typedef enum { PLUS, MINUS, DIV, MULT }binop;
typedef enum { EQUAL, DIF, LESS, GT, LE, GE }relop;

typedef struct _Instr Instr;

struct _Instr {
  enum { ATOM_VAR, ATOM_NUMBER, BINOP, GOTO, IF_CONDITION, LABEL }kind;
  union {
    char *var;
    int number;
    struct {
      struct _Expr *left;
      struct _Expr *right;
      binop oper;
    }op;
    char *label;
    union {
      relop bool_oper;
      struct _Expr *if_condition;
      char *if_label;
      char *else_label;
    }if_else;
  }attr;
};

Instr *int_instr(int n);
Instr *char_instr(char *v);
Instr *mkBinop(binop o);
Instr *binop_instr(binop op, Expr *l, Expr *r);
Instr *goto_instr(char *g);
Instr *if_instr(relop op, Expr *a, char *l1, char *l2);
Instr *label_instr(char *l);
char *newVar();
char *newLabel();

typedef struct _InstrList InstrList;

struct _InstrList {
  Instr *instr;
  InstrList *next;
};

InstrList *mkIList(Instr *i, InstrList *n);
Instr *getFirst(InstrList *l);
InstrList *nextInstrs(InstrList *n);
InstrList *append(InstrList *l1, InstrList *l2);
InstrList *compileExp(Expr *e, char *r);
InstrList *compileBool(ExprBool *e, char *labelTrue, char *labelFalse);
InstrList *compileCmd(Cmd *c);

void printInstr(Instr *i);
void printListInstrs(InstrList *l);