Antlr4 Python:解析JSON时不会显示所有内容

Question

我正在使用此处给出的G4 JSON语法：

grammar JSON;
json
   : value
   ;
obj
   : '{' pair (',' pair)* '}'
   | '{' '}'
   ;
pair
   : STRING ':' value
   ;
array
   : '[' value (',' value)* ']'
   | '[' ']'
   ;
value
   : STRING
   | NUMBER
   | obj
   | array
   | 'true'
   | 'false'
   | 'null'
   ;

STRING
   : '"' (ESC | SAFECODEPOINT)* '"'
   ;

fragment ESC
   : '\' (["\/bfnrt] | UNICODE)
   ;
fragment UNICODE
   : 'u' HEX HEX HEX HEX
   ;
fragment HEX
   : [0-9a-fA-F]
   ;
fragment SAFECODEPOINT
   : ~ ["\u0000-u001F]
   ;

NUMBER
   : '-'? INT ('.' [0-9] +)? EXP?
   ;

fragment INT
   : '0' | [1-9] [0-9]*
   ;
// no leading zeros
fragment EXP
   : [Ee] [+-]? INT
   ;
// - since - means "range" inside [...]
WS
   : [ tnr] + -> skip
;

这是Wikipedia的JSON样本下方，我想使用上面的语法解析：

to_parse = r'''
{
  "firstName": "John",
  "lastName": "Smith",
  "isAlive": true,
  "age": 27,
  "address": {
    "streetAddress": "21 2nd Street",
    "city": "New York",
    "state": "NY",
    "postalCode": "10021-3100"
  },
  "phoneNumbers": [
    {
      "type": "home",
      "number": "212 555-1234"
    },
    {
      "type": "office",
      "number": "646 555-4567"
    },
    {
      "type": "mobile",
      "number": "123 456-7890"
    }
  ],
  "children": [],
  "spouse": null
}
'''

我正在使用antlr4 python运行时（在生成lexer [ lexer_class]，parser [ parser_class]和侦听器[ listener_class]之后）：

class MyListener(listener_class):
    def enterJson(self, ctx):
        print(inspect.stack()[0][3])
    def exitJson(self, ctx):
        print(inspect.stack()[0][3])
    def enterObj(self, ctx):
        print(inspect.stack()[0][3])
    def exitObj(self, ctx):
        print(inspect.stack()[0][3])
    def enterPair(self, ctx):
        print(inspect.stack()[0][3])
    def exitPair(self, ctx):
        print(inspect.stack()[0][3])
    def enterArray(self, ctx):
        print(inspect.stack()[0][3])
    def exitArray(self, ctx):
        print(inspect.stack()[0][3])
    def enterValue(self, ctx):
        print(inspect.stack()[0][3])
    def exitValue(self, ctx):
        print(inspect.stack()[0][3])

input_stream = InputStream(to_parse)
lexer = lexer_class(input_stream)
token_stream = CommonTokenStream(lexer)
parser = parser_class(token_stream)
# Entry point in the json g4 grammar: json
tree = parser.json()
my_listener = MyListener()
walker = ParseTreeWalker()
walker.walk(my_listener, tree)

仅输出：

enterJson
enterValue
exitValue
exitJson

我的代码不显示任何数组是正常的，obj？

[编辑]

我正在使用以下命令来生成 *.py文件（Lexer，Parser和Listorer）：

java -cp antlr-4.7.2-complete.jar org.antlr.v4.Tool -o ./generation -Dlanguage=Python3 JSON.g4

Answer 1

我无法再现。当我从您发布的语法中生成类时，然后运行以下脚本：

from antlr4 import *
from JSONLexer import JSONLexer as lexer_class
from JSONParser import JSONParser as parser_class
from JSONListener import JSONListener as listener_class

class MyListener(listener_class):
    def enterJson(self, ctx):
        print("enterJson")
    def exitJson(self, ctx):
        print("exitJson")
    def enterObj(self, ctx):
        print("enterObj")
    def exitObj(self, ctx):
        print("exitObj")
    def enterPair(self, ctx):
        print("enterPair")
    def exitPair(self, ctx):
        print("exitPair")
    def enterArray(self, ctx):
        print("enterArray")
    def exitArray(self, ctx):
        print("exitArray")
    def enterValue(self, ctx):
        print("enterValue")
    def exitValue(self, ctx):
        print("exitValue")

to_parse = r'''
{
  "firstName": "John",
  "lastName": "Smith",
  "isAlive": true,
  "age": 27,
  "address": {
    "streetAddress": "21 2nd Street",
    "city": "New York",
    "state": "NY",
    "postalCode": "10021-3100"
  },
  "phoneNumbers": [
    {
      "type": "home",
      "number": "212 555-1234"
    },
    {
      "type": "office",
      "number": "646 555-4567"
    },
    {
      "type": "mobile",
      "number": "123 456-7890"
    }
  ],
  "children": [],
  "spouse": null
}
'''
input_stream = InputStream(to_parse)
lexer = lexer_class(input_stream)
token_stream = CommonTokenStream(lexer)
parser = parser_class(token_stream)
tree = parser.json()
my_listener = MyListener()
walker = ParseTreeWalker()
walker.walk(my_listener, tree)

以下内容打印到我的控制台：

enterJson
enterValue
enterObj
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
enterObj
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
exitObj
exitValue
exitPair
enterPair
enterValue
enterArray
enterValue
enterObj
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
exitObj
exitValue
enterValue
enterObj
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
exitObj
exitValue
enterValue
enterObj
enterPair
enterValue
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
exitObj
exitValue
exitArray
exitValue
exitPair
enterPair
enterValue
enterArray
exitArray
exitValue
exitPair
enterPair
enterValue
exitValue
exitPair
exitObj
exitValue
exitJson