/*** definition section ***/
%{
  /* C to be copied verbatim */
  #include "lexer.h"
  #include "node.h"
  void yyerror(Node **root, const char *msg);
%}

%code requires {
  #include "node.h"
}

%union {
  Node *node;
  int ival;
  char *sval;
};

%locations
%start input
%parse-param {Node **root}

%token L_PAREN R_PAREN L_BRACK R_BRACK SEMI_COL COMP MULT DIV MOD MINUS PLUS INT VOID RET
%token <sval> WORD
%token <ival> NUMBER

%type <node> input
%type <node> func
%type <node> stmt
%type <node> exp
%type <node> term
%type <node> factor
%type <ival> un_op


/*** rules section ***/
%%
input:   func {
    *root = create_node(PROG);
    add_child(*root, $1);
  }
;

func:   INT WORD L_PAREN VOID R_PAREN L_BRACK stmt R_BRACK {
    $$ = create_function($2);
    add_child($$, $7);
  }
;

stmt:   RET exp SEMI_COL {
    $$ = create_node(STMT);
    add_child($$, $2);
  }
;

exp:    term {
    $$ = $1;
  }
|       exp PLUS term {
    $$ = create_expr(PLUS_SYM);
    add_child($$, $1);
    add_child($$, $3);
  }
|       exp MINUS term {
    $$ = create_expr(MINUS_SYM);
    add_child($$, $1);
    add_child($$, $3);
  }
;

term:   factor {
    $$ = $1;
  }
|       term MULT factor {
    $$ = create_expr(MULT_SYM);
    add_child($$, $1);
    add_child($$, $3);
  }
|       term DIV factor {
    $$ = create_expr(DIV_SYM);
    add_child($$, $1);
    add_child($$, $3);
  }
|       term MOD factor {
    $$ = create_expr(MOD_SYM);
    add_child($$, $1);
    add_child($$, $3);
  }
;

factor: NUMBER {
    $$ = create_const($1);
  }
|       un_op factor {
    $$ = create_expr($1);
    add_child($$, $2);
  }
|       L_PAREN exp R_PAREN {
    $$ = $2;
  }
;

un_op:  COMP {
    $$ = COMP_SYM;
  }
|       MINUS {
    $$ = NEG_SYM;
  }
;

%%

void yyerror(Node **root, const char *msg) {
  printf("** Line %d: %s\n", yylineno, msg);
}