python json字符串类型的value换行方案 |
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python json字符串类型的value换行方案
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按照标准json语法,字符串类型的value是不能换行写的. 例如,以下是错误的写法 { "key":"hello world" }但是遇到了需要在json中写代码与服务器交互的情况,无奈只能这样写: { "key":"var a = 1\nvar b = 2\n var c=a+b" }代码行数少了还好,多了极其**,于是想办法可以在json中换行写代码. 尝试1: json5 JSON5号称"JSON for Humans",相比标准json主要特点如下: 字符串value支持换行key可以不加""key和value可以使用’'代替""支持注释二进制数值栗子: 以下是一个合法的json5 { // comments unquoted: 'and you can quote me on that', singleQuotes: 'I can use "double quotes" here', lineBreaks: "Look, Mom! \ No \\n's!", hexadecimal: 0xdecaf, leadingDecimalPoint: .8675309, andTrailing: 8675309., positiveSign: +1, trailingComma: 'in objects', andIn: ['arrays',], "backwardsCompatible": "with JSON", }优点:现成 缺点: 换行需要用 \ \标识; 解析之后因为没有了换行,代码无法执行,所以是达不到目的的; { "key":"var a = 1\ var b = 2\ var c=a+b" }解析之后的结果为 { "key":"var a = 1var b = 2var c=a+b" }尝试2: 编写自己的json解释器 优点: 可根据自己定义的规则解析数据缺点: 成本高.以下为用python实现的json解释器,支持换行,目前没有做完整的错误处理,请不要用于生产: """ 遇到问题没人解答？小编创建了一个Python学习交流QQ群：778463939 寻找有志同道合的小伙伴，互帮互助,群里还有不错的视频学习教程和PDF电子书！ Topic: 下降解析器 Desc : """ import re import collections # Token specification NUM = r'(?P\d+)' STR_D = r'"(?P[^"]*?)"' STR_S = r'(?P\'.*?\')' COLON = r'(?P:)' COMMA = r'(?P,)' LLB = r'(?P\[)' RLB = r'(?P\])' LDB = r'(?P\{)' RDB = r'(?P\})' WS = r'(?P\s+)' NULL = r'(?Pnull)' FALSE = r'(?Pfalse)' TRUE = r'(?Ptrue)' master_pat = re.compile('|'.join([NUM, STR_D, STR_S, LLB, RLB, LDB, RDB, COLON, COMMA, FALSE, TRUE, NULL, WS]), re.M | re.S) # Tokenizer Token = collections.namedtuple('Token', ['type', 'value']) def generate_tokens(text): scanner = master_pat.scanner(text) for m in iter(scanner.match, None): tok = Token(m.lastgroup, m.group()) if tok.type != 'WS': yield tok def simple_join(text): li = [] for t in generate_tokens(text): res = t[1] if t[0] == "STR_S": res = t[1].replace("'", "\"") elif t[0].startswith("STR_"): res = t[1].replace("\n", "\\n").replace("\r\n", "\\n") li.append(str(res)) return "".join(li) class Evaluator: def __init__(self, text): self.text = text def parse(self): self.tokens = generate_tokens(self.text) self.nexttok = next(self.tokens, None) self._advance() return self._parse() def _advance(self): '''Advance one token ahead''' self.tok, self.nexttok = self.nexttok, next(self.tokens, None) def _parse(self): if self.tok[0] == "LLB": return self.get_list() if self.tok[0] == "LDB": return self.get_dict() if self.tok[0].startswith("STR_"): return self.tok[1].strip('"') if self.tok[0] == "NUM": return int(self.tok[1]) if self.tok[0] == "NULL": return None if self.tok[0] == "FALSE": return False if self.tok[0] == "TRUE": return True raise Exception("未知token:{}".format(self.tok[1])) def get_dict(self): """ { 开头 中间内容必须为 k:v, 结尾必须为 } """ res = {} self._advance() # } if self.tok[0] == "RDB": return {} def parse_value(): if not self.tok[0].startswith("STR_"): raise Exception(f"KEY需是字符串形式,{self.tok[1]}") new_key = self._parse() self._advance() if self.tok[0] != "COLON": raise Exception("KEY和VALUE需用:分割") self._advance() res[new_key] = self._parse() self._advance() parse_value() while self.tok[0] == "COMMA": self._advance() parse_value() return res def get_list(self): res = [] self._advance() # } if self.tok[0] == "RLB": return [] def parse_value(): if self.tok[0] in ["NUM", "STR_D", "STR_S", "NULL", "FALSE", "TRUE"]: res.append(self._parse()) elif self.tok[0] == "LLB": res.append(self.get_list()) elif self.tok[0] == "LDB": res.append(self.get_dict()) parse_value() self._advance() while self.tok[0] == "COMMA": self._advance() parse_value() self._advance() return res if __name__ == '__main__': text = """ { "k1":1, "k2":"v2", "is_true":true, "is_none":null, "k2":"v2", "k3":{ "a1":"a1", "a2":"a2", "code":" var code = 0 code = 1 " }, "list":[1,2,3,4] } """ # test(text) e = Evaluator(text) res = e.parse() print(res) #{'k1': 1, 'k2': 'v2', 'is_true': True, 'is_none': None, 'k3': {'a1': 'a1', 'a2': 'a2', 'code': '\n var code = 0\n code = 1\n '}, 'list': [1, 2, 3, 4]}尝试3: 全局替换 \n 为 \n 优点:简单粗暴 { "key":" var a = 1 var b = 2 var c=a+b" }替换之后的结果为 { "key":"\nvar a = 1\nvar b = 2\n var c=a+b" }缺点:虽然写的时候有换行,但是上传到服务器再查询的时候只能看到\n,依然缺乏可读性; 尝试4(最终采用方案): 结合UI将json生成树状节点,将代码类型的value单独显示. |
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