def _expression(self):
tree = ParseTree("Expr")
node = self._log_expr()
if node is not None:
tree.add_child(node)
return tree
return None
def _log_value(self):
tree = ParseTree("log value")
if self.string[self.index: self.index + 4] == "true":
self.index += 4
tree.add_child(ParseTree("true"))
return tree
if self.string[self.index: self.index + 5] == "false":
self.index += 5
tree.add_child(ParseTree("false"))
return tree
return None
def _log_mon(self):
tree = ParseTree("log mon")
sec_expr_node = self._sec_expr()
if sec_expr_node:
tree.add_child(sec_expr_node)
log_mon_node = self._log_mon_()
if log_mon_node is not None:
tree.add_child(log_mon_node)
if tree.childs:
return tree
return None
def _log_expr(self):
tree = ParseTree("log expr")
log_node = self._log_mon()
if log_node is not None:
tree.add_child(log_node)
log_expr_node = self._log_expr_()
if log_expr_node is not None:
tree.add_child(log_expr_node)
if tree.childs:
return tree
return None
def _first_expr(self):
tree = ParseTree("first_expr")
log_value_node = self._log_value()
if log_value_node:
tree.add_child(log_value_node)
return tree
identifier_node = self._identifier()
if identifier_node:
tree.add_child(identifier_node)
return tree
return None
def _identifier(self):
tree = ParseTree("identifier")
count = 0
while True:
if self._out_of_range():
break
if self.string[self.index] in self.identifiers:
self.index += 1
count += 1
else:
break
if count:
tree.add_child(ParseTree(self.string[self.index-count: self.index]))
return tree
return None
def _log_expr_(self):
if self._out_of_range():
return None
tree = ParseTree("log expr'")
if self.string[self.index] == "!":
self.index += 1
tree.add_child(ParseTree("!"))
log_mon_node = self._log_mon()
if log_mon_node:
tree.add_child(log_mon_node)
log_expr_node = self._log_expr_()
if log_expr_node:
tree.add_child(log_expr_node)
return tree
return None
def _sec_expr(self):
tree = ParseTree("sec_expr")
first_exp_node = self._first_expr()
if first_exp_node:
tree.add_child(first_exp_node)
return tree
if self._out_of_range():
return None
if self.string[self.index] == "~":
self.index += 1
tree.add_child(ParseTree("~"))
first_exp_node = self._first_expr()
if first_exp_node:
tree.add_child(first_exp_node)
return tree
return None