/*
 * Start symbol
 */

LANGUAGE_DIRECTIVE: "#declare" "identifier" "=" RVALUE {
                    dmnsn_declare_symbol(symtable, $2, $4);
                    free($2);
                    dmnsn_delete_astnode($4);
                  }
                  | "#local" "identifier" "=" RVALUE {
                    dmnsn_local_symbol(symtable, $2, $4);
                    free($2);
                    dmnsn_delete_astnode($4);
                  }
                  | "#undef" "identifier" {
                    dmnsn_undef_symbol(symtable, $2);
                    free($2);
                  }
                  | "#if" "(" CONDITIONAL ")" {
                    dmnsn_astnode cond = dmnsn_eval($3, symtable);
                    dmnsn_delete_astnode($3);

                    if (cond.type == DMNSN_AST_NONE) {
                      dmnsn_delete_astnode(cond);
                      YYERROR;
                    }

                    dmnsn_local_symbol(symtable, "__cond__", cond);
                    dmnsn_delete_astnode(cond);
                  }

RVALUE: ARITH_EXPR ";" %dprec 2 {
        $$ = dmnsn_eval($1, symtable);
        dmnsn_delete_astnode($1);

        if ($$.type == DMNSN_AST_NONE) {
          dmnsn_delete_astnode($$);
          YYERROR;
        }
      }
      | COLOR ";" %dprec 1
      | OBJECT
      | TEXTURE
      | PIGMENT
      | FINISH
      | CAMERA
      | TRANSFORMATION

CONDITIONAL: ARITH_EXPR {
             /* Force the expression to be evaluated logically */
             dmnsn_astnode zero = dmnsn_new_astnode(DMNSN_AST_INTEGER, @$);
             zero.ptr = malloc(sizeof(long));
             if (!zero.ptr)
               dmnsn_error(DMNSN_SEVERITY_HIGH,
                           "Failed to allocate room for integer.");
             *(long *)zero.ptr = 0;

             $$ = dmnsn_new_astnode2(DMNSN_AST_OR, @$, zero, $1);
           }
           | ARITH_EXPR "="  ARITH_EXPR {
             $$ = dmnsn_new_astnode2(DMNSN_AST_EQUAL, @$, $1, $3);
           }
           | ARITH_EXPR "!=" ARITH_EXPR {
             $$ = dmnsn_new_astnode2(DMNSN_AST_NOT_EQUAL, @$, $1, $3);
           }
           | ARITH_EXPR "<"  ARITH_EXPR {
             $$ = dmnsn_new_astnode2(DMNSN_AST_LESS, @$, $1, $3);
           }
           | ARITH_EXPR "<=" ARITH_EXPR {
             $$ = dmnsn_new_astnode2(DMNSN_AST_LESS_EQUAL, @$, $1, $3);
           }
           | ARITH_EXPR ">"  ARITH_EXPR {
             $$ = dmnsn_new_astnode2(DMNSN_AST_GREATER, @$, $1, $3);
           }
           | ARITH_EXPR ">=" ARITH_EXPR {
             $$ = dmnsn_new_astnode2(DMNSN_AST_GREATER_EQUAL, @$, $1, $3);
           }
           | CONDITIONAL "&" CONDITIONAL {
             $$ = dmnsn_new_astnode2(DMNSN_AST_AND, @$, $1, $3);
           }
           | CONDITIONAL "|" CONDITIONAL {
             $$ = dmnsn_new_astnode2(DMNSN_AST_OR, @$, $1, $3);
           }
           | "(" CONDITIONAL ")" {
             $$ = $2;
           }