feat(lexer): Add diagnostic and impl error recovering

src/ast/types.rs

@@ -0,0 +1,75 @@
+#[derive(Debug, Clone, Copy)]
+pub struct Span {
+    start: usize,
+    end: usize,
+}
+pub struct CompileUnit {
+    pub global_decls: Vec<GlobalDeclStmt>,
+}
+pub enum GlobalDeclStmt {
+    VarDecl(VarDeclStmt),
+    FuncDecl(FuncDeclStmt),
+}
+
+pub struct VarDeclStmt {
+    pub name: String,
+    pub var_type: Type,
+    pub span: Span,
+}
+
+pub struct FuncDeclStmt {
+    pub name: String,
+    pub return_type: Type,
+    pub params: Vec<Param>,
+    pub body: BlockStmt,
+    pub span: Span,
+}
+pub struct BlockStmt {
+    pub statements: Vec<Statement>,
+    pub span: Span,
+}
+
+pub enum Statement {
+    Return(ReturnStmt),
+    Block(BlockStmt),
+    Expr(Expr),
+    VarDecl(VarDeclStmt),
+}
+pub struct ReturnStmt {
+    pub value: Option<Expr>,
+    pub span: Span,
+}
+pub struct Expr {
+    pub value: ExprValue,
+    pub span: Span,
+}
+pub enum ExprValue {
+    IntLit(i64),
+    Var(String),
+    BinaryOp {
+        lhs: Box<Expr>, 
+        op: BinaryOp, 
+        rhs: Box<Expr>
+    },
+    FuncCall(String, Vec<Expr>),
+    Assign {
+        lvalue: Box<Expr>, 
+        rvalue: Box<Expr>
+    },
+}
+
+pub enum BinaryOp {
+    Add, Sub, Mul, Div, Mod,
+    Equal, NotEqual, Less, LessEqual, Greater, GreaterEqual,
+}
+
+pub enum Type {
+    Int,
+    Void,
+}
+
+pub struct Param {
+    name: String,
+    param_type: Type,
+    span: Span,
+}