Add tree structure code

tree.hpp

@@ -0,0 +1,94 @@
+#pragma once
+#include <memory>
+#include <vector>
+
+enum class binop {
+    plus,
+    minus,
+    times,
+    divide,
+    land,
+    lor,
+    eq,
+    neq,
+    lt,
+    lte,
+    gt,
+    gte
+};
+
+enum class unop {
+    lnot
+};
+
+struct expr {
+    virtual ~expr() = default;
+};
+
+typedef std::unique_ptr<expr> expr_ptr;
+
+struct expr_binop : expr {
+    binop op;
+    expr_ptr left;
+    expr_ptr right;
+
+    expr_binop(binop nop, expr_ptr l, expr_ptr r) :
+        op(nop), left(std::move(l)), right(std::move(r)) {}
+};
+
+struct expr_unop : expr {
+    unop op;
+    expr_ptr child;
+
+    expr_unop(unop nop, expr_ptr c) :
+        op(nop), child(std::move(c)) {}
+};
+
+struct expr_assign : expr {
+    std::string var;
+    expr_ptr child;
+
+    expr_assign(std::string v, expr_ptr c) :
+        var(std::move(v)), child(std::move(c)) {}
+};
+
+template <typename T, typename ... Ts>
+expr_ptr make_expr(Ts&& ... ts) {
+    return expr_ptr(new T(std::move(ts)...));
+}
+
+struct stmt {
+    virtual ~stmt() = default;
+};
+
+typedef std::unique_ptr<stmt> stmt_ptr;
+
+struct stmt_block : stmt {
+    std::vector<stmt_ptr> children;
+};
+
+struct stmt_if : stmt {
+    expr_ptr cond;
+    stmt_ptr then;
+    stmt_ptr els;
+
+    stmt_if(expr_ptr c, stmt_ptr t, stmt_ptr e = nullptr) :
+        cond(std::move(c)), then(std::move(t)), els(std::move(e)) {}
+};
+
+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)) {}
+};
+
+struct stmt_break : stmt {
+
+};
+
+template <typename T, typename ... Ts>
+stmt_ptr make_stmt(Ts&& ... ts) {
+    return stmt_ptr(new T(std::move(ts)...));
+}