antlr4 Python：侦听器在解析json时不会显示所有内容

Question

我使用的是这里给出的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
   : [ \t\n\r] + -> skip
;

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
}
'''

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)

enterJson
enterValue
exitValue
exitJson

我使用以下命令生成*.py文件(lexer、parser和listener）：

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

Answer 1

我不能复制它。当我从您发布的语法生成类，然后运行以下脚本时：

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