この例のAntLR 3 Python文法の問題は何ですか？

Question

AntLRを使用することをお勧めし、この「チュートリアル」の後にエラーに遭遇したようです。 https://theantlrguy.atlassian.net/Wiki / Display / AntLR3 / 5 +分+はじめに+ + ANTLR + 3

基本的に、simplecalc.gファイルを作成します。

grammar SimpleCalc;
 
options {
    language = Python;
}
 
tokens {
    PLUS    = '+' ;
    MINUS   = '-' ;
    MULT    = '*' ;
    DIV = '/' ;
}
 
@header {
import sys
import traceback
 
from SimpleCalcLexer import SimpleCalcLexer
}
 
@main {
def main(argv, otherArg=None):
  char_stream = ANTLRFileStream(sys.argv[1])
  lexer = SimpleCalcLexer(char_stream)
  tokens = CommonTokenStream(lexer)
  parser = SimpleCalcParser(tokens);
 
  try:
        parser.expr()
  except RecognitionException:
    traceback.print_stack()
}
 
/*------------------------------------------------------------------
 * PARSER RULES
 *------------------------------------------------------------------*/
 
expr    : term ( ( PLUS | MINUS )  term )* ;
 
term    : factor ( ( MULT | DIV ) factor )* ;
 
factor  : NUMBER ;
 
 
/*------------------------------------------------------------------
 * LEXER RULES
 *------------------------------------------------------------------*/
 
NUMBER  : (DIGIT)+ ;
 
WHITESPACE : ( '\t' | ' ' | '\r' | '\n'| '\u000C' )+    { $channel = HIDDEN; } ;
 
fragment DIGIT  : '0'..'9' ;

.

ANTLRツールを実行すると

 java -classpath antlr-3.1.3.jar antlr.Tool SimpleCalc.g

.

最初の行から始めて、エラーを受け取ります：

ANTLR Parser Generator   Version 2.7.7 (20060906)   1989-2005
SimpleCalc.g:2:1: unexpected token: grammar
error: Token stream error reading grammar(s):
SimpleCalc.g:15:1: unexpected char: '@'
SimpleCalc.g:2:1: rule grammar trapped:
SimpleCalc.g:2:1: unexpected token: grammar
TokenStreamException: unexpected char: '@'

.

これは私が愚かなことをしていると信じるように私を導きます、しかし私は何をしていません。

Answer 1

You're using the wrong Tool class to generate the lexer and parser. Most ANTLR 3.x versions still have dependencies with the older v2.7 version, which is therefor included in v3.x. The Tool class from v2.7 is called antlr.Tool, while the v3.x version is called org.antlr.Tool. The latter is the one you should be using:

java -classpath antlr-3.1.3.jar org.antlr.Tool SimpleCalc.g

EDIT

Here's a little demo based on the grammar from the Wiki, but then with a bit of Python code added to it that evaluates the expression:

grammar SimpleCalc;

options {
  language=Python;
}

@header {
import sys
import traceback

from SimpleCalcLexer import SimpleCalcLexer
}

@main {
def main(argv, otherArg=None):
  char_stream = ANTLRStringStream(sys.argv[1])
  lexer = SimpleCalcLexer(char_stream)
  tokens = CommonTokenStream(lexer)
  parser = SimpleCalcParser(tokens);

  try:
    print parser.eval()
  except RecognitionException:
    traceback.print_stack()
}

eval returns [value]
 : add EOF {$value = $add.value}
 ;

add returns [value]
 : m1=mult {$value = $m1.value} ( '+' m2=mult {$value += $m2.value}
                                | '-' m2=mult {$value -= $m2.value}
                                )* 
 ;

mult returns [value]
 : a1=atom {$value = $a1.value} ( '*' a2=atom {$value *= $a2.value}
                                | '/' a2=atom {$value /= $a2.value}
                                )* 
 ;

atom returns [value]
 : NUMBER      {$value = float($NUMBER.text)}
 | '(' add ')' {$value = $add.value}
 ;

NUMBER         : DIGIT+ ('.' DIGIT*)?;
WHITESPACE     : ('\t' | ' ' | '\r' | '\n')+ {$channel = HIDDEN;};
fragment DIGIT : '0'..'9' ;

Generating a lexer/parser and evaluating an expression:

java -cp antlr-3.1.3.jar org.antlr.Tool SimpleCalc.g
python SimpleCalcParser.py "5 * (8 + 2)"

produces the output:

50.0