Make parser create trees

tree.hpp

@@ -25,7 +25,26 @@ struct expr {
     virtual ~expr() = default;
 };
 
-typedef std::unique_ptr<expr> expr_ptr;
+typedef expr* expr_ptr;
+
+struct expr_id : expr {
+    std::string id;
+
+    expr_id(std::string i) :
+        id(std::move(i)) {}
+};
+
+struct expr_int : expr {
+    int val;
+
+    expr_int(int i) : val(i) {}
+};
+
+struct expr_float : expr {
+    double val;
+
+    expr_float(double f) : val(f) {}
+};
 
 struct expr_binop : expr {
     binop op;
@@ -61,7 +80,7 @@ struct stmt {
     virtual ~stmt() = default;
 };
 
-typedef std::unique_ptr<stmt> stmt_ptr;
+typedef stmt* stmt_ptr;
 
 struct stmt_block : stmt {
     std::vector<stmt_ptr> children;
@@ -80,14 +99,21 @@ struct stmt_while : stmt {
     expr_ptr cond;
     stmt_ptr body;
 
-    stmt_while(expr_ptr c, stmt_ptr b)
-        : cond(std::move(c)), body(std::move(b)) {}
+    stmt_while(expr_ptr c, stmt_ptr b) :
+        cond(std::move(c)), body(std::move(b)) {}
 };
 
 struct stmt_break : stmt {
 
 };
 
+struct stmt_expr : stmt {
+    expr_ptr child;
+
+    stmt_expr(expr_ptr c) :
+        child(std::move(c)) {}
+};
+
 template <typename T, typename ... Ts>
 stmt_ptr make_stmt(Ts&& ... ts) {
     return stmt_ptr(new T(std::move(ts)...));