3 files changed, 105 insertions, 0 deletions
diff --git a/src/ast/display.rs b/src/ast/display.rs
new file mode 100644
index 0000000..25b4d23
--- /dev/null
+++ b/src/ast/display.rs
@@ -0,0 +1,45 @@
+use std::fmt::Display;
+
+use super::{Expression, Statement, Value};
+
+impl<'a> Display for Statement<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{{")?;
+        let value = match self {
+            Statement::Val {
+                identifier,
+                initializer,
+            } => format!("val {} {}", identifier.lexeme, initializer),
+            Statement::Var {
+                identifier,
+                initializer,
+            } => format!("var {} {}", identifier.lexeme, initializer),
+            Statement::Expression { expr } => expr.to_string(),
+        };
+        write!(f, "{value}")?;
+        write!(f, "}}")?;
+
+        Ok(())
+    }
+}
+
+impl<'a> Display for Expression<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "(")?;
+        let value = match self {
+            Expression::Literal(value) => value.0.to_string(),
+            Expression::Unary { expr, .. } => format!("+ {}", expr),
+            Expression::Binary { lhs, rhs, .. } => format!("+ {lhs} {rhs}"),
+        };
+        write!(f, "{value}")?;
+        write!(f, ")")?;
+
+        Ok(())
+    }
+}
+
+impl Display for Value {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
diff --git a/src/ast/evaluate.rs b/src/ast/evaluate.rs
new file mode 100644
index 0000000..4d47994
--- /dev/null
+++ b/src/ast/evaluate.rs
@@ -0,0 +1,5 @@
+impl<'a> Expression<'a> {
+    fn evaluate() -> Value {
+        Value(5)
+    }
+}
diff --git a/src/ast/mod.rs b/src/ast/mod.rs
new file mode 100644
index 0000000..73e73b3
--- /dev/null
+++ b/src/ast/mod.rs
@@ -0,0 +1,55 @@
+#![allow(dead_code)]
+
+pub mod display;
+
+use crate::lexer::Token;
+
+#[derive(Clone)]
+pub enum Statement<'a> {
+    Val {
+        identifier: &'a Token<'a>,
+        initializer: &'a Expression<'a>,
+    },
+    Var {
+        identifier: &'a Token<'a>,
+        initializer: &'a Expression<'a>,
+    },
+    Expression {
+        expr: &'a Expression<'a>,
+    },
+}
+
+#[derive(Clone)]
+pub enum Expression<'a> {
+    // Basic
+    Literal(Value),
+    Unary {
+        operation: Operation,
+        expr: &'a Expression<'a>,
+    },
+    Binary {
+        operation: Operation,
+        lhs: &'a Expression<'a>,
+        rhs: &'a Expression<'a>,
+    },
+    // Grouping
+}
+
+#[derive(Clone)]
+pub enum Operation {
+    Add,
+    Subtract,
+}
+
+#[derive(Clone)]
+pub struct Value(pub i32);
+
+#[test]
+fn test() {
+    let right = Expression::Literal(Value(7));
+    let _ = Expression::Binary {
+        operation: Operation::Add,
+        lhs: &Expression::Literal(Value(5)),
+        rhs: &right,
+    };
+}