我正在尝试使用antlr4 版本 4.4和python2运行时。语法来自antlr4书,第6页,文件:Hello.g4:
grammar Hello;
r : 'hello' ID ;
ID : [a-z]+ ;
WS : [ \t\r\n]+ -> skip ;
我用命令生成词法分析器和解析器
antlr4 -Dlanguage=Python2 Hello.g4
文件HelloLexer.py, HelloParser.py and HelloListener.py其中,然后生成。我创建了一个主程序 test.py 来测试生成的 python 解析器:
from antlr4 import *
from HelloLexer import HelloLexer
from HelloParser import HelloParser
def main(argv):
input = FileStream(argv[1])
lexer = HelloLexer(input)
stream = CommonTokenStream(lexer)
parser = HelloParser(stream)
tree = parser.r()
print tree.toStringTree(parser) <= the problem is here!
if __name__ == '__main__':
import sys
main(sys.argv)
一切似乎都正常,除了我无法打印解析树。
C:\Users\LG\antlr\tpantlr2-code\code\install>Test.py data.txt
Traceback (most recent call last):
File "C:\Users\LG\antlr\tpantlr2-code\code\install\Test.py", line 15, in <module>
main(sys.argv)
File "C:\Users\LG\antlr\tpantlr2-code\code\install\Test.py", line 11, in main
print tree.toStringTree(parser)
File "C:\Python27\lib\site-packages\antlr4\RuleContext.py", line 181, in toStringTree
return Trees.toStringTree(self, ruleNames=ruleNames, recog=recog)
File "C:\Python27\lib\site-packages\antlr4\tree\Trees.py", line 48, in toStringTree
s = escapeWhitespace(cls.getNodeText(t, ruleNames), False)
File "C:\Python27\lib\site-packages\antlr4\tree\Trees.py", line 68, in getNodeText
return ruleNames[t.getRuleContext().getRuleIndex()]
TypeError: 'HelloParser' object does not support indexing
我还没弄清楚问题是什么。