chapter 8 done

src/parser/stmt.rs

@@ -0,0 +1,49 @@
+use std::fmt::Display;
+
+use super::Expr;
+
+pub enum Stmt {
+    ExprStmt { expr: Box<Expr> },
+    Print { expr: Box<Expr> },
+    VarDecl { name: String, initializer: Box<Expr> },
+    Block { statements: Vec<Stmt> },
+}
+
+impl Stmt {
+    pub fn expr_stmt(expr: Expr) -> Self {
+        let expr = Box::new(expr);
+        Stmt::ExprStmt { expr }
+    }
+
+    pub fn print_stmt(expr: Expr) -> Self {
+        let expr = Box::new(expr);
+        Stmt::Print { expr }
+    }
+
+    pub fn var_decl(name: String, initializer: Expr) -> Self {
+        let initializer = Box::new(initializer);
+        Stmt::VarDecl { name, initializer }
+    }
+}
+
+impl Display for Stmt {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Stmt::ExprStmt { expr } => write!(f, "{expr}"),
+            Stmt::Print { expr } => write!(f, "print {expr}"),
+            Stmt::VarDecl { name, initializer } => write!(f, "var {name} = {initializer}"),
+            Stmt::Block { statements } => {
+                writeln!(f, "{{")?;
+                for statement in statements {
+                    // for each statement: statement to string, split by lines, preprend each line with tab, print
+                    // return first error or, on success, "collect" the resulting () into a Vec (ZST, so no allocation)
+                    format!("{statement}")
+                        .split("\n")
+                        .map(|line| writeln!(f, "\t{line}"))
+                        .collect::<Result<Vec<()>, std::fmt::Error>>()?;
+                }
+                write!(f, "}}")
+            }
+        }
+    }
+}