, Term<Name>), input| Term::Lambda {
                     parameter_name: Name {
                         unique: input.state.intern(&parameter_name),
                         text: parameter_name,
@@ -162,7 +162,7 @@ where
     )
 }
 
-fn apply<Input>() -> impl Parser<StateStream<Input>, Output = Term>
+fn apply<Input>() -> impl Parser<StateStream<Input>, Output = Term<Name>>
 where
     Input: Stream<Token = char>,
     Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
@@ -177,7 +177,7 @@ where
     )
 }
 
-fn builtin<Input>() -> impl Parser<StateStream<Input>, Output = Term>
+fn builtin<Input>() -> impl Parser<StateStream<Input>, Output = Term<Name>>
 where
     Input: Stream<Token = char>,
     Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
@@ -194,7 +194,7 @@ where
     )
 }
 
-fn error<Input>() -> impl Parser<StateStream<Input>, Output = Term>
+fn error<Input>() -> impl Parser<StateStream<Input>, Output = Term<Name>>
 where
     Input: Stream<Token = char>,
     Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
@@ -208,7 +208,7 @@ where
     )
 }
 
-fn constant<Input>() -> impl Parser<StateStream<Input>, Output = Term>
+fn constant<Input>() -> impl Parser<StateStream<Input>, Output = Term<Name>>
 where
     Input: Stream<Token = char>,
     Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,