c-repl/src/include/parser.h

#ifndef DEF_PARSER_H
#define DEF_PARSER_H

#include <vector>
#include "tokenize.h"
using namespace std;

/** Grammar:
Prog -> Instruction; Prog | \epsilon

Instruction -> Statement | ExprStatement | Expr

Statement -> // Rien pour l'instant, mais "for", "if" etc
ExprStatement -> 
    | Type Identifier = Expr // AssignedDeclaration
    | Type Identifier // Declaration


Expr ->
    | T
    | T + Expr
    | T - Expr

T ->
    | F
    | F * T
    | F / T
    | F % T

U ->
    | F
    | - U
    | + U

F ->
    | (Expr)
    | Identifier
    | Number
    | Identifier = Expr // Assignment
*/

enum class NodeType {
    Prog, //                  -> Instruction; Prog
    AssignedDeclaration, //   -> Type Identifier = Expr
    Declaration, //           -> Type Identifier
    Plus, //                  -> T + Expr
    Minus, //                 -> T - Expr
    Mult, //                  -> F * T
    Div, //                   -> F / T
    Mod, //                   -> F % T
    UnaryMinus, //            -> -F
    UnaryPlus, //             -> +F
    Parenthesis, //           -> (Expr)
    Assignment //             -> Identifier = Expr
};

struct Node;
struct InnerNode {
    NodeType type;
    vector<Node> children;
};


// A Leaf is always corresponding to a Token
struct Node {
    bool is_leaf;
    union {
        InnerNode node;
        Token leaf;
    };

    Node() : is_leaf(true), leaf{} {}

    // Explicitly define the destructor
    ~Node() {
        if (!is_leaf) node.~InnerNode();
    }
};


#endif