Question

I am trying to create a parser for a PGN file and am getting errors on the moves. If my input is Ng4, the output should be (standard_move (moving_Piece N) (moving_File g) (moving_Rank 4) ). This works well with the below .g4 file:

grammar MOVE;

standard_move: moving_Piece moving_File moving_Rank Newline;
moving_Piece: Moving_Piece ;
moving_File: Moving_File;
moving_Rank: Moving_Rank;


Moving_Piece: ( K | Q | R | B | N ) ;
Moving_File: [a-h];
Moving_Rank: [1-8];
Newline: [
]; 
WHITESPACE :     -> skip ;

然而,如果我把同样的逻辑列入我较大型的.g4文档中,有其他的国产总值要素,那么我就获得了<代码>1:0不匹配的投入。 Ng Requesting Moving_Piece

grammar PGN;

annotations: annotation+;
annotation  : Open_Bracket tag value Close_Bracket Newline ; 
value: String;
tag: Chars;
move_time: Move_time Newline;
move_number: Move_Number Newline;
standard_move: moving_Piece moving_File moving_Rank Newline;
moving_Piece: Moving_Piece ;
moving_File: Moving_File;
moving_Rank: Moving_Rank;


Moving_Piece: ( K | Q | R | B | N ) ;
Moving_File: [a-h];
Moving_Rank: [1-8];
Move_Number: [0-9]+  . ;
Move_time:  {[%emt  .*?  ]} ;
Chars: [a-zA-Z]*;
String :  "  ~["]*  " ;
Quote :  " ;
Open_Bracket :  [  ;
Close_Bracket :  ]  ;
Newline: [
]; 
WHITESPACE :     -> skip ;

任何帮助为什么发生这种情况都会受到高度赞赏!

Answer 1

问题的根源是较法规则中的冲突重叠。

Moving_Piece: ( K | Q | R | B | N ) ;
Moving_File: [a-h];
Moving_Rank: [1-8];
Move_Number: [0-9]+  . ;
Chars: [a-zA-Z]*;

见。 Bart s response to a similar question for a details interpret.

实际固定装置见以下有详细记录的例子:PGNgrammar。

BTW, the Antlr Grammars 储藏处是一个巨大的学习资源。

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