ast: add a naive ast for now

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

src/ast.rs

@@ -0,0 +1,88 @@
+/// A very naive AST definition using recursive enums
+/// See the parser for implementation
+use std::rc::Rc;
+
+/// Primitives
+///
+/// TODO: add arrays and pointers maybe
+#[derive(Debug)]
+pub enum Type {
+    Int,
+    Float,
+    Char,
+}
+
+pub type Parent = Vec<Entity>;
+
+/// Entities are functions, classes, and modules
+#[derive(Debug)]
+pub enum Entity {
+    Fn(Fn),
+    Class(Class),
+    Module(Module),
+}
+
+#[derive(Debug)]
+pub struct Module {
+    pub name: Rc<str>,
+    pub children: Vec<ModuleChildren>,
+}
+
+/// Modules contain functions, classes and statements
+#[derive(Debug)]
+pub enum ModuleChildren {
+    Fn(Fn),
+    Class(Class),
+    Statement(Statement),
+}
+
+#[derive(Debug)]
+pub struct Class {
+    pub name: Rc<str>,
+    pub children: Vec<ClassChildren>,
+}
+
+/// Classes contain functions and statements.
+///
+/// TODO: Maybe change statements to something else
+#[derive(Debug)]
+pub enum ClassChildren {
+    Fn(Fn),
+    Statement(Statement),
+}
+
+#[derive(Debug)]
+pub struct Fn {
+    pub name: Rc<str>,
+    pub return_typ: Option<Type>,
+    pub params: Vec<Rc<str>>,
+    pub block: Vec<Statement>,
+}
+
+#[derive(Debug)]
+pub enum Statement {
+    Let(Let),
+    Expr(Expr),
+    Block(Vec<Statement>),
+}
+
+#[derive(Debug)]
+pub struct Let {
+    pub name: Rc<str>,
+    pub typ: Type,
+    pub expr: Option<Expr>,
+}
+
+type Op = crate::lexer::TokenSymbol;
+
+#[derive(Debug)]
+pub enum Expr {
+    Int(i32),
+    Float(f32),
+    Char(char),
+    Op(Op, Box<Expr>, Option<Box<Expr>>),
+    If(Box<Expr>, Box<Expr>, Option<Box<Expr>>),
+    Loop,
+    Break,
+    Continue,
+}