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我不确定这是缺陷、限制还是我做错了什么……如果这是讨论这个问题的错误地方，我提前道歉。

我正在尝试更改解析“oil 0w prod or e12b/cpc”时使用的语法的优先级，以便将其处理为等效于“（oil 0w prod）或e12b / cpc”而不是“oil 0w（prod或e12b/cpc)"。

我有以下语法：

parse           : statement EOF ;

statement       : statement proximityOp statement        # ProximityExpression
                | statement booleanOperator statement    # BooleanExpression
                | statement IN delimited                 # InExpression
                | delimited                              # NoSynonyms
                ;

delimited       : operand
                | operand delimiters+=DELIMITER values+=WORD
                ;

operand         : value                                  # SingleValue
                ;

value           : WORD                                   # Term
                ;

booleanOperator : AND|OR|NOT|LOW_RELATION|SAME_RELATION|HIGH_RELATION;

proximityOp     : W_PROX_OP|D_PROX_OP|S_PROX_OP|P_PROX_OP;

LBRACE      : '{';
RBRACE      : '}';
WS              : (' '|'\t'|'\r'|'\n') -> skip;
AND     : 'and' | 'AND' | '.' ;
OR      : 'or' | 'OR' | ',' ;
NOT     : 'not' | 'NOT' ;
DIGIT       : ('0'..'9');
W_PROX_OP   : DIGIT 'w' | DIGIT 'W' ;
S_PROX_OP   : DIGIT 's' | DIGIT 'S' ;
P_PROX_OP   : DIGIT 'p' | DIGIT 'P' ;
D_PROX_OP   : DIGIT 'd' | DIGIT 'D' ;
DELIMITER       : '/' | ':';
SYN_DELIM       : '|' ;
USE_SYN         : '~' ;
USE_QUERYLET    : '$' ;
LPAREN      : '(';
RPAREN      : ')';
EXCLUSION       : '!' ;
EQUALS      : '=';
GREATER     : '>';
LOWER       : '<';
MT_EQUALS       : GREATER EQUALS ;
LT_EQUALS       : LOWER EQUALS ;
DOUBLE_EQUALS   : EQUALS EQUALS ;
SAME_RELATION   : '=/same' | '=/SAME';
HIGH_RELATION   : '=/high' | '=/HIGH';
LOW_RELATION    : '=/low' | '=/LOW';
IN              : WS 'in' WS;

COMMENTED       : LBRACE .*? RBRACE -> skip ;

WORD            : OTHER+ ;

OTHER           : ~[\{\}()!,/:|\[\] "=<>\~$];

我已经更改了 ProximityExpression 和 BooleanExpression 的顺序，但它对优先级没有影响 - 尽管我可以看到它会影响转换后的语法：

statement[int _p]
    :   ( {} delimited                                                  
        )
        ( options{preventepsilon=true;}:
          {4 >= $_p}? booleanOperator statement
                  | {3 >= $_p}? proximityOp statement
                  | {2 >= $_p}? IN delimited
        )*
    ;

记录 ParserRuleContext 时，无论语法中 ProximityExpression 和 BooleanExpression 的顺序如何，我总是得到以下信息：

parsing... oil 0w prod or e12b/cpc
IN.... ParseContext, depth=1: oil0wprodore12b/cpc<EOF>
IN.... ProximityExpressionContext, depth=2: oil0wprodore12b/cpc
IN.... NoSynonymsContext, depth=3: oil
IN.... DelimitedContext, depth=4: oil
IN.... SingleValueContext, depth=5: oil
IN.... TermContext, depth=6: oil
OUT... TermContext
OUT... SingleValueContext
OUT... DelimitedContext
OUT... NoSynonymsContext
IN.... ProximityOpContext, depth=3: 0w
OUT... ProximityOpContext
IN.... BooleanExpressionContext, depth=3: prodore12b/cpc
IN.... NoSynonymsContext, depth=4: prod
IN.... DelimitedContext, depth=5: prod
IN.... SingleValueContext, depth=6: prod
IN.... TermContext, depth=7: prod
OUT... TermContext
OUT... SingleValueContext
OUT... DelimitedContext
OUT... NoSynonymsContext
IN.... BooleanOperatorContext, depth=4: or
OUT... BooleanOperatorContext
IN.... NoSynonymsContext, depth=4: e12b/cpc
IN.... DelimitedContext, depth=5: e12b/cpc
IN.... SingleValueContext, depth=6: e12b
IN.... TermContext, depth=7: e12b
OUT... TermContext
OUT... SingleValueContext
OUT... DelimitedContext
OUT... NoSynonymsContext
OUT... BooleanExpressionContext
OUT... ProximityExpressionContext

我已经在 ANTlr 4 版本和来自 github 的今天的 master 中尝试过这个。

戴夫

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