static struct node_t *comp_expr(struct c_desc *cd)
{
int tok,opr;
struct node_t *p,*q;
p = term_expr(cd);
/* don't do while, see syntax. */
if(S_LESS <= cd->op && cd->op <= S_MORE) {
tok = cd->op;
get_sym(cd);
q = term_expr(cd);
switch(tok) {
case S_LESS: opr = O_LESS; break;
case S_LESSEQ: opr = O_LESSEQ; break;
case S_EQ: opr = O_EQ; break;
case S_MOREEQ: opr = O_MOREEQ; break;
case S_MORE: opr = O_MORE; break;
default: opr = O_ERR; break; /* impossible */
}
p = new_node_t(opr,p,q);
}
return p;
}
static struct ast_node*
exp_expr(void)
{
struct ast_node *node;
struct ast_node *rest_node;
node = term_expr();
if (node == NULL)
return NULL;
rest_node = rest_exp(node);
return rest_node;
}
static struct ast_node*
rest_exp(struct ast_node *node)
{
struct ast_node *expr_node;
struct ast_node *prev_node;
struct ast_node *ret_node;
char op;
prev_node = node;
while(TRUE) {
switch(current_token) {
case TOKEN_CARET:
op = '^';
break;
default:
goto exit_exp;
}
consume_token();
expr_node = term_expr();
if (expr_node == NULL) {
error_msg("error: syntax error");
expr_node = (struct ast_node *)ast_node_stub();
sync_stream();
goto exit_exp;
}
prev_node = (struct ast_node *)ast_node_op(op, prev_node, expr_node);
}
exit_exp:
ret_node = prev_node;
return ret_node;
}
