python-flask-路由匹配源码分析

@app.route('/')
def hello_world():
    return 'Hello World!'

第1步：

class Flask(_PackageBoundObject):
    def route(self, rule, **options):
        def decorator(f):                 #f = hello_world
  #1.1获取别名
            endpoint = options.pop('endpoint', None) 
  #1.2
            self.add_url_rule(rule, endpoint, f, **options)
            return f
        return decorator

第1.2步：

class Flask(_PackageBoundObject):
    def add_url_rule(self, rule, endpoint=None, view_func=None, **options):
        #1.2.1如果别名是None，执行_endpoint_from_view_func函数
        if endpoint is None:
            endpoint = _endpoint_from_view_func(view_func)
#1.2.2 给endpoint赋值
        options['endpoint'] = endpoint
 #1.2.3 获取允许的请求方法
        methods = options.pop('methods', None)
　　　　 #1.2.4如果方法为None
        if methods is None:
#默认为GET
            methods = getattr(view_func, 'methods', None) or ('GET',)
 #1.2.5如果方法是字符串，抛出异常： 必须是methods=["POST"]这样可迭代的
        if isinstance(methods, string_types):
            raise TypeError('Allowed methods have to be iterables of strings, '
                            'for example: @app.route(..., methods=["POST"])')
 #1.2.6把方法变成大写
        methods = set(item.upper() for item in methods)
　　　　 #1.2.7把匹配url和允许请求的方法封装到了Rule的一个对象中
        rule = self.url_rule_class(rule, methods=methods, **options)
    #self.url_rule_class = Rul
 #1.2.8
        self.url_map.add(rule)
#self.url_map = Map()
        if view_func is not None:
　　　　　　　#1.2.9 此步完成后： {"别名"：被装饰的函数名}
            self.view_functions[endpoint] = view_func

第1.2.1步：

def _endpoint_from_view_func(view_func):
    #返回被装饰的函数名
    return view_func.__name__

第1.2.8步：

class Map(object):
    def add(self, rulefactory):
        #1.2.8.1
        for rule in rulefactory.get_rules(self):
#1.2.8.2 Rule对象进行re正则绑定
            rule.bind(self)
#1.2.8.3 添加到self._rules列表中，此时列表中就有了url
            self._rules.append(rule)
#1.2.8.4 此步完成后：  {"别名"：url}
            self._rules_by_endpoint.setdefault(rule.endpoint, []).append(rule)

第1.2.8.1步：

class Rule(RuleFactory):
def get_rules(self, map):
        yield self
     #返回Rule对

第1.2.8.2步：

class Rule(RuleFactory):
def bind(self, map, rebind=False):
#1.2.8.2.1
        self.compile()

第1.2.8.2.1步： 看不懂，猜里面是把url进行了re正则处理

class Rule(RuleFactory):
    def compile(self):
        if self.map.host_matching:
            domain_rule = self.host or ''
        else:
            domain_rule = self.subdomain or ''

        self._trace = []
        self._converters = {}
        self._static_weights = []
        self._argument_weights = []
        regex_parts = []

        def _build_regex(rule):
            index = 0
            for converter, arguments, variable in parse_rule(rule):
                if converter is None:
                    regex_parts.append(re.escape(variable))
                    self._trace.append((False, variable))
                    for part in variable.split('/'):
                        if part:
                            self._static_weights.append((index, -len(part)))
                else:
                    if arguments:
                        c_args, c_kwargs = parse_converter_args(arguments)
                    else:
                        c_args = ()
                        c_kwargs = {}
                    convobj = self.get_converter(
                        variable, converter, c_args, c_kwargs)
                    regex_parts.append('(?P<%s>%s)' % (variable, convobj.regex))
                    self._converters[variable] = convobj
                    self._trace.append((True, variable))
                    self._argument_weights.append(convobj.weight)
                    self.arguments.add(str(variable))
                index = index + 1

        _build_regex(domain_rule)
        regex_parts.append('\\|')
        self._trace.append((False, '|'))
        _build_regex(self.is_leaf and self.rule or self.rule.rstrip('/'))
        if not self.is_leaf:
            self._trace.append((False, '/'))

        if self.build_only:
            return
        regex = r'^%s%s$' % (
            u''.join(regex_parts),
            (not self.is_leaf or not self.strict_slashes) and
            '(?<!/)(?P<__suffix__>/?)' or ''
        )
        self._regex = re.compile(regex, re.UNICODE)

到此为止：

路由规则列表里新增了一条绑定正则的rule ；{"别名"：rule} ；{"别名"：被装饰的函数名}