def p_pattern_list(self, p):
'pattern_list : pattern_list pattern_element'
p[0] = cross_product(p[1], p[2])
def p_rhs_item_only_right_context(self, p):
'rhs_item : UNDER pattern_list'
p[0] = cross_product(self.ast.lhs, p[2])
self.ast.rc = p[2]
def p_rhs_item_both_left_right_context(self, p):
'rhs_item : pattern_list UNDER pattern_list'
p[0] = cross_product(p[1], cross_product(self.ast.lhs, p[3]))
self.ast.lc = p[1]
self.ast.rc = p[3]
def p_rhs_item_only_left_context(self, p):
'rhs_item : pattern_list UNDER'
p[0] = cross_product(p[1], self.ast.lhs)
self.ast.lc = p[1]
